之前的项目里要做一个异步更新UI的功能，可是结果出现了ANR，所以想写个demo来測试究竟是哪个地方出现了问题，结果发现原来的思路是没有问题，郁闷
~~
如今这个demo 就是模拟项目里面 的步骤
1、接收到系统的广播（如今模拟为人工发送）
2、广播接收到后，handler通知异步线程从网上下载数据，是异步（模拟为sleep）
3、数据下载完后handler再通知UI更新
以下是基本的两个代码，可以正确执行
package com.example.testanr;
import android.support.v7.app.ActionBarActivity;
import android.content.Intent;
import android.content.IntentFilter;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.TextView;
public class MainActivity extends ActionBarActivity {
public TextView hellworld = null;
public Button sendBroadcast = null;
public final static String MY_ACTION = "com.example.testanr.MY_ACTION";
public static int i = 0;
public Handler updateUI =new Handler(){
@Override
public void handleMessage(Message msg) {
// TODO Auto-generated method stub
super.handleMessage(msg);
if(msg.arg1 ==0){
hellworld.setText("更新UI - "+ i);
i++;
}
}
};
public Handler mHandler =new Handler(){
@Override
public void handleMessage(Message msg) {
// TODO Auto-generated method stub
super.handleMessage(msg);
if (msg.arg1 == 1 ){
new Thread(new Runnable(){
@Override
public void run() {
// TODO Auto-generated method stub
System.out.println("Thread id is "+Thread.currentThread().getId()+",and Thread name is "+Thread.currentThread().getName());
try {
Thread.currentThread().sleep(15000);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
Message msg =new Message();
msg.arg1 =0;
updateUI.sendMessage(msg);
}
}).start();
}
}
};
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
hellworld = (TextView)findViewById(R.id.hello_world);
sendBroadcast = (Button)findViewById(R.id.sendBroadcast);
//生成一个BroadcastReceiver对象
TestReceiver testReceiver = new TestReceiver(mHandler);
//生成一个IntentFilter对象
IntentFilter filter = new IntentFilter();
filter.addAction(MainActivity.MY_ACTION);
//将BroadcastReceiver对象注冊到系统其中
MainActivity.this.registerReceiver(testReceiver, filter);
System.out.println("Thread id is "+Thread.currentThread().getId()+",and Thread name is "+Thread.currentThread().getName());
sendBroadcast.setOnClickListener(new OnClickListener(){
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
//发送广播
Intent intent = new Intent();
intent.setAction(MainActivity.MY_ACTION);
sendBroadcast(intent);
}
});
}
@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;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
}
还有reciever
package com.example.testanr;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.os.Handler;
import android.os.Message;
public class TestReceiver extends BroadcastReceiver {
public Handler handler;
public Message message = null;
public TestReceiver(Handler handler){
this.handler = handler;
}
@Override
public void onReceive(Context context, Intent intent) {
// TODO Auto-generated method stub
//这里每次都要new，否者会报错
message = new Message();
message.arg1 = 1;
handler.sendMessage(message);
}
}
如今才发现一个message是不能往MessageQueue里面发送多次的，否则会报这种错
java.lang.IllegalStateException: The specified message queue synchronization barrier token has not been posted or has already been removed.
就说这个message的synchronization barrier token 已经发送过了的
可是项目里面的问题还没有解决，回头找出原因再发上来
我们知道ANR一般有三种类型：
1：KeyDispatchTimeout(5 seconds) --主要类型
按键或触摸事件在特定时间内无响应
2：BroadcastTimeout(10 seconds)
BroadcastReceiver在特定时间内无法处理完毕
3：ServiceTimeout(20 seconds) --小概率类型
Service在特定的时间内无法处理完毕
所以原因还是应该是另外一种，可能没有模拟对
ANR的分析
怎样调查并解决ANR
1：首先分析log
2: 从trace.txt文件查看调用stack.
3: 看代码
4：细致查看ANR的成因（iowait?block?memoryleak?）
可是项目里面log没有输出，是最奇怪的~~~
//************************************9-29更新****************8
回去一看果然是一个message往looper的messagequeue发送了多次！！！可是log没有输出exception，并且为什么会导致ANR，非常奇怪~~~求大神解答