目錄

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基本概念

代碼及演示

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基本概念

此篇博文記錄了JNI的基本規范，與使用：

https://blog.csdn.net/qq78442761/article/details/94849374

在本篇不再說明，只說下簡單參數和返回值。

官方對基礎數據類型的解釋如下：

看看代碼里面的可以看到：

這些數據類型還是很想象的。

下面對這些傳入和返回值作下演示。

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代碼及演示

使用javah -jni xxxx后生成.h文件，Windows上配置號VS的包含目錄，IDEA配置好依賴后（在https://blog.csdn.net/qq78442761/article/details/94849374此博文有詳細的說明），

Java運行截圖如下：

源碼如下：

main.java

public class Main {public native boolean booleanFun(boolean boolValue);public native byte byteFun(byte byteValue);public native char charFun(char charValue);public native short shortFun(short shortValue);public native int intFun(int intValue);public native long longFun(long longValue);public native float floatFun(float floatValue);public native double doubleFun(double doubleValue);public static void main(String[] args) {System.loadLibrary("JNIParamentAndReturn");Main mainTest = new Main();System.out.println("The result is : " + mainTest.booleanFun(true) + "\n");System.out.println("The result is : " + mainTest.byteFun((byte) 110) + "\n");System.out.println("The result is : " + mainTest.charFun('a') + "\n");System.out.println("The result is : " + mainTest.shortFun((short) 66) + "\n");System.out.println("The result is : " + mainTest.longFun( 666666) + "\n");System.out.println("The result is : " + mainTest.floatFun((float) 250.25) + "\n");System.out.println("The result is : " + mainTest.doubleFun( 11.1101) + "\n");System.out.println("The result is : " + mainTest.intFun(10086) + "\n");} }

main.h

/* DO NOT EDIT THIS FILE - it is machine generated */ #include <jni.h> /* Header for class Main */#ifndef _Included_Main #define _Included_Main #ifdef __cplusplus extern "C" { #endif /** Class: Main* Method: booleanFun* Signature: (Z)Z*/ JNIEXPORT jboolean JNICALL Java_Main_booleanFun(JNIEnv *, jobject, jboolean);/** Class: Main* Method: byteFun* Signature: (B)B*/ JNIEXPORT jbyte JNICALL Java_Main_byteFun(JNIEnv *, jobject, jbyte);/** Class: Main* Method: charFun* Signature: (C)C*/ JNIEXPORT jchar JNICALL Java_Main_charFun(JNIEnv *, jobject, jchar);/** Class: Main* Method: shortFun* Signature: (S)S*/ JNIEXPORT jshort JNICALL Java_Main_shortFun(JNIEnv *, jobject, jshort);/** Class: Main* Method: intFun* Signature: (I)I*/ JNIEXPORT jint JNICALL Java_Main_intFun(JNIEnv *, jobject, jint);/** Class: Main* Method: longFun* Signature: (J)J*/ JNIEXPORT jlong JNICALL Java_Main_longFun(JNIEnv *, jobject, jlong);/** Class: Main* Method: floatFun* Signature: (F)F*/ JNIEXPORT jfloat JNICALL Java_Main_floatFun(JNIEnv *, jobject, jfloat);/** Class: Main* Method: doubleFun* Signature: (D)D*/ JNIEXPORT jdouble JNICALL Java_Main_doubleFun(JNIEnv *, jobject, jdouble);#ifdef __cplusplus } #endif #endif

main.cpp

#include "Main.h" #include <iostream> using namespace std;JNIEXPORT jboolean JNICALL Java_Main_booleanFun(JNIEnv *, jobject, jboolean jb) {cout << "---------- C++ Java_Main_booleanFun start ----------" << endl;cout << "The parament is : " << boolalpha << (bool)jb << endl;bool retValue = false;cout << "---------- C++ Java_Main_booleanFun end ----------" << endl;return retValue; }JNIEXPORT jbyte JNICALL Java_Main_byteFun(JNIEnv *, jobject, jbyte jb) {cout << "---------- C++ Java_Main_byteFun start ----------" << endl;cout << "The parament is : " << (int)jb << endl;signed char sc = 0x01;cout << "---------- C++ Java_Main_byteFun end ----------" << endl;return sc; }JNIEXPORT jchar JNICALL Java_Main_charFun(JNIEnv *, jobject, jchar jc) {cout << "---------- C++ Java_Main_charFun start ----------" << endl;cout << "The parament is : " << jc << endl;unsigned short retValue = 'F';cout << "---------- C++ Java_Main_charFun end ----------" << endl;return retValue; }JNIEXPORT jshort JNICALL Java_Main_shortFun(JNIEnv *, jobject, jshort js) {cout << "---------- C++ Java_Main_shortFun start ----------" << endl;cout << "The parament is : " << js << endl;short ret = 21;cout << "---------- C++ Java_Main_shortFun end ----------" << endl;return ret; }JNIEXPORT jint JNICALL Java_Main_intFun(JNIEnv *, jobject, jint ji) {cout << "---------- C++ Java_Main_intFun start ----------" << endl;cout << "The parament is : " << ji << endl;int ret = 200;cout << "---------- C++ Java_Main_intFun end ----------" << endl;return ret; }JNIEXPORT jlong JNICALL Java_Main_longFun(JNIEnv *, jobject, jlong jl) {cout << "---------- C++ Java_Main_longFun start ----------" << endl;cout << "The parament is : " << jl << endl;__int64 ret = 100;cout << "---------- C++ Java_Main_longFun end ----------" << endl;return ret; }JNIEXPORT jfloat JNICALL Java_Main_floatFun(JNIEnv *, jobject, jfloat jf) {cout << "---------- C++ Java_Main_floatFun start ----------" << endl;cout << "The parament is : " << jf << endl;float ret = 100.001;cout << "---------- C++ Java_Main_floatFun end ----------" << endl;return ret; }JNIEXPORT jdouble JNICALL Java_Main_doubleFun(JNIEnv *, jobject, jdouble jd) {cout << "---------- C++ Java_Main_doubleFun start ----------" << endl;cout << "The parament is : " << jd << endl;double ret = 200.00001;cout << "---------- C++ Java_Main_doubleFun end ----------" << endl;return ret; }

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