数据库转移到sd卡AsyncTask，ProgressDialog使用

最新推荐文章于 2025-09-11 16:31:04 发布

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本文介绍了一个用于异步导出数据库文件的任务类实现。该任务通过Android AsyncTask在后台线程从应用程序的数据目录复制数据库文件到外部存储设备，并使用进度对话框显示操作状态。

private class ExportDatabaseFileTask extends AsyncTask<String, Void, Boolean> {
private final ProgressDialog dialog = new ProgressDialog(ctx);

// can use UI thread here
protected void onPreExecute() {
this.dialog.setMessage("Exporting database...");
this.dialog.show();
}

// automatically done on worker thread (separate from UI thread)
protected Boolean doInBackground(final String... args) {

File dbFile =
new File(Environment.getDataDirectory() + "/data/com.mypkg/databases/mydbfile.db");

File exportDir = new File(Environment.getExternalStorageDirectory(), "");
if (!exportDir.exists()) {
exportDir.mkdirs();
}
File file = new File(exportDir, dbFile.getName());

try {
file.createNewFile();
this.copyFile(dbFile, file);
return true;
} catch (IOException e) {
Log.e("mypck", e.getMessage(), e);
return false;
}
}

// can use UI thread here
protected void onPostExecute(final Boolean success) {
if (this.dialog.isShowing()) {
this.dialog.dismiss();
}
if (success) {
Toast.makeText(ctx, "Export successful!", Toast.LENGTH_SHORT).show();
} else {
Toast.makeText(ctx, "Export failed", Toast.LENGTH_SHORT).show();
}
}

void copyFile(File src, File dst) throws IOException {
FileChannel inChannel = new FileInputStream(src).getChannel();
FileChannel outChannel = new FileOutputStream(dst).getChannel();
try {
inChannel.transferTo(0, inChannel.size(), outChannel);
} finally {
if (inChannel != null)
inChannel.close();
if (outChannel != null)
outChannel.close();
}
}

}