深入Ajax代理的Java Servlet的实现详解

代码如下所示：
复制代码 代码如下:
import java.io.IOException;
import java.io.InputStream;
import java.net.URL;
import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class ProxyServlet extends HttpServlet
{
 private final static String COPYRIGHT = com.ibm.dogear.Copyright.SHORT;
 public static final String REDIRECT_base = "com.ibm.bl.servlet.RedirectServlet.redirect_base";
 private String redirectbase;

 
 @Override
 public void init(ServletConfig config) throws ServletException
 {
  super.init(config);
  redirectbase = getRequiredParam(REDIRECT_base);
 }
 @Override
 protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws IOException
 {
  String queryString = req.getQueryString();
  URL url = new URL(redirectbase + (queryString != null ? "?" + queryString : ""));
  copyInputStreamToOutputStream(url.openStream(), resp.getOutputStream());
 }
 private void copyInputStreamToOutputStream(InputStream in, ServletOutputStream out)
   throws IOException
 {
  try
  {
   try
   {
    byte[] buffer = new byte[1024];
    int n;
    while ((n = in.read(buffer)) != -1)
     out.write(buffer, 0, n);
   }
   finally
   {
    out.close();
   }
  }
  finally
  {
   in.close();
  }
 }
 protected String getRequiredParam(String param) throws ServletException
 {
  String result = getServletConfig().getInitParameter(param);
  if (result == null) {
   throw new ServletException(getClass() + " requires " + param + " param");
  }
  return result;
 }
}