execlp()函数

          execlp函数简单的来说就是C语言中执行系统命令的函数
          execlp()会从PATH 环境变量所指的目录中查找符合参数file 的文件名, 找到后便执行该文件, 然后将第二个以后的参数当做该文件的argv[0], argv[1], ..., 最后一个参数必须用空指针(NULL)作结束.
          android开发中,execlp函数对应android的path路径为system/bin/目录下

调用格式:

execlp("am","am","start","--user","0","-a","android.intent.action.VIEW","-d","http://www.google.com.hk",(char*)NULL);

监听APP被卸载后打开浏览器跳到指定网址实例源码如下:

.h代码:

/*
* MonitorUnistall.h
*
*/
#include <jni.h>

#ifndef MONITORUNISTALL_H_
#define MONITORUNISTALL_H_

#ifdef __cplusplus
extern "C" {
#endif
/*
* Class: com.vkex.vkmonitoruninstall.MainActivity
* Method: uninstall
* Signature: (Ljava/lang/String;I)V
*/
JNIEXPORT void JNICALL Java_com_vkex_vkmonitoruninstall_MainActivity_uninstall
(JNIEnv *, jobject, jstring, jint);

#ifdef __cplusplus
}
#endif

#endif /* MONITORUNISTALL_H_ */

.cpp代码:

#include<MonitorUnistall.h>
#include <stdio.h>
#include <jni.h>
#include <malloc.h>
#include <string.h>
#include <strings.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/inotify.h>
#include <fcntl.h>
#include <stdint.h>
#include <android/log.h>

#define LOG_TAG "System.out.c"
#define LOGD(...) __android_log_print(ANDROID_LOG_DEBUG, LOG_TAG, __VA_ARGS__)
#define LOGI(...) __android_log_print(ANDROID_LOG_INFO, LOG_TAG, __VA_ARGS__)

/**
* 返回值 char* 这个代表char数组的首地址
* Jstring2CStr 把java中的jstring的类型转化成一个c语言中的char 字符串
*/
char* Jstring2CStr(JNIEnv* env, jstring jstr) {
char* rtn = NULL;
jclass clsstring = env->FindClass("java/lang/String"); //String
jstring strencode = env->NewStringUTF("GB2312"); // 得到一个java字符串 "GB2312"
jmethodID mid = env->GetMethodID(clsstring, "getBytes",
"(Ljava/lang/String;)[B"); //[ String.getBytes("gb2312");
jbyteArray barr = (jbyteArray) env->CallObjectMethod(jstr, mid, strencode); // String .getByte("GB2312");
jsize alen = env->GetArrayLength(barr); // byte数组的长度
jbyte* ba = env->GetByteArrayElements(barr, JNI_FALSE);
if (alen > 0) {
rtn = (char*) malloc(alen + 1); //"\0"
memcpy(rtn, ba, alen);
rtn[alen] = 0;
}
env->ReleaseByteArrayElements(barr, ba, 0); //
return rtn;
}

JNIEXPORT void JNICALL Java_com_vkex_vkmonitoruninstall_MainActivity_uninstall(
JNIEnv * env, jobject obj, jstring packageDir, jint sdkVersion) {
// 1,将传递过来的java的包名转为c的字符串
char * pd = Jstring2CStr(env, packageDir);

// 2,创建当前进程的克隆进程
pid_t pid = fork();

// 3,根据返回值的不同做不同的操作,<0,>0,=0
if (pid < 0) {
// 说明克隆进程失败
LOGD("current crate process failure");
} else if (pid > 0) {
// 说明克隆进程成功,而且该代码运行在父进程中
LOGD("crate process success,current parent pid = %d", pid);
} else {
// 说明克隆进程成功,而且代码运行在子进程中
LOGD("crate process success,current child pid = %d", pid);

// 4,在子进程中监视/data/data/包名这个目录
//初始化inotify进程
int fd = inotify_init();
if (fd < 0) {
LOGD("inotify_init failed !!!");
exit(1);
}

//添加inotify监听器
int wd = inotify_add_watch(fd, pd, IN_DELETE);
if (wd < 0) {
LOGD("inotify_add_watch failed !!!");
exit(1);
}

//分配缓存,以便读取event,缓存大小=一个struct inotify_event的大小,这样一次处理一个event
void *p_buf = malloc(sizeof(struct inotify_event));
if (p_buf == NULL) {
LOGD("malloc failed !!!");
exit(1);
}

//开始监听
LOGD("start observer");
ssize_t readBytes = read(fd, p_buf, sizeof(struct inotify_event));

//read会阻塞进程,走到这里说明收到目录被删除的事件,注销监听器
free(p_buf);
inotify_rm_watch(fd, IN_DELETE);

// 应用被卸载了,通知系统打开用户反馈的网页
LOGD("app uninstall,current sdkversion = %d", sdkVersion);
if (sdkVersion >= 17) {
// Android4.2系统之后支持多用户操作,所以得指定用户
execlp("am", "am", "start", "--user", "0", "-a",
"android.intent.action.VIEW", "-d", "http://www.baidu.com",
(char*) NULL);
} else {
// Android4.2以前的版本无需指定用户
execlp("am", "am", "start", "-a", "android.intent.action.VIEW",
"-d", "http://www.baidu.com", (char*) NULL);
}

}
}

android.mk 代码:

LOCAL_PATH := $(call my-dir)

include $(CLEAR_VARS)

LOCAL_MODULE := MonitorUninstall
LOCAL_SRC_FILES := MonitorUninstall.cpp
LOCAL_LDLIBS += -llog

include $(BUILD_SHARED_LIBRARY)

MainActivity代码:

public class MainActivity extends Activity {

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

public native void uninstall(String packageDir, int sdkVersion);

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);

String packageDir = "/data/data/" + getPackageName();
int sdkVersion = android.os.Build.VERSION.SDK_INT;
uninstall(packageDir, sdkVersion);
}

}

 

04-25 09:29