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1st：min sdk > target sdk >和target sdk编译器在创建android应用程序和比较编译器符合性级别时有什么区别？min sdk> target sdk>目标编译器在创建android应用程序时的差异
第二：确定目标sdk前。 4.2与Android设备有关，例如我用于开发的4.0.3 (Ice Cream Sandwich)？
3rd：使用下面的代码创建使用Android 4.2作为新项目。我被通知了permgen空间。我有512M ..为什么？
这里是代码
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
credential = GoogleAccountCredential.usingOAuth2(this, DriveScopes.DRIVE);
startActivityForResult(credential.newChooseAccountIntent(), REQUEST_ACCOUNT_PICKER);
}
@Override
protected void onActivityResult(final int requestCode, final int resultCode, final Intent data) {
switch (requestCode) {
case REQUEST_ACCOUNT_PICKER:
if (resultCode == RESULT_OK && data != null && data.getExtras() != null) {
String accountName = data.getStringExtra(AccountManager.KEY_ACCOUNT_NAME);
if (accountName != null) {
credential.setSelectedAccountName(accountName);
service = getDriveService(credential);
startCameraIntent();
}
}
break;
case REQUEST_AUTHORIZATION:
if (resultCode == Activity.RESULT_OK) {
saveFileToDrive();
} else {
startActivityForResult(credential.newChooseAccountIntent(), REQUEST_ACCOUNT_PICKER);
}
break;
case CAPTURE_IMAGE:
if (resultCode == Activity.RESULT_OK) {
saveFileToDrive();
}
}
}
private void startCameraIntent() {
String mediaStorageDir = Environment.getExternalStoragePublicDirectory(
Environment.DIRECTORY_PICTURES).getPath();
String timeStamp = new SimpleDateFormat("yyyyMMdd_HHmmss", Locale.US).format(new Date());
fileUri = Uri.fromFile(new java.io.File(mediaStorageDir + java.io.File.separator + "IMG_"
+ timeStamp + ".jpg"));
Intent cameraIntent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
cameraIntent.putExtra(MediaStore.EXTRA_OUTPUT, fileUri);
startActivityForResult(cameraIntent, CAPTURE_IMAGE);
}
private void saveFileToDrive() {
Thread t = new Thread(new Runnable() {
@Override
public void run() {
try {
// File's binary content
java.io.File fileContent = new java.io.File(fileUri.getPath());
FileContent mediaContent = new FileContent("image/jpeg", fileContent);
// File's metadata.
File body = new File();
body.setTitle(fileContent.getName());
body.setMimeType("image/jpeg");
File file = service.files().insert(body, mediaContent).execute();
if (file != null) {
showToast("Photo uploaded: " + file.getTitle());
startCameraIntent();
}
} catch (UserRecoverableAuthIOException e) {
startActivityForResult(e.getIntent(), REQUEST_AUTHORIZATION);
} catch (IOException e) {
e.printStackTrace();
}
}
});
t.start();
}
private Drive getDriveService(GoogleAccountCredential credential) {
return new Drive.Builder(AndroidHttp.newCompatibleTransport(), new GsonFactory(), credential)
.build();
}
public void showToast(final String toast) {
runOnUiThread(new Runnable() {
@Override
public void run() {
Toast.makeText(getApplicationContext(), toast, Toast.LENGTH_SHORT).show();
}
});
}
}