android 12如何对sd卡进行读写文件

冷不防 2024-03-30 13:12 47阅读 0赞

#### 重点关于android 12的sd卡读写以及Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY\_DOWNLOADS)的使用 ####

> 首先要有对sd卡读写的权限 android 12 申请权限大全

<uses-permission android:name="android.permission.INTERNET" /> 
        <uses-permission android:name="android.permission.RECEIVE_BOOT_COMPLETED" />
        <uses-permission android:name="android.permission.WAKE_LOCK" />
        <uses-permission android:name="android.permission.DISABLE_KEYGUARD" /> 
        <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" /> 
        
        <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
        <uses-permission
            android:name="android.permission.MOUNT_UNMOUNT_FILESYSTEMS"
            tools:ignore="ProtectedPermissions" /> 
        <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" /> 
        <uses-permission android:name="android.permission.SYSTEM_ALERT_WINDOW" />
        <uses-permission android:name="android.permission.ACCESS_WIFI_STATE" />
    
        <uses-permission android:name="android.permission.READ_PHONE_STATE" />
        <uses-permission android:name="android.permission.CHANGE_WIFI_MULTICAST_STATE" />
        <uses-permission android:name="android.permission.CHANGE_WIFI_STATE" />
        <uses-permission android:name="android.permission.CHANGE_NETWORK_STATE" />
        <uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
    
        <uses-permission android:name="android.permission.READ_MEDIA_IMAGES" />
        <uses-permission android:name="android.permission.MANAGE_EXTERNAL_STORAGE" />

> 然后需要在AndroidManifest.xml文件中<application 加入  
> android:requestLegacyExternalStorage=“true”

> 其次在activity中动态申请权限

@Override
        protected void onCreate(Bundle savedInstanceState) {
        
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main);
    
            
    
    if (ContextCompat.checkSelfPermission(this, Manifest.permission.READ_EXTERNAL_STORAGE)
                    != PackageManager.PERMISSION_GRANTED) {
        
                // Permission is not granted, request it
                int MY_PERMISSIONS_REQUEST_READ_EXTERNAL_STORAGE = 1;
                ActivityCompat.requestPermissions(this,
                        new String[]{
        Manifest.permission.READ_EXTERNAL_STORAGE},
                        MY_PERMISSIONS_REQUEST_READ_EXTERNAL_STORAGE);
            } else {
        
                // Permission has already been granted, read the file
                video   = ImageSaverUtil.readImageFromSDCard("video");
            }
    
      
        }

package com.example.zhuoyuadvert.utils;
    
    import static org.greenrobot.eventbus.EventBus.TAG;
    
    import android.content.Context;
    import android.os.Build;
    import android.os.Environment;
    import android.util.Log;
    
    import java.io.File;
    import java.io.FileOutputStream;
    import java.io.InputStream;
    import java.io.OutputStream;
    import java.net.URL;
    import java.util.ArrayList;
    import java.util.List;
    import java.util.concurrent.locks.ReentrantLock;
    
    public class ImageSaverUtil {
        
        private static ReentrantLock lock = new ReentrantLock(); 
        // 写入sd卡需要保证线程使用
        public static void saveImageToInternalStorage(Context context, List<String> imageUrl, String folderName, String name) {
        
            new Thread(() -> {
        
                lock.lock();
                String savedImagePath = null;
                if (Build.VERSION.SDK_INT >= 29) {
        
                    File folder = new File(Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS), folderName);
                    if (!folder.exists()) {
        
                        folder.mkdirs();
                    } else {
        
                        deleteFiles(folder);
                    }
                    for (int i = 0; i < imageUrl.size(); i++) {
        
                        try {
        
                            // Get the input stream from the URL
                            InputStream inputStream = new URL(imageUrl.get(i)).openStream();
                            // Create a request to save the image to the app's internal storage
                            File imageFile = new File(folder, folderName + System.currentTimeMillis() + name);
                            OutputStream outputStream = new FileOutputStream(imageFile);
    
                            // Copy the image from the input stream to the output stream
                            byte[] buffer = new byte[1024];
                            int bytesRead;
                            while ((bytesRead = inputStream.read(buffer)) != -1) {
        
                                outputStream.write(buffer, 0, bytesRead);
                            }
    
                            // Close the streams
                            outputStream.close();
                            inputStream.close();
    
                            savedImagePath = imageFile.getAbsolutePath();
                        } catch (Exception e) {
        
                            e.printStackTrace();
                        }
                    }
                    // Use the Scoped Storage APIs on Android 12 and higher
                    Log.d("ImageSaver", "Saved image to path: " + savedImagePath);
                }
               lock.unlock();
    
            }).start();
              
        }
    
    	//每次写入前有需要可以先把文件清空
        private static boolean deleteFiles(File file) {
        
            try {
        
                if (file.isDirectory()) {
         //判断是否是文件夹
                    File[] files = file.listFiles();//遍历文件夹里面的所有的
                    for (int i = 0; i < files.length; i++) {
        
                        Log.e(TAG, "删除文件>>>>>> " + files[i].toString());
                        deleteFiles(files[i]); //删除
                    }
                } else {
        
                    boolean delete = file.delete();
                    System.out.println(delete);
                }
                System.gc();//系统回收垃圾
                return true;
            } catch (Exception e) {
        
                Log.e(TAG, "删除报错！！！: " + e.toString());
                return false;
    
            }
    
        }
    	//读取sd卡内容
        public static List<String> readImageFromSDCard( String folderName) {
        
    
    
            List<String> bitmaps = new ArrayList<>();
            try {
        
                // Get  path
                // Create a request to save the image to the app's internal storage
                File folder = new File(Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS), folderName);
                File[] files = folder.listFiles();
                List<String> imagePaths = new ArrayList<>();
                if (files != null) {
        
                    for (int i = 0; i < files.length; i++) {
        
                        imagePaths.add(files[i].getPath());
                        File imageFile = new File(files[i].getPath());
                        //Bitmap image = BitmapFactory.decodeFile(imageFile.getAbsolutePath());
                        bitmaps.add(imageFile.getAbsolutePath());
                    }
                }
                return bitmaps;
            } catch (Exception e) {
        
                e.printStackTrace();
                return null;
            }
        }
    }