java非法的字符集名称异常,java.lang.IllegalArgumentException异常：引起主机名称不能为空...

I am using four Strings in my code. The first String contains "http://", the second String contains user host URL (entered by user), the third contains "/musics/a.mp3" and the fourth String contains complete URL, by combining the previous Strings, like this:

String fourth = first+second+third;

Then I'm using the fourth String in AsyncTask's execute, like this:

new JSONAsyncTask().execute(fourth);

And I'm getting the error below.

Log:

10-07 06:17:15.934: E/AndroidRuntime(1194): FATAL EXCEPTION: AsyncTask #1

10-07 06:17:15.934: E/AndroidRuntime(1194): java.lang.RuntimeException: An error occured while executing doInBackground()

10-07 06:17:15.934: E/AndroidRuntime(1194): at android.os.AsyncTask$3.done(AsyncTask.java:278)

10-07 06:17:15.934: E/AndroidRuntime(1194): at java.util.concurrent.FutureTask$Sync.innerSetException(FutureTask.java:273)

10-07 06:17:15.934: E/AndroidRuntime(1194): at java.util.concurrent.FutureTask.setException(FutureTask.java:124)

10-07 06:17:15.934: E/AndroidRuntime(1194): at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:307)

10-07 06:17:15.934: E/AndroidRuntime(1194): at java.util.concurrent.FutureTask.run(FutureTask.java:137)

10-07 06:17:15.934: E/AndroidRuntime(1194): at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:208)

10-07 06:17:15.934: E/AndroidRuntime(1194): at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1076)

10-07 06:17:15.934: E/AndroidRuntime(1194): at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:569)

10-07 06:17:15.934: E/AndroidRuntime(1194): at java.lang.Thread.run(Thread.java:856)

10-07 06:17:15.934: E/AndroidRuntime(1194): Caused by: java.lang.IllegalArgumentException: Host name may not be null

10-07 06:17:15.934: E/AndroidRuntime(1194): at org.apache.http.HttpHost.(HttpHost.java:83)

10-07 06:17:15.934: E/AndroidRuntime(1194): at org.apache.http.impl.client.AbstractHttpClient.determineTarget(AbstractHttpClient.java:497)

10-07 06:17:15.934: E/AndroidRuntime(1194): at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:487)

10-07 06:17:15.934: E/AndroidRuntime(1194): at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:465)

10-07 06:17:15.934: E/AndroidRuntime(1194): at com.app.ifko.HomeActivity$JSONAsyncTask.doInBackground(HomeActivity.java:101)

10-07 06:17:15.934: E/AndroidRuntime(1194): at com.app.ifko.HomeActivity$JSONAsyncTask.doInBackground(HomeActivity.java:1)

10-07 06:17:15.934: E/AndroidRuntime(1194): at android.os.AsyncTask$2.call(AsyncTask.java:264)

10-07 06:17:15.934: E/AndroidRuntime(1194): at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:305)

10-07 06:17:15.934: E/AndroidRuntime(1194): ... 5 more

10-07 06:17:22.764: E/WindowManager(1194): Activity com.app.ifko.HomeActivity has leaked window com.android.internal.policy.impl.PhoneWindow$DecorView@416b80b0 that was originally added here

10-07 06:17:22.764: E/WindowManager(1194): android.view.WindowLeaked: Activity com.app.ifko.HomeActivity has leaked window com.android.internal.policy.impl.PhoneWindow$DecorView@416b80b0 that was originally added here

10-07 06:17:22.764: E/WindowManager(1194): at android.view.ViewRootImpl.(ViewRootImpl.java:343)

10-07 06:17:22.764: E/WindowManager(1194): at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:245)

10-07 06:17:22.764: E/WindowManager(1194): at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:193)

10-07 06:17:22.764: E/WindowManager(1194): at android.view.WindowManagerImpl$CompatModeWrapper.addView(WindowManagerImpl.java:118)

10-07 06:17:22.764: E/WindowManager(1194): at android.view.Window$LocalWindowManager.addView(Window.java:537)

10-07 06:17:22.764: E/WindowManager(1194): at android.app.Dialog.show(Dialog.java:274)

10-07 06:17:22.764: E/WindowManager(1194): at com.app.ifko.HomeActivity$JSONAsyncTask.onPreExecute(HomeActivity.java:90)

10-07 06:17:22.764: E/WindowManager(1194): at android.os.AsyncTask.executeOnExecutor(AsyncTask.java:561)

10-07 06:17:22.764: E/WindowManager(1194): at android.os.AsyncTask.execute(AsyncTask.java:511)

10-07 06:17:22.764: E/WindowManager(1194): at com.app.ifko.HomeActivity.onCreate(HomeActivity.java:74)

10-07 06:17:22.764: E/WindowManager(1194): at android.app.Activity.performCreate(Activity.java:4465)

10-07 06:17:22.764: E/WindowManager(1194): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1049)

10-07 06:17:22.764: E/WindowManager(1194): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1919)

10-07 06:17:22.764: E/WindowManager(1194): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1980)

10-07 06:17:22.764: E/WindowManager(1194): at android.app.ActivityThread.access$600(ActivityThread.java:122)

10-07 06:17:22.764: E/WindowManager(1194): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1146)

10-07 06:17:22.764: E/WindowManager(1194): at android.os.Handler.dispatchMessage(Handler.java:99)

10-07 06:17:22.764: E/WindowManager(1194): at android.os.Looper.loop(Looper.java:137)

10-07 06:17:22.764: E/WindowManager(1194): at android.app.ActivityThread.main(ActivityThread.java:4340)

10-07 06:17:22.764: E/WindowManager(1194): at java.lang.reflect.Method.invokeNative(Native Method)

10-07 06:17:22.764: E/WindowManager(1194): at java.lang.reflect.Method.invoke(Method.java:511)

10-07 06:17:22.764: E/WindowManager(1194): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)

10-07 06:17:22.764: E/WindowManager(1194): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)

10-07 06:17:22.764: E/WindowManager(1194): at dalvik.system.NativeStart.main(Native Method)

10-07 06:17:24.144: I/Process(1194): Sending signal. PID: 1194 SIG: 9

Activity code:

public class HomeActivity extends Activity {

String first, second, third, fourth;

TextView etTextToSave;

private SharedPreferences sharedprefs;

@Override

protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.home);

etTextToSave = (TextView) findViewById(R.id.etTextToSave);

sharedprefs = getSharedPreferences("MyPrefs", MODE_PRIVATE);

etTextToSave.setText(sharedprefs.getString("SharedPrefsData",""));

second = etTextToSave.getText().toString();

first = "http://";

third = "/musics/a.mp3";

fourth = first+second+third;

.........................

new JSONAsyncTask().execute(fourth);

}

解决方案

If the host part of the URL comes from the user, you must validate it before using it to construct a URL.

Don't call new JSONAsyncTask().execute(fourth); if second is null.