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 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。

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

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

来自：http://blog.csdn.net/rain_butterfly/article/details/38404293