基本概念

此篇博文记录了JNI的基本规范，与使用：

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

在本篇不再说明，只说下简单参数和返回值。

官方对基础数据类型的解释如下：

看看代码里面的可以看到：

这些数据类型还是很想象的。

下面对这些传入和返回值作下演示。

代码及演示

使用javah -jni xxxx后生成.h文件，Windows上配置号VS的包含目录，IDEA配置好依赖后（在https://blog.csdn.net/qq78442761/article/details/94849374此博文有详细的说明），

Java运行截图如下：

源码如下：

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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Java笔记-JNI中简单的参数与返回值处理

基本概念

代码及演示

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