数据存储——四种存储方式——存储卡的文件操作——私有存储空间与公共存储空间

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<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:padding="5dp" >

    <TextView
        android:id="@+id/tv_path"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:textColor="@color/black"
        android:textSize="17sp" />

</LinearLayout>

package com.example.myapplication;

import android.os.Build;
import android.os.Environment;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.widget.TextView;

public class MainActivity extends AppCompatActivity
{
    @Override
    protected void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        TextView tv_path = findViewById(R.id.tv_path);

        // Android7.0之后默认禁止访问公共存储目录
        // 获取系统的公共存储路径
        String publicPath = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS).toString();

        // 获取当前App的私有存储路径
        String privatePath = getExternalFilesDir(Environment.DIRECTORY_DOWNLOADS).toString();

        boolean isLegacy = true;

        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.Q)
        {
            // Android10的存储空间默认采取分区方式，此处判断是传统方式还是分区方式
            isLegacy = Environment.isExternalStorageLegacy();
        }

        String desc = "系统的公共存储路径位于" + publicPath +
                "\n\n当前App的私有存储路径位于" + privatePath +
                "\n\nAndroid7.0之后默认禁止访问公共存储目录" +
                "\n\n当前App的存储空间采取" + (isLegacy?"传统方式":"分区方式");

        tv_path.setText(desc);
    }
}

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<!-- 存储卡读写 -->
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />

<!-- Android10新增权限MANAGE_EXTERNAL_STORAGE -->
<uses-permission android:name="android.permission.MANAGE_EXTERNAL_STORAGE" />