java 调用c++类对象方法

java 调用c++类对象方法

背景描述

• java如何通过jni native方法调用c++类对象，通过传递对象的句柄，来控制调用类的成员函数以及获取成员变量的值，并手动释放类对象

• 废话不多说，直接上代码。

  • jni对应的cpp

    #include <stdlib.h>
    #include <string>
    #include "class_test.h"
    #include "test_class_jni.h"
    
    //返回类对象实例化之后的地址，地址的存储数据类型为long
    JNIEXPORT jlong JNICALL Java_com_test_jni_utils_ClassTest_init(JNIEnv *env, jobject thisObj) {
    	Test* pTest = NULL;
    	pTest = new Test();
    	pTest->init();
    	return jlong(pTest);
    }
    
    //传对象地址，并且调用对象的成员函数，对某一个成员变量进行自增长+1
    JNIEXPORT jint JNICALL Java_com_test_jni_utils_ClassTest_addSum(JNIEnv *env, jobject thisObj, jlong nativeId) {
    	Test* p = (Test*)nativeId;
    	int sum = p->add();
    	return sum;
    }
    
    //主动释放对象空间
    JNIEXPORT jint JNICALL Java_com_test_jni_utils_ClassTest_deInit(JNIEnv *env, jobject thisObj, jlong nativeId) {
    	Test* p = (Test*)nativeId;
    	if (p) {
    		delete p;
    		p = NULL;
    	}
    	return 0;
    }			
    

  • jni对应的头文件

    /* DO NOT EDIT THIS FILE - it is machine generated */
    #include "jni.h"
    
    #ifndef _Included_com_jni_object_array
    #define _Included_com_jni_object_array
    #ifdef __cplusplus
    extern "C" {
    #endif
    	/*
    	 * Class:     com_test_jni_utils_ClassTest
    	 * Method:    createInit
    	 * Signature: (Ljava/lang/String;Ljava/lang/String;)I
    	 */
    	JNIEXPORT jlong JNICALL Java_com_test_jni_utils_ClassTest_init(JNIEnv*, jobject);
    	JNIEXPORT jint JNICALL Java_com_test_jni_utils_ClassTest_addSum(JNIEnv*, jobject, jlong);
    	JNIEXPORT jint JNICALL Java_com_test_jni_utils_ClassTest_deInit(JNIEnv*, jobject, jlong);
    
    #ifdef __cplusplus
    }
    #endif
    #endif //_Included_com_jni_object_array
    

  • 类对象cpp

    #include "class_test.h"
    
    Test::Test() {
    
    }
    
    Test::~Test() {
    
    }
    void Test::init() {
    	m_index = 1;
    }
    
    void Test::push_result() {
    	m_array.push_back(m_index);
    }
    
    int Test::add() {
    	return m_index++;
    }
    

  • 类对象头文件

    #pragma once
    #include <vector>
    
    class Test{
    public:
    	Test();
    	virtual ~Test();
    	void init();
    public:
    	void push_result();
    	int add();
    private:
    	int m_index;
    	std::vector<int> m_array;
    
    };
    

• linux下华为云jdk源码下载https://repo.huaweicloud.com/java/jdk/

• centos系统下在线安装：sudo yum install java-1.8.0-openjdk* -y