test

... ...
        }
        else if (strcmp(argv[optind], "list") == 0) {
            Vector<String16> services = sm->listServices();
            aout << "Found " << services.size() << " services:" << endl;
            for (unsigned i = 0; i < services.size(); i++) {
                String16 name = services[i];
                sp<IBinder> service = sm->checkService(name);
                aout << i
                     << "\t" << good_old_string(name)
                     << ": [" << good_old_string(get_interface_name(service)) << "]"
                     << endl;
            }
        } else if (strcmp(argv[optind], "call") == 0) {
... ...

haha

// 这个好像是字符串转化相关的，String8 和 String16 都是 android 在 native 
// 对 char 串的封装
static String8 good_old_string(const String16& src)
{
    String8 name8;
    char ch8[2];
    ch8[1] = 0;
    for (unsigned j = 0; j < src.size(); j++) { 
        char16_t ch = src[j];
        if (ch < 128) ch8[0] = (char)ch;
        name8.append(ch8);
    }
    return name8;
}

haha

// get the name of the generic interface we hold a reference to
static String16 get_interface_name(sp<IBinder> service)
{
    if (service != NULL) {
        Parcel data, reply;
        status_t err = service->transact(IBinder::INTERFACE_TRANSACTION, data, &reply);              
        if (err == NO_ERROR) {
            return reply.readString16();                                                                                  
        }
    }
    return String16();
}

haha

status_t BBinder::onTransact(
    uint32_t code, const Parcel& data, Parcel* reply, uint32_t flags)
{
    switch (code) {
        case INTERFACE_TRANSACTION:
            reply->writeString16(getInterfaceDescriptor());
            return NO_ERROR;
... ...
        default:
            return UNKNOWN_TRANSACTION;
    }
}

haha

... ...
        
        } else if (strcmp(argv[optind], "call") == 0) {
            optind++;
            if (optind+1 < argc) {
                int serviceArg = optind;
                // 从 sm 那获取指定的 service 接口（Bp）
                sp<IBinder> service = sm->checkService(String16(argv[optind++]));
                // 获取服务的标示
                String16 ifName = get_interface_name(service);
                int32_t code = atoi(argv[optind++]);
                if (service != NULL && ifName.size() > 0) {
                    Parcel data, reply;
                    // 呵呵，先写服务的标示
                    // the interface name is first
                    data.writeInterfaceToken(ifName);
                    // 支持的参数有3种类型：i32、s16 和 intent
                    // then the rest of the call arguments
                    while (optind < argc) {
                        // i32 就是 int32，非常简单的类型，
                        // 直接使用 parcel 的 writeInt32 
                        if (strcmp(argv[optind], "i32") == 0) {
                            optind++;
                            if (optind >= argc) {
                                aerr << "service: no integer supplied for 'i32'" << endl;
                                wantsUsage = true;
                                result = 10;
                                break;
                            }
                            data.writeInt32(atoi(argv[optind++]));
                        } else if (strcmp(argv[optind], "s16") == 0) {
                            // s16 就是 String16，也是比较简单的类型
                            // parcel 都有现成的接口可用
                            optind++;
                            if (optind >= argc) {
                                aerr << "service: no string supplied for 's16'" << endl;
                                wantsUsage = true;
                                result = 10;
                                break;
                            }
                            data.writeString16(String16(argv[optind++]));
                        } else if (strcmp(argv[optind], "null") == 0) {
                            optind++;
                            data.writeStrongBinder(NULL);
                        } else if (strcmp(argv[optind], "intent") == 0) {
       
// 下面这个 intent 类型，就有点麻烦了，我暂时没去管它 ... ...
... ...
                        } else {
                            aerr << "service: unknown option " << argv[optind] << endl;
                            wantsUsage = true;
                            result = 10;
                            break;
                        }
                    }
                    // parcel 打好包好，调用 service 的 transact 函数
                    service->transact(code, data, &reply);
                    // 打印 parcel 打包的返回值
                    aout << "Result: " << reply << endl;
                } else {
                    aerr << "service: Service " << argv[serviceArg]
                        << " does not exist" << endl;
                    result = 10;
                }
            } else {
... ...

static final int TRANSACTION_startViewServer = (android.os.IBinder.FIRST_CALL_TRANSACTION + 0);
static final int TRANSACTION_stopViewServer = (android.os.IBinder.FIRST_CALL_TRANSACTION + 1);
static final int TRANSACTION_isViewServerRunning = (android.os.IBinder.FIRST_CALL_TRANSACTION + 2);
// 然后去翻下 IBinder 发现是从 1 开始的 
    enum {
        FIRST_CALL_TRANSACTION  = 0x00000001,
        LAST_CALL_TRANSACTION   = 0x00ffffff,
... ...
    };

/*
 * Starts the view server on the specified port.
 *
 * @param port The port to listener to.
 *
 * @return True if the server was successfully started, false otherwise.
 *
 * @see com.android.server.wm.ViewServer
 * @see com.android.server.wm.ViewServer#VIEW_SERVER_DEFAULT_PORT
 */
@Override
public boolean startViewServer(int port)

/**
 * ===== NOTICE =====
 * The first three methods must remain the first three methods. Scripts
 * and tools rely on their transaction number to work properly.
 */ 
// This is used for debugging
boolean startViewServer(int port);   // Transaction #1
boolean stopViewServer();            // Transaction #2
boolean isViewServerRunning();       // Transaction #3

@Override
public float getAnimationScale(int which) { 
    switch (which) {
        case 0: return mWindowAnimationScale;
        case 1: return mTransitionAnimationScale;
        case 2: return mAnimatorDurationScale; 
    }
    return 0;
}