[英]Java post form in JSP, get parameter in servlet returns NULL
我在提交簡單的Java表單時遇到問題。
我有我的login.jsp
<%@page contentType="text/html" pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>The best login page in the world</title>
</head>
<body>
<h1>Connexion</h1>
<form id="asdasd" name="coucou" method="post" action="doLogin">
<input type="text" name="user_email" />
<input type="password" name="user_password" />
<input type="submit" name="asd" value="Se connecter" />
</form>
</body>
</html>
我的web.xml指定了doLogin實際上是servlet loginServlet
<?xml version="1.0" encoding="UTF-8"?>
<web-app version="3.1" xmlns="http://xmlns.jcp.org/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd">
<context-param>
<param-name>javax.faces.PROJECT_STAGE</param-name>
<param-value>Development</param-value>
</context-param>
<servlet>
<servlet-name>Faces Servlet</servlet-name>
<servlet-class>javax.faces.webapp.FacesServlet</servlet-class>
<load-on-startup>1</load-on-startup>
</servlet>
<servlet>
<servlet-name>loginServlet</servlet-name>
<servlet-class>com.courses.web.servlet.loginServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>Faces Servlet</servlet-name>
<url-pattern>/faces/*</url-pattern>
</servlet-mapping>
<servlet-mapping>
<servlet-name>loginServlet</servlet-name>
<url-pattern>/loginServlet</url-pattern>
</servlet-mapping>
<servlet-mapping>
<servlet-name>loginServlet</servlet-name>
<url-pattern>/doLogin</url-pattern>
</servlet-mapping>
<session-config>
<session-timeout>
30
</session-timeout>
</session-config>
<welcome-file-list>
<welcome-file>faces/index.jsp</welcome-file>
</welcome-file-list>
</web-app>
還有我的loginServlet.java
public class loginServlet extends HttpServlet {
protected void processRequest(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setContentType("text/html;charset=UTF-8");
try (PrintWriter out = response.getWriter()) {
}
}
@Override
protected void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
processRequest(request, response);
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse response) {
String username = req.getParameter("user_email");
String password = req.getParameter("user_password");
Console console = System.console();
console.printf("mail : %s\npassword: %s\n", username,password);
}
@Override
public String getServletInfo() {
return "Short description";
}
}
沒什么真正復雜的,但是我從getParameter獲得的變量始終為NULL,我不知道為什么。
我究竟做錯了什么 ?
由於您尚未發布堆棧跟蹤,因此唯一可以返回null
值的行是以下行:
Console console = System.console();
您的評論中指出: 我正在Netbeans中運行glassfish 。 因此,此行將拋出NullPointerException
:
console.printf("mail : %s\npassword: %s\n", username,password); //console is null
嘗試使用記錄器來打印您的消息。 僅出於骯臟的快速解決方案,請改用System.out.println
直到您偶然配置和使用記錄器為止。 因此,簡而言之,替換這些行:
Console console = System.console();
console.printf("mail : %s\npassword: %s\n", username,password);
至:
System.out.printf("mail : %s\npassword: %s\n", username,password));
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