Android应用程序中奇怪的NetworkOnMainThreadException?

2022-01-19 00:00:00 network-programming android networkonmainthread java

这个想法是开始聊天.所以我的班级中有这个属性:

The idea is to start a chat. So I have this properties in my class:

private MulticastSocket so;
private EditText messageBoard;
private InetAddress serverAddress;
private int port;

然后我在 onCreate() 方法中有这段代码:

Then I have this code in the onCreate() method:

protected void onCreate(Bundle savedInstanceState) {
    // TODO Auto-generated method stub
    super.onCreate(savedInstanceState);
    setContentView(R.layout.second);

    // connect to server
    connect();

    // Associate a variable with the Button on the interface
    final Button sendButton = (Button) findViewById(R.id.button2);
    sendButton.setOnClickListener(new View.OnClickListener() {

        @Override
        public void onClick(View v) {
            // when the button is clicked the next screen is loaded
            sendMessage();
        }
    });

}   // end of onCreate

这是我的 connect() 方法:

private void connect() {

    port = 4456;

    // convert the host name to InetAddress
    try {
        serverAddress = InetAddress.getByName("my server address is here");
    } catch (Exception e) {}

    // create socket and start communicating
    try {
        so = new MulticastSocket(port);
        so.joinGroup(serverAddress);
    } catch (IOException e) {}

    // start listening for incoming messages
    new Receiver(so, messageBoard);
}

在我看来一切都是正确的，但这就是它所说的:

Everything looks right to me but this is what it says:

01-24 23:33:16.277: W/dalvikvm(569): threadid=1: thread exiting with uncaught exception (group=0x409c01f8)
01-24 23:33:16.357: E/AndroidRuntime(569): FATAL EXCEPTION: main
01-24 23:33:16.357: E/AndroidRuntime(569): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.regeduser00x.proj1/com.regeduser00x.proj1.Second}: android.os.NetworkOnMainThreadException
01-24 23:33:16.357: E/AndroidRuntime(569):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1956)
01-24 23:33:16.357: E/AndroidRuntime(569):  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1981)
01-24 23:33:16.357: E/AndroidRuntime(569):  at android.app.ActivityThread.access$600(ActivityThread.java:123)
01-24 23:33:16.357: E/AndroidRuntime(569):  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1147)
01-24 23:33:16.357: E/AndroidRuntime(569):  at android.os.Handler.dispatchMessage(Handler.java:99)
01-24 23:33:16.357: E/AndroidRuntime(569):  at android.os.Looper.loop(Looper.java:137)
01-24 23:33:16.357: E/AndroidRuntime(569):  at android.app.ActivityThread.main(ActivityThread.java:4424)
01-24 23:33:16.357: E/AndroidRuntime(569):  at java.lang.reflect.Method.invokeNative(Native Method)
01-24 23:33:16.357: E/AndroidRuntime(569):  at java.lang.reflect.Method.invoke(Method.java:511)
01-24 23:33:16.357: E/AndroidRuntime(569):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
01-24 23:33:16.357: E/AndroidRuntime(569):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
01-24 23:33:16.357: E/AndroidRuntime(569):  at dalvik.system.NativeStart.main(Native Method)
01-24 23:33:16.357: E/AndroidRuntime(569): Caused by: android.os.NetworkOnMainThreadException
01-24 23:33:16.357: E/AndroidRuntime(569):  at android.os.StrictMode$AndroidBlockGuardPolicy.onNetwork(StrictMode.java:1099)
01-24 23:33:16.357: E/AndroidRuntime(569):  at java.net.InetAddress.lookupHostByName(InetAddress.java:391)
01-24 23:33:16.357: E/AndroidRuntime(569):  at java.net.InetAddress.getAllByNameImpl(InetAddress.java:242)
01-24 23:33:16.357: E/AndroidRuntime(569):  at java.net.InetAddress.getByName(InetAddress.java:295)
01-24 23:33:16.357: E/AndroidRuntime(569):  at com.regeduser00x.proj1.Second.connect(Second.java:99)
01-24 23:33:16.357: E/AndroidRuntime(569):  at com.regeduser00x.proj1.Second.onCreate(Second.java:38)
01-24 23:33:16.357: E/AndroidRuntime(569):  at android.app.Activity.performCreate(Activity.java:4465)
01-24 23:33:16.357: E/AndroidRuntime(569):  at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1049)
01-24 23:33:16.357: E/AndroidRuntime(569):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1920)
01-24 23:33:16.357: E/AndroidRuntime(569):  ... 11 more

那个 Second.java:99 恰好是 serverAddress = InetAddress.getByName("my server address is here"); 并且第 38 行恰好是 connect(); 怎么回事?我已经在一个小型测试程序中使用 InetAddress 测试了该行，它运行良好，但这里发生了一些事情.

That Second.java:99 happens to be serverAddress = InetAddress.getByName("my server address is here"); and line 38 happens to be connect(); What's the matter with it? I have tested the line with the InetAddress in a small test program and it works perfectly but here something happens.

推荐答案

这一行:

Caused by: android.os.NetworkOnMainThreadException

告诉你发生了什么.

您正在尝试访问 Main(UI) 线程上的网络函数.从 Honeycomb 开始，系统会在您执行此操作时引发异常.

You are attempting to access a network function on the Main(UI) thread. starting with Honeycomb the system raises an Exception when you do this.

要解决此问题，您只需将任何与网络接触的东西移至其自己的线程即可.

To fix you just need to move any thing that is touching the network to its own thread.

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