[2019.01.24]JNI经验积累

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[2019.01.24]JNI经验积累

[1 jobject<--->jclass|jstring]

(1)jobject向上转型jclass|jstring:

jclass jcls = static_cast<jclass>(jobject);

jstring jstr = static_cast<jclass>(jobject);

(2)jclass|jstring向下转型jobject:

默认情况下是自动转换的

[2 jstring<--->const char*]

(1)jstring-->const char*

const char* xxx = (*env)->GetStringUTFChars(env,jstring,NULL);

(2)const char*--->jstring

jstring xxx = (*env)->NewStringUTF(env,const char*);

[3 jlong-->long]

long是基本类型，直接赋值即可

long xxx = jlong;

看这张图就懂了!!!

[4 Native获取Java层函数接口]

java层：

public void onNotifyResult(ResultInfo resInfo);

Native层：(JNI)

jclass cls = env->GetObjectClass(p_JNInstance);

jmethodID onNotifyResult = env->GetMethodID(cls, "onNotifyResult",

"(Lcom/arcsoft/wideselfie/jni/JNIManager$ResultInfo;)V");

[5 Native获取Java层byte数组，并转换为OFFSCREEN]

[6 Unicode & UTF-8]

const jchar *chars; //Unicode characters

const char *charsutf; //UTF-8 characters

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