1. 首先是对Spring mvc 进行xml配置

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xmlns:context="http://www.springframework.org/schema/context"xmlns:mvc="http://www.springframework.org/schema/mvc"xsi:schemaLocation="http://www.springframework.org/schema/beanshttp://www.springframework.org/schema/beans/spring-beans.xsdhttp://www.springframework.org/schema/contexthttp://www.springframework.org/schema/context/spring-context.xsdhttp://www.springframework.org/schema/mvchttp://www.springframework.org/schema/mvc/spring-mvc.xsd"><context:annotation-config/><mvc:annotation-driven />
</beans>

其中annotation-driven是启动注解

2. 在maven 添加类

<properties><jackson.version>2.7.3</jackson.version>
</properties>
<dependency><groupId>com.fasterxml.jackson.core</groupId><artifactId>jackson-core</artifactId><version>${jackson.version}</version>
</dependency>
<dependency><groupId>com.fasterxml.jackson.core</groupId><artifactId>jackson-databind</artifactId><version>${jackson.version}</version>
</dependency>
<dependency><groupId>com.fasterxml.jackson.core</groupId><artifactId>jackson-annotations</artifactId><version>${jackson.version}</version>
</dependency>

3. 创建Controller 处理json请求

package controller;import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.MediaType;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.ResponseBody;import javax.servlet.http.HttpSession;
import java.util.HashMap;
import java.util.Map;
@Controller
public class JsonUserExistsController {private Boolean flag ;private String message;@RequestMapping(value="json/test",produces = MediaType.APPLICATION_JSON_VALUE)public@ResponseBody Map<String,String>userchecking(@RequestParam Map<String,String> params,HttpSession session){Map<String,String> json = new HashMap<String,String>();String imageWord = params.get("imgcode");String session_word = (String) session.getAttribute("image_word");if(!session_word.equals(imageWord)){flag = false;message = "验证码错误";json.put("flag",flag.toString());json.put("message",message);return json;}}
}

4. 结果

{"flag":"false","message":"验证码错误"}