Android 2.3发短信详细流程

在android中，APP通过SmsManager.java一系列方法实现发送短信的功能，而发送的内容有很很多种，比如sendTextMessage、sendMultipartTextMessage、sendDataMessage等等，在这篇文章里我们就以其中一个为例阐述发送短信的完整流程，如果有不对的地方，请大家指正，一起学习。

1. 起点：SmsManager.java (frameworks/base/telephony/java/android/telephony/SmsManager.java)

sendTextMessage的核心代码如下：

view plaincopy to clipboardprint?public void sendTextMessage( 
          ...... 
       try { 
           ISms iccISms = ISms.Stub.asInterface(ServiceManager.getService("isms")); 
           if (iccISms != null) { 
               iccISms.sendText(destinationAddress, scAddress, text, sentIntent, deliveryIntent); 
           } 
       } catch (RemoteException ex) { 
           // ignore it  
       } 
   } 
 public void sendTextMessage(
           ......
        try {
            ISms iccISms = ISms.Stub.asInterface(ServiceManager.getService("isms"));
            if (iccISms != null) {
                iccISms.sendText(destinationAddress, scAddress, text, sentIntent, deliveryIntent);
            }
        } catch (RemoteException ex) {
            // ignore it
        }
    }其中，view plaincopy to clipboardprint?ISms iccISms = ISms.Stub.asInterface(ServiceManager.getService("isms")); 
ISms iccISms = ISms.Stub.asInterface(ServiceManager.getService("isms"));是通过AIDL的方式，获得服务，再调用这个服务对象的sendText()方法，那这个服务对象在哪里呢？
2. 我们知道，在eclipse中创建一个xx.aidl文件后，IDE会利用相关工具自动生成一个名为xx.java的接口，它有一个名为Stub的内部类，那我们自己创建一个类并继承这个内部类，则可以实现了进程间的通信，这个是aidl的知识，这儿不详述。我们往下看：

根据aidl的实现流程，那该服务对象应该是继承了ISms.Stub，经过查找我们发现这个服务类：IccSmsInterfaceManagerProxy.java，所以从SmsManager.sendTextMessage()方法调用了IccSmsInterfaceManagerProxy对象的sendText()方法。

3. 第二阶段：IccSmsInterfaceManagerProxy.java(frameworks/base/telephony/java/com/android/internal/telephony/IccSmsInterfaceManagerProxy)

我们看IccSmsInterfaceManagerProxy的sendText()方法核心代码：

view plaincopy to clipboardprint?private IccSmsInterfaceManager mIccSmsInterfaceManager; 
...... 
public void sendText(String destAddr, String scAddr, 
            String text, PendingIntent sentIntent, PendingIntent deliveryIntent) { 
        mIccSmsInterfaceManager.sendText(destAddr, scAddr, text, sentIntent, deliveryIntent); 
    } 
private IccSmsInterfaceManager mIccSmsInterfaceManager;
......
public void sendText(String destAddr, String scAddr,
            String text, PendingIntent sentIntent, PendingIntent deliveryIntent) {
        mIccSmsInterfaceManager.sendText(destAddr, scAddr, text, sentIntent, deliveryIntent);
    }
继续调用，此时调用的是IccSmsInterfaceManager对象的sendText()方法，那IccSmsInterfaceManager是什么玩意？？

4. 第三阶段：IccSmsInterfaceManager.java(frameworks/base/telephony/java/com/android/internal/telephony/IccSmsInterfaceManager.java)

从代码看出IccSmsInterfaceManager是一个继承了ISms.Stub的抽象类，相关核心代码如下：

view plaincopy to clipboardprint?protected SMSDispatcher mDispatcher; 
public void sendText(String destAddr, String scAddr, 
            String text, PendingIntent sentIntent, PendingIntent deliveryIntent) { 
        mPhone.getContext().enforceCallingPermission( 
                "android.permission.SEND_SMS", 
                "Sending SMS message"); 
        if (Log.isLoggable("SMS", Log.VERBOSE)) { 
            log("sendText: destAddr=" + destAddr + " scAddr=" + scAddr + 
                " text='"+ text + "' sentIntent=" + 
                sentIntent + " deliveryIntent=" + deliveryIntent); 
        } 
        mDispatcher.sendText(destAddr, scAddr, text, sentIntent, deliveryIntent); 
    } 
protected SMSDispatcher mDispatcher;
public void sendText(String destAddr, String scAddr,
            String text, PendingIntent sentIntent, PendingIntent deliveryIntent) {
        mPhone.getContext().enforceCallingPermission(
                "android.permission.SEND_SMS",
                "Sending SMS message");
        if (Log.isLoggable("SMS", Log.VERBOSE)) {
            log("sendText: destAddr=" + destAddr + " scAddr=" + scAddr +
                " text='"+ text + "' sentIntent=" +
                sentIntent + " deliveryIntent=" + deliveryIntent);
        }
        mDispatcher.sendText(destAddr, scAddr, text, sentIntent, deliveryIntent);
    }
IccSmsInterfaceManager对象的sendText()方法调用了SMSDispatcher类的sendText()方法，继续往下：
5. 第四阶段：SMSDispatcher.java(frameworks/base/telephony/java/com/android/internal/telephony/SMSDispatcher.java)

该类是一个抽象类，它的sendText()并没有实现，它的实现类是GsmSMSDispatcher.java或者CdmaSMSDispatcher.java,假设我们用的GSM网络，则此时调用到GsmSMSDispatcher的sendText()方法。

6. 第五阶段：GsmSMSDispatcher.java(frameworks/base/telephony/java/com/android/internal/telephony/gsm/GsmSMSDispatcher.java)

核心代码如下：

view plaincopy to clipboardprint?protected void sendText(String destAddr, String scAddr, String text, 
            PendingIntent sentIntent, PendingIntent deliveryIntent) { 
        SmsMessage.SubmitPdu pdu = SmsMessage.getSubmitPdu( 
                scAddr, destAddr, text, (deliveryIntent != null)); 
        sendRawPdu(pdu.encodedScAddress, pdu.encodedMessage, sentIntent, deliveryIntent); 
    } 
...... 
protected void sendText(String destAddr, String scAddr, String text,
            PendingIntent sentIntent, PendingIntent deliveryIntent) {
        SmsMessage.SubmitPdu pdu = SmsMessage.getSubmitPdu(
                scAddr, destAddr, text, (deliveryIntent != null));
        sendRawPdu(pdu.encodedScAddress, pdu.encodedMessage, sentIntent, deliveryIntent);
    }
......

到这儿，"sendText()"这个字眼就没了，换成了另外一个方法名：sendRawPdu(),追踪这个方法可以发现它是SMSDispatcher.java的一个方法，这个类看着很眼熟吧？不错，在第四阶段我们已经和它打过交道了！我们来看看它的sendRawPdu到底是干嘛的：view plaincopy to clipboardprint?protected void sendRawPdu(byte[] smsc, byte[] pdu, PendingIntent sentIntent, 
            PendingIntent deliveryIntent) { 
           ...... 
           sendSms(tracker); 
           ..... 
 } 
protected void sendRawPdu(byte[] smsc, byte[] pdu, PendingIntent sentIntent,
            PendingIntent deliveryIntent) {
           ......
           sendSms(tracker);
           .....
 }又来了一个新方法名：sendSms(),从sendRawPdu()传来的信息经过封装传递给sendSms()方法进行处理，而在SMSDispatcher.java中，这个方法只是声明了一下，它的具体实现由子类：GsmSMSDispatcher.java完成。下面我们来看GsmSMSDispatcher.java
7. 第六阶段：GsmSMSDispatcher.java(frameworks/base/telephony/java/com/android/internal/telephony/gsm/GsmSMSDispatcher.java)

GsmSMSDispatcher.java的sendSms()方法核心代码如下：

view plaincopy to clipboardprint?protected CommandsInterface mCm; 
 
protected void sendSms(SmsTracker tracker) { 
        HashMap map = tracker.mData; 
 
        byte smsc[] = (byte[]) map.get("smsc"); 
        byte pdu[] = (byte[]) map.get("pdu"); 
 
        Message reply = obtainMessage(EVENT_SEND_SMS_COMPLETE, tracker); 
        mCm.sendSMS(IccUtils.bytesToHexString(smsc), 
                IccUtils.bytesToHexString(pdu), reply); 
    } 
protected CommandsInterface mCm;

protected void sendSms(SmsTracker tracker) {
        HashMap map = tracker.mData;

        byte smsc[] = (byte[]) map.get("smsc");
        byte pdu[] = (byte[]) map.get("pdu");

        Message reply = obtainMessage(EVENT_SEND_SMS_COMPLETE, tracker);
        mCm.sendSMS(IccUtils.bytesToHexString(smsc),
                IccUtils.bytesToHexString(pdu), reply);
    }离成功已经不远了....
我们知道，CommandsInterface是一个特殊的接口，它的RIL.java息息相关，而在上面的代码中sendSms()调用来CommandsInterface对象的sendSMS()方法来做事情，而CommandsIterface是一个接口，所以事情只好由它的儿子(其实是孙子，RIL的爸爸BaseCommands是CommandsInterface的儿子)来完成，好，进入RIL.java.

8. 第七阶段：RIL.java(/frameworks/base/telephony/java/com/android/internal/telephony/RIL.java)

只要研究过ril层的，对这玩意都一定很熟悉，所以直接看它的sendSMS()方法：

view plaincopy to clipboardprint?public void sendSMS (String smscPDU, String pdu, Message result) { 
        RILRequest rr 
                = RILRequest.obtain(RIL_REQUEST_SEND_SMS, result); 
 
        rr.mp.writeInt(2); 
        rr.mp.writeString(smscPDU); 
        rr.mp.writeString(pdu); 
 
        if (RILJ_LOGD) riljLog(rr.serialString() + "> " + requestToString(rr.mRequest)); 
 
        send(rr); 
    } 
 
//send(RILRequest rr)  
<pre name="code" class="java">private void 
    send(RILRequest rr) { 
        Message msg; 
 
        msg = mSender.obtainMessage(EVENT_SEND, rr); 
 
        acquireWakeLock(); 
 
        msg.sendToTarget(); 
    } 
public void sendSMS (String smscPDU, String pdu, Message result) {
        RILRequest rr
                = RILRequest.obtain(RIL_REQUEST_SEND_SMS, result);

        rr.mp.writeInt(2);
        rr.mp.writeString(smscPDU);
        rr.mp.writeString(pdu);

        if (RILJ_LOGD) riljLog(rr.serialString() + "> " + requestToString(rr.mRequest));

        send(rr);
    }

//send(RILRequest rr)
<pre name="code" class="java">private void
    send(RILRequest rr) {
        Message msg;

        msg = mSender.obtainMessage(EVENT_SEND, rr);

        acquireWakeLock();

        msg.sendToTarget();
    }

OK!在sendSMS()方法中，我们把上面所传下来的东东写入到Parcel中，协同一个特殊的RILRequest被发送出去，发送到哪里了？接着看：view plaincopy to clipboardprint?public void 
        handleMessage(Message msg) { 
            RILRequest rr = (RILRequest)(msg.obj); 
            RILRequest req = null; 
 
            switch (msg.what) { 
                case EVENT_SEND: 
                    boolean alreadySubtracted = false; 
                    try { 
                      LocalSocket s; 
                      ...... 
                      s.getOutputStream().write(dataLength); 
                      s.getOutputStream().write(data); 
                    } catch (IOException ex) { 
                      ......      
                    } 
                    break; 
            } 
        } 
public void
        handleMessage(Message msg) {
            RILRequest rr = (RILRequest)(msg.obj);
            RILRequest req = null;

            switch (msg.what) {
                case EVENT_SEND:
                    boolean alreadySubtracted = false;
                    try {
                      LocalSocket s;
                      ......
                      s.getOutputStream().write(dataLength);
                      s.getOutputStream().write(data);
                    } catch (IOException ex) {
                      ......    
                    }
                    break;
            }
        }重点：LocalSocket、s.getOutputStream().write(data)
我们把短信相关的数据及特殊RILRequst对象写入到Socket的的输出流中，进而将数据传递到RIL层，即底层，然后RIL层通过接收Socket中传过来的数据解析得到请求内容并进行处理，到此，发短信的Java部分讲完了。

RIL层以后再分析，如果文中有不对的地方，请大家告诉我，谢谢！