Question

我使用以下算法下载和缓存图像。它运作良好。初始加载图像需要时间。我希望显示一个进度指示来显示这一点。我希望进度指示器仅在图像视图中不会阻挡屏幕的其他部分。例如，我有一个列表，每个人都有一个图像和文字。行是可点击的。所以我想显示每行图像的进度指示，直到它被加载。同时文本部分应该是可见的，列表视图应该是可点击的。用户无需等待即可完成加载。他甚至可以在加载该行的图像之前单击一行并打开详细信息页面。

按进度指标，我只是指示图像正在加载。像一些旋转轮。我不是在寻找一个百分比指示或类似的东西。感谢很多

代码

    package com.idg.reelbillboard.utils;

import java.io.IOException;
import java.io.InputStream;
import java.net.MalformedURLException;
import java.util.HashMap;
import java.util.Map;

import org.apache.http.HttpResponse;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.DefaultHttpClient;

import android.app.ProgressDialog;
import android.content.Context;
import android.graphics.drawable.Drawable;
import android.os.Handler;
import android.os.Message;
import android.util.Log;
import android.widget.ImageView;

public class DrawableManager {
    private final Map<String, Drawable> drawableMap;

    public DrawableManager() {
        drawableMap = new HashMap<String, Drawable>();
    }

    public Drawable fetchDrawable(String urlString) {
        if (drawableMap.containsKey(urlString)) {
            return drawableMap.get(urlString);
        }

        Log.d(this.getClass().getSimpleName(), "image url:" + urlString);
        try {
            InputStream is = fetch(urlString);
            Drawable drawable = Drawable.createFromStream(is, "src");


            if (drawable != null) {
                drawableMap.put(urlString, drawable);
                Log.d(this.getClass().getSimpleName(), "got a thumbnail drawable: " + drawable.getBounds() + ", "
                        + drawable.getIntrinsicHeight() + "," + drawable.getIntrinsicWidth() + ", "
                        + drawable.getMinimumHeight() + "," + drawable.getMinimumWidth());
            } else {
              Log.w(this.getClass().getSimpleName(), "could not get thumbnail");
            }

            return drawable;
        } catch (MalformedURLException e) {
            Log.e(this.getClass().getSimpleName(), "fetchDrawable failed", e);
            return null;
        } catch (IOException e) {
            Log.e(this.getClass().getSimpleName(), "fetchDrawable failed", e);
            return null;
        }
    }

    public void fetchDrawableOnThread(final String urlString, final ImageView imageView, Context context) {
        if (drawableMap.containsKey(urlString)) {
            imageView.setImageDrawable(drawableMap.get(urlString));
        }
      //  final ProgressDialog progressDialog = ProgressDialog.show(context, "", "Loading", false); 
        final Handler handler = new Handler() {
            @Override
            public void handleMessage(Message message) {
            //   if(progressDialog.isShowing()) 
            //         progressDialog.dismiss(); 
                imageView.setImageDrawable((Drawable) message.obj);
            }
        };

        Thread thread = new Thread() {
            @Override
            public void run() {
                //TODO : set imageView to a "pending" image

                Drawable drawable = fetchDrawable(urlString);
                Message message = handler.obtainMessage(1, drawable);
                handler.sendMessage(message);

            }
        };
        thread.start();
    }

    private InputStream fetch(String urlString) throws MalformedURLException, IOException {
        DefaultHttpClient httpClient = new DefaultHttpClient();
        HttpGet request = new HttpGet(urlString);
        HttpResponse response = httpClient.execute(request);
        return response.getEntity().getContent();
    }

}

Answer 1

使用当前的实现，进度条将无法正常工作，因为整个“加载图像数据并构建可绘制的”是在一行Drawable drawable = Drawable.createFromStream(is, "src");中完成的。因此，您无法确定加载的百分比。

您可以做的是使用不确定进度指示器（又称旋转轮）。

你可以，例如在图像加载时覆盖图像上的此类ProgressBar视图的实例，并在图像加载完成后立即删除（或隐藏）。

android：图像加载的进度指示器

1 个答案: