SpringMVC 整合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 {
  @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.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 --*/
}