本文執行個體講述了JAVA防止重複送出Web表單的方法。分享給大家供大家參考，具體如下：
package cn.com.form;
import java.io.IOException;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.Random;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import sun.misc.BASE64Encoder;
//産生表單
public class FormServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//産生随機數
TokenProcessor tp=TokenProcessor.getInstance();
String token=tp.generateToken();
request.getSession().setAttribute("token", token);
request.getRequestDispatcher("/form.jsp").forward(request, response);
}
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
doGet(request,response);
}
}
class TokenProcessor//令牌
{
private static final TokenProcessor instance=new TokenProcessor();
private TokenProcessor(){}
public static TokenProcessor getInstance()
{
return instance;
}
public String generateToken()
{
String token=System.currentTimeMillis()+new Random().nextInt()+"";
try {
MessageDigest md=MessageDigest.getInstance("md5");
byte[] md5=md.digest(token.getBytes());
//base64編碼
BASE64Encoder encoder=new BASE64Encoder();
return encoder.encode(md5);
} catch (NoSuchAlgorithmException e) {
// TODO Auto-generated catch block
throw new RuntimeException(e);
}
}
}
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>
My JSP 'form.jsp' starting page
使用者名：
package cn.com.form;
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class DoForm extends HttpServlet {
private static final long serialVersionUID = 1L;
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
boolean b=isTokenValid(request);
if(!b)
{
System.out.println("請不要重複送出！");
return;
}
request.getSession().removeAttribute("token");
System.out.println("向資料庫中注冊使用者==");
}
private boolean isTokenValid(HttpServletRequest request) {
String client_token=request.getParameter("token");
if(client_token==null)
{
return false;
}
String server_token=(String)request.getSession().getAttribute("token");
if(server_token==null)
{
return false;
}
if(!client_token.equals(server_token))
{
return false;
}
return true;
}
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
doGet(request,response);
}
}
希望本文所述對大家Java web程式設計有所幫助。