自从KitKat以来,我在Android和SD卡上读了很多东西。但最终,我找不到明确的全球答案,所以我会试着从你们那里得到相关的答案。有没有什么办法可以在Android上的SD卡上随意写字?
我想编写一个文件,文本文件,在SD卡上的任意位置。
让我们专注于Android的6这个简单的例子。写权限出现在清单
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
我有这样的helper方法
private void writeFile(File parent)
{
try
{
File f = new File(parent, "test.txt");
OutputStreamWriter outputStreamWriter = new OutputStreamWriter(new FileOutputStream(f));
outputStreamWriter.write("test");
outputStreamWriter.close();
Log.i(TAG, "File created : " + f.getAbsolutePath());
}
catch (IOException e)
{
Log.e(TAG, "File write failed", e);
}
}
而且在测试活动:
if (Build.VERSION.SDK_INT >= 23)
{
if (ContextCompat.checkSelfPermission(MainActivity.this, android.Manifest.permission.WRITE_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED
|| ContextCompat.checkSelfPermission(MainActivity.this, android.Manifest.permission.READ_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED)
{
ActivityCompat.requestPermissions(MainActivity.this, new String[] {
android.Manifest.permission.WRITE_EXTERNAL_STORAGE,
android.Manifest.permission.READ_EXTERNAL_STORAGE }, 1);
}
else
{
File path = getExternalFilesDirs(Environment.DIRECTORY_PICTURES)[1];
writeFile(path);
path = getExternalFilesDirs(null)[1];
writeFile(path);
writeFile(new File("/storage/3635-3533/"));
}
}
/\ 是为第三测试的路径!通过检索正确的SD卡路径硬编码在主体这里 /!\
首先推出,permission asked,一切正常(对不起法国设备)
第二次发射,这里是结果
10-03 12:40:10.414: I/TESTSDCARD(26006): File created : /storage/3635-3533/Android/data/com.example.testsdcard/files/Pictures/test.txt
10-03 12:40:10.415: I/TESTSDCARD(26006): File created : /storage/3635-3533/Android/data/com.example.testsdcard/files/test.txt
10-03 12:40:10.426: E/TESTSDCARD(26006): File write failed
10-03 12:40:10.426: E/TESTSDCARD(26006): java.io.FileNotFoundException: /storage/3635-3533/test.txt: open failed: EACCES (Permission denied)
10-03 12:40:10.426: E/TESTSDCARD(26006): at libcore.io.IoBridge.open(IoBridge.java:459)
10-03 12:40:10.426: E/TESTSDCARD(26006): at java.io.FileOutputStream.<init>(FileOutputStream.java:87)
10-03 12:40:10.426: E/TESTSDCARD(26006): at java.io.FileOutputStream.<init>(FileOutputStream.java:72)
10-03 12:40:10.426: E/TESTSDCARD(26006): at com.example.testsdcard.MainActivity.writeFile(MainActivity.java:61)
10-03 12:40:10.426: E/TESTSDCARD(26006): at com.example.testsdcard.MainActivity.onCreate(MainActivity.java:50)
10-03 12:40:10.426: E/TESTSDCARD(26006): at android.app.Activity.performCreate(Activity.java:6367)
10-03 12:40:10.426: E/TESTSDCARD(26006): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1110)
10-03 12:40:10.426: E/TESTSDCARD(26006): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2397)
10-03 12:40:10.426: E/TESTSDCARD(26006): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2504)
10-03 12:40:10.426: E/TESTSDCARD(26006): at android.app.ActivityThread.access$900(ActivityThread.java:165)
10-03 12:40:10.426: E/TESTSDCARD(26006): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1368)
10-03 12:40:10.426: E/TESTSDCARD(26006): at android.os.Handler.dispatchMessage(Handler.java:102)
10-03 12:40:10.426: E/TESTSDCARD(26006): at android.os.Looper.loop(Looper.java:150)
10-03 12:40:10.426: E/TESTSDCARD(26006): at android.app.ActivityThread.main(ActivityThread.java:5546)
10-03 12:40:10.426: E/TESTSDCARD(26006): at java.lang.reflect.Method.invoke(Native Method)
10-03 12:40:10.426: E/TESTSDCARD(26006): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:794)
10-03 12:40:10.426: E/TESTSDCARD(26006): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:684)
10-03 12:40:10.426: E/TESTSDCARD(26006): Caused by: android.system.ErrnoException: open failed: EACCES (Permission denied)
10-03 12:40:10.426: E/TESTSDCARD(26006): at libcore.io.Posix.open(Native Method)
10-03 12:40:10.426: E/TESTSDCARD(26006): at libcore.io.BlockGuardOs.open(BlockGuardOs.java:186)
10-03 12:40:10.426: E/TESTSDCARD(26006): at libcore.io.IoBridge.open(IoBridge.java:445)
10-03 12:40:10.426: E/TESTSDCARD(26006): ... 16 more
正如你所看到的,使用getExternalFilesDirs
工作两个测试(不要惊讶,它应该到) 但第三个尝试在SD卡的根目录写入失败。
我做错了吗?有什么方法可以执行此操作?希望不使用存储访问框架,这在我的应用上下文中对我来说是一个真正的痛苦。
旁边,并存储访问框架允许没有一个巨大的代码量上的文件执行每个基本操作(写,删除,重命名......)?
没有根目录,你没有对'/ storage'的写入权限 –
你是指SD卡? – ToYonos
嗯,有些设备没有“SD卡”,所以我只是指文件系统 –