我已经阅读了几个问题和 Android Guide保存文件,但不知道哪里出了问题。
我正在尝试将图像保存到 SD 卡图片目录中的新文件夹中。
我有<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
在 list 中。
此方法抛出异常
String storageStage = Environment.getExternalStorageState();
File mediaStorageDir = new File(Environment.getExternalStoragePublicDirectory (
Environment.DIRECTORY_PICTURES),"/WordResolver");
mediaStorageDir.mkdirs();
if (! mediaStorageDir.exists()){
if(! mediaStorageDir.mkdirs()) {
Log.d("WordResolver", "Failed to create directory");
return null;
}
}
//Creating Media File Name
String timeStamp = new SimpleDateFormat("yyyyMMdd_HHmmss").format(new Date());
File mediaFile;
if (type == MEDIA_TYPE_IMAGE) {
mediaFile = new File (mediaStorageDir.getPath() + File.separator + "IMG_WR" +
timeStamp + ".jpg");
} else {
return null;
}
return mediaFile;
}
它抛出的错误是 NullPointerException。这是一个奇怪的问题的原因是因为程序试图保存在内部存储而不是 SD 卡中,如下所示:
我的印象是Environment.getExternalStoragePublicDirectory
会保存到外部存储吗?
这是堆栈跟踪:
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.aaron.wordresolver/com.example.aaron.wordresolver.cameraShot}: java.lang.NullPointerException: file
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2416)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476)
at android.app.ActivityThread.-wrap11(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:148)
at android.app.ActivityThread.main(ActivityThread.java:5417)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
Caused by: java.lang.NullPointerException: file
at android.net.Uri.fromFile(Uri.java:452)
at com.example.aaron.wordresolver.cameraShot.getOutputMediaFileUri(cameraShot.java:55)
at com.example.aaron.wordresolver.cameraShot.onCreate(cameraShot.java:45)
at android.app.Activity.performCreate(Activity.java:6237)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1107)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2369)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476)
at android.app.ActivityThread.-wrap11(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:148)
at android.app.ActivityThread.main(ActivityThread.java:5417)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
如果重要的话,我正在使用模拟设备!
干杯
最佳答案
Where as I was under the impression that Environment.getExternalStoragePublicDirectory would save to the external storage?
是的。您可以通过查看路径来判断。目前使用的设备大约为零,其中 external storage是“SD 卡”。 SD卡是removable storage ,并且在 Android 4.4+ 上无法通过文件系统访问它。
关于堆栈跟踪,您需要确定您的问题是否与 mediaStorageDir
或 type
有关,因为在这两种情况下您都会遇到相同的症状。请记住,如果您的 targetSdkVersion
为 23 或更高,并且您运行的是 Android 6.0 或更高版本,you need to request your external storage permission at runtime .
关于java - 保存文件选择内部路径而不是 SD 卡路径。,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/37324861/