0

我正在尝试从 Web url 加载图像。我发现了一个回答这个问题的堆栈问题，并说要使用这段代码：

try {
  ImageView i = (ImageView)findViewById(R.id.image);
  Bitmap bitmap = BitmapFactory.decodeStream((InputStream)new URL(imageUrl).getContent());
  i.setImageBitmap(bitmap); 
} catch (MalformedURLException e) {
  e.printStackTrace();
} catch (IOException e) {
  e.printStackTrace();
}

但是当我尝试运行它时，我得到了这个错误：

06-19 14:45:02.598: E/AndroidRuntime(10230): FATAL EXCEPTION: main
06-19 14:45:02.598: E/AndroidRuntime(10230): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.beerportfoliopro/com.example.beerportfoliopro.BeerPage}: android.os.NetworkOnMainThreadException
06-19 14:45:02.598: E/AndroidRuntime(10230):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2307)
06-19 14:45:02.598: E/AndroidRuntime(10230):    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2357)
06-19 14:45:02.598: E/AndroidRuntime(10230):    at android.app.ActivityThread.access$600(ActivityThread.java:153)
06-19 14:45:02.598: E/AndroidRuntime(10230):    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1247)
06-19 14:45:02.598: E/AndroidRuntime(10230):    at android.os.Handler.dispatchMessage(Handler.java:99)
06-19 14:45:02.598: E/AndroidRuntime(10230):    at android.os.Looper.loop(Looper.java:137)
06-19 14:45:02.598: E/AndroidRuntime(10230):    at android.app.ActivityThread.main(ActivityThread.java:5226)
06-19 14:45:02.598: E/AndroidRuntime(10230):    at java.lang.reflect.Method.invokeNative(Native Method)
06-19 14:45:02.598: E/AndroidRuntime(10230):    at java.lang.reflect.Method.invoke(Method.java:511)
06-19 14:45:02.598: E/AndroidRuntime(10230):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:795)
06-19 14:45:02.598: E/AndroidRuntime(10230):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:562)
06-19 14:45:02.598: E/AndroidRuntime(10230):    at dalvik.system.NativeStart.main(Native Method)
06-19 14:45:02.598: E/AndroidRuntime(10230): Caused by: android.os.NetworkOnMainThreadException
06-19 14:45:02.598: E/AndroidRuntime(10230):    at android.os.StrictMode$AndroidBlockGuardPolicy.onNetwork(StrictMode.java:1117)
06-19 14:45:02.598: E/AndroidRuntime(10230):    at java.net.InetAddress.lookupHostByName(InetAddress.java:385)
06-19 14:45:02.598: E/AndroidRuntime(10230):    at java.net.InetAddress.getAllByNameImpl(InetAddress.java:236)
06-19 14:45:02.598: E/AndroidRuntime(10230):    at java.net.InetAddress.getAllByName(InetAddress.java:214)
06-19 14:45:02.598: E/AndroidRuntime(10230):    at libcore.net.http.HttpConnection.<init>(HttpConnection.java:70)
06-19 14:45:02.598: E/AndroidRuntime(10230):    at libcore.net.http.HttpConnection.<init>(HttpConnection.java:50)
06-19 14:45:02.598: E/AndroidRuntime(10230):    at libcore.net.http.HttpConnection$Address.connect(HttpConnection.java:340)
06-19 14:45:02.598: E/AndroidRuntime(10230):    at libcore.net.http.HttpConnectionPool.get(HttpConnectionPool.java:87)
06-19 14:45:02.598: E/AndroidRuntime(10230):    at libcore.net.http.HttpConnection.connect(HttpConnection.java:128)
06-19 14:45:02.598: E/AndroidRuntime(10230):    at libcore.net.http.HttpEngine.openSocketConnection(HttpEngine.java:316)
06-19 14:45:02.598: E/AndroidRuntime(10230):    at libcore.net.http.HttpsURLConnectionImpl$HttpsEngine.makeSslConnection(HttpsURLConnectionImpl.java:461)
06-19 14:45:02.598: E/AndroidRuntime(10230):    at libcore.net.http.HttpsURLConnectionImpl$HttpsEngine.connect(HttpsURLConnectionImpl.java:433)
06-19 14:45:02.598: E/AndroidRuntime(10230):    at libcore.net.http.HttpEngine.sendSocketRequest(HttpEngine.java:290)
06-19 14:45:02.598: E/AndroidRuntime(10230):    at libcore.net.http.HttpEngine.sendRequest(HttpEngine.java:240)
06-19 14:45:02.598: E/AndroidRuntime(10230):    at libcore.net.http.HttpURLConnectionImpl.connect(HttpURLConnectionImpl.java:81)
06-19 14:45:02.598: E/AndroidRuntime(10230):    at java.net.URLConnection.getContent(URLConnection.java:190)
06-19 14:45:02.598: E/AndroidRuntime(10230):    at libcore.net.http.HttpsURLConnectionImpl.getContent(HttpsURLConnectionImpl.java:175)
06-19 14:45:02.598: E/AndroidRuntime(10230):    at java.net.URL.getContent(URL.java:447)
06-19 14:45:02.598: E/AndroidRuntime(10230):    at com.example.beerportfoliopro.BeerPage.onCreate(BeerPage.java:52)
06-19 14:45:02.598: E/AndroidRuntime(10230):    at android.app.Activity.performCreate(Activity.java:5104)
06-19 14:45:02.598: E/AndroidRuntime(10230):    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1080)
06-19 14:45:02.598: E/AndroidRuntime(10230):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2261)
4

2 回答 2

2

你得到一个NetworkOnMainThreadException. 这是因为从 Android 3.0 及以上版本开始，网络操作不应该在 UI 线程中进行，而是在单独的线程中进行。为此，您可以使用AsyncTask或IntentService 。
换句话说，连接到互联网并下载图像的那段代码应该在一个AsyncTask或IntentService

于 2013-06-19T19:04:01.060 回答
0

请尝试以下代码

   private Bitmap downloadImage(String imageUrl)
   {

    Bitmap bitmap=null;
    InputStream is;
    try 
    {
    is=openHttp(imageUrl);
    bitmap=BitmapFactory.decodeStream(is);
    is.close();
} 
    catch (Exception e) 
    {
        // TODO: handle exception
}
    return bitmap;
}
private InputStream openHttp(String url) throws IOException
{
    InputStream is=null;
    int res=-1;
    URL u=new URL(url);
    URLConnection con=u.openConnection();
    if(!(con instanceof HttpURLConnection))
        throw new IOException("Not Http Connection");
    try {
        HttpURLConnection httpCon=(HttpURLConnection)con;
        httpCon.setAllowUserInteraction(false);
        httpCon.setInstanceFollowRedirects(true);
        httpCon.setRequestMethod("GET");
        httpCon.connect();
        res=httpCon.getResponseCode();
        if(res==HttpURLConnection.HTTP_OK)
        {
            is=httpCon.getInputStream();
        }
    } 
    catch (Exception e) {
        // TODO: handle exception
    }

    return is;
}

这里在 downloadImage 函数中重新运行位图对象。并 openHttp 返回图像 url 的输入流...签入您的应用程序...

于 2013-06-21T09:53:31.710 回答