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