Android 使用Gson解析json用法

目前解析json有三种工具：org.json（Java常用的解析），fastjson（阿里巴巴工程师开发的），Gson（Google官网出的），解析速度最快的是Gson，下载地址：https://code.google.com/p/google-gson/

什么是JSON:

JSON即JavaScript Object Natation, 它是一种轻量级的数据交换格式, 与XML一样, 是广泛被采用的客户端和服务端交互的解决方案.

JSON对象: 

JSON中对象(Object)以"{"开始, 以"}"结束. 对象中的每一个item都是一个key-value对, 表现为"key:value"的形式, key-value对之间使用逗号分隔. 如:{"name":"coolxing", "age"=24, "male":true, "address":{"street":"huiLongGuan", "city":"beijing", "country":"china"}}. JSON对象的key只能是string类型的, 而value可以是string, number, false, true, null, Object对象甚至是array数组, 也就是说可以存在嵌套的情况.

JSON数组: 

JSON数组(array)以"["开始, 以"]"结束, 数组中的每一个元素可以是string, number, false, true, null, Object对象甚至是array数组, 数组间的元素使用逗号分隔. 如["coolxing", 24, {"street":"huiLongGuan", "city":"beijing", "country":"china"}].

Gson的基本使用方法：

通过获取JsonReader对象解析JSON数据：

String jsonData = "[{\"username\":\"arthinking\",\"userId\":001},{\"username\":\"Jason\",\"userId\":002}]";
try{
	JsonReader reader = new JsonReader(new StringReader(jsonData));
	reader.beginArray();
	while(reader.hasNext()){
		reader.beginObject();
		while(reader.hasNext()){
			String tagName = reader.nextName();
			if(tagName.equals("username")){
				System.out.println(reader.nextString());
			}
			else if(tagName.equals("userId")){
				System.out.println(reader.nextString());
			}
		}
		reader.endObject();
	}
	reader.endArray();
}
catch(Exception e){
	e.printStackTrace();
}

通过把JSON数据映射成一个对象，使用Gson对象的fromJson()方法获取一个对象数组进行操作：

创建JSON数据对应的一个POJO对象User.java：

public class User {
	private String username ;
	private int userId ;
	public String getUsername() {
		return username;
	}
	public void setUsername(String username) {
		this.username = username;
	}
	public int getUserId() {
		return userId;
	}
	public void setUserId(int userId) {
		this.userId = userId;
	}
}

使用Gson对象获取User对象数据进行相应的操作：

Type listType = new TypeToken>(){}.getType();
Gson gson = new Gson();
LinkedList users = gson.fromJson(jsonData, listType);
for (Iterator iterator = users.iterator(); iterator.hasNext();) {
	User user = (User) iterator.next();
	System.out.println(user.getUsername());
	System.out.println(user.getUserId());
}

如果要处理的JSON字符串只包含一个JSON对象，则可以直接使用fromJson获取一个User对象：

String jsonData = "{\"username\":\"arthinking\",\"userId\":001}";
Gson gson = new Gson();
User user = gson.fromJson(jsonData, User.class);
System.out.println(user.getUsername());
System.out.println(user.getUserId());

解析复杂实例：

数据格式：

 {
     "data": {
         "partnerteamlist": [
             {
                 "pteamId": 72825,
                 "ptitle": "随摄影/共6套服装/准爸准妈共拍/免费肚画/底片全送。",
                 "pteamprice": 288
             },
             {
                 "pteamId": 72598,
                 "ptitle": "随摄影/拍摄200张/4本相册/品质拍摄/送全新婚纱。",
                 "pteamprice": 2888
             },
             {
                 "pteamId": 72613,
                 "ptitle": "随摄影/送全新婚纱/多外景拍摄/服装不限数量/绝无二次消费！",
                 "pteamprice": 3699
             },
             {
                 "pteamId": 72638,
                 "ptitle": "随摄影/服装不限数量/高品质拍摄260张/送全新婚纱。",
                 "pteamprice": 4299
             },
             {
                 "pteamId": 72716,
                 "ptitle": "随摄影/3组服装造型/内外景拍摄/完全透明消费！",
                 "pteamprice": 388
             }
         ],
         "liketeamlist": [
             {
                 "lteamId": 65886,
                 "ltitle": "爱丽尔婚纱摄影/2本相册/6套服装造型/拍摄不限最低拍摄150张。",
                 "limage": "http://img.pztuan.com/upfile/team/2013/0712/201307120257551465.jpg",
                 "lteamprice": 518,
                 "lmarketprice": 3999
             },
             {
                 "lteamId": 57133,
                 "ltitle": "陶冶摄影/婚纱闺蜜/6组服装造型/拍摄不低于120张！",
                 "limage": "http://img.pztuan.com/upfile/team/2013/0628/201306281115249737.jpg",
                 "lteamprice": 580,
                 "lmarketprice": 3380
             }
         ],
         "feedbacks": {
             "feedbacklist": [
                 {
                     "comment": "5分",
                     "createtime": "2014.07.08 13:38",
                     "score": 5,
                     "username": "l***2"
                 }
             ],
             "totalcount": 1,
             "totalscore": 5
         }
     },
     "err": null,
     "state": 1
 }

实体类（里面的成员变量和接口的返回值名称一 一对应才能保证解析正确）：

 package com.pztuan.entity;

 import java.util.List;

 public class OtherDetail {

     private int state;
     private List err;
     private OtherDetail2 data;

     public int getState() {
         return state;
     }

     public void setState(int state) {
         this.state = state;
     }

     public List getErr() {
         return err;
     }

     public void setErr(List err) {
         this.err = err;
     }

     public OtherDetail2 getData() {
         return data;
     }

     public void setData(OtherDetail2 data) {
         this.data = data;
     }

     public class OtherDetail2 {
         private List partnerteamlist;
         private List liketeamlist;
         private List feedbacks;

         public List getLiketeamlist() {
             return liketeamlist;
         }

         public void setLiketeamlist(List liketeamlist) {
             this.liketeamlist = liketeamlist;
         }

         public List getFeedbacks() {
             return feedbacks;
         }

         public void setFeedbacks(List feedbacks) {
             this.feedbacks = feedbacks;
         }

         public class partnerteamlist {
             private int pteamId;
             private String ptitle;
             private Double pteamprice;

             public int getPteamId() {
                 return pteamId;
             }

             public void setPteamId(int pteamId) {
                 this.pteamId = pteamId;
             }

             public String getPtitle() {
                 return ptitle;
             }

             public void setPtitle(String ptitle) {
                 this.ptitle = ptitle;
             }

             public Double getPteamprice() {
                 return pteamprice;
             }

             public void setPteamprice(Double pteamprice) {
                 this.pteamprice = pteamprice;
             }

         }

         public class liketeamlist {
             private int lteamId;
             private String ltitle;
             private String limage;
             private Double lteamprice;
             private Double lmarketprice;

             public int getLteamId() {
                 return lteamId;
             }

             public void setLteamId(int lteamId) {
                 this.lteamId = lteamId;
             }

             public String getLtitle() {
                 return ltitle;
             }

             public void setLtitle(String ltitle) {
                 this.ltitle = ltitle;
             }

             public String getLimage() {
                 return limage;
             }

             public void setLimage(String limage) {
                 this.limage = limage;
             }

             public Double getLteamprice() {
                 return lteamprice;
             }

             public void setLteamprice(Double lteamprice) {
                 this.lteamprice = lteamprice;
             }

             public Double getLmarketprice() {
                 return lmarketprice;
             }

             public void setLmarketprice(Double lmarketprice) {
                 this.lmarketprice = lmarketprice;
             }
         }

         public class feedbacks {
             private int totalcount;
             private Double totalscore;
             private List feedbacklist;

             public int getTotalcount() {
                 return totalcount;
             }

             public void setTotalcount(int totalcount) {
                 this.totalcount = totalcount;
             }

             public Double getTotalscore() {
                 return totalscore;
             }

             public void setTotalscore(Double totalscore) {
                 this.totalscore = totalscore;
             }

             public List getFeedbacklist() {
                 return feedbacklist;
             }

             public void setFeedbacklist(List feedbacklist) {
                 this.feedbacklist = feedbacklist;
             }

             public class feedbacklist {
                 private String username;
                 private String comment;
                 private String createtime;
                 private Double score;

                 public String getUsername() {
                     return username;
                 }

                 public void setUsername(String username) {
                     this.username = username;
                 }

                 public String getComment() {
                     return comment;
                 }

                 public void setComment(String comment) {
                     this.comment = comment;
                 }

                 public String getCreatetime() {
                     return createtime;
                 }

                 public void setCreatetime(String createtime) {
                     this.createtime = createtime;
                 }

                 public Double getScore() {
                     return score;
                 }

                 public void setScore(Double score) {
                     this.score = score;
                 }

             }
         }

         public List getPartnerteamlist() {
             return partnerteamlist;
         }

         public void setPartnerteamlist(List partnerteamlist) {
             this.partnerteamlist = partnerteamlist;
         }
     }

     public class err {
         private int code;
         private String msg;

         public int getCode() {
             return code;
         }

         public void setCode(int code) {
             this.code = code;
         }

         public String getMsg() {
             return msg;
         }

         public void setMsg(String msg) {
             this.msg = msg;
         }
     }
 }

注意上面内部类的运用。

解析：

 Gson gson = new Gson();
 OtherDetail d = gson.fromJson(jsonString,Detail.class);//取值的时候就从父类一层一层调子类成员（重要）

若出现引用异常，请查看Java内部类设计原则。

如有问题请留言，转载注明出处。

参考：http://www.itzhai.com/android-to-parse-json-data-using-gson.html

           http://blog.csdn.net/caijunjun1006/article/details/11762841