Android 模拟系统事件（二）

简介
JNI（Java Native Interface）是本地编程接口，它允许Java代码和其他语言写的代码进行交互，它可以在
Java 虚拟机 (VM) 内部运行的 Java 代码与用其它编程语言(如 C、C++ 和汇编语言)编写的应用程序和库进行交互操作。

功能
通过jni实现向Android系统注入事件，从而实现模拟按键、模拟触屏等操作！用它直接跳过上面的Android平台权限的问题！

原理是在jni中通过Linux内核的ioctl函数和c语言函数（memset、write）来实现对设备的I/O通道进行管理的。所谓对I/O通道进行管理，就是对设备的一些特性进行控制，例如串口的传输波特率、马达的转速等等。它的调用个数如下：

int ioctl(int fd, ind cmd, …)

void *memset(void *s,int c,size_t n)  //总的作用：将已开辟内存空间 s 的首 n 个字节的值设为值 c。

ssize_t write(int fd,const void *buf,size_t nbytes) //将buf中的nbytes字节内容写入文件描述符fd.成功时返回写的字节数.失败时返回-1. 并设置errno变量. 在网络程序中,当我们向套接字文件描述符写时有俩种可能.

其中fd就是用户程序打开设备时使用open函数返回的文件标示符，cmd就是用户程序对设备的控制命令，至于后面的省略号，那是一些补充参数，一般最多一个，有或没有是和cmd的意义相关的。

代码实现

关键代码如下：

jint Java_net_pocketmagic_keyinjector_NativeInput_intEnableDebug( JNIEnv* env,jobject thiz, jint enable ) {

	g_debug = enable;
	if (enable == 1) debug("Debug enabled.");
	return g_debug;
}

jint Java_net_pocketmagic_keyinjector_NativeInput_intCreate( JNIEnv* env,jobject thiz, jstring inputdev, jint keyboard, jint mouse)
{
	
	jboolean iscopy;
	char szDev[255] = "";
	const char *pszDev = (*env)->GetStringUTFChars(env, inputdev, &iscopy);
	if (pszDev) strncpy(szDev, pszDev, 255);
	(*env)->ReleaseStringUTFChars(env, inputdev, pszDev);
	debug("intCreate call (%s)", szDev);
	
	struct uinput_dev dev;
	int fd_kb, aux;

	fd_kb = open(szDev, O_RDWR);
	if (fd_kb < 0) {
		debug("Can't open input device:%s ", szDev);
		return -1;
	}

	memset(&dev, 0, sizeof(dev));
	strcpy(dev.name, "AndroidKeyInjector Input");
	dev.id.bustype = 0x0003;// BUS_USB;
	dev.id.vendor  = 0x0000;
	dev.id.product = 0x0000;
	dev.id.version = 0x0000;

	if (write(fd_kb, &dev, sizeof(dev)) < 0) {
		debug("Can't write device information");
		close(fd_kb);
		return -1;
	}

	if (mouse) {
		ioctl(fd_kb, UI_SET_EVBIT, EV_REL);
		for (aux = REL_X; aux <= REL_MISC; aux++)
			ioctl(fd_kb, UI_SET_RELBIT, aux);
	}

	if (keyboard) {
		ioctl(fd_kb, UI_SET_EVBIT, EV_KEY);
		ioctl(fd_kb, UI_SET_EVBIT, EV_LED);
		ioctl(fd_kb, UI_SET_EVBIT, EV_REP);

		for (aux = KEY_RESERVED; aux <= KEY_UNKNOWN; aux++)
			ioctl(fd_kb, UI_SET_KEYBIT, aux);

		//for (aux = LED_NUML; aux <= LED_MISC; aux++)
		//	ioctl(fd_kb, UI_SET_LEDBIT, aux);
	}

	if (mouse) {
		ioctl(fd_kb, UI_SET_EVBIT, EV_KEY);

		for (aux = BTN_LEFT; aux <= BTN_BACK; aux++)
			ioctl(fd_kb, UI_SET_KEYBIT, aux);
	}

	ioctl(fd_kb, UI_DEV_CREATE);
	debug("intCreate success: %d",  fd_kb);
	return fd_kb;
}

void  Java_net_pocketmagic_keyinjector_NativeInput_intClose( JNIEnv* env,jobject thiz, jint fd_kb)
{
	close(fd_kb);
}

void Java_net_pocketmagic_keyinjector_NativeInput_intSendEvent( JNIEnv* env,jobject thiz, int fd_kb, uint16_t type, uint16_t code, int32_t value)
{
	debug("intSendEvent call (%d,%d,%d,%d)", fd_kb, type, code, value);
	struct uinput_event event;
	int len;

	if (fd_kb <= fileno(stderr))
		return;

	memset(&event, 0, sizeof(event));
	event.type = type;
	event.code = code;
	event.value = value;

	len = write(fd_kb, &event, sizeof(event));
	debug("intSendEvent done:%d",len);
}

其中的事件id 可以参考Android源码地址。

调用代码如下：

public class NativeInput {
	int m_fd;
	final static int EV_KEY = 0x01;

	public NativeInput() {
		intEnableDebug(1);
		for (int i = 0; i < 8; i++) {
			m_fd = intCreate("/dev/input/event" + i, 1, 0);
			if (m_fd != -1)
				break;
		}
	}

	public static int chmod(String path, int mode) throws Exception {
		Class fileUtils = Class.forName("android.os.FileUtils");
		Method setPermissions = fileUtils.getMethod("setPermissions",
				String.class, int.class, int.class, int.class);
		return (Integer) setPermissions.invoke(null, path, mode, -1, -1);
	}

	public int SendKey(int key, boolean state) {
		if (state)
			return intSendEvent(m_fd, EV_KEY, key, 1); // key down
		else
			return intSendEvent(m_fd, EV_KEY, key, 0); // key up
	}

	native int intEnableDebug(int enabled); // 1 will output to logcat, 0 will
											// disable
	//

	native int intCreate(String dev, int kb, int mouse);

	native void intClose(int fd);

	native int intSendEvent(int fd, int type, int code, int value);

	static {
		System.loadLibrary("input");
	}
}

其它相关代码如下：

int EVT_open(struct NATIVE_INFO *info)
{
    struct input_absinfo absinfo;
 
    if(initEVT)
        return 0;
 
    if(info == NULL)
    {
        LOGE("info null point.");
        goto fail;
    }
 
    if(info->FB_width == 0 || info->FB_height == 0)
    {
        LOGE("error width %d and height %d.", info->FB_width, info->FB_height);
        goto fail;
    }
 
    memset(&ei, 0, sizeof(ei));
    ei.screen_width = info->FB_width;
    ei.screen_height = info->FB_height;
 
    scan_dir(DEV_DIR);
 
    if(ioctl(ei.fd_touch, EVIOCGABS(ABS_X), &absinfo)) {
        LOGI("Error reading absolute controller ABS_X[%d]: %s", errno, strerror(errno));
        return;
    }
    ei.abs_x_min = absinfo.minimum;
    ei.abs_x_max = absinfo.maximum;
 
    if(ioctl(ei.fd_touch, EVIOCGABS(ABS_Y), &absinfo)) {
        LOGI("Error reading absolute controller ABS_Y[%d]: %s", errno, strerror(errno));
        return;
    }
    ei.abs_y_min = absinfo.minimum;
    ei.abs_y_max = absinfo.maximum;
 
    initEVT = 1;
    return 0;
 
fail:
    EVT_close();
    return -1;
}
 
int EVT_close()
{
    if(ei.fd_key > 0)
        close(ei.fd_key);
    if(ei.fd_touch > 0)
        close(ei.fd_touch);
 
    initEVT = 0;
    return 0;
}
 
int EVT_touch(int action, float x, float y)
{
    int abs_x, abs_y;
 
    if(initEVT == 0)
    {
        LOGE("event not inital");
        return -1;
    }
 
    switch(action)
    {
    case ACTION_DOWN:
        calculateXY(x, y, &abs_x, &abs_y);
        write_event(ei.fd_touch, 3, 0, abs_x);
        write_event(ei.fd_touch, 3, 1, abs_y);
        write_event(ei.fd_touch, 1, 330, 1);
        write_event(ei.fd_touch, 0, 0, 0);
        break;
    case ACTION_UP:
        write_event(ei.fd_touch, 1, 330, 0);
        write_event(ei.fd_touch, 0, 0, 0);
        break;
    case ACTION_MOVE:
        calculateXY(x, y, &abs_x, &abs_y);
        write_event(ei.fd_touch, 3, 0, abs_x);
        write_event(ei.fd_touch, 3, 1, abs_y);
        write_event(ei.fd_touch, 0, 0, 0);
        break;
    }
    return 0;
}
 
int EVT_key(int action, int key)
{
    if(initEVT == 0)
    {
        LOGE("event not inital");
        return -1;
    }
 
    switch(action)
    {
    case ACTION_DOWN:
        write_event(ei.fd_key, 1, key, 1);
        break;
    case ACTION_UP:
        write_event(ei.fd_key, 1, key, 0);
        break;
    }
    return 0;
}
 
 
int scan_dir(const char *dirname)
{
    char devname[PATH_MAX];
    char *filename;
    DIR *dir;
    struct dirent *de;
    dir = opendir(dirname);
    if(dir == NULL)
        return -1;
    strcpy(devname, dirname);
    filename = devname + strlen(devname);
    *filename++ = '/';
    while((de = readdir(dir))) {
        if(de->d_name[0] == '.' &&
           (de->d_name[1] == '\0' ||
            (de->d_name[1] == '.' && de->d_name[2] == '\0')))
            continue;
        strcpy(filename, de->d_name);
        open_dev(devname);
    }
    closedir(dir);
    return 0;
}
 
int open_dev(const char *deviceName)
{
    int fd;
    int version;
    uint8_t key_bitmask[sizeof_bit_array(KEY_MAX + 1)];
    uint8_t abs_bitmask[sizeof_bit_array(ABS_MAX + 1)];
 
    fd = open(deviceName, O_RDWR);
    if(fd < 0) {
        LOGI("could not open device[%d]: %s", errno, strerror(errno));
        return -1;
    }
 
    if(ioctl(fd, EVIOCGVERSION, &version)) {
        return -1;
    }
 
    memset(key_bitmask, 0, sizeof(key_bitmask));
    if (ioctl(fd, EVIOCGBIT(EV_KEY, sizeof(key_bitmask)), key_bitmask) >= 0) {
        if (containsNonZeroByte(key_bitmask, 0, sizeof_bit_array(BTN_MISC))
                || containsNonZeroByte(key_bitmask, sizeof_bit_array(BTN_GAMEPAD),
                        sizeof_bit_array(BTN_DIGI))
                || containsNonZeroByte(key_bitmask, sizeof_bit_array(KEY_OK),
                        sizeof_bit_array(KEY_MAX + 1))) {
            ei.fd_key = fd;
            LOGI("get key input device: %s", deviceName);
        }
    }
 
    memset(abs_bitmask, 0, sizeof(abs_bitmask));
    if (ioctl(fd, EVIOCGBIT(EV_ABS, sizeof(abs_bitmask)), abs_bitmask) >= 0) {
        // Is this a new modern multi-touch driver?
        if (test_bit(ABS_MT_POSITION_X, abs_bitmask)
                && test_bit(ABS_MT_POSITION_Y, abs_bitmask)) {
            ei.fd_touch = fd;
            LOGI("get multi-touch input device: %s", deviceName);
 
        // Is this an old style single-touch driver?
        } else if (test_bit(BTN_TOUCH, key_bitmask)
                && test_bit(ABS_X, abs_bitmask) && test_bit(ABS_Y, abs_bitmask)) {
            ei.fd_touch = fd;
            LOGI("get single-touch input device: %s", deviceName);
        }
    }
}
 
int write_event(int fd, int type, int code, int value)
{
    struct input_event event;
 
    memset(&event, 0, sizeof(event));
    event.type = type;
    event.code = code;
    event.value = value;
    if(write(fd, &event, sizeof(event)) < sizeof(event)) {
        LOGI("write event failed[%d]: %s", errno, strerror(errno));
        return -1;
    }
    return 0;
}
 
void calculateXY(float x, float y, int *abs_x, int *abs_y)
{
    *abs_x = ei.abs_x_min +
            (int)((x * (float)(ei.abs_x_max - ei.abs_x_min)) / ei.screen_width + 0.5);
    *abs_y = ei.abs_y_min +
            (int)((y * (float)(ei.abs_y_max - ei.abs_y_min)) / ei.screen_height + 0.5);
}
 
int containsNonZeroByte(const uint8_t* array, uint32_t startIndex, uint32_t endIndex)
{
    const uint8_t* end = array + endIndex;
    array += startIndex;
    while (array != end) {
        if (*(array++) != 0) {
            return 1;
        }
    }
    return 0;
}

结论
以上是使用ioctl来实现对设备i/o控制，如果不用ioctl的话，也可以实现对设备I/O通道的控制。例如，我们可以在驱动程序中实现write的时候检查一下是否有特殊约定的数据流通过，如果有的话，那么后面就跟着控制命令。但是如果这样做的话，会导致代码分工不明，程序结构混乱，程序员自己也会头昏眼花的。所以，我们就使用ioctl来实现控制的功能。

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