How does Java call com compiled by VB through VC?

 

The following reproduced from: http://blog.csdn.net/tiger119/archive/2005/11/16/531081.aspx

 

 

A few days ago, a colleague asked me how to call com written in VB in Java. I used to know how to use native in Java and implement it through windows DLL, but I have never practiced it. I am busy today, I just tried it. The simplest example is written.
The procedure is very simple. Maybe someone may use it in the future. I will help you sort it out:

Step 1: generate the simplest COM (using vb60)

1.1: VB Code

Progid: testvbcom. clstest

Thread model: Multi-instance model of sta

Package COM. kingdee; <br/> public class testcallnative {<br/> static <br/>{< br/> system. loadlibrary ("callcomapi"); <br/>}< br/> Public native string callapi (string str1, int N); <br/> ...... <Br/>}

 

That's simple.

Step 2: Define the native method and export the output section declaration of Windows DLL (using eclipse3.1)

2.1 Java code:

Package COM. kingdee; <br/> public class testcallnative {<br/> static <br/>{< br/> system. loadlibrary ("callcomapi"); <br/>}< br/> Public native string callapi (string str1, int N); <br/> ...... <Br/>}

2.2: Export Declaration

Javah-JNI com. Kingdee. testcallnative

Obtain the com_kingdee_testcallnative.h file.
Note: This is a standard method for calling Java Virtual Machine and Windows DLL. The output name cannot be changed. In this example, the output name is:
Jniexport jstring jnicall java_com_kingdee_testcallnative_callapi
(Jnienv *, jobject, jstring, jint );

Step 3: Compile Windows DLL (using vc6.0)

First, I want to write a Windows DLL using MFC or SDK. In order to access COM more conveniently, I used MFC in my example and used part of ATL, however, you can actually use the simplest SDK method.

3.1: generate the api dll framework

A: Use the VC Wizard to generate a DLL in the MFC mode (Note: it is a conventional DLL and cannot be extended)
B: Define the def file content:
Exports
Java_com_kingdee_testcallnative_callapi @ 1

C: contains the. h file from the previous step.
D: add the necessary include directory in path or VC option.
For example, on my machine:
D:/program files/Java/jdk1.5.0/include
D:/program files/Java/jdk1.5.0/include/Win32

E: add the implementation process name.
Jniexport jstring jnicall parameters <br/> (jnienv * jenv, jobject, jstring jsinput, jint jninput) <br/>{< br/> jstring jsret; <br/> return jsret; <br/>}

3.2: code for calling COM. (Use the # import method to call standard Com)

Stdafx. h: <br/> # include <atlbase. h> <br/> # import ".. // vbcom // testvbcom. DLL "named_guids <br/> callcomapi. CPP <br/> # include "com_kingdee_testcallnative.h" <br/> void getjstring (jnienv * jenv, lpctstr lpszbuffer, jstring & JS) <br/>{< br/> uses_conversion; <br/> lpwstr PW = T2W (lpszbuffer); <br/> JS = jenv-> newstring (PW, wcslen (PW); <br/> return; <br/>}< br/> jniexport jstring jnicall java_com_kingdee_tes Tcallnative_callapi <br/> (jnienv * jenv, jobject, jstring jsinput, jint jninput) <br/>{< br/>:: coinitialize (null ); <br/> // convert input Params <br/> cstring sinput = jenv-> getstringutfchars (jsinput, 0); <br/> cstring sret; <br/> testvbcom :: _ clstest * Ptest = NULL; <br/> jstring jsret; <br/> try <br/> {<br/> // get com's interface <br/> If (failed (: cocreateinstance (testvbcom: clsid_clstest, null, c Lsctx_inproc, <br/> testvbcom: IID _ clstest, (lpvoid *) & Ptest) <br/> throw (_ T ("Get com's interface failed! "); <Br/> // call com's method <br/> _ bstr_t bstr1 (sinput); <br/> bstr1 = Ptest-> functest (bstr1, jninput); <br/> sret = bstr1.copy (); <br/> getjstring (jenv, sret, jsret); <br/>}< br/> catch (lpctstr lpszerr) <br/>{< br/> getjstring (jenv, lpszerr, jsret); <br/>}< br/> catch (...) <br/>{< br/> getjstring (jenv, _ T ("Unknown error! "), Jsret); <br/>}< br/> If (Ptest) Ptest-> release (); <br/>:: couninitialize (); <br/> return jsret; <br/>}
Step 4: compile Java testing (using eclipse 3.1)

4.1: Related paths for adding native:

The path on my machine is:
-Djava. Library. Path = E:/work/callcomforjava/example/callcomapi/release

4.2: Test code:

Public static void main (string [] ARGs) {<br/> system. out. println ("start... "); <br/> testcallnative testobj = new testcallnative (); <br/> system. out. println (testobj. callapi ("test", 1); <br/> system. out. println ("end... "); <br/>}

4.3: Run

Expected result:
Start...
Vbcom test: test1
End...

Simple, hey.

Note:

1: The debug version DLL written in vc6.0 cannot be normally called by Java. The reason is unknown and must be release.
2: the order of console output in the API is not as expected.

For example, add the following to the first end of an API:
Printf ("/napi DLL start..."); <br/> ...... <Br/> printf ("/napi dll ebd ...");

Run. The output on the console is:
Start...
Vbcom test: test1
End...
Api dll start...
Api dll end...

Stone on-11-16

This article from the csdn blog, reproduced please indicate the source: http://blog.csdn.net/tiger119/archive/2005/11/16/531081.aspx