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SpringMVC8-HttpMessageConverter

news 2024/10/25 19:48:03

@RequestBody

RequestEntity

@ResponseBody

SpringMVC处理json

SpringMVC处理ajax

@RestController注解

ResponseEntity

HttpMessageConverter，报文信息转换器，将请求报文转换为Java对象或将Java对象转换为响应报文

HttpMessageConverter提供了两个注解和两个类型：@RequestBody，@ResponseBody，RequestEntity，ResponseEntity

模块springMVC-demo4

@RequestBody

@RequestBody可以获取请求体，需要在控制器方法设置一个形参，使用@RequestBody进行标识，当前请求的请求体就会为当前注解所标识的形参赋值

<!DOCTYPE html>
<html lang="en" xmlns:th="http://www.thymeleaf.org">
<head><meta charset="UTF-8"><title>首页</title>
</head>
<body>
<h1>首页</h1>
<form th:action="@{/testRequestBody}" method="post"><input type="text" name="username"><input type="password" name="password"><input type="submit" value="测试@RequestBody">
</form>
</body>
</html>

package com.qcby.mvc.controller;import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;@Controller
public class HttpController {@RequestMapping("/testRequestBody")public String testRequestBody(@RequestBody String requestBody){System.out.println("requestBody：" + requestBody);return "success";}
}

RequestEntity

RequestEntity封装请求报文的一种类型，需要在控制器方法的形参中设置该类型的形参，当前请求的请求报文就会赋值给该形参，可以通过getHeaders()获取请求头信息，通过getBody()获取请求体信息

<!DOCTYPE html>
<html lang="en" xmlns:th="http://www.thymeleaf.org">
<head><meta charset="UTF-8"><title>首页</title>
</head>
<body>
<h1>首页</h1>
<form th:action="@{/testRequestEntity}" method="post"><input type="text" name="username"><input type="password" name="password"><input type="submit" value="测试RequestEntity">
</form>
</body>
</html>

package com.qcby.mvc.controller;import org.springframework.http.RequestEntity;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;@Controller
public class HttpController {@RequestMapping("/testRequestEntity")public String testRequestEntity(RequestEntity<String> requestEntity){//当前requestEntity表示整个请求报文的信息System.out.println("请求头："+requestEntity.getHeaders());System.out.println("请求体："+requestEntity.getBody());return "success";}
}

@ResponseBody

@ResponseBody用于标识一个控制器方法，可以将该方法的返回值直接作为响应报文的响应体响应到浏览器

<!DOCTYPE html>
<html lang="en" xmlns:th="http://www.thymeleaf.org">
<head><meta charset="UTF-8"><title>首页</title>
</head>
<body>
<h1>首页</h1>
<a th:href="@{/testResponseBody}">通过@ResponseBody响应浏览器数据</a>
</body>
</html>

package com.qcby.mvc.controller;import org.springframework.http.RequestEntity;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;@Controller
public class HttpController {@RequestMapping("/testResponseBody")@ResponseBody //返回的success不再是视图，而是响应报文，直接出现在浏览器上public String testResponseBody(){return "success11111";}}

SpringMVC处理json

<dependency><groupId>com.fasterxml.jackson.core</groupId><artifactId>jackson-databind</artifactId><version>2.12.1</version>
</dependency>

在SpringMVC的核心配置文件中开启mvc的注解驱动，此时在HandlerAdaptor中会自动装配一个消息转换器：MappingJackson2HttpMessageConverter，可以将响应到浏览器的Java对象转换为json格式的字符串：

<!--开启MVC的注解驱动-->
<mvc:annotation-driven></mvc:annotation-driven>

package com.qcby.mvc.bean;public class User {private Integer id;private String username;private String password;private Integer age;private String sex;public User(Integer id, String username, String password, Integer age, String sex) {this.id = id;this.username = username;this.password = password;this.age = age;this.sex = sex;}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;}
}

<!DOCTYPE html>
<html lang="en" xmlns:th="http://www.thymeleaf.org">
<head><meta charset="UTF-8"><title>首页</title>
</head>
<body>
<h1>首页</h1>
<a th:href="@{/testResponseUser}">通过@ResponseBody响应浏览器User对象</a>
</body>
</html>

将Java对象直接作为控制器方法的返回值返回，就会自动转换为json格式的字符串：

package com.qcby.mvc.controller;import com.qcby.mvc.bean.User;
import org.springframework.http.RequestEntity;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;@Controller
public class HttpController {@RequestMapping("/testResponseUser")@ResponseBodypublic User testResponseUser(){return new User(1001,"admin","123456",20,"男");}}

SpringMVC处理ajax

<!DOCTYPE html>
<html lang="en" xmlns:th="http://www.thymeleaf.org">
<head><meta charset="UTF-8"><title>首页</title>
</head>
<script src="https://cdn.jsdelivr.net/npm/vue@2/dist/vue.js"></script>
<script src="https://cdn.jsdelivr.net/npm/vue@2/dist/axios.min.js"></script>
<body>
<h1>首页</h1>
<div id="app"><a @click="testAxios" th:href="@{/testAxios}">SpringMVC处理ajax</a>
</div>
<script type="text/javascript">new Vue({el:"#app",methods:{testAxios:function (event){axios({method: "post",url: event.target.href,params:{username:"admin",password:"123456"}}).then(function (response){alert(response.data);});event.preventDefault();}}})
</script>
</body>
</html>

package com.qcby.mvc.controller;import com.qcby.mvc.bean.User;
import org.springframework.http.RequestEntity;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;@Controller
public class HttpController {@RequestMapping("/testAxios")@ResponseBodypublic String testAxios(String username,String password){System.out.println(username+","+password);return "hello,axios";}
}