以前用fastjson也只是硬编码，就好像这篇博文写的http://blog.csdn.net/jadyer/article/details/24395015
昨天心血来潮突然想和SpringMVC整合，然后利用@ResponseBody注解的方式序列化输出json字符串
下面是研究成果
首先是applicationContext.xml中的相关配置
<?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:mvc="http://www.springframework.org/schema/mvc"xmlns:context="http://www.springframework.org/schema/context"xsi:schemaLocation="http://www.springframework.org/schema/beanshttp://www.springframework.org/schema/beans/spring-beans-3.2.xsdhttp://www.springframework.org/schema/mvchttp://www.springframework.org/schema/mvc/spring-mvc-3.2.xsdhttp://www.springframework.org/schema/contexthttp://www.springframework.org/schema/context/spring-context-3.2.xsd"><context:component-scan base-package="com.jadyer"/><mvc:annotation-driven><mvc:message-converters register-defaults="true"><bean class="com.alibaba.fastjson.support.spring.FastJsonHttpMessageConverter"><property name="supportedMediaTypes" value="text/html;charset=UTF-8"/><property name="features"><array><value>WriteMapNullValue</value><value>WriteNullStringAsEmpty</value></array></property></bean></mvc:message-converters></mvc:annotation-driven><!-- fastjson-1.1.41与SpringMVC整合 --><!-- 1)若按照jackson和SpringMVC的整合方式,应按照下面的写法,但测试发现这样会报告"HTTP Status 406"The resource identified by this request is only capable of generating responseswith characteristics not acceptable according to the request "accept" headers.2)测试通过的整合方式为上面那样在mvc:annotation-driven里面进行注册3)supportedMediaTypes增加[text/html;charset=UTF-8]值,是为了兼容IE6否则[application/json]值在IE6中会导致弹出对话框询问是否保存文件,而firefox等高级浏览器会正常打印json字符串4)若像下面这样给supportedMediaTypes属性赋两个值[text/html;charset=UTF-8]和[application/json],则[application/json]是无效的因为此时应答给浏览器(或者说请求方)的Content-Type头信息都是[text/html;charset=UTF-8],所以给它一个值就行了如果给supportedMediaTypes的值为[application/json],则应答给浏览器的Content-Type头信息就是[application/json;charset=UTF-8]5)关于features属性,不是serializerFeature,而是features,详见FastJsonHttpMessageConverter.java它是用来控制json序列化输出时的一些额外属性,比如说该字段是否输出、输出时key使用单引号还是双引号、key不使用任何引号等等QuoteFieldNames----------输出key时是否使用双引号,默认为trueWriteMapNullValue--------是否输出值为null的字段,默认为falseWriteNullNumberAsZero----数值字段如果为null,输出为0,而非nullWriteNullListAsEmpty-----List字段如果为null,输出为[],而非nullWriteNullStringAsEmpty---字符类型字段如果为null,输出为"",而非nullWriteNullBooleanAsFalse--Boolean字段如果为null,输出为false,而非null6)通常在网上搜到的fastjson和springMVC整合的例子中都像下面注释的代码那样给了两个属性WriteMapNullValue和QuoteFieldNames这就表示为json解析器设置QuoteFieldNames和WriteMapNullValue的值为true,即输出时key使用双引号,同时也输出值为null的字段7)输出时某字段为String类型,且值为null,此时若需要其输出,且输出值为空字符串,则需同时赋值WriteMapNullValue和WriteNullStringAsEmpty经测试,若只赋值WriteNullStringAsEmpty,则不会输出该字段..加上WriteMapNullValue属性后,便输出了,且输出值不是null,而是预期的空字符串--><!-- <bean class="org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter"><property name="messageConverters"><list><bean class="com.alibaba.fastjson.support.spring.FastJsonHttpMessageConverter"><property name="supportedMediaTypes"><list><value>text/html;charset=UTF-8</value><value>application/json</value></list></property><property name="serializerFeature"><array><value>QuoteFieldNames</value><value>WriteMapNullValue</value></array></property></bean></list></property></bean>--><!-- <bean class="org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter"><property name="messageConverters"><list><bean class="org.springframework.http.converter.json.MappingJacksonHttpMessageConverter"><property name="supportedMediaTypes" value="text/html;charset=UTF-8"/></bean></list></property></bean>--> </beans>接着是SpringMVC中的Controller
package com.jadyer.controller;import java.io.IOException;
import java.io.PrintWriter;import javax.annotation.Resource;
import javax.servlet.http.HttpServletResponse;import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;import com.alibaba.fastjson.JSON;
import com.jadyer.model.LoginResult;@Controller
@RequestMapping(value="/account")
public class AccountController {@Resourceprivate AccountService accountService;// @RequestMapping(value="/login")
// public String login(String username, String password, HttpServletResponse response) throws IOException{
// response.setContentType("text/plain; charset=UTF-8");
// response.setHeader("Cache-Control", "no-cache");
// response.setHeader("Pragma", "no-cache");
// response.setDateHeader("Expires", 0);
// PrintWriter out = response.getWriter();
// out.write(JSON.toJSONString(accountService.login(username, password)));
// out.flush();
// out.close();
// return null;
// }@ResponseBody@RequestMapping(value="/login")public LoginResult login(String username, String password){LoginResult result = new LoginResult();//验签过程暂略....result = accountService.login(username, password);return result;}
} 最后是login()方法的应答实体类LoginResult.java
package com.jadyer.model;public class LoginResult {private String respCode; //应答码private String respDesc; //应答描述private String userId; //用户编号private String username; //用户名private String mobileNo; //用户手机号private String integral; //用户拥有的积分/*-- 对应的setter和getter略 --*/
}