如何将图像复制到SD卡上的现有目录？

Question

我想要的图像文件复制与此代码：

InputStream fileInputStream = null; 
OutputStream fileOutputStream = null; 
String inPath = "/storage/emulated/0/Pictures/MyImage.jpg"; 
String outPath = "/storage/extSdCard/MyFolder/MyImage.jpg"; 
    try { 
    verifyStoragePermissions(this); 
    fileInputStream = new FileInputStream(new File(inPath)); 
    File outputFile = new File(outPath); 
     if (!outputFile.exists()) { 
      try { 
       outPutFile.createNewFile(); 
      } catch (IOException e) { 
       e.printStackTrace(); 
      } 
     } 
    fileOutputStream = new FileOutputStream(outputFile); 

    byte[] buffer = new byte[1024]; 
    int read; 
    while ((read = fileInputStream.read(buffer)) != -1) { 
     fileOutputStream.write(buffer, 0, read); 
    } 
    fileInputStream.close(); 
    fileInputStream = null; 
    fileOutputStream.flush(); 
    fileOutputStream.close(); 
    fileOutputStream = null; 

    } catch (Exception e) { 
    Log.e("tag", e.getMessage()); 
    } 

而这是用于在SDK> = 23

// Storage Permissions 
private static final int REQUEST_EXTERNAL_STORAGE = 1; 
private static String[] PERMISSIONS_STORAGE = { 
     Manifest.permission.READ_EXTERNAL_STORAGE, 
     Manifest.permission.WRITE_EXTERNAL_STORAGE 
}; 

/** 
* Checks if the app has permission to write to device storage 
* 
* If the app does not has permission then the user will be prompted to grant permissions 
* 
* @param activity 
*/ 
public static void verifyStoragePermissions(Activity activity) { 
    // Check if we have write permission 
    int permission = ActivityCompat.checkSelfPermission(activity, Manifest.permission.WRITE_EXTERNAL_STORAGE); 

    if (permission != PackageManager.PERMISSION_GRANTED) { 
     // We don't have permission so prompt the user 
     ActivityCompat.requestPermissions(
       activity, 
       PERMISSIONS_STORAGE, 
       REQUEST_EXTERNAL_STORAGE 
     ); 
    } 
} 

而且结果验证存储权限的方法是这样的错误发生在达到buffer行之前。

Unable to decode stream: java.io.FileNotFoundException: /storage/extSdCard/MyFolder/MyImage.jpg: open failed: ENOENT (No such file or directory) 

我有SD卡和画廊的应用程序上MyFolder在我的设备将图像复制到该目录中没有任何问题。

注意：权限是在清单中（在应用程序标记前的正确位置）和内部活动（对于skd> = 23）中授予的。

EDITS：

1. 实现创建fileOutputStream之前文件的建议（没有帮助）。

2. 降低targetSdkVersion以超过与权限相关的任何可能的问题，但仍然没有成功。

targetSdkVersion 22

创建这样File：

File outFile = new File("/storage/extSdCard", "MyFolder/MyImage.jpg");

也取得了不结果。

我测试它的Android版本22

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" /> 
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" /> 

Answer 1

这是我使用SAF来完成工作的方式。

private void newcopyFile(File fileInput, String outputParentPath, 
        String mimeType, String newFileName) { 

DocumentFile documentFileGoal = DocumentFile.fromTreeUri(this, treeUri); 

String[] parts = outputParentPath.split("\\/"); 
for (int i = 3; i < parts.length; i++) { //ex: parts:{"", "storage", "extSdCard", "MyFolder", "MyFolder", "MyFolder"} 
    if (documentFileGoal != null) { 
     documentFileGoal = documentFileGoal.findFile(parts[i]); 
    } 
} 
if (documentFileGoal == null) { 
    Toast.makeText(MainActivity.this, "Directory not found", Toast.LENGTH_SHORT).show(); 
    return; 
} 

DocumentFile documentFileNewFile = documentFileGoal.createFile(mimeType, newFileName); 

InputStream inputStream = null; 
OutputStream outputStream = null; 
try { 
    outputStream = getContentResolver().openOutputStream(documentFileNewFile.getUri()); 
    inputStream = new FileInputStream(fileInput); 
} catch (FileNotFoundException e) { 
    e.printStackTrace(); 
} 
try { 
    if (outputStream != null) { 
     byte[] buffer = new byte[1024]; 
     int read; 
     if (inputStream != null) { 
      while ((read = inputStream.read(buffer)) != -1) { 
       outputStream.write(buffer, 0, read); 
      } 
     } 
     if (inputStream != null) { 
      inputStream.close(); 
     } 
     inputStream = null; 
     outputStream.flush(); 
     outputStream.close(); 
     outputStream = null; 
    } 
} catch (IOException e) { 
    e.printStackTrace(); 
} 
} 

Answer 2

您需要先创建文件，FileOutputStream会抛出异常，如果该文件不存在FileNotFoundException

File outputFile = new File(outPath); 
file.createNewFile(); 
fileOutputStream = new FileOutputStream(outputFile); 

Answer 3

如果您在您的应用gradle文件中使用targetSdkVersion 23（或更高版本），则需要明确请求权限（可以放入Activity的onCreate方法或a吨监听方法），这样的...

private static final int CODE_WRITE_EXTERNAL = 10; 
    if (ContextCompat.checkSelfPermission(this,Manifest.permission.WRITE_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED) { 
       if (ActivityCompat.shouldShowRequestPermissionRationale(this, Manifest.permission.WRITE_EXTERNAL_STORAGE)) { 
        Log.d(TAG, "onCreate: " + "Show explanation"); 
        ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE}, CODE_WRITE_EXTERNAL); 
       } else { 
        ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE}, CODE_WRITE_EXTERNAL); 
       } 
      } else { 
       Log.d(TAG, "onCreate: " + "Permission already granted!"); 
       //Call your method to save the file 
      } 

然后，你需要实现下一个回调方法

@Override 
    public void onRequestPermissionsResult(int requestCode, String permissions[], int[] grantResults) { 
     switch (requestCode) { 
      case CODE_WRITE_EXTERNAL : { 
       if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) { 
        Log.d(TAG, "onRequestPermissionsResult: Good to go!"); 
        //Call your mehotd here 
       } else { 
        Log.d(TAG, "onRequestPermissionsResult: Bad user"); 
       } 
      } 
     } 
    }