HTTP基本认证(BasicAuthentication)的JAVA实例代码

import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import sun.misc.BASE64Decoder;

public class HTTPAuthServlet extends HttpServlet {
  
  public void doGet(HttpServletRequest request, HttpServletResponse response) throws IOException {
    String sessiOnAuth= (String) request.getSession().getAttribute("auth");

    if (sessionAuth != null) {
      System.out.println("this is next step");
      nextStep(request, response);

    } else {

      if(!checkHeaderAuth(request, response)){
        response.setStatus(401);
        response.setHeader("Cache-Control", "no-store");
        response.setDateHeader("Expires", 0);
        response.setHeader("WWW-authenticate", "Basic Realm=\"test\"");
      }      

    }

  }

  private boolean checkHeaderAuth(HttpServletRequest request, HttpServletResponse response) throws IOException {

    String auth = request.getHeader("Authorization");
    System.out.println("auth encoded in base64 is " + getFromBASE64(auth));
    
    if ((auth != null) && (auth.length() > 6)) {
      auth = auth.substring(6, auth.length());

      String decodedAuth = getFromBASE64(auth);
      System.out.println("auth decoded from base64 is " + decodedAuth);

      request.getSession().setAttribute("auth", decodedAuth);
      return true;
    }else{
      return false;
    }

  }

  private String getFromBASE64(String s) {
    if (s == null)
      return null;
    BASE64Decoder decoder = new BASE64Decoder();
    try {
      byte[] b = decoder.decodeBuffer(s);
      return new String(b);
    } catch (Exception e) {
      return null;
    }
  }

  public void nextStep(HttpServletRequest request, HttpServletResponse response) throws IOException {
    PrintWriter pw = response.getWriter();
    pw.println(" next step, authentication is : " + request.getSession().getAttribute("auth") + "
");
    pw.println("
");
  }

  public void doPost(HttpServletRequest request, HttpServletResponse response) throws IOException {
    doGet(request, response);
  }

}