Android电话拨号程序

package com.lingzhuo.dialer;

import android.net.Uri;
import android.os.Bundle;
import android.app.Activity;
import android.content.Intent;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;

public class MainActivity extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Button bt=(Button) findViewById(R.id.bt_call);
        //给按钮设置点击侦听事件
        bt.setOnClickListener(new Mylistener());
    }
     class Mylistener implements OnClickListener{
         //按钮被点击时，调用此方法
        @Override
        public void onClick(View arg0) {
            // TODO Auto-generated method stub
            //System.out.println("点击拨号");
            //获得用户输入的号码
            EditText et=(EditText) findViewById(R.id.et_text);
            String phonenum=et.getText().toString();
            //我们需要告诉系统我们的动作：我要打电话
            //创建意图对象
            Intent intent=new Intent();
            //把动作封装到意图对象当中
            intent.setAction(Intent.ACTION_CALL);
            //设置打给谁
            intent.setData(Uri.parse("tel:"+phonenum));
            //把动作告诉系统
            startActivity(intent);
        }

     }


}

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity" 
    android:orientation="vertical"
    >

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"        
        android:text="请输入号码" />
    <EditText
        android:id="@+id/et_text"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:ems="10" >

        <requestFocus android:layout_width="wrap_content" />

    </EditText>
   <Button 
       android:id="@+id/bt_call"
       android:layout_width="wrap_content"
       android:layout_height="wrap_content"
       android:text="拨号"
       />
</LinearLayout>

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.lingzhuo.dialer"
    android:versionCode="1"
    android:versionName="1.0" >

    <uses-sdk
        android:minSdkVersion="8"
        android:targetSdkVersion="17" />
    <uses-permission android:name="android.permission.CALL_PHONE"/>


    <application
        android:allowBackup="true"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >
        <activity
            android:name="com.lingzhuo.dialer.MainActivity"
            android:label="@string/app_name" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>