springMvc注解之@ResponseBody和@RequestBody详解

Z时代
2024-01-10
分类：IT

简介

springmvc对json的前后台传输做了很好封装，避免了重复编码的过程，下面来看看常用的@ResponseBody和@RequestBody注解

添加依赖

springmvc对json的处理依赖jackson


<dependency>
  <groupId>org.codehaus.jackson</groupId>
  <artifactId>jackson-core-asl</artifactId>
  <version>1.9.11</version>
</dependency>
<dependency>
  <groupId>org.codehaus.jackson</groupId>
  <artifactId>jackson-mapper-asl</artifactId>
  <version>1.9.11</version>
</dependency>

xml配置


<mvc:annotation-driven />//不要忘了命名空间配置

@ResponseBody

如果传输的是单层json对象，我们后台可以直接用 @RequestParam接收


$.ajax({
  type : "post",
  dataType : "json",
  url : "/testRequestBody",
  data:{
    name:"韦德",
    age:35
  },
  success : function(result) {
  }
});


@RequestMapping("/testRequestBody")
public String testRequestBody(@RequestParam Map<String, Object> map) {
 System.out.println(map);// {name=韦德, age=35}
 return "index";
}

如果传输的是多层嵌套json对象，这个时候会就会出现数据丢失问题

@ResponseBody很好的解决了这个问题，它会把前台传输过来的json转化为后台对应的对象


$.ajax({
  type : "post",
  dataType : "json",
  url : "/testRequestBody",
  contentType:"application/json",  
  data:JSON.stringify({
    name:"韦德",
    win:[2006,2012,2013],
    age:35
  }),
  success : function(result) {
  }
});


@RequestMapping("/testRequestBody")
public String testRequestBody(@RequestBody Map<String, Object> map) {
 System.out.println(map);//{name=韦德, win=[2006, 2012, 2013], age=35}
 return "index";
}

需要注意的是前台需要指定contentType为"application/json"

同时要把json对象转化为String，否则后台不能识别

@ResponseBody

ajax请求返回json格式，往常我们可以这样做


private void writeJson(HttpServletResponse response, Object object) {
 String json = JSON.toJSONString(object);
 response.setCharacterEncoding("UTF-8");
 response.setContentType("application/json; charset=utf-8");
 PrintWriter out = null;
 try {
  out = response.getWriter();
  out.write(json);
 } catch (IOException e) {
  e.printStackTrace();
 } finally {
  if (out != null) {
   out.close();
  }
 }
}

这个时候 @ResponseBody就派上用场了，只需要一个注解，全部搞定


$.ajax({
  type : "post",
  dataType : "json",
  url : "/testResponseBody",
  success : function(result) {
    console.info(result);
  }
});


@RequestMapping("/testResponseBody")
@ResponseBody
public Map<String, Object> testRequestBody() {
 Map<String, Object> result = new HashMap<String, Object>();
 result.put("name", "韦德");
 result.put("age", 35);
 return result;
}

前台console输出