JSON快速入门（Java版）--慕课网笔记

第1章 课程概述

1-1 JSON课程介绍

JSON是行业内使用最为广泛的数据传输格式

JSON基础知识

Java中两种常见的JSON处理方式

综合运用

第2章 基础入门

2-1 什么是JSON

JSON是一种与开发语言无关的、轻量级的数据格式。全称是JavaScript Object Notation。

优点：易于人的阅读和编写，易于程序解析与生成

{
"name": "JSON快速入门（Java版）",
"author": "李广",
"content": [
"JSON基础入门",
"常用JSON处理"
],
"time": {
"value": 30,
"unit": "分钟"
}
}

2-2 数据类型表示

数据结构

Object

使用花括号包含键值对结构，Key必须是String类型，value为任何基本类型或数据结构

Array

使用中括号[]来起始，并用逗号，来分割元素。

基本类型

String

number

true

false

null

2-3 JSON数据演示

{
"name": "王小二",
"age": 25.2,
"birthday": "1990-01-01",
"school": "蓝翔",
"major": [
"理发",
"挖掘机"
],
"has_girlfriend": false,
"car": null,
"house": null,
"comment": "这是一个注释"
}

第3章 JSON in Java

3-1 JSON使用

<dependency>
<groupId>org.json</groupId>
<artifactId>json</artifactId>
<version>20090211</version>
</dependency>

public class JsonObjectSample {

public static void main(String[] args) {
jSONObjectSample();
}

//  {
//      "name": "王小二",
//      "age": 25.2,
//      "birthday": "1990-01-01",
//      "school": "蓝翔",
//      "major": [
//          "理发",
//          "挖掘机"
//      ],
//      "has_girlfriend": false,
//      "car": null,
//      "house": null,
//      "comment": "这是一个注释"
//  }

private static void jSONObjectSample() {
JSONObject wangxiaoer = new JSONObject();
Object nullObject = null;
try {
wangxiaoer.put("name", "王小二");
wangxiaoer.put("age", 25.2);
wangxiaoer.put("birthday", "1990-01-01");
wangxiaoer.put("school", "蓝翔");
wangxiaoer.put("major", new String[] {"理发","挖掘机"});
wangxiaoer.put("has_girlfriend", false);
wangxiaoer.put("car", nullObject);
wangxiaoer.put("house", nullObject);
wangxiaoer.put("comment", "这是一个注释");
System.out.println(wangxiaoer.toString());
} catch (JSONException e) {
e.printStackTrace();
}

}

}

3-2 使用Map 构建JSON

private static void createJsonByMap() {
Map<String,Object> wangxiaoer = new HashMap<String,Object>();
Object nullObject = null;
wangxiaoer.put("name", "王小二");
wangxiaoer.put("age", 25.2);
wangxiaoer.put("birthday", "1990-01-01");
wangxiaoer.put("school", "蓝翔");
wangxiaoer.put("major", new String[] { "理发", "挖掘机" });
wangxiaoer.put("has_girlfriend", false);
wangxiaoer.put("car", nullObject);
wangxiaoer.put("house", nullObject);
wangxiaoer.put("comment", "这是一个注释");

System.out.println(new JSONObject(wangxiaoer).toString());
}

3-3 使用Java Bean构建对象

private static void createJsonByBean() {
Diaosi wangxiaoer = new Diaosi();
wangxiaoer.setName("王小二");
wangxiaoer.setAge(25.2);
wangxiaoer.setBirthday("1990-01-01");
wangxiaoer.setSchool("蓝翔");
wangxiaoer.setMajor(new String[] { "理发", "挖掘机" });
wangxiaoer.setHas_girlfriend(false);
wangxiaoer.setCar(null);
wangxiaoer.setHouse(null);
wangxiaoer.setComment("这是一个注释");
System.out.println(new JSONObject(wangxiaoer));
}

public class Diaosi {

private String name;
private String school;
private boolean has_girlfriend;
private double age;
private Object car;
private Object house;
private String[] major;
private String comment;
private String birthday;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getSchool() {
return school;
}
public void setSchool(String school) {
this.school = school;
}
public boolean isHas_girlfriend() {
return has_girlfriend;
}
public void setHas_girlfriend(boolean has_girlfriend) {
this.has_girlfriend = has_girlfriend;
}
public double getAge() {
return age;
}
public void setAge(double age) {
this.age = age;
}
public Object getCar() {
return car;
}
public void setCar(Object car) {
this.car = car;
}
public Object getHouse() {
return house;
}
public void setHouse(Object house) {
this.house = house;
}
public String[] getMajor() {
return major;
}
public void setMajor(String[] major) {
this.major = major;
}
public String getComment() {
return comment;
}
public void setComment(String comment) {
this.comment = comment;
}
public String getBirthday() {
return birthday;
}
public void setBirthday(String birthday) {
this.birthday = birthday;
}

}

3-4 从文件读取JSON

{
"birthday": "1990-01-01",
"major": [
"理发",
"挖掘机"
],
"school": "蓝翔",
"car": null,
"name": "王小二",
"has_girlfriend": false,
"comment": "这是一个注释",
"house": null,
"age": 25.2
}

public class ReadJSONSample {

public static void main(String[] args) throws IOException, JSONException {
File file = new File(ReadJSONSample.class.getResource("wangxiaoer.json").getFile());
String content = FileUtils.readFileToString(file);
JSONObject jsonObject = new JSONObject(content);
System.out.println("姓名是："+jsonObject.getString("name"));
System.out.println("年龄"+jsonObject.getDouble("age"));
System.out.println("有没有女朋友？"+jsonObject.getBoolean("has_girlfriend"));
JSONArray majorArray = jsonObject.getJSONArray("major");
for(int i = 0;i < majorArray.length(); i++) {
String m = (String)majorArray.get(i);
System.out.println("专业-" + (i+1) + m);
}
}
}

3-5 从文件读取JSON 判断null

public class ReadJSONSample {

public static void main(String[] args) throws IOException, JSONException {
File file = new File(ReadJSONSample.class.getResource("wangxiaoer.json").getFile());
String content = FileUtils.readFileToString(file);
JSONObject jsonObject = new JSONObject(content);
if(!jsonObject.isNull("name")) {
System.out.println("姓名是："+jsonObject.getString("name"));
}
if(!jsonObject.isNull("nickname")) {
System.out.println("姓名是："+jsonObject.getString("nickname"));
}
System.out.println("年龄"+jsonObject.getDouble("age"));
System.out.println("有没有女朋友？"+jsonObject.getBoolean("has_girlfriend"));
JSONArray majorArray = jsonObject.getJSONArray("major");
for(int i = 0;i < majorArray.length(); i++) {
String m = (String)majorArray.get(i);
System.out.println("专业-" + (i+1) + m);
}
}
}

3-6 JSON 总结

Json中没有Date类型

通过JSON不能将JavaBean反解析回来

第4章 第四章 GSON的使用

4-1 GSON介绍

google-gson

4-2 GSON生成JSON数据

public class GsonCreateSample {

public static void main(String[] args) {

Diaosi wangxiaoer = new Diaosi();
wangxiaoer.setName("王小二");
wangxiaoer.setAge(25.2);
wangxiaoer.setBirthday("1990-01-01");
wangxiaoer.setSchool("蓝翔");
wangxiaoer.setMajor(new String[] { "理发", "挖掘机" });
wangxiaoer.setHas_girlfriend(false);
wangxiaoer.setCar(null);
wangxiaoer.setHouse(null);
wangxiaoer.setComment("这是一个注释");

Gson gson = new Gson();
System.out.println(gson.toJson(wangxiaoer));
}
}

public class Diaosi {

@SerializedName("NAME")
private String name;
private String school;
private boolean has_girlfriend;
private double age;
private Object car;
private Object house;
private String[] major;
private String comment;
private String birthday;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getSchool() {
return school;
}
public void setSchool(String school) {
this.school = school;
}
public boolean isHas_girlfriend() {
return has_girlfriend;
}
public void setHas_girlfriend(boolean has_girlfriend) {
this.has_girlfriend = has_girlfriend;
}
public double getAge() {
return age;
}
public void setAge(double age) {
this.age = age;
}
public Object getCar() {
return car;
}
public void setCar(Object car) {
this.car = car;
}
public Object getHouse() {
return house;
}
public void setHouse(Object house) {
this.house = house;
}
public String[] getMajor() {
return major;
}
public void setMajor(String[] major) {
this.major = major;
}
public String getComment() {
return comment;
}
public void setComment(String comment) {
this.comment = comment;
}
public String getBirthday() {
return birthday;
}
public void setBirthday(String birthday) {
this.birthday = birthday;
}

}

4-3 生成JSON数据

public class GsonCreateSample {

public static void main(String[] args) {

Diaosi wangxiaoer = new Diaosi();
wangxiaoer.setName("王小二");
wangxiaoer.setAge(25.2);
wangxiaoer.setBirthday("1990-01-01");
wangxiaoer.setSchool("蓝翔");
wangxiaoer.setMajor(new String[] { "理发", "挖掘机" });
wangxiaoer.setHas_girlfriend(false);
wangxiaoer.setCar(null);
wangxiaoer.setHouse(null);
wangxiaoer.setComment("这是一个注释");
wangxiaoer.setIgnore("不要看见我");

GsonBuilder gsonBuilder = new GsonBuilder();
gsonBuilder.setPrettyPrinting();
gsonBuilder.setFieldNamingStrategy(new FieldNamingStrategy(){

public String translateName(Field f) {
if(f.getName().equals("name")) {
return "NAME";
}
return f.getName();
}
});
Gson gson = gsonBuilder.create();
System.out.println(gson.toJson(wangxiaoer));
}
}

public class Diaosi {

private String name;
private String school;
private boolean has_girlfriend;
private double age;
private Object car;
private Object house;
private String[] major;
private String comment;
private String birthday;
private transient String ignore;

public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getSchool() {
return school;
}
public void setSchool(String school) {
this.school = school;
}
public boolean isHas_girlfriend() {
return has_girlfriend;
}
public void setHas_girlfriend(boolean has_girlfriend) {
this.has_girlfriend = has_girlfriend;
}
public double getAge() {
return age;
}
public void setAge(double age) {
this.age = age;
}
public Object getCar() {
return car;
}
public void setCar(Object car) {
this.car = car;
}
public Object getHouse() {
return house;
}
public void setHouse(Object house) {
this.house = house;
}
public String[] getMajor() {
return major;
}
public void setMajor(String[] major) {
this.major = major;
}
public String getComment() {
return comment;
}
public void setComment(String comment) {
this.comment = comment;
}
public String getBirthday() {
return birthday;
}
public void setBirthday(String birthday) {
this.birthday = birthday;
}
public String getIgnore() {
return ignore;
}
public void setIgnore(String ignore) {
this.ignore = ignore;
}

}

4-4 GSON解析

public class GsonReadSample {

public static void main(String[] args) throws IOException {
File file = new File(ReadJSONSample.class.getResource("../jsonTest/wangxiaoer.json").getFile());
String content = FileUtils.readFileToString(file);
Gson gson = new Gson();
Diaosi wangxiaoer = gson.fromJson(content, Diaosi.class);
System.out.println(wangxiaoer.toString());
}

}

public class Diaosi {

private String name;
private String school;
private boolean has_girlfriend;
private double age;
private Object car;
private Object house;
private String[] major;
private String comment;
private String birthday;
private transient String ignore;

public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getSchool() {
return school;
}
public void setSchool(String school) {
this.school = school;
}
public boolean isHas_girlfriend() {
return has_girlfriend;
}
public void setHas_girlfriend(boolean has_girlfriend) {
this.has_girlfriend = has_girlfriend;
}
public double getAge() {
return age;
}
public void setAge(double age) {
this.age = age;
}
public Object getCar() {
return car;
}
public void setCar(Object car) {
this.car = car;
}
public Object getHouse() {
return house;
}
public void setHouse(Object house) {
this.house = house;
}
public String[] getMajor() {
return major;
}
public void setMajor(String[] major) {
this.major = major;
}
public String getComment() {
return comment;
}
public void setComment(String comment) {
this.comment = comment;
}
public String getBirthday() {
return birthday;
}
public void setBirthday(String birthday) {
this.birthday = birthday;
}
public String getIgnore() {
return ignore;
}
public void setIgnore(String ignore) {
this.ignore = ignore;
}
@Override
public String toString() {
return "Diaosi [name=" + name + ", school=" + school + ", has_girlfriend=" + has_girlfriend + ", age=" + age
+ ", car=" + car + ", house=" + house + ", major=" + Arrays.toString(major) + ", comment=" + comment
+ ", birthday=" + birthday + "]";
}

}

4-5 GSON解析 带日期转换

public class GsonReadSample {

public static void main(String[] args) throws IOException {
File file = new File(ReadJSONSample.class.getResource("../jsonTest/wangxiaoer.json").getFile());
String content = FileUtils.readFileToString(file);
Gson gson = new GsonBuilder().setDateFormat("yyyy-MM-dd").create();
DiaosiWithBirthday wangxiaoer = gson.fromJson(content, DiaosiWithBirthday.class);
System.out.println(wangxiaoer.getBirthday().toLocaleString());
}

}

public class DiaosiWithBirthday {

private String name;
private String school;
private boolean has_girlfriend;
private double age;
private Object car;
private Object house;
private String[] major;
private String comment;
private Date birthday;
private transient String ignore;

public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getSchool() {
return school;
}
public void setSchool(String school) {
this.school = school;
}
public boolean isHas_girlfriend() {
return has_girlfriend;
}
public void setHas_girlfriend(boolean has_girlfriend) {
this.has_girlfriend = has_girlfriend;
}
public double getAge() {
return age;
}
public void setAge(double age) {
this.age = age;
}
public Object getCar() {
return car;
}
public void setCar(Object car) {
this.car = car;
}
public Object getHouse() {
return house;
}
public void setHouse(Object house) {
this.house = house;
}
public String[] getMajor() {
return major;
}
public void setMajor(String[] major) {
this.major = major;
}
public String getComment() {
return comment;
}
public void setComment(String comment) {
this.comment = comment;
}
public String getIgnore() {
return ignore;
}
public void setIgnore(String ignore) {
this.ignore = ignore;
}

public Date getBirthday() {
return birthday;
}
public void setBirthday(Date birthday) {
this.birthday = birthday;
}
@Override
public String toString() {
return "Diaosi [name=" + name + ", school=" + school + ", has_girlfriend=" + has_girlfriend + ", age=" + age
+ ", car=" + car + ", house=" + house + ", major=" + Arrays.toString(major) + ", comment=" + comment
+ ", birthday=" + birthday + "]";
}

}

4-6 集合类解析

public class GsonReadSample {

public static void main(String[] args) throws IOException {
File file = new File(ReadJSONSample.class.getResource("../jsonTest/wangxiaoer.json").getFile());
String content = FileUtils.readFileToString(file);
Gson gson = new GsonBuilder().setDateFormat("yyyy-MM-dd").create();
DiaosiWithBirthday wangxiaoer = gson.fromJson(content, DiaosiWithBirthday.class);
System.out.println(wangxiaoer.getBirthday().toLocaleString());

System.out.println(wangxiaoer.getMajor());
System.out.println(wangxiaoer.getMajor().getClass());
}

}

public class DiaosiWithBirthday {

private String name;
private String school;
private boolean has_girlfriend;
private double age;
private Object car;
private Object house;
private List<String> major;
private String comment;
private Date birthday;
private transient String ignore;

public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getSchool() {
return school;
}
public void setSchool(String school) {
this.school = school;
}
public boolean isHas_girlfriend() {
return has_girlfriend;
}
public void setHas_girlfriend(boolean has_girlfriend) {
this.has_girlfriend = has_girlfriend;
}
public double getAge() {
return age;
}
public void setAge(double age) {
this.age = age;
}
public Object getCar() {
return car;
}
public void setCar(Object car) {
this.car = car;
}
public Object getHouse() {
return house;
}
public void setHouse(Object house) {
this.house = house;
}
public String getComment() {
return comment;
}
public void setComment(String comment) {
this.comment = comment;
}
public String getIgnore() {
return ignore;
}
public void setIgnore(String ignore) {
this.ignore = ignore;
}

public Date getBirthday() {
return birthday;
}
public void setBirthday(Date birthday) {
this.birthday = birthday;
}
public List<String> getMajor() {
return major;
}
public void setMajor(List<String> major) {
this.major = major;
}

}

4-7 总结

JSON时Android SDK官方的库

GSON适用于服务端开发

GSON比JSON功能更强大

关于JSON库的总结

功能：映射Java Object与json格式数据

通过Annotation注解来声明。

支持自定义属性名称。

支持包含或排除属性。

支持自定义接口完成解析/生成过程。

《JSON快速入门（Java版）》视频地址