在Android上对SD卡进行数据库备份
我正在使用下面的代码将备份副本写入SD卡,我得到在Android上对SD卡进行数据库备份,android,Android,我正在使用下面的代码将备份副本写入SD卡,我得到 java.io.IOException:文件的父目录不可写:/sdcard/mydbfile.db private class ExportDatabaseFileTask extends AsyncTask<String, Void, Boolean> { private final ProgressDialog dialog = new ProgressDialog(ctx); // can us
java.io.IOException:文件的父目录不可写:/sdcard/mydbfile.db
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();
}
}
}
私有类ExportDatabaseFileTask扩展了AsyncTask{
私有最终ProgressDialog=新建ProgressDialog(ctx);
//可以在这里使用UI线程
受保护的void onPreExecute(){
this.dialog.setMessage(“导出数据库…”);
this.dialog.show();
}
//在工作线程上自动完成(与UI线程分开)
受保护的布尔doInBackground(最终字符串…args){
文件dbFile=
新文件(Environment.getDataDirectory()+“/data/com.mypkg/databases/mydbfile.db”);
File exportDir=新文件(Environment.getExternalStorageDirectory(),“”);
如果(!exportDir.exists()){
exportDir.mkdirs();
}
File File=新文件(exportDir,dbFile.getName());
试一试{
createNewFile();
这个.copyFile(dbFile,file);
返回true;
}捕获(IOE异常){
Log.e(“mypck”,e.getMessage(),e);
返回false;
}
}
//可以在这里使用UI线程
受保护的void onPostExecute(最终布尔值成功){
if(this.dialog.isShowing()){
this.dialog.disclose();
}
如果(成功){
Toast.makeText(ctx,“导出成功!”,Toast.LENGTH_SHORT.show();
}否则{
Toast.makeText(ctx,“导出失败”,Toast.LENGTH_SHORT).show();
}
}
void copyFile(文件src、文件dst)引发IOException{
FileChannel inChannel=newfileinputstream(src).getChannel();
FileChannel outChannel=新的FileOutputStream(dst).getChannel();
试一试{
inChannel.transferTo(0,inChannel.size(),outChannel);
}最后{
如果(inChannel!=null)
inChannel.close();
如果(输出通道!=null)
outChannel.close();
}
}
}
您是否在清单中定义了权限
<uses-permission
android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
非常好的帖子,谢谢。我验证了该代码是否可以将数据库复制到sd卡上。您的问题对我来说是一个解决方案。Thanx!;)这是个好把戏。但我想知道如何恢复备份…很好+给你100美元:)