台州网站建设优化/关键词排名优化怎么做

1. JSON介绍

JSON（JavaScript Object Notation）是一种轻量级的数据交换格式，易于阅读和写入，同时也易于机器解析和生成。它基于JavaScript的子集，采用完全独立于语言的文本格式来存储和表示数据。JSON是纯文本，并且完全是语言无关的。

JSON使用JavaScript语法来描述数据结构，但实际上JSON所用的数据结构都是诸如对象、数组、键/值对等的常见数据结构。

* 对象是由键/值对组成的集合，使用大括号 `{}` 表示。
* 数组是由一组值组成的集合，使用方括号 `[]` 表示。

例如：

```json
{
  "name": "张三",
  "age": 30,
  "isStudent": false,
  "subjects": ["数学", "英语", "历史"]
}
```
在这个例子中，我们有一个对象，包含四个键/值对。其中，"name" 的值为 "张三"，"age" 的值为 30，"isStudent" 的值为 false。最后一个键是 "subjects"，其值是一个数组，包含三个字符串元素。

JSON的主要优点是它的简洁性和可读性。在JSON中，对象由花括号 `{}` 包围，而数组由方括号 `[]` 包围。此外，JSON支持多种数据类型，包括字符串、数字、布尔值、null、数组和对象。这使得JSON成为一种非常灵活的数据格式，可以用来表示各种复杂的数据结构。

2. 简单使用

1 .导框架 Gson

Maven 存储库：com.google.code.gson » gson (mvnrepository.com)

dependencies {// https://mvnrepository.com/artifact/com.google.code.gson/gsonimplementation("com.google.code.gson:gson:2.10.1")}

2 .Student.java

package com.example.json;public class Student {// 不要某个属性序列化 transient
//   private transient String name;//序列化时自定义名字 把 name 改成 user_name
//    @SerializedName("user_name")
//    private String name;private String name;private int age;private Score score;public Student(String name, int age, Score score) {this.name = name;this.age = age;this.score = score;}public String getName() {return name;}public void setName(String name) {this.name = name;}public int getAge() {return age;}public void setAge(int age) {this.age = age;}public Score getScore() {return score;}public void setScore(Score score) {this.score = score;}}

3. Score.java

package com.example.json;public class Score {private float math;private float english;private float chinese;private String grade;public Score(float math, float english, float chinese) {this.math = math;this.english = english;this.chinese = chinese;if (math >= 90 && english >= 90 && chinese >= 90) {this.grade = "A";} else if (math >= 80 && english >= 80 && chinese >= 80) {this.grade = "B";} else {this.grade = "C";}}public float getMath() {return math;}public void setMath(float math) {this.math = math;}public float getEnglish() {return english;}public void setEnglish(float english) {this.english = english;}public float getChinese() {return chinese;}public void setChinese(float chinese) {this.chinese = chinese;}public String getGrade() {return grade;}public void setGrade(String grade) {this.grade = grade;}
}

4.MainActivity.java

package com.example.json;import android.os.Bundle;
import android.util.Log;
import androidx.appcompat.app.AppCompatActivity;
import com.google.gson.Gson;
import com.google.gson.reflect.TypeToken;
import org.json.JSONException;
import org.json.JSONObject;
import java.util.ArrayList;
import java.util.List;public class MainActivity extends AppCompatActivity {@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);try {//JSONObject 生成Json 数据JSONObject jsonObject = new JSONObject();jsonObject.put("name", "jack");jsonObject.put("age", 19);String json = jsonObject.toString(); //{"name":"jack","age":19}Log.e("JSON", "Json 数据:" + json.toString());//JSONObject 解析 Json 数据String data = "{ name:\"jack\", age: 19 }";JSONObject js = new JSONObject(data);String name = (String) js.get("name");Integer age = (Integer) js.get("age");Log.e("JSON", "解析 Json 数据---name:" + name + "---age:" + age);//Gson  对象 生成json数据Student student = new Student("jack", 25, new Score(60, 60, 60));String json2 = new Gson().toJson(student);//{"age":25,"name":"jack","score":{"chinese":60.0,"english":60.0,"grade":"C","math":60.0}}Log.e("JSON", "Json 数据:" + json2);//Gson  解析json数据 生成对象String data2 = "{\"age\":25,\"name\":\"jack\",\"score\":{\"chinese\":60.0,\"english\":60.0,\"grade\":\"C\",\"math\":60.0}}";Student student2 = new Gson().fromJson(data2, Student.class);Log.e("JSON", "Json student2 数据:" + student2);//Gson  数组对象 生成json数据Student student3 = new Student("jack", 25, new Score(90, 90, 90));Student student4 = new Student("Tom", 24, new Score(80, 80, 80));Student[] students = new Student[]{student3, student4};String json3 = new Gson().toJson(students);//[{"age":25,"name":"jack","score":{"chinese":90.0,"english":90.0,"grade":"A","math":90.0}},// {"age":24,"name":"Tom","score":{"chinese":80.0,"english":80.0,"grade":"B","math":80.0}}]Log.e("JSON", "Json 数据:" + json3);//  Gson  解析json数据 数组对象String data3 = "[{\"age\":25,\"name\":\"jack\",\"score\":{\"chinese\":90.0,\"english\":90.0,\"grade\":\"A\",\"math\":90.0}}," +"{\"age\":24,\"name\":\"Tom\",\"score\":{\"chinese\":80.0,\"english\":80.0,\"grade\":\"B\",\"math\":80.0}}]";Student[] students2 = new Gson().fromJson(data3, Student[].class);Log.e("JSON", "Json 数据:" + students2);//Gson  List 对象 生成json数据List<Student> studentList = new ArrayList<>();studentList.add(new Student("jack", 25, new Score(90, 90, 90)));studentList.add(new Student("Tom", 24, new Score(80, 80, 80)));String json4 = new Gson().toJson(studentList);//[{"age":25,"name":"jack","score":{"chinese":90.0,"english":90.0,"grade":"A","math":90.0}},// {"age":24,"name":"Tom","score":{"chinese":80.0,"english":80.0,"grade":"B","math":80.0}}]Log.e("JSON", "Json 数据:" + json4);//Gson  解析json数据  生成 List 对象String data4 = "[{\"age\":25,\"name\":\"jack\",\"score\":{\"chinese\":90.0,\"english\":90.0,\"grade\":\"A\",\"math\":90.0}}," +"{\"age\":24,\"name\":\"Tom\",\"score\":{\"chinese\":80.0,\"english\":80.0,\"grade\":\"B\",\"math\":80.0}}]";List<Student> students3 = new Gson().fromJson(data4, new TypeToken<List<Student>>() {}.getType());Log.e("JSON", "Json 数据:" + students3);} catch (JSONException e) {throw new RuntimeException(e);}}
}