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）