duanlove

[android] frameworks sendRawPdu 详解

frameworks/opt/telephony/src/java/com/android/internal/telephony/gsm/gsmSMSDispatcher.java

gsmSMSDispatcher.java 里有很多文件都调用了 sendRawPdu()

sendTextWithEncodingType()

sendRawPdu(pdu.encodedScAddress, pdu.encodedMessage, sentIntent, deliveryIntent, destAddr);

frameworks/opt/telephony/src/java/com/android/internal/telephony/SMSDispatcher.java

下定义了 4 个类

public abstract class SMSDispatcherextends Handler

以下3个类都是嵌套在SMSDispatcher 类当中的。
           private static class SettingsObserverextends ContentObserver
           protected static final class SmsTracker
           private final class ConfirmDialogListener

发送sms是通过如下sendTextWithEncodingType函数来的。它是被 gemini 层的相关函数调用，然后发送的。

关于它是被哪儿调用的，我们可以参考 “http://blog.csdn.net/duanlove/article/details/9499539”。

那我们看看sendTextWithEncodingType的实现。

frameworks/opt/telephony/src/java/com/android/internal/telephony/gsm/gsmSMSDispatcher.java

    // MTK-END [ALPS00094284] Filter hyphen of phone number by mtk80589 in 2011.11.23
    // MTK-END [ALPS000xxxxx] MTK code port to ICS added by mtk80589 in 2011.11.16

    // MTK-START [ALPS00094531] Orange feature SMS Encoding Type Setting by mtk80589 in 2011.11.22
    /** {@inheritDoc} */
    protected void sendTextWithEncodingType( //单条发送，不需要拆分，就调用这个。
            String destAddr,
            String scAddr,
            String text,
            int encodingType,
            PendingIntent sentIntent,
            PendingIntent deliveryIntent) {
        // impl
        // MTK_OPTR_PROTECT_START
        if (isDmLock == true) {
            Log.d(TAG, "DM status: lock-on");
            return;
        }
        // MTK_OPTR_PROTECT_END

        int encoding = encodingType;
        TextEncodingDetails details = SmsMessage.calculateLength(text, false); // 需理解的重点1.
        if (encoding != details.codeUnitSize &&
            (encoding == SmsConstants.ENCODING_UNKNOWN ||
             encoding == SmsConstants.ENCODING_7BIT)) {
            Log.d(TAG, "[enc conflict between details[" + details.codeUnitSize
                    + "] and encoding " + encoding);
            details.codeUnitSize = encoding;
        }

        SmsMessage.SubmitPdu pdu = SmsMessage.getSubmitPdu(  // 需理解的重点2.
                scAddr, destAddr, text, (deliveryIntent != null),
                null, encoding, details.languageTable, details.languageShiftTable);

        if (pdu != null) {
            sendRawPdu(pdu.encodedScAddress, pdu.encodedMessage, sentIntent, deliveryIntent, destAddr);  // 需理解的重点3
        } else {
            Log.d(TAG, "sendText: pdu is null");
            if (sentIntent != null) {
                try {
                    sentIntent.send(RESULT_ERROR_NULL_PDU);
                } catch (CanceledException ex) {
                    Log.e(TAG, "failed to send back RESULT_ERROR_NULL_PDU");
                }
            }
        }
    }

    /** {@inheritDoc} */
    protected void sendMultipartTextWithEncodingType( // 需要拆分成多条发送，就使用这个函数
            String destAddr,
            String scAddr,
            ArrayList parts,
            int encodingType,
            ArrayList sentIntents,
            ArrayList deliveryIntents) {
        // impl
        // MTK_OPTR_PROTECT_START
        if (isDmLock == true) {
            Log.d(TAG, "DM status: lock-on");
            return;
        }
        // MTK_OPTR_PROTECT_END

        int refNumber = getNextConcatenatedRef() & 0xff;
        int msgCount = parts.size();
        int encoding = encodingType;

        mRemainingMessages = msgCount;
        TextEncodingDetails[] encodingForParts = new TextEncodingDetails[msgCount];
        for (int i = 0; i < msgCount; ++i) {
            TextEncodingDetails details = SmsMessage.calculateLength(parts.get(i), false);
            if (encoding != details.codeUnitSize &&
                (encoding == SmsConstants.ENCODING_UNKNOWN ||
                 encoding == SmsConstants.ENCODING_7BIT)) {
                Log.d(TAG, "[enc conflict between details[" + details.codeUnitSize
                        + "] and encoding " + encoding);
                details.codeUnitSize = encoding;
            }
            encodingForParts[i] = details;
        }

        for (int i = 0; i < msgCount; ++i) {// 按照拆分的条数，一条一条发送。
            SmsHeader.ConcatRef concatRef = new SmsHeader.ConcatRef();
            concatRef.refNumber = refNumber;
            concatRef.seqNumber = i + 1; // 1-based sequence
            concatRef.msgCount = msgCount;
            // TODO: We currently set this to true since our messaging app will never
            // send more than 255 parts (it converts the message to MMS well before that).
            // However, we should support 3rd party messaging apps that might need 16-bit
            // references
            // Note: It's not sufficient to just flip this bit to true; it will have
            // ripple effects (several calculations assume 8-bit ref).
            concatRef.isEightBits = true;
            SmsHeader smsHeader = new SmsHeader();
            smsHeader.concatRef = concatRef;
            if (encoding == SmsConstants.ENCODING_7BIT) {
                smsHeader.languageTable = encodingForParts[i].languageTable;
                smsHeader.languageShiftTable = encodingForParts[i].languageShiftTable;
            }

            PendingIntent sentIntent = null;
            if (sentIntents != null && sentIntents.size() > i) {
                sentIntent = sentIntents.get(i);
            }

            PendingIntent deliveryIntent = null;
            if (deliveryIntents != null && deliveryIntents.size() > i) {
                deliveryIntent = deliveryIntents.get(i);
            }

            SmsMessage.SubmitPdu pdu = SmsMessage.getSubmitPdu(
                    scAddr, destAddr, parts.get(i), (deliveryIntent != null),
                    SmsHeader.toByteArray(smsHeader), encoding,
                    smsHeader.languageTable, smsHeader.languageShiftTable);

            if (pdu != null) {
                sendRawPdu(pdu.encodedScAddress, pdu.encodedMessage, sentIntent, deliveryIntent, destAddr);
            } else {
                Log.d(TAG, "sendText: pdu is null");
                if (sentIntent != null) {
                    try {
                        sentIntent.send(RESULT_ERROR_NULL_PDU);
                    } catch (CanceledException ex) {
                        Log.e(TAG, "failed to send back RESULT_ERROR_NULL_PDU");
                    }
                }
            }
        }
    }

GsmAlphabet.java (fram\base\telephony\java\com\android\internal\telephony)

package com.android.internal.telephony;

import android.content.res.Resources;
import android.text.TextUtils;
import android.util.SparseIntArray;

import android.util.Log;

import java.nio.ByteBuffer;
import java.nio.charset.Charset;
import com.android.internal.telephony.SmsConstants;
import com.android.internal.R;

import java.util.ArrayList;
import java.util.List;

/**
* This class implements the character set mapping between
* the GSM SMS 7-bit alphabet specified in TS 23.038 6.2.1
* and UTF-16
*
* {@hide}
*/
public class GsmAlphabet {
private static final String TAG = "GSM";

private GsmAlphabet() { }

    /**
     * This escapes extended characters, and when present indicates that the
     * following character should be looked up in the "extended" table.
     *
     * gsmToChar(GSM_EXTENDED_ESCAPE) returns 0xffff
     */
    public static final byte GSM_EXTENDED_ESCAPE = 0x1B;

    /**
     * User data header requires one octet for length. Count as one septet, because
     * all combinations of header elements below will have at least one free bit
     * when padding to the nearest septet boundary.
     */
    public static final int UDH_SEPTET_COST_LENGTH = 1;

    /**
     * Using a non-default language locking shift table OR single shift table
     * requires a user data header of 3 octets, or 4 septets, plus UDH length.
     */
    public static final int UDH_SEPTET_COST_ONE_SHIFT_TABLE = 4;

    /**
     * Using a non-default language locking shift table AND single shift table
     * requires a user data header of 6 octets, or 7 septets, plus UDH length.
     */
    public static final int UDH_SEPTET_COST_TWO_SHIFT_TABLES = 7;

    /**
     * Multi-part messages require a user data header of 5 octets, or 6 septets,
     * plus UDH length.
     */
    public static final int UDH_SEPTET_COST_CONCATENATED_MESSAGE = 6;

    /**
     * For a specific text string, this object describes protocol
     * properties of encoding it for transmission as message user
     * data.
     */
    public static class TextEncodingDetails {
        /**
         *The number of SMS's required to encode the text.
         */
        public int msgCount;

        /**
         * The number of code units consumed so far, where code units
         * are basically characters in the encoding -- for example,
         * septets for the standard ASCII and GSM encodings, and 16
         * bits for Unicode.
         */
        public int codeUnitCount;

        /**
         * How many code units are still available without spilling
         * into an additional message.
         */
        public int codeUnitsRemaining;

        /**
         * The encoding code unit size (specified using
         * android.telephony.SmsMessage ENCODING_*).
         */
        public int codeUnitSize;

        /**
         * The GSM national language table to use, or 0 for the default 7-bit alphabet.
         */
        public int languageTable;

        /**
         * The GSM national language shift table to use, or 0 for the default 7-bit extension table.
         */
        public int languageShiftTable;

// MTK-START [ALPS000xxxxx] MTK code port to ICS added by mtk80589 in 2011.11.16
public boolean useSingleShift = false;

public boolean useLockingShift = false;

public int shiftLangId = -1;
// MTK-END [ALPS000xxxxx] MTK code port to ICS added by mtk80589 in 2011.11.16

        @Override
        public String toString() {
            return "TextEncodingDetails " +
                    "{ msgCount=" + msgCount +
                    ", codeUnitCount=" + codeUnitCount +
                    ", codeUnitsRemaining=" + codeUnitsRemaining +
                    ", codeUnitSize=" + codeUnitSize +
                    ", languageTable=" + languageTable +
                    ", languageShiftTable=" + languageShiftTable +
                    " }";
        }
    }

对于 sms 流程中非常重要的一个函数 sendRawPdu 定义于SMSDispatcher类当中。我们来看看它的实现：

    /**
     * Send a SMS
     *
     * @param smsc the SMSC to send the message through, or NULL for the
     * default SMSC
     * @param pdu the raw PDU to send
     * @param sentIntent if not NULL this Intent is
     * broadcast when the message is successfully sent, or failed.
     * The result code will be Activity.RESULT_OK for success,      * or one of these errors:      * RESULT_ERROR_GENERIC_FAILURE      * RESULT_ERROR_RADIO_OFF      * RESULT_ERROR_NULL_PDU      * RESULT_ERROR_NO_SERVICE.      * The per-application based SMS control checks sentIntent. If sentIntent      * is NULL the caller will be checked against all unknown applications,      * which cause smaller number of SMS to be sent in checking period.      * @param deliveryIntent if not NULL this Intent is      * broadcast when the message is delivered to the recipient. The      * raw pdu of the status report is in the extended data ("pdu").      * @param destAddr the destination phone number (for short code confirmation)      */     protected void sendRawPdu(byte[] smsc, byte[] pdu, PendingIntent sentIntent, PendingIntent deliveryIntent, String destAddr)

 
  {
 
  
     if (mSmsSendDisabled) 
     {
         if (sentIntent != null) 
         {
             try {
                 sentIntent.send(RESULT_ERROR_NO_SERVICE);
             } catch (CanceledException ex) {}
         }
         Log.d(TAG, "Device does not support sending sms.");
         return;
     } 
      if (pdu == null) 
     {
         if (sentIntent != null) 
         {
             try {
                 sentIntent.send(RESULT_ERROR_NULL_PDU);
             } catch (CanceledException ex) {}
         }
         return;
     } 
      HashMap map = new HashMap();
     map.put("smsc", smsc);
     map.put("pdu", pdu); 
      // Get calling app package name via UID from Binder call
     PackageManager pm = mContext.getPackageManager();
     String[] packageNames = pm.getPackagesForUid(Binder.getCallingUid()); 
      if (packageNames == null || packageNames.length == 0) 
     {
         // Refuse to send SMS if we can't get the calling package name.
         Log.e(TAG, "Can't get calling app package name: refusing to send SMS");
         if (sentIntent != null) 
         {
             try 
             {
                 sentIntent.send(RESULT_ERROR_GENERIC_FAILURE);
             } catch (CanceledException ex) {
                 Log.e(TAG, "failed to send error result");
             }
         }
         return;
     } 
      // MTK-START
     /* Because it may have multiple apks use the same uid, ex. Mms.apk and omacp.apk, we need to
      * exactly find the correct calling apk. We should use running process to check the correct
      * apk. If we could not find the process via pid, this apk may be killed. We will use the
      * default behavior, find the first package name via uid. 
      */
     if (packageNames.length > 1)
     {
         int callingPid = Binder.getCallingPid(); 
          ActivityManager am = (ActivityManager) mContext.getSystemService(Context.ACTIVITY_SERVICE);
         List processList = am.getRunningAppProcesses();
         Iterator index = processList.iterator();
         while (index.hasNext())
         {
             ActivityManager.RunningAppProcessInfo processInfo = (ActivityManager.RunningAppProcessInfo)(index.next());
             if (callingPid == processInfo.pid)
             {
                 packageNames[0] = processInfo.processName;
                 break;
             }
         }
     }
     // MTK-END 
      // Get package info via packagemanager
     PackageInfo appInfo = null;
     try 
     {
         // XXX this is lossy- apps can share a UID
         appInfo = pm.getPackageInfo(packageNames[0], PackageManager.GET_SIGNATURES);
     } catch (PackageManager.NameNotFoundException e) {
         Log.e(TAG, "Can't get calling app package info: refusing to send SMS");
         if (sentIntent != null) {
             try {
                 sentIntent.send(RESULT_ERROR_GENERIC_FAILURE);
             } catch (CanceledException ex) {
                 Log.e(TAG, "failed to send error result");
             }
         }
         return;
     } 
      // Strip non-digits from destination phone number before checking for short codes
     // and before displaying the number to the user if confirmation is required.
     SmsTracker  tracker = new  SmsTracker(map, sentIntent, deliveryIntent, appInfo,
             PhoneNumberUtils.extractNetworkPortion(destAddr)); 
      // checkDestination() returns true if the destination is not a premium short code or the
     // sending app is approved to send to short codes. Otherwise, a message is sent to our
     // handler with the SmsTracker to request user confirmation before sending. 
    
  // checkDestination(tracker):  true !      mUsageMonitor.check(appInfo.packageName, SINGLE_PART_SMS):   false   
   // 此打印表明 并没有进入下面的第二个if语句，sendMessage 没有被调用。 
  
    if (checkDestination(tracker)) 
     {
         // check for excessive outgoing SMS usage by this app
         if (!mUsageMonitor.check(appInfo.packageName, SINGLE_PART_SMS)) { // 下面并没有执行
             sendMessage(obtainMessage(EVENT_SEND_LIMIT_REACHED_CONFIRMATION, tracker));
            return;
         } 
  // 流程到这里，继续往下走 
          int ss = mPhone.getServiceState().getState(); 
  // ss != ServiceState.STATE_IN_SERVICE:   false   ；表明，并没有执行             handleNotInService(ss, tracker.mSentIntent); 
          if (ss != ServiceState.STATE_IN_SERVICE) 
         {
             handleNotInService(ss, tracker.mSentIntent);
        } else 
         {  // 实际上，走到了下面这个分支
             String appName = getAppNameByIntent(sentIntent);
             // MTK-START [ALPS000xxxxx] MTK code port to ICS added by mtk80589 in 2011.11.16 
  // MTK_SMS_FILTER_SUPPORT true, call createMessageFromSubmitPdu 
  
             if(FeatureOption.MTK_SMS_FILTER_SUPPORT == true) {    // 短信正常，进入这里
                SmsMessage msg =  createMessageFromSubmitPdu(smsc, pdu); // 从PDU创建 SmsMessage 类，以方便下面的 checkSmsWithNqFilter 函数使用
                if(msg != null) 
                 {    // 短信不为空，进入if分支； 上面的msg 是为了方便获取 sms的目的地址 和 消息体！以检查是否需要过滤！
                     boolean ret = checkSmsWithNqFilter(msg.getDestinationAddress(), msg.getMessageBody(), sentIntent);
                     if(ret == false) 
                     {
                         Log.d(TAG, "[NQ this message is safe");
                        if (mUsageMonitor.check(appName, SINGLE_PART_SMS))
                         {
                             sendSms(tracker);// 发送短信 分支1 
                         } else 
                         {
                             sendMessage(obtainMessage(EVENT_SEND_LIMIT_REACHED_CONFIRMATION, tracker));//发送短信 分支1
                         }
                    } else 
                     {
                         Log.d(TAG, "[NQ this message may deduct fees");
                     
                         SmsHeader.ConcatRef newConcatRef = null;
                         if(msg.getUserDataHeader() != null) {
                             newConcatRef = msg.getUserDataHeader().concatRef;
                         }
                     
                         if(newConcatRef != null) {
                             if(sConcatRef == null || sConcatRef.refNumber != newConcatRef.refNumber) {
                                 Log.d(TAG, "[NQ this is a new concatenated message, just update");
                                 sConcatRef = newConcatRef;
                                 //sConcatMsgCount = 1;
                                 sendMessage(obtainMessage(EVENT_HANDLE_REDUCTED_MESSAGE, tracker));
                             } else {
                                 Log.d(TAG, "[NQ this is the same concatenated message, keep previous operation");
                                 //mSTrackers.add(tracker);
                                 sConcatMsgCount += 1;
                             }
                         } else {
                             Log.d(TAG, "[NQ this is a non-concatenated message");
                             //sConcatMsgCount = 0;
                             sendMessage(obtainMessage(EVENT_HANDLE_REDUCTED_MESSAGE, tracker));
                         }
                     }
                 } else 
                 {
                     Log.d(TAG, "[NQ fail to create message from pdu");
                     if (mUsageMonitor.check(appName, SINGLE_PART_SMS)) {
                         sendSms(tracker);
                     } else {
                         sendMessage(obtainMessage(EVENT_SEND_LIMIT_REACHED_CONFIRMATION, tracker));
                     }
                 }
             } else 
             {
             // MTK-END [ALPS000xxxxx] MTK code port to ICS added by mtk80589 in 2011.11.16
                 if (mUsageMonitor.check(appName, SINGLE_PART_SMS)) {
                     sendSms(tracker);
                 } else {
                     sendMessage(obtainMessage(EVENT_SEND_LIMIT_REACHED_CONFIRMATION, tracker));
                 }
             // MTK-START [ALPS000xxxxx] MTK code port to ICS added by mtk80589 in 2011.11.16
             }
             // MTK-END   [ALPS000xxxxx] MTK code port to ICS added by mtk80589 in 2011.11.16
         }
         // 短信发送完成，直接跳到这里。
     }
 
    
  }
 
    
  同一个文件也定义了：class SmsTracker 和 sendSms 
  
     /**
      * Send the message along to the radio.
      *
      * @param tracker holds the SMS message to send
      */
     protected abstract void sendSms(SmsTracker tracker); 
    
      protected static final class SmsTracker 
     {
         // fields need to be public for derived SmsDispatchers
         public final HashMap mData;
         public int mRetryCount;
         public int mMessageRef; 
          public final PendingIntent mSentIntent;
         public final PendingIntent mDeliveryIntent; 
          public final PackageInfo mAppInfo;
         public final String mDestAddress; 
         //构造函数 
          public SmsTracker(HashMap data, PendingIntent sentIntent,
                 PendingIntent deliveryIntent, PackageInfo appInfo, String destAddr) 
        {
             mData = data;
             mSentIntent = sentIntent;
             mDeliveryIntent = deliveryIntent;
             mRetryCount = 0;
             mAppInfo = appInfo;
             mDestAddress = destAddr;
         } 
          /**
          * Returns whether this tracker holds a multi-part SMS.
          * @return true if the tracker holds a multi-part SMS; false otherwise
          */
         protected boolean isMultipart() {
             HashMap map = mData;
             return map.containsKey("parts");
         }
     } 
    
    
    
  而 以下文件中也定义了 sendSms 函数 
  frameworks/opt/telephony/src/java/com/android/internal/telephony/gsm/SMSDispatcher.java
   
  class GsmSMSDispatcher  中定义了： 
    
      /** {@inheritDoc} */
     @Override
     protected void sendSms(SmsTracker tracker) 
     {
         HashMap map = tracker.mData; 
          byte smsc[] = (byte[]) map.get("smsc");
         byte pdu[] = (byte[]) map.get("pdu"); 
          // MTK-START [ALPS000xxxxx] MTK code port to ICS added by mtk80589 in 2011.11.16
         synchronized (mSTrackersQueue) 
         {
             if (mSTrackersQueue.isEmpty() || mSTrackersQueue.get(0) == tracker) {// 如果队列为空，且当前第一个消息是本消息，那么，就发送这个消息。
         // MTK-END [ALPS000xxxxx] MTK code port to ICS added by mtk80589 in 2011.11.16
                Message reply =  obtainMessage(EVENT_SEND_SMS_COMPLETE, tracker);
                 mCm.sendSMS(IccUtils.bytesToHexString(smsc),  IccUtils.bytesToHexString(pdu), reply);//  发送消息
        // MTK-START [ALPS000xxxxx] MTK code port to ICS added by mtk80589 in 2011.11.16
             } 
              if (mSTrackersQueue.isEmpty() || mSTrackersQueue.get(0) != tracker) { // 如果队列为空，且第一个不是 本消息 ，那么就把本消息加入到队列中去。
                 Log.d(TAG, "Add tracker into the list: " + tracker);                //如果 队列不为空，第一个 消息，也不是本消息，还是把本消息加入到队列中去。
                 mSTrackersQueue.add(tracker);
             }
         }
         // MTK-END [ALPS000xxxxx] MTK code port to ICS added by mtk80589 in 2011.11.16
     } 
    
  GsmSMSDispatcher 实际上是 SMSDispatcher 的一个 子类，也就是派生类。 
           public final class GsmSMSDispatcherextendsSMSDispatcher 
    
  它还包含了一个 嵌套类： 
      private static final class SmsCbConcatInfo{ 
          private final SmsCbHeader mHeader;
         private final SmsCbLocation mLocation; 
          public SmsCbConcatInfo(SmsCbHeader header, SmsCbLocation location) {
             mHeader = header;
             mLocation = location;
         } 
          @Override
         public int hashCode() {
             return (mHeader.getSerialNumber() * 31) + mLocation.hashCode();
         } 
          @Override
         public boolean equals(Object obj) {
             if (obj instanceof SmsCbConcatInfo) {
                 SmsCbConcatInfo other = (SmsCbConcatInfo)obj; 
                  // Two pages match if they have the same serial number (which includes the
                 // geographical scope and update number), and both pages belong to the same
                 // location (PLMN, plus LAC and CID if these are part of the geographical scope).
                 return mHeader.getSerialNumber() == other.mHeader.getSerialNumber()
                         && mLocation.equals(other.mLocation);
             } 
              return false;
         } 
          /**
          * Compare the location code for this message to the current location code. The match is
          * relative to the geographical scope of the message, which determines whether the LAC
          * and Cell ID are saved in mLocation or set to -1 to match all values.
          *
          * @param plmn the current PLMN
          * @param lac the current Location Area (GSM) or Service Area (UMTS)
          * @param cid the current Cell ID
          * @return true if this message is valid for the current location; false otherwise
          */
         public boolean matchesLocation(String plmn, int lac, int cid) {
             return mLocation.isInLocationArea(plmn, lac, cid);
         }
     } 
    
    
  #### 下面我们看一下 createMessageFromSubmitPdu返回  android.telephony.SmsMessage 的这个流程 ###### 
    
  GsmSMSDispatcher  中的createMessageFromSubmitPdu  可以从 一个PDU BYTE数组创建一个 android.telephony.SmsMessage  类。 
      protected android.telephony.SmsMessage  createMessageFromSubmitPdu(byte[] smsc, byte[] tpdu) 
  {
         // smsc + tpdu
         Log.d(TAG, "[NQ tpdu first byte is " + tpdu[0]);
         int tpduLen = tpdu.length;
         int smscLen = 1;
         if (smsc != null) {// 如果 smsc不为null的话 ，就取出 smsc的长度 赋值给 smscLen  ，否则 smscLen   就是 默认为1 。
             smscLen = smsc.length; 
         } else {
             Log.d(TAG, "[NQ smsc is null");
         }
         byte[] msgPdu = new byte[smscLen + tpduLen]; 
         int curIndex = 0;
         try {
             if (smsc != null) {  //smsc ：需要注意的是smsc第一个byte的低八位 代表了发送者地址的长度。
                 System.arraycopy(smsc, 0, msgPdu, curIndex, smscLen);// // 如果 smsc不为null的话 ， 就先把smsc （发送者的地址）存入到 msgPdu
             } else {
                 msgPdu[0] = 0;   // 否则的话，就只占一个byte，并且这个 byte是第一个byte，内容是 0
             }
             curIndex += smscLen;
             System.arraycopy(tpdu, 0,  msgPdu, curIndex, tpduLen); // 接着把剩下的tpdu部分原始的pdu数据，追加到 smsc后面。 其实到这里为止做的主要工作就是把发送者的地址和pdu数据整合到一起。并准备传入下面的函数。
            Log.d(TAG, "[NQ mti byte in msgPdu is " + msgPdu[1]);
         } catch (IndexOutOfBoundsException e) {
             Log.d(TAG, "[NQ out of bounds error when copy pdu data");
         } 
          return android.telephony.SmsMessage.createFromPdu(msgPdu, getFormat());
     }
      
      @Override
     protected String getFormat() {
         return SmsConstants.FORMAT_3GPP;   //  import com.android.internal.telephony.SmsConstants;
    }
 
    
    
  frameworks/opt/telephony/src/java/android/telephony/SmsMessage.java: 
  package android.telephony; 
  import android.os.Parcel;
 import android.util.Log; 
  import com.android.internal.telephony.EncodeException;
 import com.android.internal.telephony.GsmAlphabet;
 import com.android.internal.telephony.GsmAlphabet.TextEncodingDetails;
 import com.android.internal.telephony.SmsConstants;
 import com.android.internal.telephony.SmsHeader;
 import com.android.internal.telephony.SmsMessageBase;
 import com.android.internal.telephony.SmsMessageBase.SubmitPduBase;
 import com.mediatek.common.featureoption.FeatureOption; 
  import java.lang.Math;
 import java.util.ArrayList;
 import java.util.Arrays; 
  import static android.telephony.TelephonyManager.PHONE_TYPE_CDMA; 
  
 /**
  * A Short Message Service message.
  */
 public class SmsMessage    类中： 
    
      public SmsMessageBase mWrappedSmsMessage; 
      public static class SubmitPdu{ 
          public byte[] encodedScAddress; // Null if not applicable.
         public byte[] encodedMessage; 
          public String toString() {
             return "SubmitPdu: encodedScAddress = "
                     + Arrays.toString(encodedScAddress)
                     + ", encodedMessage = "
                     + Arrays.toString(encodedMessage);
         } 
          /**
          * @hide
          */
         protected SubmitPdu(SubmitPduBase spb) {
             this.encodedMessage = spb.encodedMessage;
             this.encodedScAddress = spb.encodedScAddress;
         } 
      } 
      private SmsMessage(SmsMessageBase smb) {
         mWrappedSmsMessage = smb;
    } 
    
    
  对 createFromPdu 进行了重载： 
       */
     public static SmsMessage createFromPdu(byte[] pdu) 
    {
         int activePhone = TelephonyManager.getDefault().getCurrentPhoneType();
         String format = (PHONE_TYPE_CDMA == activePhone) ?
                 SmsConstants.FORMAT_3GPP2 : SmsConstants.FORMAT_3GPP;
         return createFromPdu(pdu, format);
     } 
      /**
      * Create an SmsMessage from a raw PDU with the specified message format. The
      * message format is passed in the {@code SMS_RECEIVED_ACTION} as the{@code format}
      * String extra, and will be either "3gpp" for GSM/UMTS/LTE messages in 3GPP format
      * or "3gpp2" for CDMA/LTE messages in 3GPP2 format.
      *
      * @param pdu the message PDU from the SMS_RECEIVED_ACTION intent
      * @param format the format extra from the SMS_RECEIVED_ACTION intent
      * @hide pending API council approval
      */
    public static SmsMessage createFromPdu(byte[] pdu, String format) 
    {
         SmsMessageBase wrappedMessage; 
          if (SmsConstants.FORMAT_3GPP2.equals(format)) {
             wrappedMessage = com.android.internal.telephony.cdma.SmsMessage.createFromPdu(pdu);
         } else if (SmsConstants.FORMAT_3GPP.equals(format)) { // 因为传入的是FORMAT_3GPP 所以走这个分支
             wrappedMessage = com.android.internal.telephony.gsm.SmsMessage.createFromPdu(pdu);   //java/com/android/internal/telephony/gsm/SmsMessage.java 中 的 createFromPdu 根据 pdu参数生成的对象，返回到 wrappedMessage
         } else {
             Log.e(LOG_TAG, "createFromPdu(): unsupported message format " + format);
             return null;
         } 
          return new SmsMessage(wrappedMessage);   //返回了一个SmsMessage 对象 . 那最后 SmsMessage 构造函数通过 传入上面包含信息的的 wrappedMessage 对象 构造了一个  android.telephony.SmsMessage对象。
    }
 
    
    
  frameworks/opt/telephony/src/java/com/android/internal/telephony/gsm/SmsMessage.java： 
  package com.android.internal.telephony.gsm; 
  import android.os.Parcel;
 import android.telephony.PhoneNumberUtils;
 import android.text.format.Time;
 import android.util.Log; 
  import com.android.internal.telephony.EncodeException;
 import com.android.internal.telephony.GsmAlphabet;
 import com.android.internal.telephony.GsmAlphabet.TextEncodingDetails;
 import com.android.internal.telephony.IccUtils;
 import com.android.internal.telephony.SmsHeader;
import com.android.internal.telephony.SmsMessageBase; 
  import java.io.ByteArrayOutputStream;
 import java.io.UnsupportedEncodingException;
 import java.text.ParseException; 
  import static com.android.internal.telephony.SmsConstants.MessageClass;
 import static com.android.internal.telephony.SmsConstants.ENCODING_UNKNOWN;
 import static com.android.internal.telephony.SmsConstants.ENCODING_7BIT;
 // MTK-START [ALPS000xxxxx] MTK code port to ICS added by mtk80589 in 2011.11.16
 import android.os.SystemProperties;
 import android.util.Config;
 import com.android.internal.telephony.GsmAlphabet.TextEncodingDetails;
import static android.telephony.SmsMessage.MWI_VIDEO;
 // MTK-END   [ALPS000xxxxx] MTK code port to ICS added by mtk80589 in 2011.11.16 
  import com.android.internal.telephony.IMessageWaitingExt; 
  /**
  * A Short Message Service message.
  *
  */
 public class SmsMessageextendsSmsMessageBase 
  在这个SmsMessage   中也定义了  createFromPdu  这个函数 
      /**
      * Create an SmsMessage from a raw PDU.
      */
     public static SmsMessage createFromPdu(byte[] pdu) {
         try {
             SmsMessage msg = new SmsMessage();
             msg.parsePdu(pdu);  // 解析PDU。其实就是根据原始的PDU 解析出来的各种东东存在msg对象里头。 于是下行返回的msg就具备有用的信息了。
             return  msg;  //实际上最后返回的是这个SmsMessage 类型的实例 
        } catch (RuntimeException ex) {
             Log.e(LOG_TAG, "SMS PDU parsing failed: ", ex);
             return null;
         }
     } 
  同时我们也可以看到上面调用的函数parsePdu 来解析 PDU byte数组： 
  
     /**
      * TS 27.005 3.1, <pdu> definition "In the case of SMS: 3GPP TS 24.011 [6]
      * SC address followed by 3GPP TS 23.040 [3] TPDU in hexadecimal format:
      * ME/TA converts each octet of TP data unit into two IRA character long
      * hex number (e.g. octet with integer value 42 is presented to TE as two
      * characters 2A (IRA 50 and 65))" ...in the case of cell broadcast,
      * something else...
      */
     private void  parsePdu(byte[] pdu) {
         mPdu = pdu; // 首先把原始的pdu保存在 全局变量mPdu里头。这样我们可以随时取出原始的PDU
         // Log.d(LOG_TAG, "raw sms message:");
         // Log.d(LOG_TAG, s); 
          PduParser p = new PduParser(pdu);  // 通过 PduParser 的构造函数解析PDU 
          scAddress = p.getSCAddress();  //获取解析好的原始地址。 
          if (scAddress != null) {
             if (false) Log.d(LOG_TAG, "SMS SC address: " + scAddress);
         } 
          // TODO(mkf) support reply path, user data header indicator 
          // TP-Message-Type-Indicator
         // 9.2.3
         int firstByte = p.getByte(); 
          mti = firstByte & 0x3;    //根据第一byte的 值进行 各自的解析。
        switch (mti) {
         // TP-Message-Type-Indicator
         // 9.2.3
         case 0:
         case 3: //GSM 03.40 9.2.3.1: MTI == 3 is Reserved.
                 //This should be processed in the same way as MTI == 0 (Deliver)
             parseSmsDeliver(p, firstByte);
             break;
         case 1:
             parseSmsSubmit(p, firstByte);
             break;
         case 2:
             parseSmsStatusReport(p, firstByte);
             break;
         default:
             // TODO(mkf) the rest of these
             throw new RuntimeException("Unsupported message type");
         }
     } 
    
    
  

     /**
      * Parses a SMS-STATUS-REPORT message.
      *
      * @param p A PduParser, cued past the first byte.
      * @param firstByte The first byte of the PDU, which contains MTI, etc.
      */
     private void parseSmsStatusReport(PduParser p, int firstByte) {
         isStatusReportMessage = true;


         // TP-Status-Report-Qualifier bit == 0 for SUBMIT
         forSubmit = (firstByte & 0x20) == 0x00;
         // TP-Message-Reference
         messageRef = p.getByte();
         // TP-Recipient-Address
         recipientAddress = p.getAddress();
         // TP-Service-Centre-Time-Stamp
         scTimeMillis = p.getSCTimestampMillis();
         // TP-Discharge-Time
         dischargeTimeMillis = p.getSCTimestampMillis();
         // TP-Status
         status = p.getByte();
         
         messageBody = "";


         // The following are optional fields that may or may not be present.
         if (p.moreDataPresent()) {
             // TP-Parameter-Indicator
             int extraParams = p.getByte();
             int moreExtraParams = extraParams;
             while (((moreExtraParams & 0x80) != 0) && (p.moreDataPresent() == true)) {
                 // We only know how to parse a few extra parameters, all
                 // indicated in the first TP-PI octet, so skip over any
                 // additional TP-PI octets.
                 moreExtraParams = p.getByte();
             }
             // As per 3GPP 23.040 section 9.2.3.27 TP-Parameter-Indicator,
             // only process the byte if the reserved bits (bits3 to 6) are zero.
             if ((extraParams & 0x78) == 0) {
                 // TP-Protocol-Identifier
                 if ((extraParams & 0x01) != 0) {
                     protocolIdentifier = p.getByte();
                 }
                 // TP-Data-Coding-Scheme
                 if ((extraParams & 0x02) != 0) {
                     dataCodingScheme = p.getByte();
                 }
                 // TP-User-Data-Length (implies existence of TP-User-Data)
                 if ((extraParams & 0x04) != 0) {
                     boolean hasUserDataHeader = (firstByte & 0x40) == 0x40;
                     parseUserData(p, hasUserDataHeader);
                 }
             }
         }
     }


     private void parseSmsDeliver(PduParser p, int firstByte) {
         replyPathPresent = (firstByte & 0x80) == 0x80;


         originatingAddress = p.getAddress();


         if (originatingAddress != null) {
             if (false) Log.v(LOG_TAG, "SMS originating address: "
                     + originatingAddress.address);
         }


         // TP-Protocol-Identifier (TP-PID)
         // TS 23.040 9.2.3.9
         protocolIdentifier = p.getByte();


         // TP-Data-Coding-Scheme
         // see TS 23.038
         dataCodingScheme = p.getByte();


         if (false) {
             Log.v(LOG_TAG, "SMS TP-PID:" + protocolIdentifier
                     + " data coding scheme: " + dataCodingScheme);
         }


         scTimeMillis = p.getSCTimestampMillis();


         if (false) Log.d(LOG_TAG, "SMS SC timestamp: " + scTimeMillis);


         boolean hasUserDataHeader = (firstByte & 0x40) == 0x40;


         parseUserData(p, hasUserDataHeader);
     }


     /**
      * Parses the User Data of an SMS.
      *
      * @param p The current PduParser.
      * @param hasUserDataHeader Indicates whether a header is present in the
      *                          User Data.
      */
     private void  parseUserData(PduParser p, boolean hasUserDataHeader) {
         boolean hasMessageClass = false;
         boolean userDataCompressed = false;


         int encodingType = ENCODING_UNKNOWN;


         // Look up the data encoding scheme
         if ((dataCodingScheme & 0x80) == 0) {
             // Bits 7..4 == 0xxx
             automaticDeletion = (0 != (dataCodingScheme & 0x40));
             userDataCompressed = (0 != (dataCodingScheme & 0x20));
             hasMessageClass = (0 != (dataCodingScheme & 0x10));


             if (userDataCompressed) {
                 Log.w(LOG_TAG, "4 - Unsupported SMS data coding scheme "
                         + "(compression) " + (dataCodingScheme & 0xff));
             } else {
                 switch ((dataCodingScheme >> 2) & 0x3) {
                 case 0: // GSM 7 bit default alphabet
                     encodingType = ENCODING_7BIT;
                     break;


                 case 2: // UCS 2 (16bit)
                     encodingType = ENCODING_16BIT;
                     break;


                 case 1: // 8 bit data
                 case 3: // reserved
                     Log.w(LOG_TAG, "1 - Unsupported SMS data coding scheme "
                             + (dataCodingScheme & 0xff));
                     encodingType = ENCODING_8BIT;
                     break;
                 }
             }
         } else if ((dataCodingScheme & 0xf0) == 0xf0) {
             automaticDeletion = false;
             hasMessageClass = true;
             userDataCompressed = false;


             if (0 == (dataCodingScheme & 0x04)) {
                 // GSM 7 bit default alphabet
                 encodingType = ENCODING_7BIT;
             } else {
                 // 8 bit data
                 encodingType = ENCODING_8BIT;
             }
         } else if ((dataCodingScheme & 0xF0) == 0xC0
                 || (dataCodingScheme & 0xF0) == 0xD0
                 || (dataCodingScheme & 0xF0) == 0xE0) {
             // 3GPP TS 23.038 V7.0.0 (2006-03) section 4


             // 0xC0 == 7 bit, don't store
             // 0xD0 == 7 bit, store
             // 0xE0 == UCS-2, store


             if ((dataCodingScheme & 0xF0) == 0xE0) {
                 encodingType = ENCODING_16BIT;
             } else {
                 encodingType = ENCODING_7BIT;
             }


             userDataCompressed = false;
             boolean active = ((dataCodingScheme & 0x08) == 0x08);


             // bit 0x04 reserved


             if ((dataCodingScheme & 0x03) == 0x00) {
                 isMwi = true;
                 mwiSense = active;
                 mwiDontStore = ((dataCodingScheme & 0xF0) == 0xC0);
             } else {
                 isMwi = false;


                 Log.w(LOG_TAG, "MWI for fax, email, or other "
                         + (dataCodingScheme & 0xff));
             }
         } else if ((dataCodingScheme & 0xC0) == 0x80) {
             // 3GPP TS 23.038 V7.0.0 (2006-03) section 4
             // 0x80..0xBF == Reserved coding groups
             if (dataCodingScheme == 0x84) {
                 // This value used for KSC5601 by carriers in Korea.
                 encodingType = ENCODING_KSC5601;
             } else {
                 Log.w(LOG_TAG, "5 - Unsupported SMS data coding scheme "
                         + (dataCodingScheme & 0xff));
             }
         } else {
             Log.w(LOG_TAG, "3 - Unsupported SMS data coding scheme "
                     + (dataCodingScheme & 0xff));
         }


         // set both the user data and the user data header.
         int count = p.constructUserData(hasUserDataHeader,
                 encodingType == ENCODING_7BIT);
         this.userData = p.getUserData();
         this.userDataHeader = p.getUserDataHeader();


         switch (encodingType) {
         case ENCODING_UNKNOWN:
         case ENCODING_8BIT:
             messageBody = null;
             break;


         case ENCODING_7BIT:
             messageBody = p.getUserDataGSM7Bit(count,
                     hasUserDataHeader ? userDataHeader.languageTable : 0,
                     hasUserDataHeader ? userDataHeader.languageShiftTable : 0);
             break;


         case ENCODING_16BIT:
             messageBody = p.getUserDataUCS2(count);
             break;


         case ENCODING_KSC5601:
             messageBody = p.getUserDataKSC5601(count);
             break;
         }


         if (false) Log.v(LOG_TAG, "SMS message body (raw): '" + messageBody + "'");


         if (messageBody != null) {
             parseMessageBody();
         }


         if (!hasMessageClass) {
             messageClass = MessageClass.UNKNOWN;
         } else {
             switch (dataCodingScheme & 0x3) {
             case 0:
                 messageClass = MessageClass.CLASS_0;
                 break;
             case 1:
                 messageClass = MessageClass.CLASS_1;
                 break;
             case 2:
                 messageClass = MessageClass.CLASS_2;
                 break;
             case 3:
                 messageClass = MessageClass.CLASS_3;
                 break;
             }
         }
     }


     /**
      * {@inheritDoc}
      */
     @Override
     public MessageClass getMessageClass() {
         return messageClass;
     }
 
  
 
  
 
  ############# 从PDU返回 msg 结束################## 
    
  
     
 mCm 是定义于 “frameworks/opt/telephony/src/java/com/android/internal/telephony/SMSDispatcher.java” 中的
 public abstract class SMSDispatcher extends Handler 类中。即  SMSDispatcher 类中定义了：
     protected final CommandsInterface   mCm; 
    
  frameworks/opt/telephony/src/java/com/android/internal/telephony/CommandsInterface.java:
    /**
      * smscPDU is smsc address in PDU form GSM BCD format prefixed
      *      by a length byte (as expected by TS 27.005) or NULL for default SMSC
      * pdu is SMS in PDU format as an ASCII hex string
      *      less the SMSC address
      */
     void sendSMS (String smscPDU, String pdu, Message response);
     
     
frameworks/opt/telephony/src/java/com/android/internal/telephony/UsimDataDownloadCommands.java:
UsimDataDownloadCommands类中： 
  
     @Override
     public void sendSMS(String smscPDU, String pdu, Message response) {
     } 
      以上两个文件中，值看到 sendSMS的定义，但却没看到包含有具体的实现。如果有人知道为什么，请告诉我。谢谢！ 
    
  frameworks/opt/telephony/src/java/com/android/internal/telephony/SMSDispatcher.java:
    /**
      * This list is used to maintain the unsent Sms Tracker
      * we have this queue list to avoid we send a lot of SEND_SMS request to RIL
      * and block other commands.
      * So we only send the next SEND_SMS request after the previously request has been completed
      */
     protected ArrayList mSTrackersQueue= new ArrayList(MO_MSG_QUEUE_LIMIT); 
    
    
   在 frameworks\opt\telephony\src\java\com\android\internal\telephony\ril.java 
   public final class RIL extendsBaseCommands implements CommandsInterface 
         最后追溯到，ril 类中有 sendSMS的实现。如下： 
    
      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);
    } 
    
      private void    send(RILRequest rr) {
         Message msg; 
          boolean show = (requestToString(rr.mRequest).compareTo("LAST_CALL_FAIL_CAUSE") == 0);
         if (show) riljLog("###send start"); 
          if (mSocket == null) {
            if (show) riljLog("###mSocket == null");
             rr.onError(RADIO_NOT_AVAILABLE, null);
             rr.release();
             return;
         } 
         //正常的发送流程应该走这里： 
          if (show) riljLog("###send 1");
         msg = mSender.obtainMessage(EVENT_SEND, rr);
         if (show) riljLog("###send 2"); 
          acquireWakeLock();
         if (show) riljLog("###send 3"); 
          msg.sendToTarget();  // 正式发送消息
        if (show) riljLog("###send end");
     } 
    
  msg.sendToTarget()  定义在如下文件中的Message 类中。   
  frameworks\base\core\java\android\os\Message.java : 
       Handler target;   // target  是 handler类型的 
      /**
      * Sends this Message to the Handler specified by {@link #getTarget}.
      * Throws a null pointer exception if this field has not been set.
      */
     public void sendToTarget() {
         target.sendMessage(this);
    }
 
    
  那么 再看 target.sendMessage(this); 的 sendMessage 方法 定义于： 
  frameworks\base\core\java\android\os\Handler.java : 
    
      /**
      * Pushes a message onto the end of the message queue after all pending messages
      * before the current time. It will be received in {@link #handleMessage},
      * in the thread attached to this handler.
      *  
      * @return Returns true if the message was successfully placed in to the 
      *         message queue.  Returns false on failure, usually because the
      *         looper processing the message queue is exiting.
      */
     public final boolean sendMessage(Message msg)
     {
         return sendMessageDelayed(msg, 0);
     } 
    
    
      /**
      * Enqueue a message into the message queue after all pending messages
      * before (current time + delayMillis). You will receive it in
      * {@link #handleMessage}, in the thread attached to this handler.
      *  
      * @return Returns true if the message was successfully placed in to the 
      *         message queue.  Returns false on failure, usually because the
      *         looper processing the message queue is exiting.  Note that a
      *         result of true does not mean the message will be processed -- if
      *         the looper is quit before the delivery time of the message
      *         occurs then the message will be dropped.
      */
     public final boolean sendMessageDelayed(Message msg, long delayMillis)
     {
         if (delayMillis < 0) {
             delayMillis = 0;
         }
         return sendMessageAtTime(msg, SystemClock.uptimeMillis() + delayMillis);
     } 
    
  
     /**
      * Enqueue a message into the message queue after all pending messages
      * before the absolute time (in milliseconds) uptimeMillis.
      * The time-base is {@link android.os.SystemClock#uptimeMillis}.
      * You will receive it in {@link #handleMessage}, in the thread attached
      * to this handler.
      * 
      * @param uptimeMillis The absolute time at which the message should be
      *         delivered, using the
      *         {@link android.os.SystemClock#uptimeMillis} time-base.
      *         
      * @return Returns true if the message was successfully placed in to the 
      *         message queue.  Returns false on failure, usually because the
      *         looper processing the message queue is exiting.  Note that a
      *         result of true does not mean the message will be processed -- if
      *         the looper is quit before the delivery time of the message
      *         occurs then the message will be dropped.
      */
     public boolean sendMessageAtTime(Message msg, long uptimeMillis) {
         MessageQueue queue = mQueue;
         if (queue == null) {
             RuntimeException e = new RuntimeException(
                     this + " sendMessageAtTime() called with no mQueue");
             Log.w("Looper", e.getMessage(), e);
             return false;
         }
         return enqueueMessage(queue, msg, uptimeMillis);
    } 
    
      /// MSG Logger Manager @} 
      private boolean enqueueMessage(MessageQueue queue, Message msg, long uptimeMillis) {
         msg.target = this;
         if (mAsynchronous) {
             msg.setAsynchronous(true);
         }
         return queue.enqueueMessage(msg, uptimeMillis);
    }
 
    
    
  frameworks\base\core\java\android\os\MessageQueue.java : 
      final boolean enqueueMessage(Message msg, long when) {
         if (msg.isInUse()) {
             throw new AndroidRuntimeException(msg + " This message is already in use.");
         }
         if (msg.target == null) {
             throw new AndroidRuntimeException("Message must have a target.");
         } 
          boolean needWake;
         synchronized (this) {
             if (mQuiting) {
                 RuntimeException e = new RuntimeException(
                         msg.target + " sending message to a Handler on a dead thread");
                 Log.w("MessageQueue", e.getMessage(), e);
                 return false;
             } 
              /// M: Protection of sending the same message instance
             if(IS_ENG_BUILD)
             {
                 Message tempP = mMessages;
                 while(tempP != null)
                 {
                     if(tempP == msg)
                     {
                         Log.wtf("MessageQueue", "Warning: Sending the same message instance! Ignored. msg=" + msg);
                         return false;
                     }//if 
                      tempP = tempP.next;
                 }//while
             }//if 
              msg.when = when;
             Message p = mMessages;
             if (p == null || when == 0 || when < p.when) {
                 // New head, wake up the event queue if blocked.
                 msg.next = p;
                 mMessages = msg;
                 needWake = mBlocked;
             } else {
                 // Inserted within the middle of the queue.  Usually we don't have to wake
                 // up the event queue unless there is a barrier at the head of the queue
                 // and the message is the earliest asynchronous message in the queue.
                 needWake = mBlocked && p.target == null && msg.isAsynchronous();
                 Message prev;
                 for (;;) {
                     prev = p;
                     p = p.next;
                     if (p == null || when < p.when) {
                         break;
                     }
                     if (needWake && p.isAsynchronous()) {
                         needWake = false;
                     }
                 }
                 msg.next = p; // invariant: p == prev.next
                 prev.next = msg;
             }
         }
         if (needWake) {
             nativeWake(mPtr);
        }
         return true;
     } 
    
    
    
  public class MessageQueue  类中 有定义如下变量：
     /// M: for enqueueMessage debug enhancement used
     private static final boolean IS_ENG_BUILD = "eng".equals(Build.TYPE); 
      // True if the message queue can be quit.
     private final boolean mQuitAllowed; 
      @SuppressWarnings("unused")
     private int mPtr; // used by native code 
   
    
    
   http://wenku.baidu.com/view/33a31767783e0912a2162a88.html

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