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！