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。
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 downelsereturn 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;}结论微笑拥抱每一天，做像向日葵般温暖的女子。
