AsyncTaskLoader使用方法

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AsyncTaskLoader

 ↳ android.support.v4.content.Loader<D>
      ↳ android.support.v4.content.AsyncTaskLoader<D>

基本用法

创建一个继承于AsyncTaskLoader的自定义Loder类

cancelLoadInBackground

实现以下三个常用方法和一个默认构造函数：

public SycnTasker(@NonNull Context context) {}

@Override
protected void onStartLoading() {}

@Nullable
@Override
public Integer loadInBackground() {}

@Override
protected boolean onCancelLoad() {}

其中默认构造函数和loadInBackground必不可少

• onStartLoading

• 在执行完方法onCreateLoader返回一个自定义Loader对象后开始执行

• loadInBackground

• 当在onStartLoading中调用forceLoad()时开始执行

• onCancelLoad

• 当调用cancleLoad方法时会执行

  实现android.support.v4.app.LoaderManager.LoaderCallbacks接口

  @Override
  public void onLoadFinished(Loader loader, D d) {}
  
  @Override
  public Loader onCreateLoader(int i, Bundle bundle) {}
  
  @Override
  public void onLoaderReset(Loader loader) {}

• onCreateLoader

• 当调用以下代码后开始执行

  getLoaderManager().initLoader(int id,Bundle bundle,LoaderCallbacks loaderCallbacks);

• onLoadFinished

• 执行完成loadInBackground后，数据可从onLoadFinished参数d中获得

• onLoaderReset

• 自定义Loader销毁后

  各方法执行顺序：

  onCreateLoader
  onStartLoading
  loadInBackground

  示例代码

  实现LoaderCallbacks接口所在类：

  import android.app.LoaderManager;
  import android.content.Loader;
  import android.graphics.Bitmap;
  import android.graphics.BitmapFactory;
  import android.os.AsyncTask;
  import android.os.Bundle;
  import android.support.annotation.Nullable;
  import android.support.v7.app.AppCompatActivity;
  import android.util.Log;
  import io.githubs.grooters.luffy.R;
  public class LoaderActivity extends AppCompatActivity implements LoaderManager.LoaderCallbacks<Integer>{
      private static final String TAG= LoaderActivity.class.getSimpleName();
      private AsyncTasker asyncTasker;
      @Override
      protected void onCreate(@Nullable final Bundle savedInstanceState) {
          super.onCreate(savedInstanceState);
          setContentView(R.layout.activity_loader);
          getLoaderManager().initLoader(1,savedInstanceState,this);
  
      @Override
      public void onLoadFinished(Loader loader, Integer i) {
          Log.i(TAG,"onLoadFinished："+i);
      }
  
      @Override
      public Loader onCreateLoader(int i, Bundle bundle) {
          Log.i(TAG,"onCreateLoader");
          CustomLoader customLoader=new CustomLoader(this);
          customLoader.getInfo("LoaderActivity");
          return customLoader;
      }
  
      @Override
      public void onLoaderReset(Loader loader) {
          Log.i(TAG,"onLoaderReset");
      }
  }

  自定义Loader：

  import android.content.AsyncTaskLoader;
  import android.content.Context;
  import android.content.Intent;
  import android.support.annotation.NonNull;
  import android.support.annotation.Nullable;
  import android.util.Log;
  import luffy_intent.Intenter;
  
  public class CustomLoader extends AsyncTaskLoader<Integer> {
  
      private static final String TAG=CustomLoader.class.getSimpleName();
      public CustomLoader(@NonNull Context context) {
          super(context);
          Log.i(TAG,"CustomLoader");
      }
      @Override
      protected void onStartLoading() {
          super.onStartLoading();
          Log.i(TAG,"onStartLoading");
          forceLoad();
      }
      @Nullable
      @Override
      public Integer loadInBackground() {
          Log.i(TAG,"loadInBackground");
          int i=0;
          while(i<10){
              try {
                  Thread.sleep(1000);
                  ++i;
                  Log.i(TAG,"i: "+i);
              } catch (InterruptedException e) {
                  e.printStackTrace();
              }
              Log.i(TAG,"Finish");
          }
          return i;
      }
      @Override
      protected boolean onCancelLoad() {
          Log.i(TAG,"onCancelLoad");
          return super.onCancelLoad();
      }
      public void getInfo(String str){
          Log.i(TAG,"getInfo："+str);
      }
  }