spring web 4.1处理json

Spring mvc处理json，我们都知道使用@ResponseBody，处理xml也是用此注解。如果想spring mvc的使用@ResponseBody注解处理json，我们需要加入一些处理bean，也可以使用默认spring提供的。


通过spring源码RequestMappingHandlerAdapter类，我们知道初始化的时候这些注解已经被加载进来，如下RequestMappingHandlerAdapter类的代码如下：argumentResolvers和returnValueHandlers一个接受一个返回各自装载很多处理，有兴趣可以研究源码。

@Override
	public void afterPropertiesSet() {
		if (this.argumentResolvers == null) {
			List<HandlerMethodArgumentResolver> resolvers = getDefaultArgumentResolvers();
			this.argumentResolvers = new HandlerMethodArgumentResolverComposite().addResolvers(resolvers);
		}
		if (this.initBinderArgumentResolvers == null) {
			List<HandlerMethodArgumentResolver> resolvers = getDefaultInitBinderArgumentResolvers();
			this.initBinderArgumentResolvers = new HandlerMethodArgumentResolverComposite().addResolvers(resolvers);
		}
		if (this.returnValueHandlers == null) {
			List<HandlerMethodReturnValueHandler> handlers = getDefaultReturnValueHandlers();
			this.returnValueHandlers = new HandlerMethodReturnValueHandlerComposite().addHandlers(handlers);
		}
		initControllerAdviceCache();
	}

言归正传，下面介绍处理json
spring配置文件如下：

<?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:tx="http://www.springframework.org/schema/tx"
	xmlns:mvc="http://www.springframework.org/schema/mvc" xmlns:context="http://www.springframework.org/schema/context"
	xmlns:aop="http://www.springframework.org/schema/aop"
	xsi:schemaLocation="
		http://www.springframework.org/schema/beans 
		http://www.springframework.org/schema/beans/spring-beans.xsd 
		http://www.springframework.org/schema/tx 
		http://www.springframework.org/schema/tx/spring-tx.xsd 
	    http://www.springframework.org/schema/mvc
         http://www.springframework.org/schema/mvc/spring-mvc-4.0.xsd
		http://www.springframework.org/schema/context 
		http://www.springframework.org/schema/context/spring-context.xsd
		http://www.springframework.org/schema/aop
		http://www.springframework.org/schema/aop/spring-aop.xsd"
	default-lazy-init="false">

	<!-- mvc:annotation-driven使用注解功能 -->
	<mvc:annotation-driven>
		<mvc:message-converters register-defaults="true">
			<!--json处理-->
			<bean
				class="org.springframework.http.converter.json.MappingJackson2HttpMessageConverter">
				<property name="supportedMediaTypes">
					<list>
						<value>application/json;charset=UTF-8</value>
						<value>text/html;charset=UTF-8</value>
					</list>
				</property>
			</bean>
		</mvc:message-converters>
	</mvc:annotation-driven>

	<!-- 只扫描Controller 注解 -->
	<context:component-scan base-package="com.zx.web"
		use-default-filters="false">
		<context:include-filter type="annotation"
			expression="org.springframework.stereotype.Controller" />
	</context:component-scan>

	<!-- 动态资源访问，默认使用其他handlerAdapter解析 -->
	<mvc:resources mapping="/images/**" location="/images/" />
	<mvc:resources mapping="/js/**" location="/js/" />
	<mvc:resources mapping="/css/**" location="/css/" />


	<!-- jsp视图 -->
	<bean id="jspViewResolver"
		class="org.springframework.web.servlet.view.InternalResourceViewResolver">
		<property name="viewClass"
			value="org.springframework.web.servlet.view.JstlView" />
		<property name="prefix" value="/jsp/" />
		<property name="suffix" value=".jsp" />
		<property name="order" value="0" />
	</bean>


</beans>

我使用的是spring自带的类MappingJackson2HttpMessageConverter处理，在spring4.1以前都是使用MappingJacksonHttpMessageConverter类处理，在spring4.1以后都是用MappingJackson2HttpMessageConverter处理，然而换了类，自然依赖的jackson也进行升级了，spring4,1以后使用jackson-annotations-2.5.0.jar，jackson-core-2.5.0.jar，jackson-databind-2.5.0.jar

Controller层代码如下：

package com.zx.web;

import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;

import com.zx.entity.User;

@org.springframework.web.bind.annotation.RestController
public class RestController {
	
	@RequestMapping("/rest")
	@ResponseBody
	public User getUser()
	{
		User user = new User();
		user.setName("nihao");
		user.setAddress("anhui");
		user.setAge("89");
		user.setWork("软件");
		
		return user;
	}
}

结果如下：



项目spring-web代码如下，有兴趣的可以load，自己研究吧，绝对可以运行