JNA调用c++动态库返回数据

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JNA Examples

1、返回String, pch.h头文件

// pch.h: 这是预编译标头文件。
// 下方列出的文件仅编译一次，提高了将来生成的生成性能。
// 这还将影响 IntelliSense 性能，包括代码完成和许多代码浏览功能。
// 但是，如果此处列出的文件中的任何一个在生成之间有更新，它们全部都将被重新编译。
// 请勿在此处添加要频繁更新的文件，这将使得性能优势无效。#ifndef PCH_H
#define PCH_H// 添加要在此处预编译的标头
#include "framework.h"#ifdef __cplusplus
#define EXPORT extern "C" __declspec(dllexport)
#else 
#define EXPORT __declspec(dllexport)
#endifstruct  VideoAiReq {//行人告警频率int intervalP;//停车告警频率int intervalC;//应急车道告警频率int intervalR;//视频流地址char* videoUrl;//结果请求地址char* resultUrl;//无人机idchar* deviceId;//控制文件绝对路径  有则算法开始输出char* startFile;
};EXPORT char* startVideoAi(VideoAiReq videoAiReq);#endif //PCH_H

pch.cpp代码

// pch.cpp: 与预编译标头对应的源文件#include "pch.h"
#include "iostream"char* startVideoAi(VideoAiReq videoAiReq) {std::cout << videoAiReq.deviceId << std::endl;std::cout << videoAiReq.startFile << std::endl;std::cout << videoAiReq.intervalP << std::endl;std::cout << videoAiReq.videoUrl << std::endl;std::cout << videoAiReq.resultUrl << std::endl;std::cout << videoAiReq.intervalC << std::endl;std::cout << videoAiReq.intervalR << std::endl;return videoAiReq.startFile;
}// 当使用预编译的头时，需要使用此源文件，编译才能成功。

编译成动态库 videoai1

java代码如下

VideoAiLibrary.java 动态库

package com.pojo.util;import com.sun.jna.Library;
import com.sun.jna.Native;
import com.sun.jna.NativeLibrary;import java.nio.ByteBuffer;/*** JNA Wrapper for library <b>mycpp3</b><br>* This file was autogenerated by <a href="http://jnaerator.googlecode.com/">JNAerator</a>,<br>* a tool written by <a href="http://ochafik.com/">Olivier Chafik</a> that <a href="http://code.google.com/p/jnaerator/wiki/CreditsAndLicense">uses a few opensource projects.</a>.<br>* For help, please visit <a href="http://nativelibs4java.googlecode.com/">NativeLibs4Java</a> , <a href="http://rococoa.dev.java.net/">Rococoa</a>, or <a href="http://jna.dev.java.net/">JNA</a>.*/
public interface VideoAiLibrary extends Library {public static final String JNA_LIBRARY_NAME = "videoai1";public static final VideoAiLibrary INSTANCE = (VideoAiLibrary) Native.load(VideoAiLibrary.JNA_LIBRARY_NAME, VideoAiLibrary.class);/*** Original signature : <code>void startVideoAi(char*, char*, char*, char*, int)</code><br>* <i>native declaration : C:\Users\Administrator\mycpp3.h:6</i>*/String startVideoAi(VideoAiReq videoAiReq);
}

传参实体类

package com.pojo.util;import com.sun.jna.Structure;/*** 属性顺序和c++代码一致*/
@Structure.FieldOrder({"intervalP", "intervalC", "intervalR", "videoUrl", "resultUrl", "deviceId", "startFile"})
public class VideoAiReq extends Structure {/*** 行人告警频率*/public int intervalP;/*** 停车告警频率*/public int intervalC;/*** 应急车道告警频率*/public int intervalR;/*** 视频流地址*/public String videoUrl;/*** 结果请求地址*/public String resultUrl;/*** 无人机id*/public String deviceId;/*** 控制文件绝对路径  有则算法开始输出*/public String startFile;public int getIntervalP() {return intervalP;}public void setIntervalP(int intervalP) {this.intervalP = intervalP;}public int getIntervalC() {return intervalC;}public void setIntervalC(int intervalC) {this.intervalC = intervalC;}public int getIntervalR() {return intervalR;}public void setIntervalR(int intervalR) {this.intervalR = intervalR;}public String getVideoUrl() {return videoUrl;}public void setVideoUrl(String videoUrl) {this.videoUrl = videoUrl;}public String getResultUrl() {return resultUrl;}public void setResultUrl(String resultUrl) {this.resultUrl = resultUrl;}public String getDeviceId() {return deviceId;}public void setDeviceId(String deviceId) {this.deviceId = deviceId;}public String getStartFile() {return startFile;}public void setStartFile(String startFile) {this.startFile = startFile;}public VideoAiReq() {}}

测试类和测试结果

package com.pojo.util;import lombok.SneakyThrows;import java.io.File;
import java.nio.ByteBuffer;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;public class JnaTest {@SneakyThrowspublic static void main(String[] args) {VideoAiReq videoAiReq = new VideoAiReq();videoAiReq.setIntervalP(10);videoAiReq.setIntervalC(20);videoAiReq.setIntervalR(30);videoAiReq.setVideoUrl("videoUrl");videoAiReq.setStartFile("startFile");videoAiReq.setDeviceId("deviceId");videoAiReq.setResultUrl("resultUrl");String ss = VideoAiLibrary.INSTANCE.startVideoAi(videoAiReq);System.out.println("return===" + ss);
//        Path newFile = Paths.get("D:\\home\\smart\\newfile.txt");
//        if (!Files.exists(newFile)) {
//            Files.createFile(newFile);
//        }
//        Files.deleteIfExists(newFile);}
}