Servlet 实现登录与注册

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本文介绍了如何利用Servlet技术进行用户注册与登录的功能实现。通过Servlet处理HTTP请求，结合HTML页面，实现用户信息的录入与验证。配置了web.xml文件以完成相关功能设置。

注册就是加入一个实体，而登陆就是已注册的信息进行验证的过程。

代码内嵌在HTML页面中

web.XML部分配置

Servlet1.java（Servlet）
Public class Servlet1 extends HttpServlet{
Public Servlet(){
Super();
}
Public void doGet(HttpServletRequest request , HttpServletResponse response) throws ServletException , IOException{
response.setCharacterEncoding(“utf-8”);
response.setContentType(“html/text”);
PrintlnWriter 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>");
		out.println("  this is");
		out.println(this.getClass());
		out.println(" ,using the GET methed!");
		out.println("<br>");
		
		out.println("注册<br>");
		out.println("<form action='Register'>");
		out.println("姓名：<input type='text' name='name' />");
		out.println("<br/>");
		out.println("密码：<input type='text' name='pass' />");
		out.println("<br/>");
		out.println("      ");
		out.println("      ");
		out.println("<input type='submit' value='Register' />");
		out.println("      ");
		out.println("<input type='reset' value='reset' />");
		out.println("<br/>");
		out.println("</form>");
		out.println("登录<br>");
		
		out.println("<form action='Login'>");
		out.println("姓名：<input type='text' name='name' />");
		out.println("<br/>");
		out.println("密码：<input type='text' name='pass' />");
		out.println("<br/>");
		out.println("      ");
		out.println("      ");
		out.println("<input type='submit' value='Login' />");
		out.println("      ");
		out.println("<input type='reset' value='reset' />");
		out.println("<br/>");
		out.println("</form>");
		
		
		out.println(" </BODY>");
		out.println(" </HTML>");
		out.flush();
		out.close();
}
}
Action指向另外的Servlet（XML配置中的<URL-pattern>），
对应的文本如name,pass,在以下的Servlet中调用时通过request对象的getParameter( )方法中进行调用。
Login.java（Servlet）
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
		response.setCharacterEncoding("utf-8");
	 	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>");
		out.println("  this is");
		out.println(this.getClass());
		out.println(" ,using the GET methed!");
		out.println("<br>");
		
		String name = request.getParameter("name");
		String pass = request.getParameter("pass");
		
		try{
			Class.forName("com.mysql.jdbc.Driver");
			String url="jdbc:mysql://192.168.1.137/test";
			Connection con=DriverManager.getConnection(url,"mydata","123");
			Statement stmt=con.createStatement();
			String sql = "select * from AUser where name='"+name+"'and pass='"+pass+"';";
			
			System.out.println("sql:"+sql);
			
			ResultSet rs = stmt.executeQuery(sql);
			
			if(rs.next()){
				System.out.println("login seccess");
			}else{				
				response.sendRedirect("Four");//跳转指令，跳向XML配置中 URL-pattern的Four
			}
			stmt.executeUpdate(sql);
			stmt.close();
			con.close();
			
		}catch(Exception e){
			System.out.println(e.getMessage());
			e.printStackTrace();
		}
		
		out.println(" </BODY>");
		out.println(" </HTML>");
		out.flush();
		out.close();
	}

Register.java（Servlet）
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
		response.setCharacterEncoding("utf-8");
	 	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>");
		out.println("  this is");
		out.println(this.getClass());
		out.println(" ,using the GET methed!");
		out.println("<br>");
		
		String name = request.getParameter("name");
		String pass = request.getParameter("pass");
		
		try{
			Class.forName("com.mysql.jdbc.Driver");
			String url="jdbc:mysql://192.168.1.137/test";
			Connection con=DriverManager.getConnection(url,"mydata","123");
			Statement stmt=con.createStatement();
			String sql = "insert into AUser (name,pass) values('"+name+"','"+pass+"');";
			stmt.executeUpdate(sql);
			stmt.close();
			con.close();
			System.out.println(sql);
			response.sendRedirect("Four");
		}catch(Exception e){
			System.out.println(e.getMessage());
			e.printStackTrace();
		}
		
		out.println(" </BODY>");
		out.println(" </HTML>");
		out.flush();
		out.close();	
	}