android网络请求问题:android.os.NetworkOnMainThreadException
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手把手教你解决android网络请求问题:android.os.NetworkOnMainThreadException
- 博客分类:
- android
public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); this.setContentView(R.layout.share_mblog_view); new Thread(runnable).start();}Handler handler = new Handler(){ @Override public void handleMessage(Message msg) { super.handleMessage(msg); Bundle data = msg.getData(); String val = data.getString("value"); Log.i("mylog","请求结果-->" + val); }}Runnable runnable = new Runnable(){ @Override public void run() { // // TODO: http request. // Message msg = new Message(); Bundle data = new Bundle(); data.putString("value","请求结果"); msg.setData(data); handler.sendMessage(msg); }}
最近在搞基于android虚拟机的通信项目,就是实现android虚拟机上的客户端和其所在电脑上的服务器进行通信。但是在所有的东西都写好后,发现android虚拟机端总是在代码:
HttpResponse response = new DefaultHttpClient().execute(request);
处包错,其错误为:
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.andconweb/com.example.andconweb.MainActivity}: android.os.NetworkOnMainThreadException10-02 09:13:37.500: E/AndroidRuntime(2657): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2180)10-02 09:13:37.500: E/AndroidRuntime(2657): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2230)10-02 09:13:37.500: E/AndroidRuntime(2657): at android.app.ActivityThread.access$600(ActivityThread.java:141)10-02 09:13:37.500: E/AndroidRuntime(2657): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1234)10-02 09:13:37.500: E/AndroidRuntime(2657): at android.os.Handler.dispatchMessage(Handler.java:99)10-02 09:13:37.500: E/AndroidRuntime(2657): at android.os.Looper.loop(Looper.java:137)10-02 09:13:37.500: E/AndroidRuntime(2657): at android.app.ActivityThread.main(ActivityThread.java:5041)10-02 09:13:37.500: E/AndroidRuntime(2657): at java.lang.reflect.Method.invokeNative(Native Method)10-02 09:13:37.500: E/AndroidRuntime(2657): at java.lang.reflect.Method.invoke(Method.java:511)10-02 09:13:37.500: E/AndroidRuntime(2657): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)10-02 09:13:37.500: E/AndroidRuntime(2657): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)10-02 09:13:37.500: E/AndroidRuntime(2657): at dalvik.system.NativeStart.main(Native Method)10-02 09:13:37.500: E/AndroidRuntime(2657): Caused by: android.os.NetworkOnMainThreadException10-02 09:13:37.500: E/AndroidRuntime(2657): at android.os.StrictMode$AndroidBlockGuardPolicy.onNetwork(StrictMode.java:1117)10-02 09:13:37.500: E/AndroidRuntime(2657): at libcore.io.BlockGuardOs.connect(BlockGuardOs.java:84)10-02 09:13:37.500: E/AndroidRuntime(2657): at libcore.io.IoBridge.connectErrno(IoBridge.java:127)10-02 09:13:37.500: E/AndroidRuntime(2657): at libcore.io.IoBridge.connect(IoBridge.java:112)10-02 09:13:37.500: E/AndroidRuntime(2657): at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:192)10-02 09:13:37.500: E/AndroidRuntime(2657): at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:459)10-02 09:13:37.500: E/AndroidRuntime(2657): at java.net.Socket.connect(Socket.java:842)10-02 09:13:37.500: E/AndroidRuntime(2657): at org.apache.http.conn.scheme.PlainSocketFactory.connectSocket(PlainSocketFactory.java:119)10-02 09:13:37.500: E/AndroidRuntime(2657): at org.apache.http.impl.conn.DefaultClientConnectionOperator.openConnection(DefaultClientConnectionOperator.java:144)10-02 09:13:37.500: E/AndroidRuntime(2657): at org.apache.http.impl.conn.AbstractPoolEntry.open(AbstractPoolEntry.java:164).......
本来以为是代码出错或者是获取Http连接时传入的URL有问题,传入的URL如下:
http://10.0.2.2:8080/AndroidWeb/loadMessage
但是,在android虚拟机中的浏览器上输入该网址后,却得到了想要的信息。有此推断出错的地方不是服务器端的代码。
调试了好久,才发现是因为Http请求写在了主线程里,在4.0之后在主线程里面执行Http请求都会报这个错,大概是怕Http请求时间太长造成程序假死的情况吧。
解决方法有两种,下面我分别介绍:
第一种,是在主线程中直接忽略,强制执行。(不推荐这种方法,但是该方法修改起来简单)
在MainActivity文件的setContentView(R.layout.activity_main)下面加上如下代码
if (android.os.Build.VERSION.SDK_INT > 9) { StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder().permitAll().build(); StrictMode.setThreadPolicy(policy);}
如果,有报错就在class头上加上
@TargetApi(Build.VERSION_CODES.GINGERBREAD)@SuppressLint("NewApi")
在onCreate上面加上:
@SuppressLint("NewApi")
第二种,启动另一个线程执行网络连接任务,比如使用Thread、Runnable、Handler(推荐使用这种方法)
代码如下:
public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); this.setContentView(R.layout.share_mblog_view); new Thread(runnable).start();}Handler handler = new Handler(){ @Override public void handleMessage(Message msg) { super.handleMessage(msg); Bundle data = msg.getData(); String val = data.getString("value"); Log.i("mylog","请求结果-->" + val); }}Runnable runnable = new Runnable(){ @Override public void run() { // // TODO: http request. // Message msg = new Message(); Bundle data = new Bundle(); data.putString("value","请求结果"); msg.setData(data); handler.sendMessage(msg); }}
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