Android 使用Gson解析json案例详解

一、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/

二、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.

三、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.

四、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”}].

五、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();}
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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;    }}
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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());}
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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());
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解析复杂实例：

数据格式：（对于格式比较乱json数据，我们可以使用HIJSON工具进行代码的格式化！）

{    "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}
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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）：

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;        }    }}
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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）
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