Android AsyncTack 异步任务实例详解

图片加载器(通用型)

/**
 * Created by Lulu on 2016/8/31.
 * 图片网络加载器
 * 下载成功返回Bitmap
 * 否则返回null
 */
public class ImageLoader extends AsyncTask<String, Void, Bitmap>{

  private ImageView image;

  public ImageLoader(ImageView image) {
    this.image = image;
    image.setImageResource(R.mipmap.ic_launcher);
  }

  @Override
  protected void onPreExecute() {
    super.onPreExecute();

  }

  @Override
  protected Bitmap doInBackground(String... params) {
    String url = params[0];
    try {
      HttpURLConnection connection = (HttpURLConnection) new URL(url).openConnection();
      connection.setRequestMethod("GET");
      connection.setDoInput(true);
      int code = connection.getResponseCode();
      if (code == 200) {
        InputStream is = connection.getInputStream();
        return BitmapFactory.decodeStream(is);
      }
    } catch (IOException e) {
      e.printStackTrace();
    }
    return null;
  }


  @Override
  protected void onPostExecute(Bitmap bitmap) {
    super.onPostExecute(bitmap);
    if (bitmap != null) {
      image.setImageBitmap(bitmap);
    } else {
      image.setImageResource(R.mipmap.failed);
    }
  }
}

4, 测试Activity

注意: 看如何解决大图在webView中不左右滑动的问题!

public class Main2Activity extends AppCompatActivity implements NetWorkTask.Callback<Entry>{
  private WebView web;
  private ImageView image;
  //解决大图在webView中不左右滑动的问题
  private static final String CSS = "<style>img{max-width:100%} </style>";
  private String title;
  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main2);
    web = (WebView) findViewById(R.id.main2_web);
    image = (ImageView) findViewById(R.id.main2_image);
    new NetWorkTask<>("http://www.tngou.net/api/top/show?id=13122", Entry.class).execute(this);
  }
  @Override
  public void onSuccess(Entry t) {
    web.loadDataWithBaseURL("", t.getMessage(), "text/html; charset=utf-8", "UTF-8", null);
    new ImageLoader(image).execute("http://img.blog.csdn.net/20160829134937003");
  }
  @Override
  public void onFailed(Exception e) {
    web.loadDataWithBaseURL("", "加载失败", "text/html; charset=utf-8", "UTF-8", null);
  }
}

5.效果图：

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