我有一个简单的LinearLayout，上面有Button，我想在按下按钮时创建一个图像并从URL加载其内容。
我创建了AsyncTask来执行此操作，但是当我按下按钮时程序崩溃。
这是我的代码：
package com.example.image;
import java.io.IOException;
import java.net.MalformedURLException;
import java.net.URL;
import android.app.Activity;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.AsyncTask;
import android.os.Bundle;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.LinearLayout;
public class MainActivity extends Activity {
Button testButton;
LinearLayout layout;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
testButton = (Button) findViewById(R.id.button1);
layout = (LinearLayout) findViewById(R.id.LinearLayout1);
testButton.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View arg0) {
new GetData().execute();
}
});
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
class GetData extends AsyncTask<String, Void, String> {
Bitmap bitmap;
ImageView image = new ImageView(MainActivity.this);
@Override
protected void onPreExecute() {
};
@Override
protected String doInBackground(String... params) {
try {
URL url = new URL("http://www.android.com/images/logo.png");
Bitmap bitmap = BitmapFactory.decodeStream(url.openConnection().getInputStream());
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
return null;
}
@Override
protected void onPostExecute(String result) {
super.onPostExecute(result);
image.setImageBitmap(bitmap);
layout.addView(image);
}
}
}
这里是logcat：
06-02 12:58:57.880: E/Trace(1572): error opening trace file: No such file or directory (2)
06-02 12:58:58.580: D/gralloc_goldfish(1572): Emulator without GPU emulation detected.
06-02 12:59:02.331: W/dalvikvm(1572): threadid=11: thread exiting with uncaught exception (group=0x40a13300)
06-02 12:59:02.401: E/AndroidRuntime(1572): FATAL EXCEPTION: AsyncTask #1
06-02 12:59:02.401: E/AndroidRuntime(1572): java.lang.RuntimeException: An error occured while executing doInBackground()
06-02 12:59:02.401: E/AndroidRuntime(1572): at android.os.AsyncTask$3.done(AsyncTask.java:299)
06-02 12:59:02.401: E/AndroidRuntime(1572): at java.util.concurrent.FutureTask$Sync.innerSetException(FutureTask.java:273)
06-02 12:59:02.401: E/AndroidRuntime(1572): at java.util.concurrent.FutureTask.setException(FutureTask.java:124)
06-02 12:59:02.401: E/AndroidRuntime(1572): at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:307)
06-02 12:59:02.401: E/AndroidRuntime(1572): at java.util.concurrent.FutureTask.run(FutureTask.java:137)
06-02 12:59:02.401: E/AndroidRuntime(1572): at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:230)
06-02 12:59:02.401: E/AndroidRuntime(1572): at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1076)
06-02 12:59:02.401: E/AndroidRuntime(1572): at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:569)
06-02 12:59:02.401: E/AndroidRuntime(1572): at java.lang.Thread.run(Thread.java:856)
06-02 12:59:02.401: E/AndroidRuntime(1572): Caused by: java.lang.SecurityException: Permission denied (missing INTERNET permission?)
06-02 12:59:02.401: E/AndroidRuntime(1572): at java.net.InetAddress.lookupHostByName(InetAddress.java:418)
06-02 12:59:02.401: E/AndroidRuntime(1572): at java.net.InetAddress.getAllByNameImpl(InetAddress.java:236)
06-02 12:59:02.401: E/AndroidRuntime(1572): at java.net.InetAddress.getAllByName(InetAddress.java:214)
06-02 12:59:02.401: E/AndroidRuntime(1572): at libcore.net.http.HttpConnection.<init>(HttpConnection.java:70)
06-02 12:59:02.401: E/AndroidRuntime(1572): at libcore.net.http.HttpConnection.<init>(HttpConnection.java:50)
06-02 12:59:02.401: E/AndroidRuntime(1572): at libcore.net.http.HttpConnection$Address.connect(HttpConnection.java:341)
06-02 12:59:02.401: E/AndroidRuntime(1572): at libcore.net.http.HttpConnectionPool.get(HttpConnectionPool.java:87)
06-02 12:59:02.401: E/AndroidRuntime(1572): at libcore.net.http.HttpConnection.connect(HttpConnection.java:128)
06-02 12:59:02.401: E/AndroidRuntime(1572): at libcore.net.http.HttpEngine.openSocketConnection(HttpEngine.java:315)
06-02 12:59:02.401: E/AndroidRuntime(1572): at libcore.net.http.HttpEngine.connect(HttpEngine.java:310)
06-02 12:59:02.401: E/AndroidRuntime(1572): at libcore.net.http.HttpEngine.sendSocketRequest(HttpEngine.java:289)
06-02 12:59:02.401: E/AndroidRuntime(1572): at libcore.net.http.HttpEngine.sendRequest(HttpEngine.java:239)
06-02 12:59:02.401: E/AndroidRuntime(1572): at libcore.net.http.HttpURLConnectionImpl.getResponse(HttpURLConnectionImpl.java:273)
06-02 12:59:02.401: E/AndroidRuntime(1572): at libcore.net.http.HttpURLConnectionImpl.getInputStream(HttpURLConnectionImpl.java:168)
06-02 12:59:02.401: E/AndroidRuntime(1572): at com.example.image.MainActivity$GetData.doInBackground(MainActivity.java:63)
06-02 12:59:02.401: E/AndroidRuntime(1572): at com.example.image.MainActivity$GetData.doInBackground(MainActivity.java:1)
06-02 12:59:02.401: E/AndroidRuntime(1572): at android.os.AsyncTask$2.call(AsyncTask.java:287)
06-02 12:59:02.401: E/AndroidRuntime(1572): at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:305)
06-02 12:59:02.401: E/AndroidRuntime(1572): ... 5 more
06-02 12:59:02.401: E/AndroidRuntime(1572): Caused by: libcore.io.GaiException: getaddrinfo failed: EAI_NODATA (No address associated with hostname)
06-02 12:59:02.401: E/AndroidRuntime(1572): at libcore.io.Posix.getaddrinfo(Native Method)
06-02 12:59:02.401: E/AndroidRuntime(1572): at libcore.io.ForwardingOs.getaddrinfo(ForwardingOs.java:55)
06-02 12:59:02.401: E/AndroidRuntime(1572): at java.net.InetAddress.lookupHostByName(InetAddress.java:405)
06-02 12:59:02.401: E/AndroidRuntime(1572): ... 22 more
06-02 12:59:02.401: E/AndroidRuntime(1572): Caused by: libcore.io.ErrnoException: getaddrinfo failed: EACCES (Permission denied)
06-02 12:59:02.401: E/AndroidRuntime(1572): ... 25 more
答案 0 :(得分：2)
在日志中：
SecurityException：Permission denied（缺少INTERNET权限？）
表示您忘记添加INTERNET权限AndroidManifest。将其添加为：
<uses-permission android:name="android.permission.INTERNET"></uses-permission>
答案 1 :(得分：0)
尝试在Android清单中添加权限。
<uses-permission android:name="android.permission.INTERNET"></uses-permission>
答案 2 :(得分：0)
删除位图
你为那个
创建了全局变量 Bitmap bitmap = BitmapFactory.decodeStream(url.openConnection().getInputStream());
只写这个
bitmap = BitmapFactory.decodeStream(url.openConnection().getInputStream());