SpringBoot前后端json数据交互

时间:2022-05-28 北冥友余人气:4

一、参考文献

原生Ajax与JQuery Ajax

SpringMVC接受JSON参数详解及常见错误总结

提交方式为 POST 时，
JQuery Ajax 以 application/x-www-form-urlencoded 上传 JSON对象，
后端用 @RequestParam 或者Servlet 获取参数。
JQuery Ajax 以 application/json 上传 JSON字符串，
后端用 @RquestBody 获取参数。
总结成表

Controller接收参数以及参数校验

AJAX POST请求中参数以form data和request payload形式在servlet中的获取方式

二、勇敢尝试

前端js发送ajax请求（ application/x-www-form-urlencoded ）

       var jsonObj = {"openid":"xxx","username":"Ed sheeran","password":"123"};
          /*
              Jquery默认Content-Type为application/x-www-form-urlencoded类型
           */
          $.ajax({
              type: 'POST',
              url: "/login",
              dataType: "json",
              data: JSON.stringify(jsonObj),
              success: function(data) {
                  console.log(data)
              },
              error: function() {
                  console.log("fucking error")
              }
          });

后端Servlet接受参数。前端报 200，后端报返回值都是null

@Controller
public class LoginController {
  @PostMapping("/login")
  public void login(HttpServletRequest request){
      System.err.println(request.getParameter("openid"));
      System.err.println(request.getParameter("username"));
      System.err.println(request.getParameter("password"));
}

后端改 @RequestParam 接受参数。前端报 404，后端报 Required String parameter ‘username’ is not present

@Controller
public class LoginController {
  @PostMapping("/login")
  public void login(@RequestParam("username") String username,
                    @RequestParam("password") String password,
                    @RequestParam("openid") String openid){
      System.err.println(username);
      System.err.println(password);
      System.err.println(openid);
  }

后端改 @RequestBody 接受参数。前端报 415，后端报 Content type ‘application/x-www-form-urlencoded;charset=UTF-8’ not supported

Http status 415 Unsupported Media Type

What is 415 ?

HTTP 415 Unsupported Media Type

The client error response code indicates that the server refuses to accept the request because the payload format is in an unsupported format.

Let’s look at the broswer ?

How to resolve 405 problem when using ajax post @ResponseBody return json data ?

if you use Spring 4.x jar,please following me(Maven Repository-Spring 4.x.jar)
add related jar package

spring-webmvc.x.x.jar

jackson-databind.jar

jackson-core.jar

jackson-annotations.jar

In Spring Configuration file,add following code
<bean class="org.springframework.web.servlet.mvc.
annotation.AnnotationMethodHandlerAdapter">  
    <property name="messageConverters">  
        <list>  
            <ref bean="jsonHttpMessageConverter" />  
        </list>  
    </property>  
</bean>  

<bean id="jsonHttpMessageConverter" class="org.springframework.http.converter.json.
MappingJackson2HttpMessageConverter">  
    <property name="supportedMediaTypes">  
        <list>  
          <value>application/json;charset=UTF-8</value>  
        </list>  
    </property>  
</bean>
In ajax , set contentType : ‘application/json;charse=UTF-8’
    var data = {"name":"jsutin","age":18};
    $.ajax({  
        url : "/ASW/login.html",  
        type : "POST",  
        data : JSON.stringify(data),  
        dataType: 'json',  
        contentType:'application/json;charset=UTF-8',      
        success : function(result) {  
            console.log(result);  
        }  
    }); 
In server ，using @RequestBody anotation receive json data,and using @ResponseBody anotation response json to jsp page
@RequestMapping(value = "/login",method = RequestMethod.POST)
public @ResponseBody User login(@RequestBody User user){
    system.out.println(user.getName);
    system.out.println(user.getAge);
}

@Controller
public class LoginController {
  @PostMapping("/login")
  public void login(@RequestBody Map<String,Object> map){
      System.err.println(map.get("username"));
      System.err.println(map.get("password"));
      System.err.println(map.get("openid"));
  }

前端加 contentType : “application/json”。前端报 200，后端能接受到参数

    $.ajax({
              type: 'POST',
              url: "/login",
              dataType: "json",
              data: JSON.stringify(jsonObj),
              contentType : "application/json",
              success: function(data) {
                  console.log(data)
              },
              error: function() {
                  console.log("fucking error")
              }
          });

@Controller
public class LoginController {
  @PostMapping("/login")
  public void login(@RequestBody Map<String,Object> map){
      System.err.println(map.get("username"));
      System.err.println(map.get("password"));
      System.err.println(map.get("openid"));
}
}

有时候，我想在后端使用对象来获取参数。前端报 200，后端也ok

@Controller
public class LoginController {
  @PostMapping("/login")
  public void login(@RequestBody Form form){
      System.err.println(form);
}
}

public class Form {
  private String openid;
  private String username;
  private String password;

  public String getOpenid() {
      return openid;
  }

  public void setOpenid(String openid) {
      this.openid = openid;
  }

  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;
  }

  @Override
  public String toString() {
      return "Form{" +
              "openid='" + openid + '\'' +
              ", username='" + username + '\'' +
              ", password='" + password + '\'' +
              '}';
  }
}

三、最终选择交互方式

前端 application/json，上传 josn字符串，后端使用对象或者 Map

前端代码

       var jsonObj = {"openid":"xxx","username":"Ed sheeran","password":"123"};
          /*
              Jquery默认Content-Type为application/x-www-form-urlencoded类型
           */
          $.ajax({
              type: 'POST',
              url: "/login",
              dataType: "json",
              data: JSON.stringify(jsonObj),
              contentType : "application/json",
              success: function(data) {
                  console.log(data)
              },
              error: function() {
                  console.log("fucking error")
              }
          });

后端代码1

@Controller
public class LoginController {
  @PostMapping("/login")
  public void login(@RequestBody Form form){
      System.err.println(form);
}
}

后端代码2

@Controller
public class LoginController {
  @PostMapping("/login")
  public void login(@RequestBody Map<String,Object> map){
      System.err.println(map.get("username"));
      System.err.println(map.get("password"));
      System.err.println(map.get("openid"));
}
}

总结

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