AsyncTask后台线程的简单应用（进度条更新显示）

1.MainActivity的内容

importandroid.os.Bundle;

importandroid.app.Activity;

importandroid.view.Menu;

importandroid.view.View;

importandroid.view.View.OnClickListener;

importandroid.widget.Button;

importandroid.widget.ProgressBar;

importandroid.widget.TextView;

 

publicclass MainActivity extendsActivity {

     

    privateTextView textview;

    privateButton button;

    privateProgressBar bar;

     

 

    @Override

    protectedvoid onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);

        findview();

        setview();

    }

    privateOnClickListener beginPro = newOnClickListener() {

         

        @Override

        publicvoid onClick(View v) {

            // TODO Auto-generated method stub

            FirstAsyncTask fat = newFirstAsyncTask(textview,bar);

            //execute方法传递一个参数到doInBackground

            fat.execute(1000);

        }

    };

 

    @Override

    publicboolean onCreateOptionsMenu(Menu menu) {

        // Inflate the menu; this adds items to the action bar if it is present.

        getMenuInflater().inflate(R.menu.main, menu);

        returntrue;

    }

    //关联控件

    publicvoid findview(){

        textview = (TextView)findViewById(R.id.textview);

        button = (Button)findViewById(R.id.button);

        bar = (ProgressBar)findViewById(R.id.progressbar);

    }

    //设置控件响应

    publicvoid setview(){

        button.setOnClickListener(beginPro);

    }

 

}

2.添加FirstAnsyicTask类，其中中的代码如下：

importandroid.os.AsyncTask;

importandroid.widget.ProgressBar;

importandroid.widget.TextView;

 

 

publicclass FirstAsyncTask extendsAsyncTask<Integer, Integer, String>{

     

    privateTextView textview;

    privateProgressBar bar;

     

    publicFirstAsyncTask(TextView textview,ProgressBar progressbar){

        this.textview = textview;

        this.bar = progressbar;

    }

 

    //这个函数里面不能写修改控件内容的代码

    @Override

    protectedString doInBackground(Integer... params) {

        // TODO Auto-generated method stub

        UIOperator op = newUIOperator();

        inti;

        for(i=0;i<=100;i+=10){

            op.operator();

            publishProgress(i);

        }

         

        returni+params[0].intValue()+"";

    }

    //在doInBackground之后执行

    @Override

    protectedvoid onPostExecute(String result){

        textview.setText("异步操作执行结束"+result);

    }

    //在doInBackground之前执行

    @Override

    protectedvoid onPreExecute(){

        textview.setText("开始执行异步操作");

    }

    //每次执行publishprogress()之后执行以下函数

    @Override

    protectedvoid onProgressUpdate(Integer... values){

        intvalue = values[0];

        bar.setProgress(value);

    }

     

     

 

}

3.创建一个很简单的操作类

publicclass UIOperator {

    publicvoid operator(){

        try{

            Thread.sleep(1000);

        }catch(InterruptedException e){

            e.printStackTrace();

        }

    }

}