Android Gson深入分析
阿新 • • 發佈：2019-01-05
目前解析json有三種工具：org.json（Java常用的解析），fastjson（阿里巴巴工程師開發的），Gson（Google官網出的），解析速度最快的是Gson，下載地址：https://code.google.com/p/google-gson/
什麼是JSON:
JSON即JavaScript Object Natation, 它是一種輕量級的資料交換格式, 與XML一樣, 是廣泛被採用的客戶端和服務端互動的解決方案.
JSON物件:
JSON中物件(Object)以"{"開始, 以"}"結束. 物件中的每一個item都是一個key-value對, 表現為"key:value"的形式, key-value對之間使用逗號分隔. 如:{"name":"coolxing", "age"=24, "male":true, "address":{"street":"huiLongGuan", "city":"beijing", "country":"china"}}. JSON物件的key只能是string型別的, 而value可以是string, number, false, true, null, Object物件甚至是array陣列, 也就是說可以存在巢狀的情況.
JSON陣列:
JSON陣列(array)以"["開始, 以"]"結束, 陣列中的每一個元素可以是string, number, false, true, null, Object物件甚至是array陣列, 陣列間的元素使用逗號分隔. 如["coolxing", 24, {"street":"huiLongGuan", "city":"beijing", "country":"china"}].
Gson的基本使用方法：
通過獲取JsonReader物件解析JSON資料：
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();
}通過把JSON資料對映成一個物件，使用Gson物件的fromJson()方法獲取一個物件陣列進行操作：
建立JSON資料對應的一個POJO物件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物件獲取User物件資料進行相應的操作：
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());
}如果要處理的JSON字串只包含一個JSON物件，則可以直接使用fromJson獲取一個User物件：
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());解析複雜例項：資料格式：
{
"data": {
"partnerteamlist": [
{
"pteamId": 72825,
"ptitle": "隨攝影/共6套服裝/準爸準媽共拍/免費肚畫/底片全送。",
"pteamprice": 288
},
{
"pteamId": 72598,
"ptitle": "隨攝影/拍攝200張/4本相簿/品質拍攝/送全新婚紗。",
"pteamprice": 2888
},
{
"pteamId": 72613,
"ptitle": "隨攝影/送全新婚紗/多外景拍攝/服裝不限數量/絕無二次消費！",
"pteamprice": 3699
},
{
"pteamId": 72638,
"ptitle": "隨攝影/服裝不限數量/高品質拍攝260張/送全新婚紗。",
"pteamprice": 4299
},
{
"pteamId": 72716,
"ptitle": "隨攝影/3組服裝造型/內外景拍攝/完全透明消費！",
"pteamprice": 388
}
],
"liketeamlist": [
{
"lteamId": 65886,
"ltitle": "愛麗爾婚紗攝影/2本相簿/6套服裝造型/拍攝不限最低拍攝150張。",
"limage": "http://img.pztuan.com/upfile/team/2013/0712/201307120257551465.jpg",
"lteamprice": 518,
"lmarketprice": 3999
},
{
"lteamId": 57133,
"ltitle": "陶冶攝影/婚紗閨蜜/6組服裝造型/拍攝不低於120張！",
"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
}實體類（裡面的成員變數和介面的返回值名稱一 一對應才能保證解析正確）：
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 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;
}
}
}
注意上面內部類的運用。
解析：
Gson gson = new Gson();
OtherDetail d = gson.fromJson(jsonString,Detail.class);//取值的時候就從父類一層一層調子類成員（重要）若出現引用異常，請檢視Java內部類設計原則。
如有問題請留言，轉載註明出處。