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();
}

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：（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 }

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;
        }
    }
}

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）