springMvc注解之@ResponseBody和@RequestBody

簡介

springmvc對json的前后台傳輸做了很好封裝，避免了重復編碼的過程，下面來看看常用的@ResponseBody和@RequestBody注解

添加依賴

springmvc對json的處理依賴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 />//不要忘了命名空間配置

@ResponseBody

如果傳輸的是單層json對象，我們后台可以直接用 @RequestParam接收

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

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

如果傳輸的是多層嵌套json對象，這個時候會就會出現數據丟失問題

注解@RequestMapping很好的解決了這個問題，它會把前台傳輸過來的json轉化為后台對應的對象

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

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

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

同時要把json對象轉化為String，否則后台不能識別

@ResponseBody

ajax請求返回json格式，往常我們可以這樣做

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();
    }
  }
}

這個時候 @ResponseBody就派上用場了，只需要一個注解，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", "韋德");
  result.put("age", 35);
  return result;
}

前台console輸出

{
    "age": 35,
    "name": "韋德"
}

總結

在網上看到很不錯的流程圖，作為總結吧