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

1. 通过Annotation注解来声明。
2. 支持自定义属性名称。
3. 支持包含或排除属性。
4. 支持自定义接口完成解析/生成过程。

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