为什么我会得到一个空的位图？
为什么我会得到一个空的位图？
提问于 2014-10-10 12:59:18
我试着从网上获取图像。我只需使用以下代码：
public Bitmap getBitmapFromUrl(String src)
{
try
{
URL url = new URL(src);
HttpURLConnection connection = (HttpURLConnection) url.openConnection();
connection.setDoInput(true);
connection.connect();
InputStream input = connection.getInputStream();
Bitmap myBitmap = BitmapFactory.decodeStream(input);
return myBitmap;
} catch (Exception e) {
e.printStackTrace();
return null;
}
}然后，当我不想启动这段代码时，我会这样做：
this.getBitmapFromUrl("http://icons.iconarchive.com/icons/mazenl77/I-like-buttons-3a/512/Cute-Ball-Go-icon.png");如果我确实调试，我会看到我输入了try，但它是返回的空值。
我能做什么错事？
我的最后一只原木猫
10-10 15:15:51.085 12935-12974/com.example.android.navigationdrawerexample W/System.err﹕ java.net.UnknownHostException: Unable to resolve host "icons.iconarchive.com": No address associated with hostname
10-10 15:15:51.085 12935-12974/com.example.android.navigationdrawerexample W/System.err﹕ at java.net.InetAddress.lookupHostByName(InetAddress.java:394)
10-10 15:15:51.085 12935-12974/com.example.android.navigationdrawerexample W/System.err﹕ at java.net.InetAddress.getAllByNameImpl(InetAddress.java:236)
10-10 15:15:51.085 12935-12974/com.example.android.navigationdrawerexample W/System.err﹕ at java.net.InetAddress.getAllByName(InetAddress.java:214)
10-10 15:15:51.085 12935-12974/com.example.android.navigationdrawerexample W/System.err﹕ at libcore.net.http.HttpConnection.<init>(HttpConnection.java:70)
10-10 15:15:51.095 12935-12974/com.example.android.navigationdrawerexample W/System.err﹕ at libcore.net.http.HttpConnection.<init>(HttpConnection.java:50)
10-10 15:15:51.095 12935-12974/com.example.android.navigationdrawerexample W/System.err﹕ at libcore.net.http.HttpConnection$Address.connect(HttpConnection.java:340)
10-10 15:15:51.095 12935-12974/com.example.android.navigationdrawerexample W/System.err﹕ at libcore.net.http.HttpConnectionPool.get(HttpConnectionPool.java:87)
10-10 15:15:51.095 12935-12974/com.example.android.navigationdrawerexample W/System.err﹕ at libcore.net.http.HttpConnection.connect(HttpConnection.java:128)
10-10 15:15:51.095 12935-12974/com.example.android.navigationdrawerexample W/System.err﹕ at libcore.net.http.HttpEngine.openSocketConnection(HttpEngine.java:316)
10-10 15:15:51.095 12935-12974/com.example.android.navigationdrawerexample W/System.err﹕ at libcore.net.http.HttpEngine.connect(HttpEngine.java:311)
10-10 15:15:51.095 12935-12974/com.example.android.navigationdrawerexample W/System.err﹕ at libcore.net.http.HttpEngine.sendSocketRequest(HttpEngine.java:290)
10-10 15:15:51.095 12935-12974/com.example.android.navigationdrawerexample W/System.err﹕ at libcore.net.http.HttpEngine.sendRequest(HttpEngine.java:240)
10-10 15:15:51.095 12935-12974/com.example.android.navigationdrawerexample W/System.err﹕ at libcore.net.http.HttpURLConnectionImpl.connect(HttpURLConnectionImpl.java:81)
10-10 15:15:51.095 12935-12974/com.example.android.navigationdrawerexample W/System.err﹕ at com.example.android.navigationdrawerexample.MainActivity$PlanetFragment$1.run(MainActivity.java:311)
10-10 15:15:51.095 12935-12974/com.example.android.navigationdrawerexample W/System.err﹕ at android.os.Handler.handleCallback(Handler.java:725)
10-10 15:15:51.095 12935-12974/com.example.android.navigationdrawerexample W/System.err﹕ at android.os.Handler.dispatchMessage(Handler.java:92)
10-10 15:15:51.095 12935-12974/com.example.android.navigationdrawerexample W/System.err﹕ at android.os.Looper.loop(Looper.java:176)
10-10 15:15:51.095 12935-12974/com.example.android.navigationdrawerexample W/System.err﹕ at android.os.HandlerThread.run(HandlerThread.java:60)
10-10 15:15:51.095 12935-12974/com.example.android.navigationdrawerexample E/TAG﹕ Fetch failed回答 2
Stack Overflow用户
回答已采纳
发布于 2014-10-10 13:11:27
您的代码工作正常，但是网络操作必须在单独的线程(而不是UI线程)中完成。你给我的网址是这样的：
HandlerThread thread = new HandlerThread("MyThread");
thread.start();
Handler handler = new Handler(thread.getLooper());
handler.post(new Runnable() {
@Override
public void run() {
Bitmap myBitmap = null;
try {
URL url = new URL("http://icons.iconarchive.com/icons/mazenl77/I-like-buttons-3a/512/Cute-Ball-Go-icon.png");
HttpURLConnection connection = (HttpURLConnection) url.openConnection();
connection.setDoInput(true);
connection.connect();
InputStream input = connection.getInputStream();
myBitmap = BitmapFactory.decodeStream(input);
} catch (Exception e) {
e.printStackTrace();
}
if (myBitmap == null) {
Log.e("TAG", "Fetch failed");
} else {
Log.e("TAG", myBitmap.toString());
}
}
});注意:使用处理程序将阻止您有一个获取位图的方法。但是，您可以创建一个方法，当图像提取失败/成功时，该方法将从处理程序接收回调。
Stack Overflow用户
发布于 2014-10-10 13:03:12
看一看：this question。为了节省你的时间，这里有一个公认的答案：
try {
URL url = new URL("http://www.helpinghomelesscats.com/images/cat1.jpg");
InputStream in = url.openConnection().getInputStream();
BufferedInputStream bis = new BufferedInputStream(in,1024*8);
ByteArrayOutputStream out = new ByteArrayOutputStream();
int len=0;
byte[] buffer = new byte[1024];
while((len = bis.read(buffer)) != -1){
out.write(buffer, 0, len);
}
out.close();
bis.close();
byte[] data = out.toByteArray();
Bitmap bitmap = BitmapFactory.decodeByteArray(data, 0, data.length);
imageView.setImageBitmap(bitmap);
}
catch (IOException e) {
e.printStackTrace();
}页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/26300056
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