Android线程问题，为什么当我使用工作线程时ui仍会阻塞？

Question

package com.commonsware.android.threads;

import android.app.Activity;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.ProgressBar;
import android.widget.TextView;
import android.widget.Toast;

public class HandlerDemo extends Activity {
   Thread mBackground;
   ProgressBar bar;
    Handler handler = new Handler() {
            @Override
            public void handleMessage(Message msg) {
                    bar.incrementProgressBy(5);
            }
    };
    boolean isRunning = false;

    @Override
    public void onCreate(Bundle icicle) {
            super.onCreate(icicle);
            setContentView(R.layout.main);
            bar = (ProgressBar) findViewById(R.id.progress);
    }

    public void onStart() {
            super.onStart();
            bar.setProgress(0);

            mBackground = new Thread(new Runnable() {
                    public void run() {
                            try {
                                    int a = 0;
                                    for (int i = 0; i < 20 && isRunning; i++) {
                                            for (int j = 0; j < 2000; j++) {
                                                    for (int k = 0; k < 1000; k++) {
                                                            a++;
                                                    }
                                            }
                                            handler.sendMessage(handler.obtainMessage());
                                    }
                            } catch (Throwable t) {
                                    // just end the background thread
                            }
                    }
            });

            findViewById(R.id.LoginButton).setOnClickListener(
                            new OnClickListener() {
                                    public void onClick(View v) {
                                            mBackground.run();
                                    }
                            });

            isRunning = true;

    }

    public void onStop() {
            super.onStop();
            isRunning = false;
    }

}

我真的很困惑 ......

Answer 1

你需要调用start（）而不是run（）。

public void onClick(View v) {
      mBackground.start();  //Start will spawn the Thread and then call it's run method.
}

通过在主线程中调用run（），就像任何正常的方法调用一样阻塞它。

Answer 2

试试这段代码

private void showProgrssBar(){
pLayout.setVisibility(View.VISIBLE);
final StringBuffer s=new StringBuffer();
final Thread progressThread=new Thread(){
    @Override
    public void run(){


            while(CreateVideoService.processingFrame>1) {
                 inc=100-((CreateVideoService.processingFrame*100)/(CreateVideoService.numberofRecordedFrames));
                 if(s.length()>0)
                 s.delete(0, s.length());
                 s.append("Processing... ").append(inc).append("%");
                 progressBarHandler.post(new Runnable() {

                    @Override
                    public void run() {
                        // TODO Auto-generated method stub
                        progressBar.setProgress(inc);
                        textProgrs.setText(s); 
                    }
                });
                 //progressBar.setProgress(100-inc);
                 try {
                     // Sleep for 5 seconds
                     Thread.sleep(200);
                 } catch (InterruptedException e) {
                     //Log.d("TAG", "sleep failure");
                 }
            }
            layoutHandler.post(new Runnable() {

                @Override
                public void run() {
                    // TODO Auto-generated method stub
                    pLayout.setVisibility(View.GONE);
                }
            });

    }
};
progressThread.start();
}