标签：String int jna char 类型 JNA outstr 字符串 public

1. 返回字符串类型

c/c++代码

• 全局变量

char retp[1024];
const char* getStr1(int a, int b){
    memset(retp, 0, 1024);
    char outstr[256];
    memset(outstr, 0, 256);
    if (outstr != 0){
        sprintf_s(outstr, "汉字out DLL汉字: %d + %d==%d\n", a, b, (a + b));
    }
    strcpy_s(retp, outstr);
    return retp;
}

• malloc函数分配空间

const char* getStr2(int a, int b){
    char* retp = (char*)malloc(1024);
    memset(retp, 0, 1024);
    char outstr[256];
    memset(outstr, 0, 256);
    if (outstr != 0){
        sprintf_s(outstr, "汉字out DLL汉字: %d + %d==%d\n", a, b, (a + b));
        //printf("%s",outstr);
    }
    strcpy_s(retp, strlen(outstr) + 1, outstr);
    return retp;
}

java代码

package com.jnademo;

import com.sun.jna.Library;
import com.sun.jna.Native;

public class JnaTest {

	public interface CLibrary extends Library {
		CLibrary INSTANCE = (CLibrary) Native.load("E:\\dllws\\jnaTest\\x64\\Debug\\jnaTest.dll",
				CLibrary.class);
		
	    String getStr1(int a, int b);
	    
	    String getStr2(int a, int b);
	}
	
	public static void main(String[] args) {
		System.setProperty("jna.encoding","GBK");
		System.out.println(CLibrary.INSTANCE.getStr1(1, 3));
		System.out.println(CLibrary.INSTANCE.getStr2(2, 3));
	}
  
}

要注意添加System.setProperty("jna.encoding","GBK");否则会出现乱码。具体规则

• c++ char* GBK编码时

System.setProperty("jna.encoding", "GBK");

• c++ char* UTF8编码时

System.setProperty("jna.encoding", "UTF-8");

另外，其实还有个更简单的办法，JNA提供了一个宽字符字符串WString，当然c++接口参数类型要使用wchar_t*，这样WString就可以无缝转wchar_t*了，不用做任何修改，也绝对不会乱码。

C/C++接收字符串类型

C/C++代码

bool JavaStr(char* szText, int textLen) {
    if (szText == NULL || textLen <= 0) {
        return false;
    }
    std::string strText(szText, textLen);
    //OutputDebugStringA("JavaStr:");
    //OutputDebugStringA(strText.c_str());
    cout << strText.c_str() << endl;
    return true;
}

java代码

package com.jnademo;

import java.io.UnsupportedEncodingException;
import java.util.Arrays;
import java.util.List;

import com.sun.jna.Library;
import com.sun.jna.Native;

public class TestStructDemo {
	
	public interface TestStruct extends Library {
		
		TestStruct INSTANCE = (TestStruct) Native.load("E:\\dllws\\jnaTest\\x64\\Debug\\jnaTest.dll",
				TestStruct.class);
		
	    public boolean JavaStr(String str, int strLen);   // 使用String传参数，中文会参数乱码
	    
	    public boolean JavaStr(byte[] str, int strLen);   // 使用byte[]传参数，中文正常
	}
    
	public static void main(String[] args) throws UnsupportedEncodingException {
        //https://blog.51cto.com/softo/6009271
        String utf8Str = "UTF8转成GBK";
        String gbkStr = new String(utf8Str.getBytes("UTF-8"), "GBK"); // UTF8转成GBK
        byte[] gbkBytes = utf8Str.getBytes("UTF-8");
        TestStruct.INSTANCE.JavaStr(gbkStr, gbkStr.length());      // 传字符串C++接收时中文是乱码
        TestStruct.INSTANCE.JavaStr(gbkBytes, gbkBytes.length);    // 传字节数组C++接收中文正常
	}

}

参考：
https://blog.csdn.net/redchairman/article/details/108438202
https://blog.csdn.net/houmingyang/article/details/127071298

标签：String,int,jna,char,类型,JNA,outstr,字符串,public
From： https://www.cnblogs.com/happyhuangjinjin/p/17220049.html