我在下面有一个servlet，它从数据库中检索很多信息，然后以表格形式打印出来。我正在使用out.println（html代码）在此页面上输出所有内容。有没有在Servlet中编写此html代码的更有效方法？对于我要添加的每个html元素/属性等，我都必须使用out.println(<head>)例如。
import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
import java.sql.*;
public class PersonalInfoOutput extends HttpServlet {
protected void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setContentType("text/html;charset=UTF-8");
PrintWriter out = response.getWriter();
HttpSession session = request.getSession(false);
String employeeid = "";
if(session != null) {
employeeid = (String)session.getAttribute("employeeid");
}
boolean st = false;
try {
Class.forName("com.mysql.jdbc.Driver").newInstance();
Connection con = DriverManager.getConnection("jdbc:mysql://localhost:3306/payroll_system", "root", "");
PreparedStatement ps = con.prepareStatement("select employeeID, FirstName, LastName, Admin, DOB, Address, Email, HourlyRate, Gender, ALeaveBalance, SLeaveBalance, ActiveStatus, Role, BSB, BankName, AccNumber, SuperNumber, SuperCompany from payroll_system.employee_info where employeeID = ?");
ps.setString(1, employeeid);
ResultSet rs = ps.executeQuery();
st = rs.next();
if(st){
boolean adminTrue = rs.getBoolean("Admin");
boolean activeTrue = rs.getBoolean("ActiveStatus");
out.println("<html>");
out.println("<head>");
out.println("<style>");
out.println("table { border-collapse: collapse; width: 50%; } th, td { text-align: left; padding: 8px; } tr:nth-child(even){background-color: #f2f2f2}");
out.println("tr:hover {background-color: #e2f4ff;}");
out.println("</style>");
out.println("<link rel = stylesheet type = text/css href = main.css>");
out.println("<link rel = stylesheet type = text/css href = sidebar.css>");
out.println("<title>Personal Information</title>");
out.print("</head>");
out.println("<body>");
if(adminTrue){
out.println("<ul>");
out.println("<li><a class=active >View Personal Information</a></li>");
out.println("<li><a href=xyz>View Expense Claims</a></li>");
out.println("<li><a href=xyz>View Payslips</a></li>");
out.println("<li><a href=changePassAdmin.html>Change Password</a></li>");
out.println("<li><a href=xyz>Maintain Employee Information</a></li>");
out.println("<li><a href=xyz>Maintain Tax Information</a></li>");
out.println("<li><a href=xyz>Maintain Payroll Items</a></li>");
out.println("<li><a href=xyz>Maintain Timesheet</a></li>");
out.println("<li><a href=xyz>Maintain Employee Expenses</a></li>");
out.println("<li><a href=xyz>Run Payroll</a></li>");
out.println("<li><a href=xyz>Generate Reports</a></li>");
out.println("</ul>");
out.println("<div style=margin-left:25%;padding:1px 16px;height:1000px;>");
out.println("</div>");
}
else if(!adminTrue){
out.println("<ul>");
out.println("<li><a class=active href=PersonalInfoOutput>View Personal Information</a></li>");
out.println("<li><a href=xyz>View Expense Claims</a></li>");
out.println("<li><a href=xyz>View Payslips</a></li>");
out.println("<li><a href=.html>Change Password</a></li>");
out.println("</ul>");
out.println("<div style=margin-left:25%;padding:1px 16px;height:1000px;>");
out.println("</div>");
}
out.println("<h1>Personal Information</h1>");
out.println("<table border =1>");
out.println("<tr>");
out.println("<td>Name</td>");
out.println("<td>"+ rs.getString("FirstName") + " " + rs.getString("LastName") + "</td>");
out.println("</tr>");
out.println("<tr>");
out.println("<td>Employee ID</td>");
out.println("<td>"+ rs.getString("employeeID")+"</td>");
out.println("</tr>");
if(adminTrue) {
out.println("<tr>");
out.println("<td>Admin</td>");
out.println("<td>Yes</td>");
out.println("</tr>");
}
else{
out.println("<tr>");
out.println("<td>Admin</td>");
out.println("<td>No</td>");
out.println("</tr>");
}
out.println("<tr>");
out.println("<td>Date Of Birth</td>");
out.println("<td>"+ rs.getString("DOB")+"</td>");
out.println("</tr>");
out.println("<tr>");
out.println("<td>Residential Address</td>");
out.println("<td>"+ rs.getString("Address")+"</td>");
out.println("</tr>");
out.println("<tr>");
out.println("<td>Email</td>");
out.println("<td>"+ rs.getString("Email")+"</td>");
out.println("</tr>");
out.println("<tr>");
out.println("<td>Hourly Income</td>");
out.println("<td>"+ "$" + rs.getString("HourlyRate")+"</td>");
out.println("</tr>");
out.println("<tr>");
out.println("<td>Gender</td>");
out.println("<td>"+ rs.getString("Gender")+"</td>");
out.println("</tr>");
out.println("<tr>");
out.println("<td>Annual Leave Balance</td>");
out.println("<td>"+ rs.getString("ALeaveBalance")+"</td>");
out.println("</tr>");
out.println("<tr>");
out.println("<td>Sick Leave Balance</td>");
out.println("<td>"+ rs.getString("SLeaveBalance")+"</td>");
out.println("</tr>");
if(activeTrue) {
out.println("<tr>");
out.println("<td>Currently Active</td>");
out.println("<td>Yes</td>");
out.println("</tr>");
}
else {
out.println("<tr>");
out.println("<td>Currently Active</td>");
out.println("<td>No</td>");
out.println("</tr>");
}
out.println("<tr>");
out.println("<td>Role</td>");
out.println("<td>"+ rs.getString("Role")+"</td>");
out.println("</tr>");
out.println("<tr>");
out.println("<td>BSB</td>");
out.println("<td>"+ rs.getString("BSB")+"</td>");
out.println("</tr>");
out.println("<tr>");
out.println("<td>Bank Name</td>");
out.println("<td>"+ rs.getString("BankName")+"</td>");
out.println("</tr>");
out.println("<tr>");
out.println("<td>Bank Account Number</td>");
out.println("<td>"+ rs.getString("AccNumber")+"</td>");
out.println("</tr>");
out.println("<tr>");
out.println("<td>Superannuation Company</td>");
out.println("<td>"+ rs.getString("SuperCompany")+"</td>");
out.println("</tr>");
out.println("<tr>");
out.println("<td>Superannuation Number</td>");
out.println("<td>"+ rs.getString("SuperNumber")+"</td>");
out.println("</tr>");
out.println("</table>");
out.println("</body>");
out.println("</html>");
}
}catch(Exception e)
{
e.printStackTrace();
}
out.close();
}
}
out.println（）在可读性方面有点难看-但是与I / O时间相比，这些调用的开销很小。
在循环中使用+进行字符串连接可能会损害您的内存占用（而且也不是最快的方法）。考虑一下您拥有的这一行：
out.println("<td>"+ rs.getString("FirstName") + " " + rs.getString("LastName") + "</td>");
通过使用以下代码进行编码，您可以获得可读性和速度，并且剩下的char []更少被垃圾回收format()：
out.format ("<td>%s %s</td>", rs.getString ("FirstName"), rs.getString ("LastName"));
更多注意事项
每次调用servlet时，就创建并连接一个新的数据库连接。这将严重影响您的性能和可伸缩性。您应该考虑使用从中获取预连接的连接的连接池。您获得的性能将弥补很多String concat或println调用。
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