日期:2014-05-18  浏览次数:20723 次

MyEclipse+Tomcat环境下Java调用DLL问题
windows xp系统,在MyEclipse下做一个Java调用dll的程序 
在src下面编写javabean代码: 
 javacall.java 
public class javacall { 
static 

System.loadLibrary("calldll"); 


public native static int add(int i, int k); //在calldll.dll实现 

public static void main(String[] args) 

javacall jc = new javacall(); 
System.out.println(jc.add(3,4)); 


编译生成javacall.class文件,生成javacall.h文件 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 
在VC6.0下生成dll文件,程序如下 
#include <jni.h> 
#include "javacall.h" 


JNIEXPORT jint JNICALL Java_javacall_add (JNIEnv *, jclass, jint a,jint b) 

return a*b; 


在命令行下直接运行java javacall结果正确 
如果这时候直接在MyEclipse下run application会报错: 
java.lang.UnsatisfiedLinkError: no calldll in java.library.path 
at java.lang.ClassLoader.loadLibrary(Unknown Source) 
at java.lang.Runtime.loadLibrary0(Unknown Source) 
at java.lang.System.loadLibrary(Unknown Source) 
at javacall.<clinit>(javacall.java:4) 
Exception in thread "main" 

这时在run-java application-arguments-VM arguments下面添加 
-Djava.library.path=E:\MyEclipse\workspace\jspcall\WebRoot\WEB-INF\classes 
这个路径是calldll.dll的存放路径,也是javacall.class所在路径 
然后运行成功,得到想要的结果12 

最后我在WebRoot下面编写call.jsp文件 
  <%@ page contentType="text/html; charset=GBK" %>  
  <html>  
  <head>  
  <title>  
  Jsp调用DLL例子  
  </title>  
  </head>  
  <jsp:useBean id="JBean" scope="page" class="javacall" />  
  <body>  
  <h1>  
  <%=JBean.add(3,4)%>  
  </h1>  
  </body>  
  </html>  

配置到tomcat6.0下, 
工程结构大致为jspcall在C:\Tomcat 6.0\webapps 
call.jsp在C:\Tomcat 6.0\webapps\jspcall 
javacall.class跟calldll.dll都在 
C:\Tomcat 6.0\webapps\jspcall\WEB-INF\classes 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 
然后输入http://localhost:8080/jspcall/call.jsp 
出现错误: 
HTTP Status 500 - 

-------------------------------------------- 

type Exception report 

message 

description The server encountered an internal error () that prevented it from fulfilling this request. 

exception 

org.apache.jasper.JasperException: Unable to compile class for JSP

An error occurred at line: 8 in the jsp file: /call.jsp 
javacall cannot be resolved to a type 
5: Jsp调用DLL例子  
6: </title>  
7: </head>  
8: <jsp:useBean id="JBean" scope="page" class="javacall" />  
9: <body>  
10: <h1>  
11: <%=JBean.add(3,4)%>  


An