严重: Servlet.service() for servlet () threw exception java.lang.NullPoint
下面代码几乎是按照书上来的，怎么有空指针的错误？实在找不出来，求大神指点！此段代码功能是将项目中某图片显示在客户端。
import javax.servlet.*;
import javax.servlet.http.*;
import javax.servlet.jsp.PageContext;
import javax.swing.JPanel;
import java.awt.*;
import java.io.*;
import java.sql.*;
public class show_pathway extends HttpServlet {
public void service(HttpServletRequest request,
HttpServletResponse response) throws ServletException,IOException
{
response.setContentType("image/jpg");
InputStream in = this.getServletContext().getResourceAsStream("/WEB-INF/wei.jpg");
OutputStream outstr = response.getOutputStream();
byte[] buffer = new byte[1024];
int length = 0;
while( (length = in.read(buffer))!= -1)
{
outstr.write(buffer, 0, length);
}
in.close();
outstr.close();
}
}
