從JSP過渡到Tomcat7servlet的問題。不從JSP頁面呼叫post方法-有解無憂

我有一個 jsp 頁面 index.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<%@ taglib uri="http://java.sun.com/jsp/jstl/fmt" prefix="fmt" %>
<fmt:setLocale value="${locale}" scope="session"/>
<fmt:setBundle basename="local.pagecontent"/>
<html>
    <head>
        <title>Index Page</title>
    </head>
    <body>
        <c:redirect url="/controller?command=go_to_login_page"/>
    <h1>dd</h1>
    </body>
</html>

執行重定向到下一頁的命令

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<%@ taglib uri="http://java.sun.com/jsp/jstl/fmt" prefix="fmt" %>
<%--
<fmt:setLocale value="${locale}" scope="session" />
--%>
<fmt:setBundle basename="local.pagecontent"/>

<html>
<head>
    <title><fmt:message key="login.title"/></title>
</head>
<body>
<!DOCTYPE html>
<html>
<head>
    <title>Insert title here</title>
</head>
<body>
<div align="middle">
    <h1>Employee Login Form</h1>
    <form name="loginForm"  method="get" action="controller">
        <input type="hidden" name="command" value="login"/>
        <table>
            <tr>
                <td>Login</td>
                <td><label>
                    <input type="text" name="login" />
                </label></td>
            </tr>
            <tr>
                <td>Password</td>
                <td><label>
                    <input type="password" name="password" />
                </label></td>
            </tr>

        </table>
        <button type="submit">sign in</button>
        <a href="registration.jsp">No account?</a>
    </form>
</div>
</body>
</html>

在其中，我輸入我的用戶名和密碼，然后單擊提交按鈕。我在除錯中查看資料沒有進入 servlet，我被重定向到帶有地址的頁面

http://localhost:8094/course_war_exploded/pages/controller?command=login&login=mylogin&password=mypassword

我的 web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="https://jakarta.ee/xml/ns/jakartaee"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="https://jakarta.ee/xml/ns/jakartaee https://jakarta.ee/xml/ns/jakartaee/web-app_5_0.xsd"
         version="5.0">

    <welcome-file-list>
        <welcome-file>index.jsp</welcome-file>
    </welcome-file-list>

    <error-page>
        <exception-type>java.lang.Throwable</exception-type>
        <location>/errors/exception_error.jsp</location>
    </error-page>

    <!--<servlet>
        <servlet-name>ControllerServlet</servlet-name>
        <servlet-class>com.example.course.controller.ControllerServlet</servlet-class>
    </servlet>-->

    <!--<servlet-mapping>
        <servlet-name>ControllerServlet</servlet-name>
        <url-pattern>controller</url-pattern>
    </servlet-mapping>-->

    <error-page>
        <error-code>404</error-code>
        <location>/errors/error_404.jsp</location>
    </error-page>
</web-app>

還有 servlet 本身。你可以看到我試圖弄清楚發生了什么。

    @WebServlet(name = "ControllerServlet", value = "/controller")
public class ControllerServlet extends HttpServlet {
    private static final Logger logger = LogManager.getLogger();

    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws IOException {
        processRequest(request, response);
    }

    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws IOException {
        processRequest(request, response);
    }

    private void processRequest(HttpServletRequest request, HttpServletResponse response) throws IOException {
        String stringCommand = request.getParameter(RequestParameter.COMMAND);
        Command command = CommandProvider.defineCommand(stringCommand).orElseThrow(IllegalArgumentException::new);
/*
        Command = new CreateAccountCommand();
*/
        System.out.println(stringCommand   "--------");
        try {
            Router router = command.execute(request);
            System.out.println(router.getPage());
            System.out.println(router.getType().name());
            switch (router.getType()) {
                case FORWARD -> request.getRequestDispatcher(router.getPage()).forward(request, response);
                case REDIRECT -> response.sendRedirect(request.getContextPath()   router.getPage());
                default -> {
                    logger.log(Level.ERROR, "Router type {} is incorrect", router.getType());
                    response.sendRedirect(request.getContextPath()   PagePath.ERROR_404);
                }
            }
        } catch (IOException | ServletException | ServiceException | ControllerException e) {
            logger.log(Level.ERROR, "Error when executing command {} ", stringCommand);
            request.getSession().setAttribute(EXCEPTION, e);
            response.sendRedirect(request.getContextPath()   PagePath.EXCEPTION_ERROR_REDIRECT);
        }
    }
}

uj5u.com熱心網友回復：

您的問題繼續：我在除錯中查看了資料沒有進入 servlet，我被重定向到地址為 ...

這是由于“GET”和“POST”方法的不同。

在您的代碼中，表單操作方法是 GET，這會導致您報告的字串： http://localhost:8094/course_war_exploded/pages/controller?command=login&login=mylogin&password=mypassword

POST 方法略有不同，它不是將帶有表單資料的字串附加到 URL，而是將 POST 陣列發送到您的控制器，您可以讀取該陣列。

因此，在您的情況下，將表單方法更改為：

<form name="loginForm"  method="post" action="controller.jsp">

uj5u.com熱心網友回復：

我假設你想達到

http://localhost:8094/course_war_exploded/controller?command=login&login=mylogin&password=mypassword

代替

http://localhost:8094/course_war_exploded/pages/controller?command=login&login=mylogin&password=mypassword

為此，您應該action以<form>這種方式編輯標簽中的屬性：

<form name="loginForm"  method="get" action="${pageContext.request.contextPath}/controller">

${pageContext.request.contextPath} 是一個變數，在這種情況下計算為 /course_war_exploded

問題是您在action屬性中指定了相對路徑，因此瀏覽器假定您想要訪問./controller

轉載請註明出處，本文鏈接：https://www.uj5u.com/qukuanlian/406292.html

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