Why I won't jump duck 0.0 submit the form
<% @ page contentType="text/HTML. Charset=utf-8 "language=" Java "% & gt;
Old SAO & lt;/title> <br/><script> <br/>Window. The onl oad=function () {<br/>Document. The getElementById (" img "). The onclick=function () {<br/>This. SRC="https://bbs.csdn.net/day16/checkCodeServlet? Time="+ new Date (). GetTime (); <br/>} <br/>} <br/></script> <br/><style> <br/>Div {<br/>color: red; <br/>} <br/></style> <br/></head> <br/><body> <br/><The from action="/day16/loginServlet" method="post" & gt; <br/><Table> <br/><tr> <br/><td> The user name & lt;/td> <br/><td> <Input type="text" name="username" & gt; </td> <br/></tr> <br/><tr> <br/><td> Password & lt;/td> <br/><td> <Input type="password" name="password" & gt; </td> <br/></tr> <br/><tr> <br/><td> Verification code & lt;/td> <br/><td> <Input type="text" name="checkCode & gt;" </td> <br/></tr> <br/><tr> <br/><Td colspan="2" & gt; <Img id="img" SRC="https://bbs.csdn.net/day16/checkCodeServlet" & gt; </td> <br/></tr> <br/><tr> <br/><Td colspan="2" & gt; <Input type="submit" value="https://bbs.csdn.net/topics/" & gt; </td> <br/></tr> <br/></table> <br/></from> <br/><br/><% -- -- <br/>If incorrect authentication code or the user name password, login. JSP need to decide what is the error and the output message <br/>Here you can use JSP script & lt; %=% & gt; To output tip <br/>- % & gt; <br/><Div> <br/><% -- -- <br/>Judge whether the "login_error" attribute of the Request the domain is empty, don't print it is empty, the same as the following cc_error null will print "" won't show so redundant information <br/>JSP output script can't write the if - else, we can use the ternary operator? Judging: <br/>- % & gt; <br/><%=request. The getAttribute (" login_error ")==null? "" : the request. The getAttribute (" login_error") % & gt; <br/></div> <br/><br/><Div> <br/><%=request. The getAttribute (" cc_error ")==null? "" : the request. The getAttribute (" cc_error") % & gt; <br/></div> <br/><br/></body> <br/></html> <br/><br/><br/><br/><br/><br/><br/>Package cn. Itcast. Servlet. <br/><br/>The import javax.mail. Servlet. ServletException; <br/>The import javax.mail. Servlet. The annotation. WebServlet; <br/>The import javax.mail. Servlet. HTTP. HttpServlet; <br/>The import javax.mail. Servlet. HTTP. It; <br/>The import javax.mail. Servlet. HTTP. HttpServletResponse; <br/>The import javax.mail. Servlet. HTTP. HttpSession; <br/>import java.io.IOException; <br/><br/>@ WebServlet ("/loginServlet ") <br/>Public class LoginServlet extends the HttpServlet {<br/>Protected void doPost (it request, HttpServletResponse response) throws ServletException, IOException {<br/>//1. Set the request code <br/>Request. SetCharacterEncoding (" utf-8 "); <br/>The response. SetContentType (" text/HTML "); <br/>//2. Obtain parameter <br/>String username=request. The getParameter (" username "); <br/>String password=request. The getParameter (" password "); <br/>String checkCode=request. The getParameter (" checkCode "); <br/><br/>//2.1 get first generated captcha <br/>The HttpSession session=request. GetSession (); <br/>String checkCode_session=(String) session. The getAttribute (" checkCode_session "); <br/>Session. RemoveAttribute (" checkCode_session "); <br/><br/>//3. Determine whether captcha first right <br/>If (checkCode_session!=null& & CheckCode_session. EqualsIgnoreCase (checkCode)) {<br/>//ignore case is <br/>//verification code right <br/>//determine whether the user name and password consistent <br/>If (" 123 ". The equals (username) & amp; & "123". The equals (password)) {//call the UserDao query the database <br/>//login success <br/>//storing user information <br/>The session. The setAttribute (" user ", username); <br/>//a redirect to success. The JSP <br/>Response. SendRedirect (request. GetContextPath () + "/success. JSP"); <br/>} else {<br/>//login failed <br/>//store the message to request <br/>Request. SetAttribute (" login_error ", "user name or password error"); <br/>//forwarded to the login page <br/>request.getRequestDispatcher("/login.jsp").forward(request, response); <br/>} <br/>} else {<br/>//inconsistent authentication code <br/>//store the message to request <br/>Request. SetAttribute (" cc_error ", "verification code error"); <br/>//forwarded to the login page <br/>request.getRequestDispatcher("/login.jsp").forward(request, response); <br/>} <br/>} <br/><br/>Protected void doGet (it request, HttpServletResponse response) throws ServletException, IOException {<br/>Enclosing the doPost (request, response); <br/>} <br/>} <br/><p class="article - content rp"> CodePudding user response: </p>See if form form is to see the action or @ webServket path problem (" ")<p class="article - content rp"> CodePudding user response: </p>At the servlet output it and see if invoked the method of the servlet<p class="article - content rp"> CodePudding user response: </p><fieldset> <legend> refer to the second floor JayEOS response: <legend> <blockquote> at the servlet output, look to whether calling the servlet method </blockquote> <fieldset> is no output, but to build a project </div>
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