Android中打电话的数据流程分析

dialButtonPressed() { 
......... 
final String number = mDigits.getText().toString(); 
startActivity(newDialNumberIntent(number)); 
mDigits.getText().clear(); 
finish(); 
} 

private Intent newDialNumberIntent(String number) { 
final Intent intent = new Intent(Intent.ACTION_CALL_PRIVILEGED, Uri.fromParts("tel", number, null)); 
............. 
} 

<PRE class=java name="code">protected void onCreate(Bundle icicle) { 
....... 
Intent intent = getIntent(); 
........ 
String action = intent.getAction(); 
....... 
final boolean emergencyNum = (number != null) && PhoneNumUtils.isEmergencyNumber(number);//判断号码是否是紧急号码 
....... 
if (Intent.ACTION_CALL_PRIVILEGED.equals(action)) ｛ 
action = emergencyNum ? Intent.ACTION_CALL_EMERGENCY : Intent.ACTION_CALL; 
intent.setAction(action); 
} 
....... 
intent.setClass(this, InCallScreen.class); 
startActivity(intent); 
}</PRE><P></P> 
<PRE></PRE> 
在这个方法中，判断如果所收到的ACTION是“ACTION_CALL_PRIVILEGED”，那么根据所输入的号码是否是紧急号码进行转换，如果是紧急号码，则ACTION ＝ Intent.ACTION_CALL_EMERGENCY,否则ACTION ＝ Intent.ACTION_CALL,并启动转换Activity ：InCallScreen.java 
<P></P> 
<P>3. InCallScreen.java依然在目录/packeges/Phone/src/com/android/phone下。</P> 
<P>InCallScreen的onCreate中调用initInCallScreen初始化打电话界面，并调用registerForPhoneStates注册电话状态监听.<BR> 
</P> 
<P>在onNewIntent()方法中有：</P> 
<P><PRE class=java name="code">protected void onNewIntent(Intent intent) { 
.......... 
String action = intent.getAction(); 
.......... 
else if (action.equals(Intent.ACTION_CALL) || action.equals(Intent.ACTION_CALL_EMERGENCY)) { 
.......... 
InCallInitStatus status = placeCall(intent); 
} 
} 
//placeCall 
private InCallInitStatus placeCall(Intent intent) { 
.............. 
int callStatus = PhoneUtils.placeCall(........); 
}</PRE>InCallScreen.java中的placeCall方法调用PhoneUtils.java文件的placeCall方法。<BR> 
<P></P> 
<P>4. PhoneUtils.java依然在目录/packeges/Phone/src/com/android/phone下。</P> 
<P><PRE class=java name="code">public static int placeCall(...) { 
Connection connection; 
connection = PhoneApp.getInstance().mCM.dial(phone, numberToDial); 
}</PRE>继续追踪，在PhoneApp.java中发现，mCM是CallManager.java类的一个对象，而CallManager.java是属于frameworks层的，所以，这个时候数据流已经进入frameworks.<P></P> 
<P>5. 进入/frameworks/base/telephony/java/com/android/internal/telephony目录。</P> 
<P>在CallManager.java的dial()方法中，有：</P> 
<P><PRE class=java name="code"><SPAN style="BACKGROUND-COLOR: rgb(255,255,255); FONT-FAMILY: Arial, Verdana, sans-serif; WHITE-SPACE: normal"></SPAN><PRE class=java name="code">public Connection dial(Phone phone, String dialNumber) throws CallStateException { 
Phone basePhone = getPhoneBase(phone); 
Connection result; 
<SPAN style="COLOR: #3333ff">result = basePhone.dial(dialString);</SPAN> 
........ 
} 
private static Phone getPhoneBase(Phone phone) { 
if (phone instanceof PhoneProxy) { 
<SPAN style="COLOR: #ff0000">return phone.getForegroundCall().getPhone();</SPAN> 
} 
return phone; 
}</PRE><P></P> 
<PRE></PRE> 
<PRE class=java name="code"><SPAN style="BACKGROUND-COLOR: rgb(255,255,255); FONT-FAMILY: Arial, Verdana, sans-serif; WHITE-SPACE: normal">继续追踪会发现：</SPAN></PRE><PRE class=java name="code"><SPAN style="BACKGROUND-COLOR: rgb(255,255,255); FONT-FAMILY: Arial, Verdana, sans-serif; WHITE-SPACE: normal">PhoneBase.java抽象类实现了接口Phone.java,而GSMPhone.java又实现了抽象类PhoneBase,所以:</SPAN></PRE> 
<P></P> 
<P>上述代码中：phone.getForegroundCall()实际相当于GSMPhone对象执行了getForegroundCall()方法。</P> 
<P>6. 继续追踪GSMPhone.java,该类位于/frameworks/base/telephony/java/com/android/internal/telephony/gsm/下。</P> 
<P><PRE class=java name="code">GSMPhone.java： 
GsmCallTracker mCT; 
public GsmCall getForegroundCall() { 
return mCT.foregroundCall; 
}</PRE>可以看出getForegroundCall()函数继续调用GsmCallTracker.java的foregroundCall属性。<P></P> 
<P>7.GsmCallTracker.java位于/frameworks/base/telephony/java/com/android/internal/telephony/gsm/下.</P> 
<P><PRE class=cpp name="code">GsmCallTracker.java: 
GSMCall foregroundCall = new GSMCall(this);</PRE><P></P> 
<P>打开GSMCall.java,找到getPhone()方法，发现：</P> 
<P><PRE class=java name="code">GSMCallTracker owner; 
public Phone getPhone() { 
return owner.phone; 
}</PRE><P></P> 
<P>而在GSMCallTracker.java中有如下声明：</P> 
<P><PRE class=cpp name="code">GSMPhone phone;</PRE><P></P> 
<P><SPAN style="COLOR: #ff0000">到此，我们得出一下结论：第5部分标记红色的代码所返回的就是GSMPhone的对象，</SPAN><SPAN style="COLOR: #3333ff">进一步可以得出，第5部分蓝色标记的代码即是调用了GSMPhone对象的dial方法。</SPAN></P> 
<P>8. 在GSMPhone.java中：</P> 
<P><PRE class=java name="code">GSMCallTracker mCT; 
public Connection dial(String dialString) throws CallStateException { 
return dial(dialString, null); 
} 
public Connection dial(String dialString, UUSInfo uusInfo) throws CallStateException { 
....... 
mCT.dial(.......); 
}</PRE><P></P> 
<P>继续调用GSMCallTracker.java中的dial()方法：</P> 
<P><PRE class=cpp name="code">GSMCallTracker.java： 
GSMCallTracker(GSMPhone phone) { 
cm = phone.mCM; 
} 
Connection dial(String dialString, int clirMode, UUSInfo uusInfo) { 
<SPAN style="COLOR: #ff0000">cm.dial(........);</SPAN> 
}</PRE>追踪mCM,发现 :<P></P> 
<P>public CommandsInterface mCM;</P> 
<P>所以GSMCallTracker持有CommandsInterface对象，即RIL.Java类的对象，所以"cm.dial(....)"即是调用RIL类对象的dial()方法。</P> 
<P>9. RIL.java</P> 
<P>BOSS出现。</P> 
<P>RIL对象负责把客户端的通话请求按照一定的格式发送给"rild"socket,至此，请求过程完毕。</P> 
</PRE>