Android Gson解析json详解

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<LinkedList<User>>(){}.getType();Gson gson = new Gson();LinkedList<User> 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> err;  private OtherDetail2 data;  public int getState() {    return state;  }  public void setState(int state) {    this.state = state;  }  public List<err> getErr() {    return err;  }  public void setErr(List<err> err) {    this.err = err;  }  public OtherDetail2 getData() {    return data;  }  public void setData(OtherDetail2 data) {    this.data = data;  }  public class OtherDetail2 {    private List<partnerteamlist> partnerteamlist;    private List<liketeamlist> liketeamlist;    private List<feedbacks> feedbacks;    public List<liketeamlist> getLiketeamlist() {      return liketeamlist;    }    public void setLiketeamlist(List<liketeamlist> liketeamlist) {      this.liketeamlist = liketeamlist;    }    public List<feedbacks> getFeedbacks() {      return feedbacks;    }    public void setFeedbacks(List<feedbacks> 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> 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<feedbacklist> getFeedbacklist() {        return feedbacklist;      }      public void setFeedbacklist(List<feedbacklist> 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<partnerteamlist> getPartnerteamlist() {      return partnerteamlist;    }    public void setPartnerteamlist(List<partnerteamlist> 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）