我是android开发新手我打算为备份联系人设计android应用程序。我需要为备份联系人添加进度条，这里有什么可能是我的代码
public class MainActivity extends AppCompatActivity {
Button backup,restore;
String vfile;
FileOutputStream mFileOutputStream = null;
Cursor cursor;
ArrayList<String> vCard ;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
backup=(Button)findViewById(R.id.btnbkp);
restore=(Button)findViewById(R.id.btnres);
vfile = "contacts.vcf";
final String storage_path = Environment.getExternalStorageDirectory().toString() +"/"+ vfile;
final File f = new File(storage_path);
backup.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
try {
if (!f.exists())
f.createNewFile();
mFileOutputStream = new FileOutputStream(storage_path, false);
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
getVcardString();
}
});
restore.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
final Intent intent = new Intent();
final MimeTypeMap mime = MimeTypeMap.getSingleton();
String tmptype = mime.getMimeTypeFromExtension("vcf");
final File file = new File(Environment.getExternalStorageDirectory().toString() + "/contacts.vcf");
intent.setDataAndType(Uri.fromFile(file), tmptype);
startActivity(intent);
}
});
}
private void getVcardString()
{
vCard = new ArrayList<String>();
cursor = getContentResolver().query(ContactsContract.CommonDataKinds.Phone.CONTENT_URI, null, null, null, null);
if(cursor!=null&&cursor.getCount()>0)
{
cursor.moveToFirst();
for(int i =0;i<cursor.getCount();i++)
{
get(cursor);
Log.d("TAG", "Contact "+(i+1)+"VcF String is"+vCard.get(i));
cursor.moveToNext();
}
}
else
{
Log.d("TAG", "No Contacts in Your Phone");
}
try
{
mFileOutputStream.close();
}
catch (IOException e)
{
// TODO Auto-generated catch block
e.printStackTrace();
}
}
public void get(Cursor cursor)
{
//cursor.moveToFirst();
String lookupKey = cursor.getString(cursor.getColumnIndex(ContactsContract.Contacts.LOOKUP_KEY));
Uri uri = Uri.withAppendedPath(ContactsContract.Contacts.CONTENT_VCARD_URI, lookupKey);
AssetFileDescriptor fd;
try
{
fd = this.getContentResolver().openAssetFileDescriptor(uri, "r");
FileInputStream fis = fd.createInputStream();
byte[] buf = new byte[(int) fd.getDeclaredLength()];
fis.read(buf);
String vcardstring= new String(buf);
vCard.add(vcardstring);
mFileOutputStream.write(vcardstring.toString().getBytes());
}
catch (Exception e1)
{
// TODO Auto-generated catch block
e1.printStackTrace();
}
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.menu_main, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
//noinspection SimplifiableIfStatement
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
}
上面是我的应用程序的代码，我想为应用程序中的备份联系人添加进度条
答案 0 :(得分：0)
使用AsyncTask进行长时间和后台操作，并在onPreExecute()中显示进度条，在dismiss() onPostExecute()中显示代码。
public class MainActivity extends AppCompatActivity {
Button backup, restore;
String vfile;
FileOutputStream mFileOutputStream = null;
Cursor cursor;
ArrayList<String> vCard;
File f;
String storage_path;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
backup = (Button) findViewById(R.id.btnbkp);
restore = (Button) findViewById(R.id.btnres);
vfile = "contacts.vcf";
storage_path = Environment.getExternalStorageDirectory().toString() + "/" + vfile;
f = new File(storage_path);
backup.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
new LongOperation().execute("");
}
});
restore.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
final Intent intent = new Intent();
final MimeTypeMap mime = MimeTypeMap.getSingleton();
String tmptype = mime.getMimeTypeFromExtension("vcf");
final File file = new File(Environment.getExternalStorageDirectory().toString() + "/contacts.vcf");
intent.setDataAndType(Uri.fromFile(file), tmptype);
startActivity(intent);
}
});
}
private class LongOperation extends AsyncTask<String, Void, String> {
ProgressDialog progress;
@Override
protected void onPreExecute() {
progress = new ProgressDialog(MainActivity.this);
progress.setMessage("Loading.... ");
progress.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);
progress.setIndeterminate(true);
progress.setProgress(0);
progress.show();
}
@Override
protected String doInBackground(String... params) {
try {
if (!f.exists())
f.createNewFile();
mFileOutputStream = new FileOutputStream(storage_path, false);
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
getVcardString();
return "Executed";
}
@Override
protected void onPostExecute(String result) {
progress.dismiss();
}
}
private void getVcardString() {
vCard = new ArrayList<String>();
cursor = getContentResolver().query(ContactsContract.CommonDataKinds.Phone.CONTENT_URI, null, null, null, null);
if (cursor != null && cursor.getCount() > 0) {
cursor.moveToFirst();
for (int i = 0; i < cursor.getCount(); i++) {
get(cursor);
Log.d("TAG", "Contact " + (i + 1) + "VcF String is" + vCard.get(i));
cursor.moveToNext();
}
} else {
Log.d("TAG", "No Contacts in Your Phone");
}
try {
mFileOutputStream.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
public void get(Cursor cursor) {
//cursor.moveToFirst();
String lookupKey = cursor.getString(cursor.getColumnIndex(ContactsContract.Contacts.LOOKUP_KEY));
Uri uri = Uri.withAppendedPath(ContactsContract.Contacts.CONTENT_VCARD_URI, lookupKey);
AssetFileDescriptor fd;
try {
fd = this.getContentResolver().openAssetFileDescriptor(uri, "r");
FileInputStream fis = fd.createInputStream();
byte[] buf = new byte[(int) fd.getDeclaredLength()];
fis.read(buf);
String vcardstring = new String(buf);
vCard.add(vcardstring);
mFileOutputStream.write(vcardstring.toString().getBytes());
} catch (Exception e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
}
}
}