JNI初步使用

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package org.cclin.hellojni;
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public class HelloJNI {
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    static {
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        //加载的 动态链接库 的文件名
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        System.loadLibrary("hello");
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    }
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    //native 表示 jni 的方法
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    private native void sayHello();
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    public static void main(String[] args) {
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        new HelloJNI().sayHello();
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    }
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}

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/* DO NOT EDIT THIS FILE - it is machine generated */
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#include <jni.h>
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/* Header for class org_cclin_hellojni_HelloJNI */
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#ifndef _Included_org_cclin_hellojni_HelloJNI
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#define _Included_org_cclin_hellojni_HelloJNI
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#ifdef __cplusplus
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extern "C" {
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#endif
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/*
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 * Class:     org_cclin_hellojni_HelloJNI
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 * Method:    sayHello
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 * Signature: ()V
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 */
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JNIEXPORT void JNICALL Java_org_cclin_hellojni_HelloJNI_sayHello
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  (JNIEnv *, jobject);
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#ifdef __cplusplus
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}
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#endif
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#endif

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cmake_minimum_required(VERSION 3.24)
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project(hellojni)
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set(CMAKE_CXX_STANDARD 20)
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# 查找 JNI 的头文件库
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find_package(JNI REQUIRED)
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# library 名字应与 `System.loadLibrary("hello")` 中的相同
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add_library(hello SHARED HelloJNI.cpp)
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target_include_directories(hello PRIVATE include)
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# 添加头文件
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target_include_directories(hello PRIVATE ${JAVA_INCLUDE_PATH} ${JAVA_INCLUDE_PATH2})

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#include <iostream>
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#include "org_cclin_hellojni_HelloJNI.h"
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JNIEXPORT void JNICALL Java_org_cclin_hellojni_HelloJNI_sayHello
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        (JNIEnv *, jobject) {
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    std::cout << "HelloJNI" << std::endl;
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}