时间紧张，先记一笔，后续优化与完善。
解决的问题：
使用GSON和泛型解析约定格式的JSON串。
背景介绍：
1.使用GSON来进行JSON串与java代码的互相转换。
2.JSON的格式如下三种：
写道
＃第一种：{ "success":true,"data":{"averageStarLevel":4.7,"remarkCount":10}}＃第二种：{ "success":true,"data":{"page":10,"pageCount":29,"list":[{"starLevel":4,"remarkCotnent":"评价方未及时做出评价，系统默认满意！","remarkTime":"2013-02-27 07:21:48","explainContent":"","postMemberId":"y**f","tpLogoURL":"http://i04.c.aliimg.com/cms/upload/2012/186/684/486681_1232736939.png"},{"starLevel":4,"remarkCotnent":"评价方未及时做出评价，系统默认满意！","remarkTime":"2013-02-27 07:21:48","explainContent":"","postMemberId":"y**f","tpLogoURL":"http://i04.c.aliimg.com/cms/upload/2012/186/684/486681_1232736939.png"}],"statistics":{"star5":20,"star4":40,"star3":30,"star2":10,"star1":0}}}＃第三种：{ "success":true,"data":[{"starLevel":4,"remarkCotnent":"评价方未及时做出评价，系统默认满意！","remarkTime":"2013-02-27 07:21:48","explainContent":"","postMemberId":"y**f","tpLogoURL":"http://i04.c.aliimg.com/cms/upload/2012/186/684/486681_1232736939.png"},{"starLevel":4,"remarkCotnent":"评价方未及时做出评价，系统默认满意！","remarkTime":"2013-02-27 07:21:48","explainContent":"","postMemberId":"y**f","tpLogoURL":"http://i04.c.aliimg.com/cms/upload/2012/186/684/486681_1232736939.png"}]} 分析：
在工作时间中，遇到一种场景，就是在应用中调用多个JSON接口，各接口返回的数据内容不一样，如果逐一解析代码会比较臃肿。JSON串如上所列有三种基本格式。经过分析，发现三种JSON串有一个共同的特点。JSON结构一致：
写道
{"success":true,"data":##} success：代表是否访问成功
data:后面跟着所需信息.
基本相同的JSON结构，所以想定义一种通用模型对应到此结构。但是，data中的数据类型不一致。如第一种是简单对象，第二种是对象中嵌套数组，第三种是List。针对data数据类型不一致的情况，使用泛型来解决。
import java.io.Serializable;import java.lang.reflect.ParameterizedType;import java.lang.reflect.Type;import com.google.gson.Gson;public class CommonJsonimplements Serializable { /** * */ private static final long serialVersionUID = -3440061414071692254L; /** * 是否成功 */ private Boolean success; /** * 数据 */ private T data; public Boolean getSuccess() { return success; } public void setSuccess(Boolean success) { this.success = success; } public T getData() { return data; } public void setData(T data) { this.data = data; }}
GSON对于泛型的支持不足，为了使GSON对于泛型进行解析，JSON解析与组装代码如下：
public static CommonJson fromJson(String json, Class clazz) { Gson gson = new Gson(); Type objectType = type(CommonJson.class, clazz); return gson.fromJson(json, objectType); } public String toJson(Class clazz) { Gson gson = new Gson(); Type objectType = type(CommonJson.class, clazz); return gson.toJson(this, objectType); } static ParameterizedType type(final Class raw, final Type... args) { return new ParameterizedType() { public Type getRawType() { return raw; } public Type[] getActualTypeArguments() { return args; } public Type getOwnerType() { return null; } }; } 以上两段代码可以满足第一种和第二种JSON的解析，对于第三种，data是List类型的，无法得到List<>的class，所以，针对第三种格式，实现代码如下：
import java.io.Serializable;import java.lang.reflect.ParameterizedType;import java.lang.reflect.Type;import java.util.List;import com.google.gson.Gson;public class CommonJson4Listimplements Serializable { /** * */ private static final long serialVersionUID = -369558847578246550L; /** * 是否成功 */ private Boolean success; /** * 数据 */ private List data; public Boolean getSuccess() { return success; } public void setSuccess(Boolean success) { this.success = success; } public List getData() { return data; } public void setData(List data) { this.data = data; } public static CommonJson4List fromJson(String json, Class clazz) { Gson gson = new Gson(); Type objectType = type(CommonJson4List.class, clazz); return gson.fromJson(json, objectType); } public String toJson(Class clazz) { Gson gson = new Gson(); Type objectType = type(CommonJson4List.class, clazz); return gson.toJson(this, objectType); } static ParameterizedType type(final Class raw, final Type... args) { return new ParameterizedType() { public Type getRawType() { return raw; } public Type[] getActualTypeArguments() { return args; } public Type getOwnerType() { return null; } }; }}
测试代码如下：
import java.util.ArrayList;import java.util.List;import com.alibaba.asc.sharewood.common.http.CommonJson;import com.alibaba.asc.sharewood.common.http.CommonJson4List;import com.alibaba.asc.sharewood.external.service.model.AverageStarLevelAndCount;import com.alibaba.asc.sharewood.external.service.model.Evalution;import com.alibaba.asc.sharewood.external.service.model.EvalutionProfile;import com.alibaba.asc.sharewood.external.service.model.StarLevelStatistics;public class Test { @SuppressWarnings("unchecked") public static void main(String[] args) { CommonJson cj = new CommonJson (); AverageStarLevelAndCount data = new AverageStarLevelAndCount(); data.setAverageStarLevel(4.7f); data.setRemarkCount(10); cj.setSuccess(Boolean.TRUE); cj.setData(data); String res1 = cj.toJson(AverageStarLevelAndCount.class); System.out.println(res1); CommonJson cj2 = CommonJson.fromJson(res1, AverageStarLevelAndCount.class); System.out.println(cj2.getSuccess()); System.out.println(cj2.getData().getAverageStarLevel()); EvalutionProfile p = new EvalutionProfile(); p.setPage(10); p.setPageCount(29); StarLevelStatistics s = new StarLevelStatistics(); s.setStar1(0); s.setStar2(10); s.setStar3(30); s.setStar4(40); s.setStar5(20); p.setStatistics(s); Evalution e1 = new Evalution(); e1.setStarLevel(4); e1.setRemarkTime("2013-02-27 07:21:48"); e1.setRemarkCotnent("评价方未及时做出评价，系统默认满意！"); e1.setTpLogoURL("http://i04.c.aliimg.com/cms/upload/2012/186/684/486681_1232736939.png"); e1.setExplainContent(""); e1.setPostMemberId("y**f"); Evalution e2 = new Evalution(); e2.setStarLevel(4); e2.setRemarkTime("2013-02-27 07:21:48"); e2.setRemarkCotnent("评价方未及时做出评价，系统默认满意！"); e2.setTpLogoURL("http://i04.c.aliimg.com/cms/upload/2012/186/684/486681_1232736939.png"); e2.setExplainContent(""); e2.setPostMemberId("y**f"); List le = new ArrayList (); le.add(e1); le.add(e2); p.setList(le); CommonJson ce = new CommonJson (); ce.setSuccess(Boolean.TRUE); ce.setData(p); String res2 = ce.toJson(EvalutionProfile.class); System.out.println(res2); String ps = "{\"data\":{\"pageCount\":29,\"page\":\"1\",\"list\":[{\"starLevel\":4,\"remarkTime\":\"2013-04-10 05:17:42\",\"explainTime\":\"\",\"remarkContent\":\"评价方未及时做出评价，系统默认满意！\",\"tpLogoURL\":\"\",\"explainContent\":\"\",\"postMemberId\":\"b**6\"},{\"starLevel\":4,\"remarkTime\":\"2013-04-05 04:42:40\",\"explainTime\":\"\",\"remarkContent\":\"评价方未及时做出评价，系统默认满意！\",\"tpLogoURL\":\"\",\"explainContent\":\"\",\"postMemberId\":\"b**8\"},{\"starLevel\":4,\"remarkTime\":\"2013-03-20 00:52:18\",\"explainTime\":\"\",\"remarkContent\":\"评价方未及时做出评价，系统默认满意！\",\"tpLogoURL\":\"\",\"explainContent\":\"\",\"postMemberId\":\"b**5\"},{\"starLevel\":4,\"remarkTime\":\"2013-03-07 01:51:01\",\"explainTime\":\"\",\"remarkContent\":\"评价方未及时做出评价，系统默认满意！\",\"tpLogoURL\":\"\",\"explainContent\":\"\",\"postMemberId\":\"b**7\"},{\"starLevel\":4,\"remarkTime\":\"2013-03-06 03:38:57\",\"explainTime\":\"\",\"remarkContent\":\"评价方未及时做出评价，系统默认满意！\",\"tpLogoURL\":\"\",\"explainContent\":\"\",\"postMemberId\":\"z**2\"},{\"starLevel\":4,\"remarkTime\":\"2013-03-06 03:17:33\",\"explainTime\":\"\",\"remarkContent\":\"评价方未及时做出评价，系统默认满意！\",\"tpLogoURL\":\"\",\"explainContent\":\"\",\"postMemberId\":\"b**2\"},{\"starLevel\":4,\"remarkTime\":\"2013-03-03 01:40:17\",\"explainTime\":\"\",\"remarkContent\":\"评价方未及时做出评价，系统默认满意！\",\"tpLogoURL\":\"\",\"explainContent\":\"\",\"postMemberId\":\"a**6\"},{\"starLevel\":4,\"remarkTime\":\"2013-03-01 02:41:31\",\"explainTime\":\"\",\"remarkContent\":\"评价方未及时做出评价，系统默认满意！\",\"tpLogoURL\":\"\",\"explainContent\":\"\",\"postMemberId\":\"b**4\"},{\"starLevel\":4,\"remarkTime\":\"2013-02-28 03:20:45\",\"explainTime\":\"\",\"remarkContent\":\"评价方未及时做出评价，系统默认满意！\",\"tpLogoURL\":\"\",\"explainContent\":\"\",\"postMemberId\":\"t**y\"},{\"starLevel\":4,\"remarkTime\":\"2013-02-27 07:21:48\",\"explainTime\":\"\",\"remarkContent\":\"评价方未及时做出评价，系统默认满意！\"," + "\"tpLogoURL\":\"" + "http://i04.c.aliimg.com/cms/upload/2012/186/684/486681_1232736939.png\",\"explainContent\":\"\",\"postMemberId\":\"y**f\"}]," + "\"statistics\":{\"star5\":59,\"star4\":38,\"star3\":2,\"star2\":1,\"star1\":0}},\"success\":true}"; CommonJson re = CommonJson.fromJson(ps, EvalutionProfile.class); System.out.println(re.getData().getStatistics().getStar5()); System.out.println(re.getData().getPageCount()); System.out.println(re.getData().getList().get(0).getPostMemberId()); CommonJson4List cjl = new CommonJson4List (); cjl.setSuccess(Boolean.TRUE); cjl.setData(le); System.out.println("###" + cjl.toJson(Evalution.class)); String sList = "{\"data\":[{\"starLevel\":4,\"remarkCotnent\":\"评价方未及时做出评价，系统默认满意！\",\"remarkTime\":\"2013-02-27 07:21:48\",\"explainContent\":\"\",\"postMemberId\":\"y**f\",\"tpLogoURL\":\"http://i04.c.aliimg.com/cms/upload/2012/186/684/486681_1232736939.png\"},{\"starLevel\":4,\"remarkCotnent\":\"评价方未及时做出评价，系统默认满意！\",\"remarkTime\":\"2013-02-27 07:21:48\",\"explainContent\":\"\",\"postMemberId\":\"y**f\",\"tpLogoURL\":\"http://i04.c.aliimg.com/cms/upload/2012/186/684/486681_1232736939.png\"}],\"success\":true}"; CommonJson4List cjle = CommonJson4List.fromJson(sList, Evalution.class); System.out.println("***" + cjle.getData().get(0).getPostMemberId()); }} 执行结果如下：
{"success":true,"data":{"averageStarLevel":4.7,"remarkCount":10}}true4.7{ "success":true,"data":{"page":10,"pageCount":29,"list":[{"starLevel":4,"remarkCotnent":"评价方未及时做出评价，系统默认满意！","remarkTime":"2013-02-27 07:21:48","explainContent":"","postMemberId":"y**f","tpLogoURL":"http://i04.c.aliimg.com/cms/upload/2012/186/684/486681_1232736939.png"},{"starLevel":4,"remarkCotnent":"评价方未及时做出评价，系统默认满意！","remarkTime":"2013-02-27 07:21:48","explainContent":"","postMemberId":"y**f","tpLogoURL":"http://i04.c.aliimg.com/cms/upload/2012/186/684/486681_1232736939.png"}],"statistics":{"star5":20,"star4":40,"star3":30,"star2":10,"star1":0}}}5929b**6{ "success":true,"data":[{"starLevel":4,"remarkCotnent":"评价方未及时做出评价，系统默认满意！","remarkTime":"2013-02-27 07:21:48","explainContent":"","postMemberId":"y**f","tpLogoURL":"http://i04.c.aliimg.com/cms/upload/2012/186/684/486681_1232736939.png"},{"starLevel":4,"remarkCotnent":"评价方未及时做出评价，系统默认满意！","remarkTime":"2013-02-27 07:21:48","explainContent":"","postMemberId":"y**f","tpLogoURL":"http://i04.c.aliimg.com/cms/upload/2012/186/684/486681_1232736939.png"}]}y**f
Ps：文中说到Gson对泛型的支持不足，其实是不正确的，Gson对泛型做了以下支持：
public static CommonJson4List fromJson(String json, Class clazz) { Gson gson = new Gson(); Type objectType = new TypeToken >() {}.getType(); return gson.fromJson(json, objectType); } 只需将获取类型的泛型类作为TypeToken的泛型参数构造一个匿名的子类，就可以通过getType方法获取一个parameterized类型，结果与type方法一致。