HTTP基本认证(Basic Authentication)的JAVA实例代码

Z时代
2024-01-10
分类：IT

大家在登录网站的时候，大部分时候是通过一个表单提交登录信息。

但是有时候浏览器会弹出一个登录验证的对话框，如下图，这就是使用HTTP基本认证。

下面来看看一看这个认证的工作过程:

第一步: 客户端发送http request 给服务器,服务器验证该用户是否已经登录验证过了，如果没有的话，

服务器会返回一个401 Unauthozied给客户端，并且在Response 的 header "WWW-Authenticate" 中添加信息。

如下图。

第三步: 服务器将Authorization header中的用户名密码取出，进行验证，如果验证通过，将根据请求，发送资源给客户端。

下面来看一个JAVA的示例代码


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("<html> next step, authentication is : " + request.getSession().getAttribute("auth") + "<br>");
    pw.println("<br></html>");
  }
  public void doPost(HttpServletRequest request, HttpServletResponse response) throws IOException {
    doGet(request, response);
  }
}