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JSON的基本语法

1.JSon的四个基本规则

(1)并列的数据之间用逗号(,)分隔

(2)映射用冒号(:)表示

(3)并列数据的集合(数组)用方括号([])表示

(4)映射的集合(对象)用大括号({})表示

2.缺点

(1)要求是unicode,否则会出现乱码

(2)语法过于严禁，必须遵循json语法四个原则

3.数据类型

(1)数据结构：object、array

(2)基本类型：string、number、true、false、null

(3)key必须是String类型的,value是任何基本类型或数据结构

实例代码：

{

"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,

"time":{

"value":30,

"unit":"分钟"

}

}

Android Studio创建json文件：

(1)在assets目录下新建text.json文件，内容如下：

{

"languages":[

{"id":1,"ide":"Eclipse","name":"Java"},

{"id":2,"ide":"XCode","name":"Swift"},

{"id":3,"ide":"Visual Studio","name":"C#"},

],

"cat":"it"

}

(2)读取json和创建json

package json.android.com.jsontest;

import android.app.Activity;

import android.os.Bundle;

import android.util.Log;

import org.json.JSONArray;

import org.json.JSONException;

import org.json.JSONObject;

import java.io.BufferedReader;

import java.io.IOException;

import java.io.InputStream;

import java.io.InputStreamReader;

import java.io.UnsupportedEncodingException;

public class MainActivity extends Activity {

@Override

protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.activity_main);

//Json数据的读写

try {

// InputStream is = this.getAssets().open("test.json");//eclipse

InputStream is = MainActivity.this.getClass().getClassLoader().getResourceAsStream("assets/" + "text.json");//android studio

BufferedReader bufr = new BufferedReader(new InputStreamReader(is));

String line;

StringBuilder builder = new StringBuilder();

while ((line = bufr.readLine()) != null) {

builder.append(line);

}

is.close();

bufr.close();

try {

JSONObject root = new JSONObject(builder.toString());

Log.d("info","cat=" + root.getString("cat"));

JSONArray array = root.getJSONArray("languages");

for (int i = 0; i < array.length(); i++) {

JSONObject lan = array.getJSONObject(i);

Log.d("info","-----------------------");

Log.d("info","id=" + lan.getInt("id"));

Log.d("info","ide=" + lan.getString("ide"));

Log.d("info","name=" + lan.getString("name"));

}

} catch (JSONException e) {

e.printStackTrace();

}

} catch (UnsupportedEncodingException e) {

e.printStackTrace();

} catch (IOException e) {

e.printStackTrace();

}

//Json数据的创建

try {

JSONObject root = new JSONObject();

root.put("cat", "it");

JSONObject lan1 = new JSONObject();

lan1.put("id", 1);

lan1.put("ide", "Eclipse");

lan1.put("name", "Java");

JSONObject lan2 = new JSONObject();

lan2.put("id", 2);

lan2.put("ide", "XCode");

lan2.put("name", "Swift");

JSONObject lan3 = new JSONObject();

lan3.put("id", 3);

lan3.put("ide", "Visual Studio");

lan3.put("name", "C#");

JSONArray array = new JSONArray();

array.put(lan1);

array.put(lan2);

array.put(lan3);

root.put("languages", array);

Log.d("info",root.toString());

} catch (JSONException e) {

e.printStackTrace();

}

}

}

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