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:
<?xml version="1.0" encoding="UTF-8"?> <web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd" version="4.0"> //配置编码过滤器 <filter> <filter-name>CharacterEncodingFilter</filter-name> <filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class> <init-param> <param-name>encoding</param-name> <param-value>UTF-8</param-value> </init-param> <init-param> <param-name>forceResponseEncoding</param-name> <param-value>true</param-value> </init-param> </filter> <filter-mapping> <filter-name>CharacterEncodingFilter</filter-name> <url-pattern>/*</url-pattern> </filter-mapping> //配置springMVC的前端控制器DispatcherServlet <servlet> <servlet-name>DispatcherServlet</servlet-name> <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class> <init-param> <param-name>contextConfigLocation</param-name> <param-value>classpath:springMVC.xml</param-value> </init-param> <load-on-startup>1</load-on-startup> </servlet> <servlet-mapping> <servlet-name>DispatcherServlet</servlet-name> <url-pattern>/</url-pattern> </servlet-mapping> </web-app>
springMVC.xml:
<?xml version="1.0" encoding="UTF-8"?> <beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:context="http://www.springframework.org/schema/context" 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"> <context:component-scan base-package="demo.controller"></context:component-scan> <!-- 配置Thymeleaf视图解析器 --> <bean id="viewResolver" class="org.thymeleaf.spring5.view.ThymeleafViewResolver"> <property name="order" value="1"/> <property name="characterEncoding" value="UTF-8"/> <property name="templateEngine"> <bean class="org.thymeleaf.spring5.SpringTemplateEngine"> <property name="templateResolver"> <bean class="org.thymeleaf.spring5.templateresolver.SpringResourceTemplateResolver"> <!-- 视图前缀 --> <property name="prefix" value="/WEB-INF/templates/"/> <!-- 视图后缀 --> <property name="suffix" value=".html"/> <property name="templateMode" value="HTML5"/> <property name="characterEncoding" value="UTF-8" /> </bean> </property> </bean> </property> </bean> </beans>
index.html:
<!DOCTYPE html> <html lang="en" xmlns:th="http://www.thymeleaf.org"> <head> <meta charset="UTF-8"> <title>Title</title> </head> <body> <h1>首页</h1> <br> <a th:href="@{/}">走到首页</a> <br> <a th:href="@{/testRest/1/admin}">测试路径中占位符-->/testRest</a> <br> <a th:href="@{/test}">测试-->/test</a> <br> <a th:href="@{/param}">测试请求参数-->param</a> <br> <a th:href="@{/param(username='哈哈哈',password='123456')}">测试请求参数-->param</a> <br> </body> </html>
success.html:
<!DOCTYPE html> <html lang="en" xmlns:th="http://www.thymeleaf.org"> <head> <meta charset="UTF-8"> <title>Title</title> </head> <body> success </body> </html>
User.java:
package demo.bean; public class User { private Integer id; private String username; private String password; private Integer age; private String sex; private String email; public User() { } public User(Integer id, String username, String password, Integer age, String sex, String email) { this.id = id; this.username = username; this.password = password; this.age = age; this.sex = sex; this.email = email; } 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 getPassword() { return password; } public void setPassword(String password) { this.password = password; } public Integer getAge() { return age; } public void setAge(Integer age) { this.age = age; } public String getSex() { return sex; } public void setSex(String sex) { this.sex = sex; } public String getEmail() { return email; } public void setEmail(String email) { this.email = email; } @Override public String toString() { return "User{" + "id=" + id + ", username='" + username + '\'' + ", password='" + password + '\'' + ", age=" + age + ", sex='" + sex + '\'' + ", email='" + email + '\'' + '}'; } }
TestController.java:
package demo.controller; import demo.bean.User; import org.springframework.stereotype.Controller; import org.springframework.web.bind.annotation.PathVariable; import org.springframework.web.bind.annotation.RequestMapping; @Controller public class TestController { @RequestMapping(value = "/") public String index(){ return "index"; } @RequestMapping(value = "/test") public String test(){ return "success"; } @RequestMapping(value = "/testRest/{id}/{username}") public String testRest(@PathVariable("id") String id,@PathVariable("username") String username){ System.out.println("id:"+id+" username:"+username); return "success"; } @RequestMapping(value = "/param") public String test_param(String username,String password){ System.out.println("username:"+username+" password:"+password); return "success"; } }
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：
<form th:action="@{/testpojo}" method="get"> 用户名：<input type="text" name="username"><br> 密码：<input type="password" name="password"><br> 性别：<input type="radio" name="sex" value="男">男<input type="radio" name="sex" value="女">女<br> 年龄：<input type="text" name="age"><br> 邮箱：<input type="text" name="email"><br> <input type="submit" value="使用pojo获取请求参数"> </form>
给控制类中传入的形参改为类：
@RequestMapping(value = "/testpojo") public String testpojo(User user){ System.out.println(user); return "success"; }
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
