您好我是Android开发中的新手，也是Stack Overflow的新手。我很好地理解了Tutorial中asynctask的概念。但我仍然感到困惑，我如何在现有代码上使用asynctask。
我正在使用 Json 从我的服务器获取数据。所以基本上我的应用程序执行一些数据获取和显示布局。我想使用asynctask，因为在 logcat 我的应用程序的 Choreographer 一直告诉我 250帧跳过，我的应用程序冻结了几秒钟。所以，基本上我的UI线程正忙于这一点并且它发生了。
我有两个活动
1）主要活动
2）团队活动
我在我的活动中使用导航抽屉。在导航中我有项目列表中的团队。
我的主要活动代码：
public class MainActivity extends AppCompatActivity implements NavigationView.OnNavigationItemSelectedListener{
private boolean doubleBackToExitPressedOnce;
private Handler mHandler = new Handler();
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
DrawerLayout drawerLayout = (DrawerLayout) findViewById(R.id.drawer_layout);
ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(
this,drawerLayout,toolbar,R.string.navigation_drawer_open,R.string.navigation_drawer_close);
drawerLayout.setDrawerListener(toggle);
toggle.syncState();
NavigationView navigationView = (NavigationView) findViewById(R.id.nav_view);
navigationView.setNavigationItemSelectedListener(this);
}
private final Runnable mRunnable = new Runnable() {
@Override
public void run() {
doubleBackToExitPressedOnce = false;
}
};
@Override
protected void onDestroy()
{
super.onDestroy();
if (mHandler != null) { mHandler.removeCallbacks(mRunnable); }
}
@Override
public void onBackPressed(){
// DrawerLayout drawerLayout = (DrawerLayout) findViewById(R.id.drawer_layout);
if (doubleBackToExitPressedOnce) {
super.onBackPressed();
return;
}
this.doubleBackToExitPressedOnce = true;
Toast.makeText(this, "Please click BACK again to exit", Toast.LENGTH_SHORT).show();
mHandler.postDelayed(mRunnable, 2000);
}
@Override
public boolean onCreateOptionsMenu(Menu menu){
getMenuInflater().inflate(R.menu.nav_drawer, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem menuItem){
int id = menuItem.getItemId();
if(id == R.id.action_settings){
return true;
}
return super.onOptionsItemSelected(menuItem);
}
public boolean onNavigationItemSelected(MenuItem menuItem){
int id = menuItem.getItemId();
if(id == R.id.home1){
Intent searchIntent = new Intent(MainActivity.this,Home.class);
startActivity(searchIntent);
overridePendingTransition(R.anim.pull_in_right, R.anim.push_out_left);
}
else if(id == R.id.service1){
Intent searchIntent = new Intent(MainActivity.this,OurService.class);
startActivity(searchIntent);
overridePendingTransition(R.anim.pull_in_right, R.anim.push_out_left);
}
else if(id == R.id.team1){
Intent searchIntent = new Intent(MainActivity.this,Team.class);
startActivity(searchIntent);
overridePendingTransition(R.anim.pull_in_right, R.anim.push_out_left);
}
else if(id == R.id.port1){
Intent searchIntent = new Intent(MainActivity.this,OurPort.class);
startActivity(searchIntent);
overridePendingTransition(R.anim.pull_in_right, R.anim.push_out_left);
}
else if(id == R.id.price1){
Intent searchIntent = new Intent(MainActivity.this,Price.class);
startActivity(searchIntent);
overridePendingTransition(R.anim.pull_in_right, R.anim.push_out_left);
}
else if(id == R.id.contact1){
Intent searchIntent = new Intent(MainActivity.this,Contact.class);
startActivity(searchIntent);
overridePendingTransition(R.anim.pull_in_right, R.anim.push_out_left);
}
else if(id == R.id.location){
Intent searchIntent = new Intent(MainActivity.this,OurLocation.class);
startActivity(searchIntent);
overridePendingTransition(R.anim.pull_in_right, R.anim.push_out_left);
}
else if(id == R.id.facebook){
Intent searchIntent = new Intent(MainActivity.this,OurFacebook.class);
startActivity(searchIntent);
overridePendingTransition(R.anim.pull_in_right, R.anim.push_out_left);
}
else if(id == R.id.linkedin){
Intent searchIntent = new Intent(MainActivity.this,OurLinkedin.class);
startActivity(searchIntent);
overridePendingTransition(R.anim.pull_in_right, R.anim.push_out_left);
}
DrawerLayout drawerLayout = (DrawerLayout) findViewById(R.id.drawer_layout);
drawerLayout.closeDrawer(GravityCompat.START);
return true;
}
}
我的团队活动代码：
public class Team extends AppCompatActivity {
private RecyclerView recyclerView;
private TeamAdapter adapter;
private List<TeamAlbum> albumList;
private TeamAlbum teamAlbum;
ProgressDialog pd;
@Override
protected void onCreate(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_team);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
ActionBar actionBar = getSupportActionBar();
actionBar.setDisplayHomeAsUpEnabled(true);
final CollapsingToolbarLayout collapsingToolbar =
(CollapsingToolbarLayout) findViewById(R.id.collapsing_toolbar);
initViews();
}
public class GridSpacingItemDecoration extends
RecyclerView.ItemDecoration {
private int spanCount;
private int spacing;
private boolean includeEdge;
public GridSpacingItemDecoration(int spanCount, int spacing, boolean includeEdge) {
this.spanCount = spanCount;
this.spacing = spacing;
this.includeEdge = includeEdge;
}
@Override
public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) {
int position = parent.getChildAdapterPosition(view); // item position
int column = position % spanCount; // item column
if (includeEdge) {
outRect.left = spacing - column * spacing / spanCount; // spacing - column * ((1f / spanCount) * spacing)
outRect.right = (column + 1) * spacing / spanCount; // (column + 1) * ((1f / spanCount) * spacing)
if (position < spanCount) { // top edge
outRect.top = spacing;
}
outRect.bottom = spacing; // item bottom
} else {
outRect.left = column * spacing / spanCount; // column * ((1f / spanCount) * spacing)
outRect.right = spacing - (column + 1) * spacing / spanCount; // spacing - (column + 1) * ((1f / spanCount) * spacing)
if (position >= spanCount) {
outRect.top = spacing; // item top
}
}
}
}
private int dpToPx(int dp) {
Resources r = getResources();
return Math.round(TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, dp, r.getDisplayMetrics()));
}
@Override
public void onBackPressed(){
Intent intent = new Intent(this,MainActivity.class);
intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
startActivity(intent);
finish();
return;
}
@Override
public boolean onOptionsItemSelected(MenuItem menuItem){
int id = menuItem.getItemId();
if(id == R.id.action_settings){
return true;
}
return super.onOptionsItemSelected(menuItem);
}
private void initViews(){
pd = new ProgressDialog(this);
pd.setMessage("Fetching Data....");
pd.setCancelable(false);
pd.show();
try {
Glide.with(this).load(R.drawable.te).into((ImageView) findViewById(R.id.backdrop));
} catch (Exception e) {
e.printStackTrace();
}
recyclerView = (RecyclerView) findViewById(R.id.recycler_view);
albumList = new ArrayList<>();
adapter = new TeamAdapter(this, albumList);
RecyclerView.LayoutManager mLayoutManager = new GridLayoutManager(this, 2);
recyclerView.setLayoutManager(mLayoutManager);
recyclerView.addItemDecoration(new GridSpacingItemDecoration(2, dpToPx(10), true));
recyclerView.setItemAnimator(new DefaultItemAnimator());
recyclerView.setAdapter(adapter);
loadJSON();
}
private void loadJSON(){
try{
Client client = new Client();
Service service = client.getClient().create(Service.class);
Call<TeamResponse> call = service.getAlbums();
call.enqueue(new Callback<TeamResponse>() {
@Override
public void onResponse(Call<TeamResponse> call, Response<TeamResponse> response) {
List<TeamAlbum> iteams = response.body().getAlbums();
recyclerView.setAdapter(new TeamAdapter(getApplicationContext(), iteams));
pd.dismiss();
}
@Override
public void onFailure(Call<TeamResponse> call, Throwable t) {
Log.d("Error", t.getMessage());
Toast.makeText(Team.this,"Error Fetching Data!", Toast.LENGTH_SHORT).show();
pd.dismiss();
}
});
}
catch (Exception e){
Log.d("Error", e.getMessage());
Toast.makeText(this, e.toString(), Toast.LENGTH_SHORT).show();
}
}
}
所以，我的团队活动中有两种方法
1。 initViews（） 2. loadJson（）
因此，正如您在我的代码中看到的那样，我在 initViews（）方法和 initViews（）中调用 loadJson（）方法 onCreate（）我的活动。
但我不知道如何在这两种方法中使用asynctask。
请有人帮助我如何实施asynctask解释。在此先感谢。
答案 0 :(得分：1)
可能是这样的，如果您需要更多澄清，请告诉我
class FantasticAsyncTask extends AsyncTask<Void, Void, TeamResponse> {
@Override
protected void onPreExecute() {
pd = new ProgressDialog(YourActivity.this);
pd.setMessage("Fetching Data....");
pd.setCancelable(false);
pd.show();
}
@Override
protected TeamResponse doInBackground(final Void... voids) {
Service service = client.getClient().create(Service.class);
Call<TeamResponse> call = service.getAlbums();
TeamResponse response = call.execute();
return response;
}
@Override
protected void onPostExecute(final TeamResponse response) {
List<TeamAlbum> iteams = response.body().getAlbums();
recyclerView.setAdapter(new TeamAdapter(getApplicationContext(), iteams));
pd.dismiss();
}
}
答案 1 :(得分：1)
class LoadAlbumsAsync extends AsyncTask<Void, Void, List<TeamAlbum>>{
@Override
protected void onPreExecute() {
pd = new ProgressDialog(this);
pd.setMessage("Fetching Data....");
pd.setCancelable(false);
pd.show();
}
@Override
protected List<TeamAlbum> doInBackground(Void... voids) {
Client client = new Client();
Service service = client.getClient().create(Service.class);
// Note: modify getAlbums() retrofit method to return the TeamResponse obj directly.
TeamResponse response = service.getAlbums();
return response.getAlbums();
}
@Override
protected void onPostExecute(List<TeamAlbum> list) {
recyclerView.setAdapter(new TeamAdapter(getApplicationContext(), list));
pd.dismiss();
}
}
private void loadJSON(){
new LoadAlbumsAsync().execute();
}
希望这会有所帮助..