1.文件下載的步驟：
1）創建一個HttpURLConnection對象HttpURLConnection urlConn = (HttpRULConnection)url.openConnection();
2)獲得一個輸入流InputStream對象：urlConn.getInputStream()
3)訪問網絡權限：android:permission.INTERNET【在manifest.xml文件中聲明】
2.Android 廣播機制:廣播的是事件。
3.BroadcastReceiver用於堅挺被廣播的事件（Intent）爲了達到這個目的，BroadCastReceiver必須進行註冊，註冊的方法有以下兩種
1）在應用程序的代碼當中進行註冊；2）在AndroidManifest.xml當中進行註冊【應用程序被關閉了依然會監聽事件，如果是更新某個控件時候就不是很合適了】
4.在代碼當中進行註冊：如果一個BroadcastReceiver用於更新UI，那麼通常會使用這種方法進行註冊，在Activity啓動時候住粗，退出就取消註冊。
註冊BroadcastReceiver：registerReceiver(receiver,filter)
取消註冊：unregisterReceiver(receiver)
實例如下————————————————————————————————————————————————————
類：TestBC2Activity
package mars.testbc2;
import android.app.Activity;
import android.content.IntentFilter;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
public class TestBC2Activity extends Activity {
/** Called when the activity is first created. */
private Button registerButton = null;
private Button unregisterButton = null;
private SMSReceiver smsReceiver = null;
private static final String SMS_ACTION = "android.provider.Telephony.SMS_RECEIVED";
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
registerButton = (Button)findViewById(R.id.register);
registerButton.setOnClickListener(new RegisterReceiverListener());
unregisterButton = (Button)findViewById(R.id.unregister);
unregisterButton.setOnClickListener(new UnRegisterReceiverListener());
}
class RegisterReceiverListener implements OnClickListener{
@Override
public void onClick(View v) {
//生成一個BroiadcastReceiver對象
smsReceiver = new SMSReceiver();
//生成一個IntentFilter對象
IntentFilter filter = new IntentFilter();
//爲IntentFilter添加一個Action
filter.addAction(SMS_ACTION);
//將BroadcastReceiver對象註冊到系統當中
TestBC2Activity.this.registerReceiver(smsReceiver, filter);
}
}
class UnRegisterReceiverListener implements OnClickListener{
@Override
public void onClick(View v) {
//解除BroadcastReceiver對象的註冊
TestBC2Activity.this.unregisterReceiver(smsReceiver);
}
}
}
接受消息的代碼：類SMSReceiver——————————————————————————————————————————
package mars.testbc2;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.os.Bundle;
import android.telephony.SmsMessage;
public class SMSReceiver extends BroadcastReceiver{
@Override
public void onReceive(Context context, Intent intent) {
// TODO Auto-generated method stub
System.out.println("receive message");
//接受Intent對象當中的數據
Bundle bundle = intent.getExtras();
//在Bundle對象當中有一個屬性名爲pdus，這個屬性的值是一個Object數組
Object[] myOBJpdus = (Object[]) bundle.get("pdus");
//創建一個SmsMessage類型的數組
SmsMessage[] messages = new SmsMessage[myOBJpdus.length];
System.out.println(messages.length);
for (int i = 0; i<myOBJpdus.length; i++)
{
//使用Object數組當中的對象創建SmsMessage對象
messages[i] = SmsMessage.createFromPdu((byte[]) myOBJpdus[i]);
//調用SmsMessage對象的getDisppalyMessageBody()方法，就可以得到消息的內容
System.out.println(messages[i].getDisplayMessageBody());
}
}
}
