Springmvc + FastJson

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/beans                        http://www.springframework.org/schema/beans/spring-beans-3.2.xsd                        http://www.springframework.org/schema/mvc                        http://www.springframework.org/schema/mvc/spring-mvc-3.2.xsd                        http://www.springframework.org/schema/context                        http://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 responses      with 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true      WriteMapNullValue--------是否输出值为null的字段,默认为false      WriteNullNumberAsZero----数值字段如果为null,输出为0,而非null      WriteNullListAsEmpty-----List字段如果为null,输出为[],而非null      WriteNullStringAsEmpty---字符类型字段如果为null,输出为"",而非null      WriteNullBooleanAsFalse--Boolean字段如果为null,输出为false,而非null    6)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Controllerpackage 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 {    @Resource    private 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.javapackage 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 --*/}