JSP refresh page form repeat submission problem solution share
- 2020-06-15 10:05:11
- OfStack
sessionID and timestamp are used for identification, and the key code is as follows:
public class SswpdjAction extends BaseAction{
public String execute(){
/** Business code **/
................
// Set the identity
this.setSessionToken();
// Go to the add page
return "toAdd";
}
public String reSave(){
if(this.token != null && this.token.equals(this.getSessionToken())){
/** Setting a new identity **/
this.setSessionToken();
/** Business code **/
..............
return "toAdd";
}else{
printWriter out = null;
try{
httpServletResponse.setContentType("text/html;charset=UTF-8");
out = httpServletResponse.getWriter();
out.println("<script>alert(' Refresh the submission form! ');</script>");
out.flush();
}catch(IOException e){
e.printStackTrace();
}finally{
if(out != null){
out.close();
}
}
}
return null;
}
}
public class BaseAction extends ActionSupport{
/**jsp Page identifier **/
protected String token;
public String getToken(){
return token;
}
public void setToken(String token){
this.token = token;
}
public String getSessionToken(){
if(null != httpSession.getAttribute("Token")){
return httpSession.getAttribute("Token");
}else{
return null;
}
}
/** Identify generated **/
public void setSessionToken(){
String flag = useMd5(httpSession.getId() + System.currentTimeMillis());
httpSession.setAttribute("Token", flag);
httpServletRequest.setAttribute("SessionToken", flag);
}
/**MD5 encryption **/
private String useMd5(String str){
byte[] bs = str.getBytes();
String result = null;
try{
MessageDigest md5 = MessageDigest.getInstance("MD5");
md5.update(bs);
result = md5.digest().toString();
}catch(NoSuchAlgorithmException e){
e.printStackTrace();
}finally{
}
return result;
}
}
JSP page sets the identity hidden domain:
<form>
<input type="hidden" name="token" value="${SessionToken}" />
</form>