JNA字符串类型操作

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