Question

在我的应用中，我正在使用this template并下载我使用ImageDownloader的图片，这在其他应用上运行良好。当我回到图片所在的标签/片段时，我可以看到下载对话框，它会消失。

logcat的：

11-13 20:23:11.856: I/Async-Example(775): onPreExecute Called
11-13 20:23:11.956: D/dalvikvm(775): GC_CONCURRENT freed 80K, 2% free 11133K/11271K, paused 28ms+31ms, total 130ms
11-13 20:23:12.126: D/libEGL(775): loaded /system/lib/egl/libEGL_emulation.so
11-13 20:23:12.146: D/(775): HostConnection::get() New Host Connection established 0x2a0f48e8, tid 775
11-13 20:23:12.156: D/libEGL(775): loaded /system/lib/egl/libGLESv1_CM_emulation.so
11-13 20:23:12.165: D/libEGL(775): loaded /system/lib/egl/libGLESv2_emulation.so
11-13 20:23:12.186: E/ImageDownloader(775): Something went wrong while retrieving bitmap.

清单：

<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.lupradoa.lakari"
    android:versionCode="1"
    android:versionName="1.0">
    <permission 
             android:name="android.permission.INTERNET"/>
             <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/>
            <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>

    <uses-sdk android:minSdkVersion="8" android:targetSdkVersion="19" />

    <application android:label="@string/app_name"
        android:icon="@drawable/ic_launcher"
        android:theme="@style/AppTheme"
        android:allowBackup ="false">

        <activity android:name="com.lupradoa.lakari.base.AppMainTabActivity" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>

    </application>

</manifest>

我认为这里有罪的是“ onPreExecute （）”

FragmentA.java：

package com.lupradoa.lakari.fragmenttabstudy.tabA;

import java.io.InputStream;

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

import android.app.ProgressDialog;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.AsyncTask;
import android.os.Bundle;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.ImageView;

import com.lupradoa.lakari.R;
import com.lupradoa.lakari.base.AppConstants;
import com.lupradoa.lakari.base.BaseFragment;

public class AppTabAFirstFragment extends BaseFragment {
    private Button mGotoButton;
    private ImageView downloadedImg;
    private ProgressDialog simpleWaitDialog;
    private String downloadUrl = "http://www.9ori.com/store/media/images/8ab579a656.jpg";
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {
        View view       =   inflater.inflate(R.layout.app_tab_a_first_screen, container, false);

        mGotoButton =   (Button) view.findViewById(R.id.id_next_tab_a_button);
        mGotoButton.setOnClickListener(listener);

        //image downloaded
        downloadedImg =(ImageView) view.findViewById(R.id.imageView);
        new ImageDownloader().execute(downloadUrl);

        return view;
    }

    private OnClickListener listener        =   new View.OnClickListener(){
        @Override
        public void onClick(View v){
            /* Go to next fragment in navigation stack*/
            mActivity.pushFragments(AppConstants.TAB_A, new AppTabASecondFragment(),true,true);
        }
    };
    private class ImageDownloader extends AsyncTask<String, Void, Bitmap>{

        @Override
        protected Bitmap doInBackground (String... param){
            return downloadBitmap(param[0]);
        }
        @Override
        protected void onPreExecute(){
            Log.i("Async-Example", "onPreExecute Called");

            **//NOT SURE IF THE CONTEXT IS SET PROPERLY**

            simpleWaitDialog = ProgressDialog.show(getActivity(), "Wait", "Downloading Image");
        }

         @Override
         protected void onPostExecute(Bitmap result) {
                 Log.i("Async-Example", "onPostExecute Called");
                 downloadedImg.setImageBitmap(result);
                 simpleWaitDialog.dismiss();

         }

        private Bitmap downloadBitmap(String url){
            final DefaultHttpClient client = new DefaultHttpClient();

            final HttpGet getRequest = new HttpGet(url);
            try{
                HttpResponse response = client.execute(getRequest);

                final int statusCode = response.getStatusLine().getStatusCode();

                if(statusCode != HttpStatus.SC_OK){
                    Log.w("ImageDownloader", "Error" + statusCode + "while retrieving bitmap from "+ url);

                    return null;
                }
                final HttpEntity entity = response.getEntity();
                if(entity != null){
                    InputStream inputStream = null;
                    try{
                            inputStream = entity.getContent();
                            final Bitmap bitmap = BitmapFactory.decodeStream(inputStream);

                            return bitmap;
                    }finally {
                        if(inputStream !=null){
                            inputStream.close();
                        }
                        entity.consumeContent();
                        }
                    }
                }catch (Exception e){
                    getRequest.abort();
                    Log.e("ImageDownloader", "Something went wrong while retrieving bitmap.");
            }
                return null;
            }
        }
}

布局：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent" android:layout_height="match_parent"
    android:orientation="vertical"  android:background="#aa5500"
    android:gravity="center">

    <ImageView
        android:id="@+id/imageView"
        android:layout_width="320dp"
        android:layout_height="0dp"
        android:layout_weight="1"
        android:contentDescription="@string/description"
        android:layout_marginBottom="50dp"
        android:layout_marginTop="50dp"/>

    <Button
        android:id="@+id/id_next_tab_a_button"
        android:layout_width="120dp"
        android:layout_height="wrap_content"
        android:padding="10dip"
        android:text="@string/como_llegar" />

</LinearLayout>

如何解决这个问题？

Answer 1

我不认为问题出现在onPreExecute（）上，但可能下载的图片太大而无法管理。

我建议您使用UniversalImageLoader来加载图片，它是许多应用中使用的功能齐全的库，可以正常工作。也许它也可以帮到你。

异步任务下载图像不显示在片段上

1 个答案: