转换函数指针的C结构来JNA代码

Question

// original c code 

struct callback { 
    void (*recv_msg_)(const char * msg, int type, unsigned int len); 
    void (*connected_)(void *cs); 
    void (*disconnected_)(void *cs); 
}; 

void recv_msg(const char *msg, int type, unsigned int len) 
{ 
    // some code 
    //...... 
} 

void connected(void *s) 
{ 
    // some code 
    //...... 
} 

void disconnected(void *s) 
{ 
    // some code 
    //...... 
} 

struct callback cb; 
cb.recv_msg_ = recv_msg; 
cb.connected_ = connected; 
cb.disconnected = disconnected; 

init("127.0.0.1", 5672, &cb); 
// C code end 
//////////////////////////////////////////////////////////////////////// 

// THE JNA code 

interface RecvMsg extends Callback { 
    void invoke(String msg, int type, int con_len); 
} 

interface CbConnected extends Callback { 
    void invoke(Pointer ctx); 
} 

interface CbDisconnected extends Callback { 
    void invoke(Pointer ctx); 
} 

class RecvMsgImpl implements RecvMsg { 
    @Override 
    public void invoke(String msg, int type, int len) { 
     System.out.println("recv msg: " + msg); 
    } 
} 

class CbConnectedImpl implements CbConnected { 
    @Override 
    public void invoke(Pointer ctx) { 
     System.out.println("connected."); 
    } 
} 

class CbDisconnectedImpl implements CbDisconnected { 
    @Override 
    public void invoke(Pointer ctx) { 
     System.out.println("diconnected."); 
    } 
} 

public class MyCallBack extends Structure { 
    public RecvMsg recv_msg_; 
    public CbConnected cb_connected_; 
    public CbDisconnected cb_disconnected_; 

    @Override 
    protected List getFieldOrder() { 
     return Arrays.asList(new String[] {"recv_msg_", "cb_connected_", "cb_disconnected_"}); 
    } 
} 

MyCallBack cb = new MyCallBack(); 
cb.recv_msg_ = new RecvMsgImpl(); 
cb.cb_connected_ = new CbConnectedImpl(); 
cb.cb_disconnected_ = new CbDisconnectedImpl(); 

Xxx xxx = (Xxx) Native.loadLibrary("***", Xxx.class); 
xxx.init("127.0.0.1", 5672, cb); 

// Java code end 
//////////////////////////////////////////////////////////////////// 

我运行java代码，有例外是这样的：

Exception in thread "main" java.lang.IllegalArgumentException: Structure field "cb_connected_" was declared as interface DLLTest.CbConnected, which is not supported within a Structure 
    at com.sun.jna.Structure.writeField(Structure.java:808) 
    at com.sun.jna.Structure.write(Structure.java:718) 
    at com.sun.jna.Structure.autoWrite(Structure.java:1923) 
    at com.sun.jna.Function.convertArgument(Function.java:505) 
    at com.sun.jna.Function.invoke(Function.java:297) 
    at com.sun.jna.Library$Handler.invoke(Library.java:212) 
    at com.sun.proxy.$Proxy1.init(Unknown Source) 
    at DLLTest.Tester.main(Tester.java:55) 

请告诉我如何翻译它与JNA到Java。

Answer 1

这是我对jna库的测试。

我认为你必须找到与我的一些区别。

我做了我自己的代码，因为你没有给我看完整的源代码。

我的发展环境与msys2一个mingw64和蚀（氧）与Java（1.8）

这里有一些更多的细节。

gcc版本

Using built-in specs. 
COLLECT_GCC=C:\DEV\COMP\msys32\mingw64\bin\gcc.exe 
COLLECT_LTO_WRAPPER=C:/DEV/COMP/msys32/mingw64/bin/../lib/gcc/x86_64-w64- 
mingw32/6.3.0/lto-wrapper.exe 
Target: x86_64-w64-mingw32 
Configured with: .....skip 
Thread model: posix 
gcc version 6.3.0 (Rev1, Built by MSYS2 project) 

Java的信息

java.class.version::52.0 
sun.management.compiler::HotSpot 64-Bit Tiered Compilers 
sun.arch.data.model::64 
sun.desktop::windows 
sun.cpu.isalist::amd64 

首先，从你一JnaTest类的完整代码。

package stackoverflow; 

import java.util.Arrays; 
import java.util.List; 

import com.sun.jna.Callback; 
import com.sun.jna.Library; 
import com.sun.jna.Native; 
import com.sun.jna.Pointer; 
import com.sun.jna.Structure; 

public class JnaTest { 
    public interface JnaInf extends Library { 
     public void init(String val, int port, MyCallBack cb); 
    } 

    public static void main(String[] args) { 
     MyCallBack cb = new MyCallBack(); 
     cb.recv_msg_ = new RecvMsgImpl(); 
     cb.cb_connected_ = new CbConnectedImpl(); 
     cb.cb_disconnected_ = new CbDisconnectedImpl(); 

     System.load("C:\\DEV\\COMP\\msys32\\home\\stackoverflow\\jna_inf.dll"); 


     JnaInf xxx = (JnaInf) Native.loadLibrary("jna_inf", JnaInf.class); 
     xxx.init("127.0.0.1", 5672, cb); 
    } 

    interface RecvMsg extends Callback { 
     void invoke(String msg, int type, int con_len); 
    } 

    interface CbConnected extends Callback { 
     void invoke(Pointer ctx); 
    } 

    interface CbDisconnected extends Callback { 
     void invoke(Pointer ctx); 
    } 

    static class RecvMsgImpl implements RecvMsg { 
     @Override 
     public void invoke(String msg, int type, int len) { 
      System.out.println("recv msg: " + msg); 
      System.out.println("type: " + type); 
      System.out.println("len: " + len); 
     } 
    } 

    static class CbConnectedImpl implements CbConnected { 
     @Override 
     public void invoke(Pointer ctx) { 
      System.out.println("connected."); 
     } 
    } 

    static class CbDisconnectedImpl implements CbDisconnected { 
     @Override 
     public void invoke(Pointer ctx) { 
      System.out.println("diconnected."); 
     } 
    } 

    public static class MyCallBack extends Structure { 
     public RecvMsg recv_msg_; 
     public CbConnected cb_connected_; 
     public CbDisconnected cb_disconnected_; 

     @Override 
     protected List getFieldOrder() { 
      return Arrays.asList(new String[] { "recv_msg_", "cb_connected_", "cb_disconnected_" }); 
     } 
    } 
} 

然后，C源代码名称，jna_info.c如下，

struct callback { 
    void (*recv_msg_)(const char * msg, int type, unsigned int len); 
    void (*connected_)(void *cs); 
    void (*disconnected_)(void *cs); 
}; 

void recv_msg(const char *msg, int type, unsigned int len) 
{ 
    // some code 
    //...... 
} 

void connected(void *s) 
{ 
    // some code 
    //...... 
    return; 
} 

void disconnected(void *s) 
{ 
    // some code 
    //...... 
    return; 
} 

void init(const char *msg, int type, struct callback *mycallback) 
{ 
    mycallback->recv_msg_("123", 22, 3); 
    mycallback->connected_("123"); 
    return; 
} 

编译C源代码

gcc -c jna_inf.c 
gcc -shared -o jna_inf.dll jna_inf.o 

输出看起来像我是什么期待..

我真诚地希望这可以帮助你。