\u901a\u8fc7\u51fd\u6570\u540d\u5efa\u7acbJNI\u548cjava\u5c42\u7684\u4e00\u4e00\u5bf9\u5e94\u5173\u7cfb\u3002<\/p>\n\n\n\n
Java\u5f00\u5934\uff0c\u7136\u540e\u662f\u4e0b\u5212\u7ebf\uff0c\u7d27\u63a5\u7740\u662f\u4e0b\u5212\u7ebf\u5206\u5272\u7684package name\uff0c\u7136\u540e\u8ddf\u7740\u7684\u662f\u4e0b\u5212\u7ebf\u548cclass name\uff0c\u6700\u540e\u662f\u4e0b\u5212\u7ebf\u548c\u65b9\u6cd5\u540d\u3002<\/p>\n\n\n\n
JNIEXPORT jstring JNICALL
Java_com_example_efan_jni_1learn2_MainActivity_stringFromJNI(
JNIEnv *env,
jobject \/* this *\/) {
std::string hello = \"Hello from C++\";
return env->NewStringUTF(hello.c_str());
}<\/pre>\n\n\n\n\u52a8\u6001\u6ce8\u518c<\/h1>\n\n\n\n
\u4f7f\u7528RegisterNatives \u65b9\u6cd5\u6765\u6ce8\u518cjni\u51fd\u6570\u4e0ejava\u65b9\u6cd5\u4e3a\u4e00\u4e00\u5bf9\u5e94\u5173\u7cfb\u3002<\/p>\n\n\n\n
\u5b9e\u73b0\u8fc7\u7a0b<\/h2>\n\n\n\n
- \u4f7f\u7528JNINativeMethod \u6570\u7ec4\u6765\u8bb0\u5f55\u5bf9\u5e94\u7684java\u548cjni\u65b9\u6cd5\uff1b<\/li>
- \u5b9e\u73b0JNI_OnLoad \u65b9\u6cd5\uff0c\u5728\u8f7d\u5165\u52a8\u6001\u5e93\u65f6\u8fdb\u884c\u52a8\u6001\u6ce8\u518c\uff1b<\/li>
- \u4f7f\u7528FindClass\u65b9\u6cd5\u6765\u83b7\u53d6java\u5bf9\u8c61\uff1b<\/li>
- \u8c03\u7528RegisterNatives\u65b9\u6cd5\uff0c\u4f20\u5165java\u5bf9\u8c61\u548cJNINativeMethod \u6570\u7ec4\uff0c\u548c\u6ce8\u518c\u53bb\u5b8c\u6210\u7684\u6570\u76ee\uff1b<\/li><\/ol>\n\n\n\n
\u4f18\u70b9<\/h3>\n\n\n\n
- \u8fc7\u7a0b\u66f4\u52a0\u6e05\u6670\u548c\u53ef\u63a7\uff1b<\/li>
- \u9ad8\u6548<\/li><\/ol>\n\n\n\n
jstring stringFromJNI(JNIEnv *env, jobject thiz){
std::string hello = \"Hello from C++\";
return env->NewStringUTF(hello.c_str());
}
static const JNINativeMethod gMethods[] = {
{\"stringFromJNI\", \"()Ljava\/lang\/String;\", (jstring*)stringFromJNI}
};
JNIEXPORT jint JNI_OnLoad(JavaVM* vm, void* reserved){
__android_log_print(ANDROID_LOG_INFO, \"native\", \"Jni_OnLoad\");
JNIEnv* env = NULL;
If(vm->GetEnv((void**)&env, JNI_VERSION_1_4) != JNI_OK) \/\/Get JNIEnv from JavaVM, generally use version 1.4
return -1;
jclass clazz = env->FindClass(\"com\/example\/efan\/jni_learn2\/MainActivity\");
if (!clazz){
__android_log_print(ANDROID_LOG_INFO, \"native\", \"cannot get class: com\/example\/efan\/jni_learn2\/MainActivity\");
return -1;
}
if(env->RegisterNatives(clazz, gMethods, sizeof(gMethods)\/sizeof(gMethods[0])))
{
__android_log_print(ANDROID_LOG_INFO, \"native\", \"register native method failed!\\n\");
return -1;
}
return JNI_VERSION_1_4;
}
\u200b<\/pre>\n\n\n\nJNINativeMethod<\/h2>\n\n\n\n
\u8be5\u7ed3\u6784\u4f53\u7528\u4e8e\u52a8\u6001\u6ce8\u518c\u8fc7\u7a0b \uff0c JNINativeMethod \u88ab\u7528\u6765\u8bb0\u5f55\u5bf9\u5e94\u7684jni\u65b9\u6cd5\u548cjava\u65b9\u6cd5\u3002<\/p>\n\n\n\n
typedef struct {
const char* name;
const char* signature;
void* fnPtr;
} JNINativeMethod;<\/pre>\n\n\n\n\u7b2c\u4e00\u4e2a\u53c2\u6570\uff0cname \uff0cjava\u65b9\u6cd5\u7684\u540d\u79f0\u3002<\/p>\n\n\n\n
\u7b2c\u4e8c\u4e2a\u53c2\u6570\uff0csignature\uff0c\u7528\u6765\u63cf\u8ff0\u65b9\u6cd5\u7684\u53c2\u6570\u548c\u8fd4\u56de\u503c\u3002<\/p>\n\n\n\n
\u7b2c\u4e09\u4e2a\u53c2\u6570\uff0cfnPtr , \u662f\u4e00\u4e2a\u51fd\u6570\u6307\u9488\u6307\u5411jni\u51fd\u6570\u3002<\/p>\n\n\n\n
\u5176\u4e2d\uff0c\u7b2c\u4e8c\u53c2\u6570signature\u7528\u5b57\u7b26\u4e32\u7c7b\u578b\u4e3a\u53c2\u6570\u8bb0\u5f55\u65b9\u6cd5\u548c\u8fd4\u56de\u503c\u7c7b\u578b\u3002\u5177\u4f53\u7684\u683c\u5f0f\u50cf”()V” , “(II)V” ,\u683c\u5f0f\u5206\u4e3a\u4e24\u4e2a\u90e8\u5206\uff0c\u62ec\u53f7\u5185\u90e8\u548c\u62ec\u53f7\u53f3\u8fb9\u7684\u53c2\u6570\uff0c\u53f3\u8fb9\u7684\u53c2\u6570\u8868\u793a\u8fd4\u56de\u503c\u3002<\/p>\n\n\n\n
\u6570\u636e\u7c7b\u578b\u6620\u5c04<\/h2>\n\n\n\n
\u57fa\u7840\u6570\u636e\u7c7b\u578b<\/h3>\n\n\n\n
Java type<\/th> Native type<\/th> Domain descriptor<\/th> supplement<\/th><\/tr><\/thead> boolean<\/td> jboolean<\/td> Z<\/td> <\/td><\/tr> byte<\/td> jbyte<\/td> B<\/td> <\/td><\/tr> char<\/td> jchar<\/td> C<\/td> <\/td><\/tr> short<\/td> jshort<\/td> S<\/td> <\/td><\/tr> int<\/td> jint<\/td> I<\/td> <\/td><\/tr> long<\/td> jlong<\/td> J<\/td> <\/td><\/tr> float<\/td> jfloat<\/td> F<\/td> <\/td><\/tr> double<\/td> jdouble<\/td> D<\/td> <\/td><\/tr> void<\/td> void<\/td> V<\/td> <\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n \u5bf9\u8c61\u5f15\u7528\u7c7b\u578b<\/h3>\n\n\n\n
\u5bf9\u4e8e\u5176\u4ed6\u5f15\u7528\u7c7b\u578b\uff0c\u4f8b\u5982java\u5bf9\u8c61\uff0c\u6620\u5c04\u89c4\u5219\u5982\u4e0b\uff1a<\/p>\n\n\n\n
<\/th> <\/th> <\/th> <\/th><\/tr><\/thead> Java type<\/td> Native type<\/td> Domain descriptor<\/td> supplement<\/td><\/tr> Class name (such as Surface)<\/td> Usually jobject, with one exception, if the java type is a String, the corresponding native type is jstring<\/td> Start with “L” and end with “;” in the middle of the package and class name separated by “\/” (such as Landroid\/view\/Surface;) if the inner class uses $ to connect the inner class;<\/td> <\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n \u5bf9\u8c61\u6570\u7ec4\u5f15\u7528\u89c4\u5219<\/h3>\n\n\n\n
\u5982\u679c\u4ed6\u662f\u4e00\u4e2a\u4e00\u7ef4\u6570\u7ec4\uff0c\u5982\u4e0b\u8868\u3002\u5982\u679c\u662f\u4e8c\u7ef4\u6216\u8005\u66f4\u9ad8\u7ef4\u6570\u7ec4\uff0c\u5bf9\u5e94\u7684native\u7c7b\u578b\u662fjobjectArray \uff0c \u5e76\u4e14'[‘ \u7684\u6570\u76ee\u8868\u793a\u7ef4\u5ea6\u3002<\/p>\n\n\n\n
Java type<\/th> Native type<\/th> Domain descriptor<\/th> supplement<\/th><\/tr><\/thead> Class name (such as Surface)<\/td> Usually jobject, with one exception, if the java type is a String, the corresponding native type is jstring<\/td> Add ‘[‘ character to the left based on the domain descriptor of the object reference type<\/td> <\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n jni \u51fd\u6570\u7684\u9ed8\u8ba4\u53c2\u6570<\/h2>\n\n\n\n
\u6709\u4e24\u4e2a\u9ed8\u8ba4\u53c2\u6570\u5728jni\u51fd\u6570<\/p>\n\n\n\n
JNIEnv *env, jobject thiz<\/pre>\n\n\n\nJNIEnv \u6307\u5411\u5f53\u524djava\u73af\u5883\uff0c\u53ef\u4ee5\u4f7f\u7528JNIEnv\u6765\u64cd\u7eb5java\u5c42\u4ee3\u7801\uff1bjobject \u6307\u5411\u5bf9\u5e94\u7684java native\u65b9\u6cd5\u5bf9\u5e94\u7684jni\u51fd\u6570\u7684\u7c7b\u5b9e\u4f8b\uff0c\u5982\u679cjava\u65b9\u6cd5\u662f\u9759\u6001\u7684\uff0c\u5b83\u5c31\u4ee3\u8868\u7c7b\u5bf9\u8c61\u7684\u5f15\u7528\uff1b<\/p>\n\n\n\n
https:\/\/github.com\/doom-man\/jnidemo<\/a><\/p>
http:\/\/zhixinliu.com\/2015\/07\/01\/2015-07-01-jni-register\/<\/a><\/p>