Android - 将 ImageView 设置为 URL [英] Android - Set ImageView to URL
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问题描述
我正在尝试将 Imageview 设置为 URL.
I am trying to set an Imageview to a URL.
下面是我的代码
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
setContentView(R.layout.getpic);
ImageView i = (ImageView)findViewById(R.id.ivget);
URL url;
try {
url = new URL("http://0-media-cdn.foolz.us/ffuuka/board/sp/thumb/1359/41/1359419073599s.jpg");
Bitmap image = BitmapFactory.decodeStream(url.openConnection().getInputStream());
i.setImageBitmap(image);
} catch (MalformedURLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
但是每当我尝试打开/运行应用程序时，它就会崩溃，为什么它不起作用?
But whenever I try to open/run the app it crashes, why isnt it working?
06-15 00:37:20.977: E/AndroidRuntime(8579): FATAL EXCEPTION: main
06-15 00:37:20.977: E/AndroidRuntime(8579): java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.OptimusApps.stayhealthy/com.OptimusApps.stayhealthy.Practice2}: java.lang.NullPointerException
06-15 00:37:20.977: E/AndroidRuntime(8579): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1993)
06-15 00:37:20.977: E/AndroidRuntime(8579): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2104)
06-15 00:37:20.977: E/AndroidRuntime(8579): at android.app.ActivityThread.access$600(ActivityThread.java:132)
06-15 00:37:20.977: E/AndroidRuntime(8579): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1157)
06-15 00:37:20.977: E/AndroidRuntime(8579): at android.os.Handler.dispatchMessage(Handler.java:99)
06-15 00:37:20.977: E/AndroidRuntime(8579): at android.os.Looper.loop(Looper.java:137)
06-15 00:37:20.977: E/AndroidRuntime(8579): at android.app.ActivityThread.main(ActivityThread.java:4575)
06-15 00:37:20.977: E/AndroidRuntime(8579): at java.lang.reflect.Method.invokeNative(Native Method)
06-15 00:37:20.977: E/AndroidRuntime(8579): at java.lang.reflect.Method.invoke(Method.java:511)
06-15 00:37:20.977: E/AndroidRuntime(8579): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:789)
06-15 00:37:20.977: E/AndroidRuntime(8579): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:556)
06-15 00:37:20.977: E/AndroidRuntime(8579): at dalvik.system.NativeStart.main(Native Method)
06-15 00:37:20.977: E/AndroidRuntime(8579): Caused by: java.lang.NullPointerException
06-15 00:37:20.977: E/AndroidRuntime(8579): at android.app.Activity.findViewById(Activity.java:1794)
06-15 00:37:20.977: E/AndroidRuntime(8579): at com.OptimusApps.stayhealthy.Practice2.<init>(Practice2.java:17)
06-15 00:37:20.977: E/AndroidRuntime(8579): at java.lang.Class.newInstanceImpl(Native Method)
06-15 00:37:20.977: E/AndroidRuntime(8579): at java.lang.Class.newInstance(Class.java:1319)
06-15 00:37:20.977: E/AndroidRuntime(8579): at android.app.Instrumentation.newActivity(Instrumentation.java:1023)
06-15 00:37:20.977: E/AndroidRuntime(8579): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1984)
06-15 00:37:20.977: E/AndroidRuntime(8579): ... 11 more
上面是 logcat，但我不确定错误具体在哪里......................................…………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………
above is the logcat, I am not sure where the error is in it specificaly though..............................................................................................................................................................
推荐答案
你不应该在主ui线程上做网络相关的操作.
You should not do network related operation on the main ui thread.
您可以找到设置为活动的当前视图层次结构的ViewById.检查 ivget.xml 中是否有 imageview.还使用如下异步任务并发出 http get 请求以获取图像.
You can findViewById of the current view hierachy set to the activity. check if you have imageview in ivget.xml. Also use a asynctask as below and make a http get request to get the image.
activity_main.xml
activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent" >
<ImageView
android:id="@+id/imageView1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentTop="true"
android:layout_centerHorizontal="true"
android:layout_marginTop="173dp"
android:src="@drawable/ic_launcher" />
</RelativeLayout>
MainActivity.java
MainActivity.java
public class AndroidCustomGalleryActivity extends Activity {
ImageView iv;
Bitmap image ;
ProgressDialog pd;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
iv = (ImageView) findViewById(R.id.imageView1);
pd = new ProgressDialog(this);
pd.setMessage("Loading..");
new TheTask().execute();
}
class TheTask extends AsyncTask<Void,Void,Void>
{
@Override
protected void onPreExecute() {
// TODO Auto-generated method stub
super.onPreExecute();
pd.show();
}
@Override
protected Void doInBackground(Void... params) {
// TODO Auto-generated method stub
try
{
//URL url = new URL( "http://a3.twimg.com/profile_images/670625317/aam-logo-v3-twitter.png");
image = downloadBitmap("http://a3.twimg.com/profile_images/670625317/aam-logo-v3-twitter.png");
}
catch(Exception e)
{
e.printStackTrace();
}
return null;
}
@Override
protected void onPostExecute(Void result) {
// TODO Auto-generated method stub
super.onPostExecute(result);
pd.dismiss();
if(image!=null)
{
iv.setImageBitmap(image);
}
}
}
private Bitmap downloadBitmap(String url) {
// initilize the default HTTP client object
final DefaultHttpClient client = new DefaultHttpClient();
//forming a HttoGet request
final HttpGet getRequest = new HttpGet(url);
try {
HttpResponse response = client.execute(getRequest);
//check 200 OK for success
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 {
// getting contents from the stream
inputStream = entity.getContent();
// decoding stream data back into image Bitmap that android understands
image = BitmapFactory.decodeStream(inputStream);
} finally {
if (inputStream != null) {
inputStream.close();
}
entity.consumeContent();
}
}
} catch (Exception e) {
// You Could provide a more explicit error message for IOException
getRequest.abort();
Log.e("ImageDownloader", "Something went wrong while" +
" retrieving bitmap from " + url + e.toString());
}
return image;
}
}
这篇关于Android - 将 ImageView 设置为 URL的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
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