SpringMVC 使用@ResponseBody 返回json 報錯,一直不出來

首先 我的

<!-- spring版本號 -->
<spring.version>4.1.6.RELEASE</spring.version>

一定要,下面的包,才行.剛開始一直報錯,不出來就是包導入錯了,  關鍵啊

<!-- https://mvnrepository.com/artifact/com.fasterxml.jackson.core/jackson-databind -->
<dependency>
    <groupId>com.fasterxml.jackson.core</groupId>
    <artifactId>jackson-databind</artifactId>
    <version>2.2.0</version>
</dependency>
<dependency>
    <groupId>com.fasterxml.jackson.core</groupId>
    <artifactId>jackson-core</artifactId>
    <version>2.2.0</version>
</dependency>
<dependency>
    <groupId>com.fasterxml.jackson.core</groupId>
    <artifactId>jackson-annotations</artifactId>
    <version>2.2.0</version>
</dependency>

代碼非常簡單拉

/**
* 返回json 例子
* @param id
* @return
* ,params="json"
*/
//restful 風格
@RequestMapping(value="/ha", method=RequestMethod.GET)
public @ResponseBody  User show()
{
System.out.println(map.get(1));
return map.get(1);//這是個User的對象
}

成功頁面是這樣的

{"id":1,"username":"安","nikename":"mimi","password":"123","type":"1"}