如何在不同的语言/平台中获取Android ID

最近开发工作中需要使用到AndroidID,在Unity和native code中也需要使用，java获取很方便，Unity中也不难，最难的是在native code中获取。

获取android ID需要有一个上下文实例，也就是Context实例，看下面的java获取方式：

在java中获取

Android原生代码，这个是最简单的：

public static String GetAndroid(Context context){ final String androidId; androidId = android.provider.Settings.Secure.getString(context.getContentResolver(), android.provider.Settings.Secure.ANDROID_ID); return androidId; }

在Unity中获取

Unity获取androidID首先需要获取Unity环境中当前的activity，由activiy调用getContentResolver。

private String GetAndroidID() { AndroidJavaClass up = new AndroidJavaClass ("com.unity3d.player.UnityPlayer"); AndroidJavaObject currentActivity = up.GetStatic<AndroidJavaObject> ("currentActivity"); AndroidJavaObject contentResolver = currentActivity.Call<AndroidJavaObject> ("getContentResolver"); AndroidJavaClass secure = new AndroidJavaClass ("android.provider.Settings$Secure"); string android_id = secure.CallStatic<string> ("getString", contentResolver, "android_id"); return android_id; }

在C中获取

在C代码中只能通过JNI方式调用java来获取,代码看起来比较乱，有很多同java进行交互的部分。获取流程如下:

首先JVM加载native code所在动态库的时候（loadlibrary）会自动调用JNI_OnLoad，这时候会初始化一个全局的JavaJVM，一个进程只能有一个JavaJVM。

当前线程获取JNIEnv,调用AttachCurrentThread来获得。通过JNI获取Java中的相关类，方法。获取Context（getGlobalContext）的方法研究了很长时间，网上搜了好多资料。得到jstring类型的Android,转换成char *

最后返回。

#include <jni.h> #include <assert.h> #include "libavutil/avassert.h" #define JNI_CLASS_PATH /JNI/CLASS/path static JavaVM* g_jvm=NULL; static jobject getGlobalContext(JNIEnv *env) { jclass activityThread = (*env)->FindClass(env,"android/app/ActivityThread"); jmethodID currentActivityThread = (*env)->GetStaticMethodID(env,activityThread, "currentActivityThread", "()Landroid/app/ActivityThread;"); jobject at = (*env)->CallStaticObjectMethod(env,activityThread, currentActivityThread); jmethodID getApplication = (*env)->GetMethodID(env,activityThread, "getApplication", "()Landroid/app/Application;"); jobject context = (*env)->CallObjectMethod(env,at, getApplication); return context; } static jstring _getAndroidID(JNIEnv *env, jobject thiz) { jclass c_settings_secure = (*env)->FindClass(env, "android/provider/Settings$Secure"); jclass c_context = (*env)->FindClass(env,"android/content/Context"); if(c_settings_secure == NULL || c_context == NULL){ return NULL; } //Get the getContentResolver method jmethodID m_get_content_resolver = (*env)->GetMethodID(env, c_context, "getContentResolver", "()Landroid/content/ContentResolver;"); if(m_get_content_resolver == NULL){ return NULL; } //Get the Settings.Secure.ANDROID_ID constant jfieldID f_android_id = (*env)->GetStaticFieldID(env, c_settings_secure, "ANDROID_ID", "Ljava/lang/String;"); if(f_android_id == NULL){ return NULL; } jstring s_android_id = (*env)->GetStaticObjectField(env, c_settings_secure, f_android_id); //create a ContentResolver instance context.getContentResolver() jobject o_content_resolver = (*env)->CallObjectMethod(env, getGlobalContext(env), m_get_content_resolver); if(o_content_resolver == NULL || s_android_id == NULL){ return NULL; } //get the method getString jmethodID m_get_string = (*env)->GetStaticMethodID(env, c_settings_secure, "getString", "(Landroid/content/ContentResolver;Ljava/lang/String;)Ljava/lang/String;"); if(m_get_string == NULL){ return NULL; } //get the Android ID jstring android_id = (*env)->CallStaticObjectMethod(env, c_settings_secure, m_get_string, o_content_resolver, s_android_id); return android_id; } static char* jstringTostr( jstring jstr) { JNIEnv* env = NULL; if ((*g_jvm)->GetEnv(g_jvm, (void**) &env, JNI_VERSION_1_4) != JNI_OK) { return -1; } assert(env != NULL); char* pStr = NULL; jclass jstrObj = (*env)->FindClass(env, "java/lang/String"); jstring encode = (*env)->NewStringUTF(env, "utf-8"); jmethodID methodId = (*env)->GetMethodID(env, jstrObj, "getBytes", "(Ljava/lang/String;)[B"); jbyteArray byteArray = (jbyteArray)(*env)->CallObjectMethod(env, jstr, methodId, encode); jsize strLen = (*env)->GetArrayLength(env, byteArray); jbyte *jBuf = (*env)->GetByteArrayElements(env, byteArray, JNI_FALSE); if (jBuf > 0) { pStr = (char*)malloc(strLen + 1); if (!pStr) { return NULL; } memcpy(pStr, jBuf, strLen); pStr[strLen] = 0; } (*env)->ReleaseByteArrayElements(env, byteArray, jBuf, 0); //av_log(NULL, AV_LOG_INFO, "the android is end%s\n", pStr); return pStr; } char * getAndroidID() { JNIEnv* env = NULL; if((*g_jvm)->AttachCurrentThread(g_jvm, &env, NULL) != JNI_OK) { return NULL; } jstring androidID = _getAndroidID(env,NULL); return jstringTostr(androidID); } JNIEXPORT jint JNI_OnLoad(JavaVM *vm, void *reserved) { JNIEnv* env = NULL; g_jvm = vm; if ((*vm)->GetEnv(vm, (void**) &env, JNI_VERSION_1_4) != JNI_OK) { return -1; } assert(env != NULL); return JNI_VERSION_1_4; }