4.Servlet基本应用

4.1 动态响应内容

实体类

package com.neuedu.entity;

import java.util.Date;

/**
 * 项目：      jdbc
 * 类名:       User
 * 创建时间：  2020/11/25  14:40
 * 描述 :
 * 作者 :     张金山
 * QQ :     314649444
 * Site:      https://jshand.gitee.io 实体类
 */
public class User {
    private Integer id;
    private String username;
    private String displayname;
    private String password;
    private Date birthday;
    private String gender;
    private String telephone;
    private String email;
    private Date last_logintime;
    private Date create_time;
    private String valid;

    public User() {
    }

    public User(Integer id, String username, String displayname, String password, Date birthday, String gender, String telephone, String email, Date last_logintime, Date create_time, String valid) {
        this.id = id;
        this.username = username;
        this.displayname = displayname;
        this.password = password;
        this.birthday = birthday;
        this.gender = gender;
        this.telephone = telephone;
        this.email = email;
        this.last_logintime = last_logintime;
        this.create_time = create_time;
        this.valid = valid;
    }

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public String getDisplayname() {
        return displayname;
    }

    public void setDisplayname(String displayname) {
        this.displayname = displayname;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }

    public Date getBirthday() {
        return birthday;
    }

    public void setBirthday(Date birthday) {
        this.birthday = birthday;
    }

    public String getGender() {
        return gender;
    }

    public void setGender(String gender) {
        this.gender = gender;
    }

    public String getTelephone() {
        return telephone;
    }

    public void setTelephone(String telephone) {
        this.telephone = telephone;
    }

    public String getEmail() {
        return email;
    }

    public void setEmail(String email) {
        this.email = email;
    }

    public Date getLast_logintime() {
        return last_logintime;
    }

    public void setLast_logintime(Date last_logintime) {
        this.last_logintime = last_logintime;
    }

    public Date getCreate_time() {
        return create_time;
    }

    public void setCreate_time(Date create_time) {
        this.create_time = create_time;
    }

    public String getValid() {
        return valid;
    }

    public void setValid(String valid) {
        this.valid = valid;
    }

    @Override
    public String toString() {
        return "User{" +
                "id=" + id +
                ", username='" + username + '\'' +
                ", displayname='" + displayname + '\'' +
                ", password='" + password + '\'' +
                ", birthday=" + birthday +
                ", gender='" + gender + '\'' +
                ", telephone='" + telephone + '\'' +
                ", email='" + email + '\'' +
                ", last_logintime=" + last_logintime +
                ", create_time=" + create_time +
                ", valid='" + valid + '\'' +
                '}';
    }
}

Servlet

java

package com.neuedu.servlet;

import com.neuedu.entity.User;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.List;

/**
 * 项目：      javaweb1206
 * 类名:       UserListServlet
 * 创建时间：  2020/12/7  11:27
 * 描述 :     用户列表
 * 作者 :     张金山
 * QQ :     314649444
 * Site:      https://jshand.gitee.io
 * http://127.0.0.1:8080/web/userList
 */
@WebServlet(name="UserListServlet" ,urlPatterns = "/userList")
public class UserListServlet  extends HttpServlet {

    private List<User> userList = new ArrayList<>();

    public UserListServlet() {
        this.userList.add(new User(1,"admin","管理员",null,null,null,null,null,null,null,null));
        this.userList.add(new User(2,"user1","管理员1",null,null,null,null,null,null,null,null));
        this.userList.add(new User(3,"user2","管理员2",null,null,null,null,null,null,null,null));
        this.userList.add(new User(4,"user3","管理员3",null,null,null,null,null,null,null,null));
        this.userList.add(new User(5,"user4","管理员4",null,null,null,null,null,null,null,null));
    }

    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        //通知浏览器 内容的类型
        response.setContentType("text/html;charset=utf-8");

        StringBuffer html = new StringBuffer();
        html.append(" <table border='1'>			");
        html.append(" <tr>               ");
        html.append(" 	<td>序号</td>   ");
        html.append(" 	<td>用户名</td> ");
        html.append(" 	<td>昵称</td>   ");
        html.append(" </tr>              ");

        for (User user : userList) {
            html.append(" <tr>               ");
            html.append(" 	<td>"+user.getId()+"</td>       ");
            html.append(" 	<td>"+user.getUsername()+"</td>       ");
            html.append(" 	<td>"+user.getDisplayname()+"</td>       ");
            html.append(" </tr>              ");
        }


        html.append(" </table>           ");



        PrintWriter out = response.getWriter();
        out.print(html.toString());


        out.flush();
        out.close();
    }



    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        this.doPost(request, response);
    }

}

4.2 参数处理

4.2.1 超链接形式的数据请求语法格式

<a href=”URL地址?参数=参数值[&参数=参数值...]”>链接文本</a>
例如：
- <a href=“http://127.0.0.1:8080/web/userList?id=3">请求</a>
  - 链接地址中的“queryServlet”为请求地址；
  - “pageNo”表示请求参数；
  - “3”为pageNo请求参数的值；
  - “&”为多个参数间的关联符；
  - “queryString”表示表示另一个请求参数；“neuedu” 为queryString请求参数的值
发送请求的URL地址可以是绝对地址，如：
- http://127.0.0.1:8080/web/userList?id=3。也可以是相对地址，如：userList、../userList等形式。在开发中大多数使用相对地址，以便于项目的移植。
当用户通过超链接发送的请求到达Servlet容器时，包含数据的请求将被容器转换为HttpServletRequest对象。对请求数据的处理工作便由HttpServletRequest对象完成。
HttpServletRequest对象常用的数据处理方法有：
- public String getParameter(String name),返回由name指定的用户请求参数的值。
- public String[] getParameterValues(String name),返回由name指定的一组用户请求参数的值。
- public Enumeration getParameterNames()返回所有客户请求的参数名。
容器在将请求转换为HttpServletRequest对象之后，还会根据请求的类型调用不同的请求方法。对用超链接的GET请求则会调用doGet()方法；对于Form表单的POST请求则会调用doPost()方法,代码

4.2.2 处理Form表单请求数据

Form表单在enctype属性缺省或取值为application/x-www-form-urlencoded情况下，无论是Get请求类型还是Post请求类型，均通过HttpServletRequest对象来获取请求数据。
超链接一般用于获取/查询资源信息，属于GET请求类型，请求的数据会附在URL之后，以?分割URL和传输数据，参数之间以&相连。由于其安全性（如：请求数据会以明文显示在地址栏上）以及请求地址的长度限制，一般仅用于传送一些简单的数据；
Form表单一般用于更新资源信息，默认使用GET请求类型，多使用POST请求类型。由于POST请求类型理论上没有数据大小限制，可用表单来传较大量的数据；
html
```
<form action="userList" method="post">
    <input name="id" value="3">
    <input type="submit">
</form>
```
1
2
3
4

4.2.3 地址栏传参

同超链接一样

路径：http://127.0.0.1:8080/web/userList?id=2
使用request获取请求的参数 String id = request.getParameter("id");

4.2.3 完整代码如下：

java

package com.neuedu.servlet;

import com.neuedu.entity.User;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.List;

/**
 * 项目：      javaweb1206
 * 类名:       UserListServlet
 * 创建时间：  2020/12/7  11:27
 * 描述 :     用户列表
 * 作者 :     张金山
 * QQ :     314649444
 * Site:      https://jshand.gitee.io
 * http://127.0.0.1:8080/web/userList
 */
@WebServlet(name="UserListServlet" ,urlPatterns = "/userList")
public class UserListServlet  extends HttpServlet {

    private List<User> userList = new ArrayList<>();

    public UserListServlet() {
        this.userList.add(new User(1,"admin","管理员",null,null,null,null,null,null,null,null));
        this.userList.add(new User(2,"user1","管理员1",null,null,null,null,null,null,null,null));
        this.userList.add(new User(3,"user2","管理员2",null,null,null,null,null,null,null,null));
        this.userList.add(new User(4,"user3","管理员3",null,null,null,null,null,null,null,null));
        this.userList.add(new User(5,"user4","管理员4",null,null,null,null,null,null,null,null));
    }

    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        String id = request.getParameter("id");

        if(id == null || "".equals(id)){
            id = "-1";
        }

        //通知浏览器 内容的类型
        response.setContentType("text/html;charset=utf-8");

        StringBuffer html = new StringBuffer();
        html.append(" <table border='1'>			");
        html.append(" <tr>               ");
        html.append(" 	<td>序号</td>   ");
        html.append(" 	<td>用户名</td> ");
        html.append(" 	<td>昵称</td>   ");
        html.append(" </tr>              ");

        for (User user : userList) {
            if(user.getId() < Integer.parseInt(id)){
                continue;
            }
            html.append(" <tr>               ");
            html.append(" 	<td>"+user.getId()+"</td>       ");
            html.append(" 	<td>"+user.getUsername()+"</td>       ");
            html.append(" 	<td>"+user.getDisplayname()+"</td>       ");
            html.append(" </tr>              ");
        }


        html.append(" </table>           ");



        PrintWriter out = response.getWriter();
        out.print(html.toString());


        out.flush();
        out.close();
    }



    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        this.doPost(request, response);
    }

}

html

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>请求方式</title>
</head>
<body>

<a href="userList?id=3" target="_blank">请求用户列表id>3</a>

<form action="userList" method="post">
    <input name="id" value="3">
    <input type="submit">
</form>

</body>
</html>

4.2.4 request对象获取参数

package com.neuedu.servlet;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.PrintWriter;

/**
 * 项目：      javaweb1206
 * 类名:       ${NAME}
 * 创建时间：  2020/12/7  14:09
 * 描述 :     ${dc}
 * 作者 :     张金山
 * QQ :     314649444
 * Site:      https://jshand.gitee.io
 */
@WebServlet(name = "StudentServlet",urlPatterns = "/stu")
public class StudentServlet extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        response.setContentType("text/html;charset=utf-8");


        String id = request.getParameter("id");
        String name = request.getParameter("name");
        String age = request.getParameter("age");


        String[] ids = request.getParameterValues("id");

        PrintWriter out = response.getWriter();
        out.write("<h3>id:"+id+"</h1>");
        out.write("<h3>name:"+name+"</h1>");
        out.write("<h3>age:"+age+"</h1>");

        for (int i = 0; i < ids.length; i++) {
            out.write("<h3>id-:"+i+"--"+ids[i]+"</h1>");
        }


        out.flush();
        out.close();


    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        this.doPost(request,response);
    }
}

form请求

html


<form action="stu" method="post">
    <input name="id" value="101">
    <input name="id" value="102">


    <input name="name" value="jshand">
    <input name="age" value="18">


    <input type="submit">
</form>

4.3 重定向

重定向是指由原请求地址重新定位到某个新地址，原有的request请求失效，客户端看到的是新的request请求返回的响应结果，客户端浏览器地址栏变为新请求地址。
重定向通过HttpServletResponse对象的sendRedirect()方法实现，该方法会通知客户端去重新访问新指定的URL地址，其语法格式如下：
- public void sendRedirect(String location)throws java.io.IOException
- location参数用以指定重定向的URL，它可以是相对路径或绝对路径。
示例
- 表示重定向到当前应用程序根目录下的index.jsp页面
  - response.sendRedirect("/ServletDemo1/index.jsp");
  - request.getContextPath() 获取上下文
sendRedirect()方法不仅可以重定向到当前应用程序中的其他资源，还可以重定向到同一个站点上的其他应用程序中的资源，甚至是使用绝对URL重定向到其他站点的资源。

4.3.1 完整代码

java

package com.neuedu.servlet;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

/**
 * 项目：      javaweb1206
 * 类名:       ${NAME}
 * 创建时间：  2020/12/7  14:55
 * 描述 :     ${dc}
 * 作者 :     张金山
 * QQ :     314649444
 * Site:      https://jshand.gitee.io
 *
 *  http://127.0.0.1:8080/web/redirect
 *
 */
@WebServlet(name = "ResirectServlet",urlPatterns = "/redirect")
public class ResirectServlet extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        this.doGet(request,response);
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        //重定向到其他资源
        /**
         * 重定向到 Tomcat外部
         */

//        response.sendRedirect("http://www.baidu.com");

        /**
         * 重定向到 Tomcat容器中的 资源
         * 获取上下文
         */

        System.out.println("request.getContextPath():"+request.getContextPath());
        response.sendRedirect(request.getContextPath()+"/param.html");
    }
}

4.4 请求转发(内部跳转)

请求转发的过程发生在服务器内部，只能从当前应用内部查找相应的转发资源，而不能转发到其它应用的资源。
请求转发使用RequestDispatcher接口中的forward()方法来实现，该方法可以把请求转发给另外一个资源，并让该资源对此请求进行响应。
RequestDispatcher接口有以下两个方法：
- forward()方法：将请求转发给其他资源。
- include()方法：将其他资源并入到当前请求中。
请求转发语法：
- RequestDispatcher dispatcher = request.getRequestDispatcher(String path);
- dispatcher.forward(ServletRequest request,ServletResponse response);
其中：
- path参数用以指定转发的URL，只能是相对路径；
- request和response参数取值为当前请求所对应的HttpServletRequest和HttpServletResponse对象。

4.4.1 完整代码

java

package com.neuedu.servlet;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

/**
 * 项目：      javaweb1206
 * 类名:       ${NAME}
 * 创建时间：  2020/12/7  15:46
 * 描述 :     ${dc}
 * 作者 :     张金山
 * QQ :     314649444
 * Site:      https://jshand.gitee.io
 *
 * http://127.0.0.1:8080/web/dispatcher
 */
@WebServlet(name = "DispatcherServlet",urlPatterns = "/dispatcher")
public class DispatcherServlet extends HttpServlet {

    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        this.doGet(request, response);
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {


        //内部跳转
        request.getRequestDispatcher("param.html").forward(request,response);


    }
}

4.5 重定向和请求转发的区别

重定向和请求转发都可以让浏览器获得另外一个URL所指向的资源，但两者的内部运行机制有很大的区别：

请求转发只能将请求转发给同一个Web应用中的组件；而重定向不仅可以重定向到当前应用程序中的其他资源，还可以重定向到同一个站点上的其他应用程序中的资源，或者重定向到其他站点的资源；
重定向的访问过程结束后，浏览器地址栏中显示的URL会发生改变，由初始的URL地址变成重定向的目标URL；而请求转发过程结束后，浏览器地址栏保持初始的URL地址不变；
请求转发调用者与被调用者之间共享相同的request对象和response对象，它们属于同一个访问请求和响应过程；而重定向调用者与被调用者使用各自的request对象和response对象，它们属于两个独立的访问请求和响应过程。
不代表方法的结束，下面的代码还会继续执行，注意在转发或重定向的语句后面不要在编写代码。

4.6 综合实例：用户管理系统

功能如下:

4.6.1 数据库

4.6.2 创建项目

4.6.3.添加pom依赖

servlet-api
jsp-api
jdbcutil(mysql-connector-java.jar)
junit

xml

 <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>4.11</version>
      <scope>test</scope>
    </dependency>

    <dependency>
      <groupId>javax.servlet</groupId>
      <artifactId>javax.servlet-api</artifactId>
      <version>3.0.1</version>
      <!--作用域  provided  参与编译，运行时抛弃 -->
      <scope>provided</scope>
    </dependency>

    <!-- https://mvnrepository.com/artifact/javax.servlet.jsp/jsp-api -->
    <dependency>
      <groupId>javax.servlet.jsp</groupId>
      <artifactId>jsp-api</artifactId>
      <version>2.1</version>
      <scope>provided</scope>
    </dependency>


    <dependency>
      <groupId>com.neuedu</groupId>
      <artifactId>jdbcutil</artifactId>
      <version>1.0</version>
    </dependency>

4.6.4.实体类

java

package com.neuedu.entity;

import java.util.Date;

/**
 * 项目：      jdbc
 * 类名:       User
 * 创建时间：  2020/11/25  14:40
 * 描述 :
 * 作者 :     张金山
 * QQ :     314649444
 * Site:      https://jshand.gitee.io 实体类
 */
public class User {
    private Integer id;
    private String username;
    private String displayname;
    private String password;
    private Date birthday;
    private String gender;
    private String telephone;
    private String email;
    private Date last_logintime;
    private Date create_time;
    private String valid;

    public User() {
    }

    public User(Integer id, String username, String displayname, String password, Date birthday, String gender, String telephone, String email, Date last_logintime, Date create_time, String valid) {
        this.id = id;
        this.username = username;
        this.displayname = displayname;
        this.password = password;
        this.birthday = birthday;
        this.gender = gender;
        this.telephone = telephone;
        this.email = email;
        this.last_logintime = last_logintime;
        this.create_time = create_time;
        this.valid = valid;
    }

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public String getDisplayname() {
        return displayname;
    }

    public void setDisplayname(String displayname) {
        this.displayname = displayname;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }

    public Date getBirthday() {
        return birthday;
    }

    public void setBirthday(Date birthday) {
        this.birthday = birthday;
    }

    public String getGender() {
        return gender;
    }

    public void setGender(String gender) {
        this.gender = gender;
    }

    public String getTelephone() {
        return telephone;
    }

    public void setTelephone(String telephone) {
        this.telephone = telephone;
    }

    public String getEmail() {
        return email;
    }

    public void setEmail(String email) {
        this.email = email;
    }

    public Date getLast_logintime() {
        return last_logintime;
    }

    public void setLast_logintime(Date last_logintime) {
        this.last_logintime = last_logintime;
    }

    public Date getCreate_time() {
        return create_time;
    }

    public void setCreate_time(Date create_time) {
        this.create_time = create_time;
    }

    public String getValid() {
        return valid;
    }

    public void setValid(String valid) {
        this.valid = valid;
    }

    @Override
    public String toString() {
        return "User{" +
                "id=" + id +
                ", username='" + username + '\'' +
                ", displayname='" + displayname + '\'' +
                ", password='" + password + '\'' +
                ", birthday=" + birthday +
                ", gender='" + gender + '\'' +
                ", telephone='" + telephone + '\'' +
                ", email='" + email + '\'' +
                ", last_logintime=" + last_logintime +
                ", create_time=" + create_time +
                ", valid='" + valid + '\'' +
                '}';
    }
}

4.6.5 Dao类

java

package com.neuedu.dao;

import com.neuedu.entity.User;
import com.neuedu.util.JDBCUtil;

import java.util.List;

/**
 * 项目：      usermanager
 * 类名:       UserDao
 * 创建时间：  2020/12/7  16:21
 * 描述 :
 * 作者 :     张金山
 * QQ :     314649444
 * Site:      https://jshand.gitee.io
 */
public class UserDao {


    /**
     * 查询集合
     * @param sql
     * @param param
     * @return
     */
    public List<User> list(String sql,Object... param){
        return JDBCUtil.executeQuery(sql,User.class,param);
    }


    /**
     *
     * @param id
     * @return
     */
    public User queryById(String id ){
        String sql = "select * from user where id = ? ";
        return JDBCUtil.getOne(sql,(rs)->{
            return new User(
                    rs.getInt("id"),
                    rs.getString("username"),
                    rs.getString("displayname"),
                    rs.getString("password"),
                    rs.getDate("birthday"),
                    rs.getString("gender"),
                    rs.getString("telephone"),
                    rs.getString("email"),
                    rs.getTimestamp("last_logintime"),
                    rs.getTimestamp("create_time"),
                    rs.getString("valid")
            );
        },id);
    }


    public boolean add(User user ){
        String sql = "insert into user(username,password,displayname,birthday) values(?,?,?,?) ";
        return JDBCUtil.executeUpdate(sql,
                user.getUsername(),
                user.getPassword(),
                user.getDisplayname(),
                user.getBirthday());
    }


    public boolean update(User user ){

        StringBuffer sql = new StringBuffer();
        sql.append( " UPDATE 				");
        sql.append( "   user                ");
        sql.append( " SET                   ");
        sql.append( "                       ");
        sql.append( "   username = ?,       ");
        sql.append( "   displayname = ?,    ");
        sql.append( "   password = ?,       ");
        sql.append( "   birthday = ?,       ");
        sql.append( "   gender =?,          ");
        sql.append( "   telephone = ?,      ");
        sql.append( "   email =?,           ");
        sql.append( "   last_logintime = ?, ");
        sql.append( "   create_time = ?,    ");
        sql.append( "   valid = ?           ");
        sql.append( " WHERE  id =  ?        ");


        return JDBCUtil.executeUpdate(sql.toString(),
                user.getUsername(),
                user.getDisplayname(),
                user.getPassword(),
                user.getBirthday(),
                user.getGender(),
                user.getTelephone(),
                user.getEmail(),
                user.getLast_logintime(),
                user.getCreate_time(),
                user.getValid(),
                user.getId()

                );
    }


    public boolean deleteById(String id ) {

        String sql =" delete from user where id = ?";
        return JDBCUtil.executeUpdate(sql,id);

    }


    public static void main(String[] args) {


        UserDao userDao = new UserDao();

        String sql = "select * from user ";
        List<User> list = userDao.list(sql);
//        for (User user : list) {
//            System.out.println(user);
//        }


        String id = "2";
        User user = userDao.queryById(id);
        System.out.println(user);


    }


}

4.6.5 单元测试类

java

package com.neuedu.dao;

import com.neuedu.entity.User;
import org.junit.Before;
import org.junit.Test;

import java.util.Date;
import java.util.List;

import static org.junit.Assert.*;

/**
 * 项目：      usermanager
 * 类名:       UserDaoTest
 * 创建时间：  2020/12/7  16:31
 * 描述 :
 * 作者 :     张金山
 * QQ :     314649444
 * Site:      https://jshand.gitee.io
 */
public class UserDaoTest {

    UserDao userDao ;

    @Before
    public void init(){
        userDao =  new UserDao();
    }


    @Test
    public void list() {

        String sql = "select * from user ";
        List<User> list = userDao.list(sql);
        for (User user : list) {
            System.out.println(user);
        }
    }

    @Test
    public void queryById() {

        String id = "2";
        User user = userDao.queryById(id);
        System.out.println(user);
    }

    @Test
    public void add() {
        User user =  new User();
        user.setUsername("132456");
        user.setPassword("4564564");
        user.setDisplayname("用户管理系统");
        user.setBirthday(new Date());

        boolean success = userDao.add(user);
        System.out.println(success);
    }


    @Test
    public void update() {

        String id = "2";
        User user = userDao.queryById(id);
        System.out.println(user);
        user.setDisplayname("用户管理系统更新");
        boolean success = userDao.update(user);
        System.out.println(success);
    }

    @Test
    public void deleteById() {
        String id = "2";
        boolean success = userDao.deleteById(id);
        System.out.println(success);
    }
}

4.6.6 创建UserManagerServlet

根据type参数区分不同的功能:

java

package com.neuedu.servlet;

import com.neuedu.dao.UserDao;
import com.neuedu.entity.User;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.PrintWriter;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.List;


/**
 * 项目：      usermanager
 * 类名:       ${NAME}
 * 创建时间：  2020/12/8  9:21
 * 描述 :     ${dc}
 * 作者 :     张金山
 * QQ :     314649444
 * Site:      https://jshand.gitee.io
 * <p>
 * <p>
 * http://127.0.0.1:8080/mis/user
 * http://127.0.0.1:8080/mis/user?type=list
 */@WebServlet(name = "UserServlet", urlPatterns = "/user")
public class UserServlet extends HttpServlet {

    private UserDao userDao = new UserDao();


    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        /**
         * type
         *  1 查询列表  list(显示页面)
         *  2 查处用户  delete                  重新查询列表
         *  3 添加用户  toAdd(显示页面)   add    重新查询列表
         *  4 修改用户  toEdit(显示页面)  edit   重新查询列表
         */
        String type = request.getParameter("type");

        //1 查询
        if ("list".equals(type) || type == null) {
            queryList(request, response);
        }
        //2 到添加用户界面
        else if ("toAdd".equals(type)) {
            toAdd(request, response);
        } 
        else if ("add".equals(type)) {
            try {
                add(request, response);
            } catch (ParseException e) {
                e.printStackTrace();
            }
        }
        //到修改页面
        else if ("toEdit".equals(type)) {
            toEdit(request, response);
        } else if ("edit".equals(type)) {
            try {
                edit(request, response);
            } catch (ParseException e) {
                e.printStackTrace();
            }
        } else if ("delete".equals(type)) {
            delete(request, response);
        }


        //2 修改

    }


    /**
     * 删除
     *
     * @param request
     * @param response
     */
    private void delete(HttpServletRequest request, HttpServletResponse response) throws IOException {
        String id = request.getParameter("id");
        boolean success = userDao.deleteById(id);
        response.sendRedirect(request.getContextPath() + "/user?type=list");

    }

    private void edit(HttpServletRequest request, HttpServletResponse response) throws ParseException, IOException {

        String id = request.getParameter("id");
        String username = request.getParameter("username");
        String displayname = request.getParameter("displayname");
        String password = request.getParameter("password");
        String birthday = request.getParameter("birthday"); //yyyy-MM-dd  1990-01-02
        String gender = request.getParameter("gender");
        String email = request.getParameter("email");


        User user = new User();
        user.setId(Integer.parseInt(id));
        user.setUsername(username);
        user.setDisplayname(displayname);
        user.setPassword(password);
        user.setBirthday(new SimpleDateFormat("yyyy-MM-dd").parse(birthday));
        user.setGender(gender);
        user.setEmail(email);

        boolean success = userDao.update(user);


        //查询列表页

//        request.getRequestDispatcher("user?type=list").forward(request,response);
        response.sendRedirect(request.getContextPath() + "/user?type=list");

    }

    private void toEdit(HttpServletRequest request, HttpServletResponse response) throws IOException {
        response.setContentType("text/html;charset=utf-8");

        String id = request.getParameter("id");

        User user = userDao.queryById(id);


        String bir = "";
        if (user.getBirthday() != null) {
            bir = new SimpleDateFormat("yyyy-MM-dd").format(user.getBirthday());
        }

        String gender = "1";

        if (user.getGender() != null && "".equals(user.getGender())) {
            gender = user.getGender();
        }


        StringBuffer html = new StringBuffer();
        html.append(" <form method='post' action='user?type=edit'>								");
        html.append(" <input type='hidden' name='id' value='" + user.getId() + "'>						");
        html.append(" 	<h3>用户添加</h3>                                           ");
        html.append(" 	<table width='100%' border='1'>                                        ");
        html.append(" 		<tr>                                                    ");
        html.append(" 			<td>username</td>                                   ");
        html.append(" 			<td><input type='text' name='username' value='" + user.getUsername() + "'></td>        ");
        html.append(" 		</tr>                                                   ");
        html.append(" 		<tr>                                                    ");
        html.append(" 			<td>displayname</td>                                ");
        html.append(" 			<td><input type='text' name='displayname'  value='" + user.getDisplayname() + "'></td>     ");
        html.append(" 		</tr>                                                   ");
        html.append(" 		<tr>                                                    ");
        html.append(" 			<td>password</td>                                   ");
        html.append(" 			<td><input type='text' name='password'  value='" + user.getPassword() + "'></td>        ");
        html.append(" 		</tr>                                                   ");
        html.append(" 		<tr>                                                    ");
        html.append(" 			<td>birthday</td>                                   ");
        html.append(" 			<td><input type='text' name='birthday' value='" + bir + "'></td>        ");
        html.append(" 		</tr>                                                   ");
        html.append("                                                               ");
        html.append(" 		<tr>                                                    ");
        html.append(" 			<td>gender</td>                                     ");
        html.append(" 			<td>                                                ");
        html.append("                                                               ");
        html.append(" 				<select name='gender'>                          ");
        html.append(" 					<option value='1' " + ("1".equals(gender) ? "selected" : "") + " >男               ");
        html.append(" 					<option value='2' " + ("2".equals(gender) ? "selected" : "") + " >女               ");
        html.append(" 				</select></td>                                  ");
        html.append(" 		</tr>                                                   ");
        html.append("                                                               ");
        html.append(" 		<tr>                                                    ");
        html.append(" 			<td>email</td>                                      ");
        html.append(" 			<td><input type='text' name='email' value='" + user.getEmail() + "'></td>           ");
        html.append(" 		</tr>                                                   ");
        html.append(" 		<tr>                                                    ");
        html.append(" 			<td colspan='2'> <input type='submit' ></td>           ");
        html.append(" 		</tr>                                                   ");
        html.append("                                                               ");
        html.append(" 	</table>                                                    ");
        html.append("                                                               ");
        html.append("                                                               ");
        html.append(" </form>                                                       ");

        PrintWriter out = response.getWriter();
        out.write(html.toString());
        out.flush();
        out.close();
    }

    private void add(HttpServletRequest request, HttpServletResponse response) throws ParseException, ServletException, IOException {

        String username = request.getParameter("username");
        String displayname = request.getParameter("displayname");
        String password = request.getParameter("password");
        String birthday = request.getParameter("birthday"); //yyyy-MM-dd  1990-01-02
        String gender = request.getParameter("gender");
        String email = request.getParameter("email");


        User user = new User();
        user.setUsername(username);
        user.setDisplayname(displayname);
        user.setPassword(password);
        user.setBirthday(new SimpleDateFormat("yyyy-MM-dd").parse(birthday));
        user.setGender(gender);
        user.setEmail(email);

        boolean success = userDao.add(user);


        //查询列表页

//        request.getRequestDispatcher("user?type=list").forward(request,response);
        response.sendRedirect(request.getContextPath() + "/user?type=list");


    }

    /**
     * 添加页面
     *
     * @param request
     * @param response
     * @throws IOException
     */
    private void toAdd(HttpServletRequest request, HttpServletResponse response) throws IOException {
        response.setContentType("text/html;charset=utf-8");
        StringBuffer html = new StringBuffer();
        html.append(" <form method='post' action='user?type=add'>								");
        html.append(" 	<h3>用户添加</h3>                                           ");
        html.append(" 	<table width='100%' border='1'>                                        ");
        html.append(" 		<tr>                                                    ");
        html.append(" 			<td>username</td>                                   ");
        html.append(" 			<td><input type='text' name='username'></td>        ");
        html.append(" 		</tr>                                                   ");
        html.append(" 		<tr>                                                    ");
        html.append(" 			<td>displayname</td>                                ");
        html.append(" 			<td><input type='text' name='displayname'></td>     ");
        html.append(" 		</tr>                                                   ");
        html.append(" 		<tr>                                                    ");
        html.append(" 			<td>password</td>                                   ");
        html.append(" 			<td><input type='text' name='password'></td>        ");
        html.append(" 		</tr>                                                   ");
        html.append(" 		<tr>                                                    ");
        html.append(" 			<td>birthday</td>                                   ");
        html.append(" 			<td><input type='text' name='birthday'></td>        ");
        html.append(" 		</tr>                                                   ");
        html.append("                                                               ");
        html.append(" 		<tr>                                                    ");
        html.append(" 			<td>gender</td>                                     ");
        html.append(" 			<td>                                                ");
        html.append("                                                               ");
        html.append(" 				<select name='gender'>                          ");
        html.append(" 					<option value='1' selected>男               ");
        html.append(" 					<option value='2'> 女                       ");
        html.append(" 				</select></td>                                  ");
        html.append(" 		</tr>                                                   ");
        html.append("                                                               ");
        html.append(" 		<tr>                                                    ");
        html.append(" 			<td>email</td>                                      ");
        html.append(" 			<td><input type='text' name='email'></td>           ");
        html.append(" 		</tr>                                                   ");
        html.append(" 		<tr>                                                    ");
        html.append(" 			<td colspan='2'> <input type='submit' ></td>           ");
        html.append(" 		</tr>                                                   ");
        html.append("                                                               ");
        html.append(" 	</table>                                                    ");
        html.append("                                                               ");
        html.append("                                                               ");
        html.append(" </form>                                                       ");

        PrintWriter out = response.getWriter();
        out.write(html.toString());
        out.flush();
        out.close();
    }

    /**
     * 查询类表
     *
     * @param request
     * @param response
     */
    private void queryList(HttpServletRequest request, HttpServletResponse response) throws IOException {


        String sql = "select * from user";
        List<User> userList = userDao.list(sql);

        //通知浏览器 内容的类型
        response.setContentType("text/html;charset=utf-8");

        StringBuffer html = new StringBuffer();
        html.append(" <a href='user?type=toAdd'>添加</a>");
        html.append(" <table border='1' width='100%'>			");
        html.append(" <tr>               ");
        html.append(" 	<td>序号</td>   ");
        html.append(" 	<td>用户名</td> ");
        html.append(" 	<td>昵称</td>   ");
        html.append(" 	<td>密码</td>   ");
        html.append(" 	<td>出生日期</td>   ");
        html.append(" 	<td>性别</td>   ");
        html.append(" 	<td>邮箱 </td>   ");
        html.append(" 	<td>操作 </td>   ");
        html.append(" </tr>              ");

        for (User user : userList) {

            html.append(" <tr>               ");
            html.append(" 	<td>" + user.getId() + "</td>       ");
            html.append(" 	<td>" + user.getUsername() + "</td>       ");
            html.append(" 	<td>" + user.getDisplayname() + "</td>       ");
            html.append(" 	<td>" + user.getPassword() + "</td>       ");
            html.append(" 	<td>" + user.getBirthday() + "</td>       ");
            html.append(" 	<td>" + user.getGender() + "</td>       ");
            html.append(" 	<td>" + user.getEmail() + "</td>       ");
            html.append(" 	<td><a href='user?type=toEdit&id=" + user.getId() + "'>编辑</a>  <a href='user?type=delete&id=" + user.getId() + "'>删除</a></td>       ");
            html.append(" </tr>              ");
        }

        html.append(" </table>           ");

        PrintWriter out = response.getWriter();
        out.print(html.toString());


        out.flush();
        out.close();
    }


    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        this.doPost(request, response);
    }
}

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4.7 乱码的问题

java

//接收的编码
/**
* Get方式
*/
String name =  request.getParameter("name");
name = new String(name.getBytes("iso8859-1"),"utf-8");
System.out.println("name:"+name);
//post提交生效
request.setCharacterEncoding("utf-8");

//响应的编码
request.setCharacterEncoding("utf-8");

4.8 作业

参考用户管理的功能，编写如下表的CRUD操作

sql

drop table if exists fmeditem;

/*==============================================================*/
/* Table: fmeditem                                              */
/*==============================================================*/
create table fmeditem
(
   id                   int not null auto_increment comment '主键',
   item_code            varchar(500) comment '项目编码',
   item_name            varchar(500) comment '项目名称',
   format               varchar(500) comment '规格',
   price                decimal(6,2) comment '单价',
   exp_class_id         varchar(500) comment '所属费用科目',
   dept                 varchar(500) comment '执行科室',
   mnemonic_code        varchar(500) comment '拼音助记码',
   record_type          varchar(500) comment '项目类型',
   createtime           datetime default CURRENT_TIMESTAMP comment '创建时间',
   valid                varchar(5) default '1' comment '是否有效',
   primary key (id)
);

alter table fmeditem comment '非药品收费项目表';

4.9 Lombok

2020-12-08_144717

4.9.1 引入lombok依赖

<!-- https://mvnrepository.com/artifact/org.projectlombok/lombok -->
    <dependency>
      <groupId>org.projectlombok</groupId>
      <artifactId>lombok</artifactId>
      <version>1.18.12</version>
      <scope>provided</scope>
    </dependency>

4.9.2 使用

java

package com.neuedu.entity;

import lombok.*;

/**
 * 项目：      usermanager
 * 类名:       Fmeditem
 * 创建时间：  2020/12/8  14:44
 * 描述 :
 * 作者 :     张金山
 * QQ :     314649444
 * Site:      https://jshand.gitee.io
 */
@NoArgsConstructor
@AllArgsConstructor
//@Setter
//@Getter
//@ToString
@Data
public class Fmeditem {

    private Integer id;
    private String itemCode;


}

测试代码如下：

java

 @Test
 public void testLomBok() {
 	Fmeditem f = new Fmeditem();

	Fmeditem f2 = new Fmeditem(1,"aaa");

	f2.setItemCode("asdfasdfasdf");
    System.out.println(f2.getId());
    System.out.println(f2);

}

4.Servlet基本应用 ​

4.1 动态响应内容 ​

4.2 参数处理 ​

4.2.1 超链接形式的数据请求语法格式 ​

4.2.2 处理Form表单请求数据 ​

4.2.3 地址栏传参 ​

4.2.3 完整代码如下： ​

4.2.4 request对象获取参数 ​

4.3 重定向 ​

4.3.1 完整代码 ​

4.4 请求转发(内部跳转) ​

4.4.1 完整代码 ​

4.5 重定向和请求转发的区别 ​

4.6 综合实例：用户管理系统 ​

4.6.1 数据库 ​

4.6.2 创建项目 ​

4.6.3.添加pom依赖 ​

4.6.4.实体类 ​

4.6.5 Dao类 ​

4.6.5 单元测试类 ​

4.6.6 创建UserManagerServlet ​

4.7 乱码的问题 ​

4.8 作业 ​

4.9 Lombok ​

4.9.1 引入lombok依赖 ​

4.9.2 使用 ​

4.Servlet基本应用

4.1 动态响应内容

4.2 参数处理

4.2.1 超链接形式的数据请求语法格式

4.2.2 处理Form表单请求数据

4.2.3 地址栏传参

4.2.3 完整代码如下：

4.2.4 request对象获取参数

4.3 重定向

4.3.1 完整代码

4.4 请求转发(内部跳转)

4.4.1 完整代码

4.5 重定向和请求转发的区别

4.6 综合实例：用户管理系统

4.6.1 数据库

4.6.2 创建项目

4.6.3.添加pom依赖

4.6.4.实体类

4.6.5 Dao类

4.6.5 单元测试类

4.6.6 创建UserManagerServlet

4.7 乱码的问题

4.8 作业

4.9 Lombok

4.9.1 引入lombok依赖

4.9.2 使用