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。
@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。
<form th:action="@{/testRequestBody}" method="post">
用户名:<input type="text" name="username"><br>
密码:<input type="password" name="password"><br>
<input type="submit">
form>
@RequestMapping("/testRequestBody")
public String testRequestBody(@RequestBody String requestBody){
System.out.println("requestBody:"+requestBody);
return "success";
}
输出结果:
requestBody:username=admin&password=123456
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。
<form th:action="@{/testRequestEntity}" method="post">
用户名:<input type="text" name="username"><br>
密码:<input type="password" name="password"><br>
<input type="submit" value="测试RequestEntity">
form>
@RequestMapping("/testRequestEntity")
public String testRequestEntity(RequestEntity<String> requestEntity){
System.out.println("requestHeader:"+requestEntity.getHeaders());
System.out.println("requestBody:"+requestEntity.getBody());
return "success";
}
输出结果:
requestHeader:[host:“localhost:8080”, connection:“keep-alive”, content-length:“27”,
cache-control:“max-age=0”, sec-ch-ua:“” Not A;Brand";v=“99”, “Chromium”;v=“90”, “Google
Chrome”;v=“90"”, sec-ch-ua-mobile:“?0”, upgrade-insecure-requests:“1”, origin:“http://localhost:8
080”, user-agent:“Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, likeGecko) Chrome/90.0.4430.93 Safari/537.36”] requestBody:username=admin&password=123
@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。
<a th:href="@{/testResponseBody}">通过ResponseBody对象响应浏览器数据</a>
@RequestMapping("/testResponseBody")
@ResponseBody
public String testResponseBody(){
return "success";
}
结果:
浏览器页面显示success
User类:
package com.dragon.mvc.bean;
public class User {
private Integer id;
private String username;
private String password;
private Integer age;
private String 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;
}
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 User() {
}
}
@ResponseBody处理json的步骤:
<dependency>
<groupId>com.fasterxml.jackson.coregroupId>
<artifactId>jackson-databindartifactId>
<version>2.12.1version>
dependency>
pom.xml=======================
<mvc:annotation-driven />
在处理器方法上使用@ResponseBody注解进行标识
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
@RequestMapping("/testResponseUser")
@ResponseBody
public User testResponseUser(){
return new User(1001,"admin","123456",23,"男");
}
<a th:href="@{/testResponseUser}">通过ResponseUser对象响应浏览器数据a>
浏览器的页面中展示的结果:
{“id”:1001,“username”:“admin”,“password”:“123456”,“age”:23,“sex”:“男”}
<div id="app">
<a th:href="@{/testAjax}" @click="testAjax">testAjaxa><br>
div>
<script type="text/javascript" th:src="@{/static/js/vue.js}"></script>
<script type="text/javascript" th:src="@{/static/js/axios.min.js}"></script>
<script type="text/javascript">
var vue = new Vue({
el:"#app",
methods:{
testAjax:function (event) {
axios({
method:"post",
url:event.target.href,
params:{
username:"admin",
password:"123456"
}
}).then(function (response) {
alert(response.data);
});
event.preventDefault();
}
}
});
</script>
@RequestMapping("/testAjax")
@ResponseBody
public String testAjax(String username, String password){
System.out.println("username:"+username+",password:"+password);
return "hello,ajax";
}
@RestController注解是springMVC提供的一个复合注解,标识在控制器的类上,就相当于为类添加了@Controller注解,并且为其中的每个方法添加了@ResponseBody注解。
ResponseEntity用于控制器方法的返回值类型,该控制器方法的返回值就是响应到浏览器的响应报文。
以上就是HttpMessageConverter有关讲解。