使用ContentResolver写入外部文件[Chrome-ARC]

时间：2015-05-12 13:27:31

标签： android google-chrome google-chrome-arc

我在使用适用于Chrome的App Runtime编译的适用于Chrome操作系统的Android应用中写入外部文件时遇到问题。这个应用程序功能可以在两个Android测试设备上运行（一个API 19，与ARC相同，我相信），但在Chromebook上测试时总是失败。我的应用的minSdkVersion为19。

我的应用是文本编辑器，我想要实现的是使用Intent.ACTION_OPEN_DOCUMENT加载文本，在此过程中保存文件Uri。稍后，当我想要保存时，我可以使用此Uri来访问该文件并更新其内容，而无需在每次要保存文件时使用“共享”对话框来打扰用户（或者如果他们设置了自动保存首选项。如果有ACTION_SEND，我的应用默认为FileNotFoundException意图。

这是相关代码。任何人都可以提出一个解决方法，或者我可以做出哪些改进？

public class EditorHost extends AppCompatActivity implements EditorFragment.EditorInterface {

private static final int REQUEST_OPEN = 15;

//...

 @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        if (mEditorFragmentChild == null)
            mEditorFragmentChild = (EditorFragment) mFragmentManager.findFragmentByTag(EDITOR_FRAGMENT_TAG);
        switch (item.getItemId()) {
            case R.id.load_file:
                open();
                break;
            case R.id.save_file:
                if (mEditorFragmentChild.getUri() == null){
                    shareTask();
                    break;
                }
                mEditorFragmentChild.saveTask();
                break;
            case R.id.share:
                mIntent = new Intent(Intent.ACTION_SEND);
                mIntent.putExtra(Intent.EXTRA_TEXT, mEditorFragmentChild.mExtendedEditText.getText().toString());
                mIntent.setType("text/plain");
                startActivity(Intent.createChooser(mIntent, getString(R.string.share_title)));
                break;

@TargetApi(Build.VERSION_CODES.KITKAT)
private void open(){
    mIntent = new Intent().setType("text/plain");
    startActivityForResult(mIntent.setAction(Intent.ACTION_OPEN_DOCUMENT).addCategory(Intent.CATEGORY_OPENABLE), REQUEST_OPEN);
}

@Override
public void onActivityResult(int requestCode, int resultCode, Intent resultData){
    if (resultCode == Activity.RESULT_OK){
        Uri uri = null;

        if (resultData != null) {
            uri = resultData.getData();

            if (requestCode == REQUEST_OPEN) {
                Cursor c = getContentResolver().query(uri,null, null, null, null);

                if (c != null && c.moveToFirst()){
                    title = c.getString(c.getColumnIndex(OpenableColumns.DISPLAY_NAME));

                    String[] cols = c.getColumnNames();
                    for (int i = 0; i < c.getColumnCount(); i++){
                        Log.e(LOG_TAG, cols[i]);
                    }

                    content = readFromFile(uri);

                    if (title == null || title.equals("")){
                        title = getString(R.string.app_name);
                    }

                    getSupportActionBar().setTitle(title);
                    mEditorFragmentChild.updateTextFromFile(content.trim());
                    mEditorFragmentChild.setUri(uri.toString());

                    if (!c.isClosed()) {
                        c.close();
                    }
                }
            }
        }
    }
}

并在EditorFragment班级中：

public class EditorFragment extends Fragment implements ... {
//...
String getUri(){
    return mUri;
}

void setUri(String newUri){
    mUri = newUri;
}

void saveTask(){
    if (mUri == null || fromShareTask) {
        fromShareTask = false;
        return;
    }
    try {
        OutputStream outputStream = mAppCompatActivity.getContentResolver().openOutputStream(Uri.parse(mUri));
        outputStream.write(mExtendedEditText.getText().toString().getBytes());
        outputStream.close();
        //Toast.makeText(mAppCompatActivity, mAppCompatActivity.getString(R.string.file_updated_confirmation), Toast.LENGTH_SHORT).show();
    } catch (IOException e){
        e.printStackTrace();
        dispatchShareEvent();
        Toast.makeText(mAppCompatActivity, mAppCompatActivity.getString(R.string.save_failed), Toast.LENGTH_LONG).show();
        mExtendedEditText.setText(e.toString() + "\n\n" + exceptionStacktraceToString(e) + "\n\n" + "mUri is " + mUri);
    }
}

最后，错误消息（从上面重复一遍，这只发生在我的Chromebook而不是Android测试设备上）：

java.io.FileNotFoundException: Can't access data/data/org.chromium.arc/external/(etc.)...

谢谢！

修改

虽然我无法弄清楚如何从我的Chromebook获取堆栈跟踪，但我可以添加following method from the accepted answer on this question将其打印到EditText。我还在最后打印了Uri。这是输出：

java.io.FileNotFoundException: Can't access /data/data/org.chromium.arc/external/E5783234425D1719508FC512B2BEE2A5/1kTest.txt
java.io.FileNotFoundException: Can't access /data/data/org.chromium.arc/external/E5783234425D1719508FC512B2BEE2A5/1kTest.txt
at com.android.providers.media.MediaProvider.checkAccess(MediaProvider.java:4620)
at com.android.providers.media.MediaProvider.openFileAndEnforcePathPermissionsHelper(MediaProvider.java:4569)
at com.android.providers.media.MediaProvider.openFile(MediaProvider.java:4493)
at android.content.ContentProvider.openAssetFile(ContentProvider.java:1211)
at android.content.ContentProvider.openAssetFile(ContentProvider.java:1274)
at android.content.ContentProvider$Transport.openAssetFile(ContentProvider.java:314)
at android.content.ContentProvider$Transport.openAssetFile(Native Method)
at android.content.ContentResolver.openAssetFileDescriptor(ContentResolver.java:926)
at android.content.ContentResolver.openOutputStream(ContentResolver.java:673)
at android.content.ContentResolver.openOutputStream(ContentResolver.java:649)
at com.werdpressed.partisan.filterforchrome.EditorFragment.saveTask(EditorFragment.java:370)
at com.werdpressed.partisan.filterforchrome.EditorHost.onOptionsItemSelected(EditorHost.java:119)
at android.app.Activity.onMenuItemSelected(Activity.java:2619)
at android.support.v4.app.FragmentActivity.onMenuItemSelected(FragmentActivity.java:353)
at android.support.v7.app.AppCompatActivity.onMenuItemSelected(AppCompatActivity.java:144)
at android.support.v7.internal.view.WindowCallbackWrapper.onMenuItemSelected(WindowCallbackWrapper.java:99)
at android.support.v7.app.AppCompatDelegateImplV7.onMenuItemSelected(AppCompatDelegateImplV7.java:538)
at android.support.v7.internal.view.menu.MenuBuilder.dispatchMenuItemSelected(MenuBuilder.java:802)
at android.support.v7.internal.view.menu.MenuItemImpl.invoke(MenuItemImpl.java:153)
at android.support.v7.internal.view.menu.MenuBuilder.performItemAction(MenuBuilder.java:949)
at android.support.v7.internal.view.menu.MenuBuilder.performItemAction(MenuBuilder.java:939)
at android.support.v7.widget.ActionMenuView.invokeItem(ActionMenuView.java:598)
at android.support.v7.internal.view.menu.ActionMenuItemView.onClick(ActionMenuItemView.java:139)
at android.view.View.performClick(View.java:4440)
at android.view.View$PerformClick.run(View.java:18407)
at android.os.Handler.handleCallback(Handler.java:733)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:156)
at android.app.ActivityThread.main(ActivityThread.java:5181)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at android.os.Process$1.run(Process.java:418)

mUri is content://media/external/file/8

错误发生在以下try/catch块中：

try {
    OutputStream outputStream = mAppCompatActivity.getContentResolver().openOutputStream(Uri.parse(mUri));
    outputStream.write(mExtendedEditText.getText().toString().getBytes());
    outputStream.close();
    //Toast.makeText(mAppCompatActivity, mAppCompatActivity.getString(R.string.file_updated_confirmation), Toast.LENGTH_SHORT).show();
} catch (IOException e){
    e.printStackTrace();
    dispatchShareEvent();
    Toast.makeText(mAppCompatActivity, mAppCompatActivity.getString(R.string.save_failed), Toast.LENGTH_LONG).show();
    mExtendedEditText.setText(e.toString() + "\n" + exceptionStacktraceToString(e) + "\n\n" + "mUri is " + mUri);
}

具体来说，这是错误日志中引用的行370：

OutputStream outputStream = mAppCompatActivity.getContentResolver().openOutputStream(Uri.parse(mUri));

1 个答案:

答案 0 :(得分：2)

我认为您只是找到了一个界面来访问我们没有想到的外部文件（或者觉得起作用并不重要）。我们修补文件系统以处理SD卡路径，但是没有对MediaProvider进行任何更改来处理内容Uri，就像您尝试使用的那样。

请随时使用示例代码（或至少链接到此帖子）file a bug，以便我们可以优先处理其他工作。

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