package com.example.qq_logindemo;

import android.Manifest;
import android.app.Activity;
import android.content.pm.PackageManager;
import android.os.Build;
import android.os.Bundle;
import android.os.Environment;
import android.text.format.Formatter;
import android.util.Log;
import android.view.View;
import android.widget.Button;

import androidx.annotation.Nullable;

import java.io.File;
import java.io.FileOutputStream;

public class SDCardDemoActivity extends Activity implements View.OnClickListener {

    private Button writeDataBtn;
    private static final String TAG="SDCardDemoActivity";
    private Button checkSDCardBtn;
    private Button getFreeSDCardBtn;

    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_sd_card);
        if (Build.VERSION.SDK_INT>=23) {
            int REQUEST_CODE_CONTACT = 101;
            String[] permissions = {Manifest.permission.WRITE_EXTERNAL_STORAGE};
            //验证是否许可权限
            for (String str : permissions) {
                if (this.checkSelfPermission(str) != PackageManager.PERMISSION_GRANTED) {
                    //申请权限
                    this.requestPermissions(permissions, REQUEST_CODE_CONTACT);
                    return;
                }
            }
        }
        initView();
        initOnClickListener();
    }

    private void initOnClickListener() {
        writeDataBtn.setOnClickListener(this);
        checkSDCardBtn.setOnClickListener(this);
        getFreeSDCardBtn.setOnClickListener(this);
    }

    private void initView() {
        getFreeSDCardBtn = this.findViewById(R.id.btn_get_free_sd_card);
        writeDataBtn = this.findViewById(R.id.btn_write_2_sd_card);
        checkSDCardBtn = this.findViewById(R.id.btn_check_sd_card);
    }


    @Override
    public void onClick(View v) {
        if (v==writeDataBtn) {
            //存储到SD卡
            File externalStorageDirectory = Environment.getExternalStorageDirectory();
            Log.d(TAG, "已经存储到 ---> "+externalStorageDirectory.toString());


            File filePath =new File("/storage/self/primary");
            File file =new File(filePath,"info.txt");
            try {
                FileOutputStream fos=new FileOutputStream(file);
                fos.write("heihei".getBytes());
                fos.close();


            } catch (Exception e) {
                e.printStackTrace();
            }
        }
        else if (v == checkSDCardBtn) {
            //检查SD卡是否挂载
            String state = Environment.getExternalStorageState();

            if(state.equals(Environment.MEDIA_MOUNTED)){
                Log.d(TAG, "SD卡已经挂载");
            }else if (state.equals(Environment.MEDIA_UNMOUNTED)){
                Log.d(TAG, " SD卡已经删除");
            }
        }
        else if(v==getFreeSDCardBtn){
            File exFile = Environment.getExternalStorageDirectory();
            Log.d(TAG, "onClick: File Path ==="+exFile.toString());
            long freeSpace =exFile.getFreeSpace();
            //转换单位，把long转化成直观的  kb，Gb等
            String freeText= Formatter.formatFileSize(this,freeSpace);
            Log.d(TAG, "onClick: SD卡空余空间为："+freeText);

        }

    }
}

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical" android:layout_width="match_parent"
    android:layout_height="match_parent">

    <Button
        android:id="@+id/btn_write_2_sd_card"
        android:layout_width="match_parent"
        android:text="存储到SD卡"
        android:layout_height="wrap_content"/>
    <Button
        android:id="@+id/btn_check_sd_card"
        android:layout_width="match_parent"
        android:text="检查SD卡是否挂载"
        android:layout_height="wrap_content"/>
    <Button
        android:id="@+id/btn_get_free_sd_card"
        android:layout_width="match_parent"
        android:text="SD卡剩余空间"
        android:layout_height="wrap_content"/>




</LinearLayout>