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SpringMVC学习（四）：通过实体类型的形参获取请求参数（以及 通过POJO获取）_请求参数是实体类

作者：Gausst松鼠会 | 2024-02-07 22:18:04

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请求参数是实体类

在SpringMVC中不需要用原生的servletAPI来获取参数了，这会大大简化我们的代码。

文档结构：

 

web.xml:

  1. <?xml version="1.0" encoding="UTF-8"?>
  2. <web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
  3.          xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  4.          xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd"
  5.          version="4.0">
  6.  
  7.  
  8.     //配置编码过滤器
  9.     <filter>
  10.         <filter-name>CharacterEncodingFilter</filter-name>
  11.         <filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class>
  12.         <init-param>
  13.             <param-name>encoding</param-name>
  14.             <param-value>UTF-8</param-value>
  15.         </init-param>
  16.         <init-param>
  17.             <param-name>forceResponseEncoding</param-name>
  18.             <param-value>true</param-value>
  19.         </init-param>
  20.     </filter>
  21.     <filter-mapping>
  22.         <filter-name>CharacterEncodingFilter</filter-name>
  23.         <url-pattern>/*</url-pattern>
  24.     </filter-mapping>
  25.  
  26.     //配置springMVC的前端控制器DispatcherServlet
  27.     <servlet>
  28.         <servlet-name>DispatcherServlet</servlet-name>
  29.         <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
  30.         <init-param>
  31.             <param-name>contextConfigLocation</param-name>
  32.             <param-value>classpath:springMVC.xml</param-value>
  33.         </init-param>
  34.         <load-on-startup>1</load-on-startup>
  35.     </servlet>
  36.     <servlet-mapping>
  37.         <servlet-name>DispatcherServlet</servlet-name>
  38.         <url-pattern>/</url-pattern>
  39.     </servlet-mapping>
  40.     
  41. </web-app>

springMVC.xml:

  1. <?xml version="1.0" encoding="UTF-8"?>
  2. <beans xmlns="http://www.springframework.org/schema/beans"
  3.        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  4.        xmlns:context="http://www.springframework.org/schema/context"
  5.        xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/context https://www.springframework.org/schema/context/spring-context.xsd">
  6.  
  7.     <context:component-scan base-package="demo.controller"></context:component-scan>
  8.  
  9.     <!-- 配置Thymeleaf视图解析器 -->
  10.     <bean id="viewResolver" class="org.thymeleaf.spring5.view.ThymeleafViewResolver">
  11.         <property name="order" value="1"/>
  12.         <property name="characterEncoding" value="UTF-8"/>
  13.         <property name="templateEngine">
  14.             <bean class="org.thymeleaf.spring5.SpringTemplateEngine">
  15.                 <property name="templateResolver">
  16.                     <bean class="org.thymeleaf.spring5.templateresolver.SpringResourceTemplateResolver">
  17.  
  18.                         <!-- 视图前缀 -->
  19.                         <property name="prefix" value="/WEB-INF/templates/"/>
  20.  
  21.                         <!-- 视图后缀 -->
  22.                         <property name="suffix" value=".html"/>
  23.                         <property name="templateMode" value="HTML5"/>
  24.                         <property name="characterEncoding" value="UTF-8" />
  25.                     </bean>
  26.                 </property>
  27.             </bean>
  28.         </property>
  29.     </bean>
  30.  
  31. </beans>

 index.html:

  1. <!DOCTYPE html>
  2. <html lang="en" xmlns:th="http://www.thymeleaf.org">
  3. <head>
  4.     <meta charset="UTF-8">
  5.     <title>Title</title>
  6. </head>
  7. <body>
  8.  
  9.     <h1>首页</h1> <br>
  10.     <a th:href="@{/}">走到首页</a> <br>
  11.     <a th:href="@{/testRest/1/admin}">测试路径中占位符-->/testRest</a>  <br>
  12.     <a th:href="@{/test}">测试-->/test</a>    <br>
  13.     <a th:href="@{/param}">测试请求参数-->param</a>   <br>
  14.     <a th:href="@{/param(username='哈哈哈',password='123456')}">测试请求参数-->param</a>   <br>
  15.  
  16.  
  17. </body>
  18. </html>

success.html:

  1. <!DOCTYPE html>
  2. <html lang="en" xmlns:th="http://www.thymeleaf.org">
  3. <head>
  4.     <meta charset="UTF-8">
  5.     <title>Title</title>
  6. </head>
  7. <body>
  8.  
  9.     success
  10.  
  11. </body>
  12. </html>

User.java:

  1. package demo.bean;
  2.  
  3. public class User {
  4.  
  5.     private Integer id;
  6.     private String username;
  7.     private String password;
  8.     private Integer age;
  9.     private String sex;
  10.     private String email;
  11.  
  12.     public User() {
  13.     }
  14.  
  15.     public User(Integer id, String username, String password, Integer age, String sex, String email) {
  16.         this.id = id;
  17.         this.username = username;
  18.         this.password = password;
  19.         this.age = age;
  20.         this.sex = sex;
  21.         this.email = email;
  22.     }
  23.  
  24.     public Integer getId() {
  25.         return id;
  26.     }
  27.  
  28.     public void setId(Integer id) {
  29.         this.id = id;
  30.     }
  31.  
  32.     public String getUsername() {
  33.         return username;
  34.     }
  35.  
  36.     public void setUsername(String username) {
  37.         this.username = username;
  38.     }
  39.  
  40.     public String getPassword() {
  41.         return password;
  42.     }
  43.  
  44.     public void setPassword(String password) {
  45.         this.password = password;
  46.     }
  47.  
  48.     public Integer getAge() {
  49.         return age;
  50.     }
  51.  
  52.     public void setAge(Integer age) {
  53.         this.age = age;
  54.     }
  55.  
  56.     public String getSex() {
  57.         return sex;
  58.     }
  59.  
  60.     public void setSex(String sex) {
  61.         this.sex = sex;
  62.     }
  63.  
  64.     public String getEmail() {
  65.         return email;
  66.     }
  67.  
  68.     public void setEmail(String email) {
  69.         this.email = email;
  70.     }
  71.  
  72.     @Override
  73.     public String toString() {
  74.         return "User{" +
  75.                 "id=" + id +
  76.                 ", username='" + username + '\'' +
  77.                 ", password='" + password + '\'' +
  78.                 ", age=" + age +
  79.                 ", sex='" + sex + '\'' +
  80.                 ", email='" + email + '\'' +
  81.                 '}';
  82.     }
  83. }

TestController.java:

  1. package demo.controller;
  2.  
  3. import demo.bean.User;
  4. import org.springframework.stereotype.Controller;
  5. import org.springframework.web.bind.annotation.PathVariable;
  6. import org.springframework.web.bind.annotation.RequestMapping;
  7.  
  8. @Controller
  9. public class TestController {
  10.  
  11.     @RequestMapping(value = "/")
  12.     public String index(){
  13.         return "index";
  14.     }
  15.  
  16.     @RequestMapping(value = "/test")
  17.     public String test(){
  18.         return "success";
  19.     }
  20.  
  21.     @RequestMapping(value = "/testRest/{id}/{username}")
  22.     public String testRest(@PathVariable("id") String id,@PathVariable("username") String username){
  23.         System.out.println("id:"+id+" username:"+username);
  24.         return "success";
  25.     }
  26.  
  27.     @RequestMapping(value = "/param")
  28.     public String test_param(String username,String password){
  29.         System.out.println("username:"+username+" password:"+password);
  30.         return "success";
  31.     }
  32.  
  33.    
  34. }

运行起来：

点击最下面的超链接：

跳转成功。再看看控制台：

和html文件中传的参数一致

这样就完成了通过实体类型的形参获取请求参数

但是还有一个小优化

如果实体类中的参数很多，那么控制类中的形参也会相应地增多，那么为了减少代码量，我们可以通过pojo获取请求参数 

在index.html中加写一个form表单，传比较多的参数：

  1. <form th:action="@{/testpojo}" method="get">
  2.         用户名：<input type="text" name="username"><br>
  3.         密码：<input type="password" name="password"><br>
  4.         性别：<input type="radio" name="sex" value="男">男<input type="radio" name="sex" value="女">女<br>
  5.         年龄：<input type="text" name="age"><br>
  6.         邮箱：<input type="text" name="email"><br>
  7.         <input type="submit" value="使用pojo获取请求参数">
  8.     </form>

 给控制类中传入的形参改为类：

  1. @RequestMapping(value = "/testpojo")
  2.     public String testpojo(User user){
  3.         System.out.println(user);
  4.         return "success";
  5.     }

运行起来

将表单填写完整，点击按钮

跳转成功，浏览器已经得到了参数。再看看控制台

 获取到了参数

这样可以减少我们传参时的代码量

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