lsa.zip_...web....jsp..._LSA_jsp注册_mysql java 注册

package servlet; import java.io.IOException; import java.sql.Connection; import java.sql.DriverManager; import java.sql.ResultSet; import java.sql.SQLException; import java.sql.Statement; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; public class RegisterServlet extends HttpServlet{ @Override protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { /* 获取表单参数 */ String userName = request.getParameter("userName_register"); String password = request.getParameter("password_register"); String repassword = request.getParameter("repassword_register"); /* 校验输入参数 */ if(userName == null || "".equals(userName)){ //报错：登录账号不能为空 request.setAttribute("register_error", "登录账号不能为空!"); //转发回register.jsp getServletContext().getRequestDispatcher("/jsp/register.jsp").forward(request, response); }else if(password == null || "".equals(password)){ //报错：登录密码不能为空 request.setAttribute("register_error", "登录密码不能为空!"); //转发回register.jsp getServletContext().getRequestDispatcher("/jsp/register.jsp").forward(request, response); }else if(repassword == null || "".equals(repassword)){ //报错：重复密码不能为空 request.setAttribute("register_error", "重复密码不能为空!"); //转发回register.jsp getServletContext().getRequestDispatcher("/jsp/register.jsp").forward(request, response); }else if(!repassword.equals(password)){ //报错：重复密码与登录密码不一致 request.setAttribute("register_error", "重复密码与登录密码不一致!"); //转发回register.jsp getServletContext().getRequestDispatcher("/jsp/register.jsp").forward(request, response); }else{ String driver = "com.mysql.jdbc.Driver"; String url = "jdbc:mysql://localhost:3306/labsite"; String mysql_user = "root"; String mysql_pawd = "1234"; Connection connection = null; Statement stmt = null; ResultSet rs = null; try { Class.forName(driver); connection = DriverManager.getConnection(url,mysql_user,mysql_pawd); stmt = connection.createStatement(); String querySQL = "select * from user where username = '" + userName + "';"; rs = stmt.executeQuery(querySQL); //判断用户是否已存在 //查到了结果 if(rs.next()){ //报错 用户已存在 request.setAttribute("register_error", "用户已存在!"); //转发回register.jsp getServletContext().getRequestDispatcher("/jsp/register.jsp").forward(request, response); }else{ //往数据库插入一条新数据 String insertSQL = "insert into user values (null,'"+userName+"','"+password+"');"; stmt.execute(insertSQL); //页面重定向到index.jsp response.sendRedirect("jsp/index.jsp"); } } catch (ClassNotFoundException e) { e.printStackTrace(); } catch (SQLException e) { e.printStackTrace(); } finally{ if(stmt != null){ try { stmt.close(); } catch (SQLException e) { e.printStackTrace(); } } if(connection != null){ try { connection.close(); } catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace(); } } } } } }