java由servlet实现登录的简单功能,并把用户名用cookie保存起来,读取cookie

你的名字 2022-07-13 22:43 101阅读 0赞

## 1.编写登录界面 ##

<!DOCTYPE html>
    <html>
      <head>
        <title>Login.html</title>
    	
        <meta name="keywords" content="keyword1,keyword2,keyword3">
        <meta name="description" content="this is my page">
        <meta name="content-type" content="text/html; charset=UTF-8">
        <title>登录界面</title>
      </head>
      
      <body>
          <h3>登录系统</h3>
        <form action="/myJavaEELearnDemo/Login" method="post">
        <label for="用户名：">用户名：</label><input type="text" name="userName" width="100px">
        </br>
        </br>
        <label for="用户名：">密　码：</label><input type="password" name="passWord" width="100px">
        </br>
        </br>
        <input type="submit" value="登录" />       <input type="reset" value="重新填写"/>
        </form>
      </body>
    </html>

## 2.网页提交表单响应servlet并在web.xml中配置servlet ##

<servlet>
        <servlet-name>Login</servlet-name>
        <servlet-class>com.lyh.serlet.Login</servlet-class>
      </servlet>

<servlet-mapping>
        <servlet-name>Login</servlet-name>
        <url-pattern>/Login</url-pattern>
      </servlet-mapping>

## 3.登录servlet 关键 源码： ##

获得用户名,并加密保存

public void doPost(HttpServletRequest request, HttpServletResponse response)
    			throws ServletException, IOException {
    
    		sun.misc.BASE64Encoder base64Encoder= new sun.misc.BASE64Encoder();
    		ByteArrayOutputStream classBytes = new ByteArrayOutputStream();
    		ObjectOutputStream oos = new ObjectOutputStream(classBytes);
    		oos.writeObject(new MyCookie());
    		oos.close();
    		String classStr=base64Encoder.encode(classBytes.toByteArray());
    		Cookie cookie= new Cookie("mycookie", classStr);
    		cookie.setMaxAge(60*60*24);
    		response.addCookie(cookie);
    		RequestDispatcher readCookieDispatcher=getServletContext().getRequestDispatcher("/ReadCookie");
    	        readCookieDispatcher.include(request, response);
    }

ReadCookie关键源码

public void doPost(HttpServletRequest request, HttpServletResponse response)
    			throws ServletException, IOException {
    		response.setContentType("text/html");
    		PrintWriter out = response.getWriter();
    		out.println("<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01 Transitional//EN\">");
    		out.println("<HTML>");
    		out.println("  <HEAD><TITLE>A Servlet</TITLE></HEAD>");
    		out.println("  <BODY>");
            
            try {
    			sun.misc.BASE64Decoder base64Decoder = new sun.misc.BASE64Decoder();
    			Cookie cookie2=getCookieValue(request.getCookies(), "mycookie");
    			if (cookie2 == null) {
    				return ;
    				
    			}
    			String classStr=cookie2.getValue();
    			out.println("<br/>"+classStr+"<br/>");
    			byte[] classBytes = base64Decoder.decodeBuffer(classStr);
    			ObjectInputStream ois=new ObjectInputStream(new ByteArrayInputStream(classBytes));
    			MyCookie myCookie= (MyCookie)ois.readObject();
    			out.println(myCookie.getMsg());
    			
    		} catch (Exception e) {
    			// TODO: handle exception
    		}
            
            
            
            
    		out.println("  </BODY>");
    		out.println("</HTML>");
    		out.flush();
    		out.close();
    		
    		
    		
    		
    		
    	}
        protected  Cookie getCookieValue(Cookie[] cookies,String name) {
    	 if (cookies!=null) {
    		for (Cookie c:cookies) {
    			 if (c.getName().equals(name)) {
    				return c;
    			}
    		}
    	  }
    	  return null;
        }