1、使用@RequestBody注解把json的字符串转换成JavaBean的对象

js代码

 // 页面加载    
$(function(){        
// 绑定点击事件        
$("#btn").click(function(){           
 $.ajax({                
    url:"user/testJson",                
    contentType:"application/json;charset=UTF-8", 
    data:'{"addressName":"aa","addressNum":100}',                                                
    dataType:"json",                
    type:"post",                
    success:function(data){                    
        alert(data);                    
        alert(data.addressName);                
}            
});        

获取请求体的数据 ：

控制器方法：

 @RequestMapping("/testJson")    
 public void testJson(@RequestBody String body) {
        System.out.println(body);    
}

2、使用@ResponseBody注解把JavaBean对象转换成json字符串，直接响应 

要求方法需要返回JavaBean的对象

// 页面加载    
$(function(){        
// 绑定点击事件        
$("#btn").click(function(){           
 $.ajax({                
    url:"user/testJson",                
    contentType:"application/json;charset=UTF-8", 
    data:'{"addressName":"aa","addressNum":100}',                                                
    dataType:"json",                
    type:"post",                
    success:function(data){                    
        alert(data);                    
        alert(data.addressName);                
}            
});        

控制器方法：

@RequestMapping("/testJson")   
 public @ResponseBody Address testJson(@RequestBody Address address) {      
          System.out.println(address);        
          address.setAddressName("上海");       
          return address;   
}

 3、 json字符串和JavaBean对象互相转换的过程中，需要使用jackson的jar包

<dependency>            
    <groupId>com.fasterxml.jackson.core</groupId>            
    <artifactId>jackson-databind</artifactId>           
    <version>2.9.0</version>        
</dependency>        
<dependency>            
    <groupId>com.fasterxml.jackson.core</groupId>      
    <artifactId>jackson-core</artifactId>            
    <version>2.9.0</version>        
 </dependency>        
<dependency>           
     <groupId>com.fasterxml.jackson.core</groupId>            
     <artifactId>jackson-annotations</artifactId>           
     <version>2.9.0</version>      
</dependency>