从.java文件访问$ {parameters}到.jsp文件

如何从servlet访问参数到.jsp文件？我正在创建一个简单的Web应用程序和所有教程，以及我关注的构建应用程序的一个，鼓励我在.jsp文件中仅使用$ {parameter}，但它不起作用(在输出中它打印$ {name} $ {password}而不是值(。

我一直在浏览答案，我唯一得到的是通过$ {}访问此参数为了使用，我该如何使$ {}工作？(我希望将其打印在inter.jsp文件中，然后将参数放入index.jsp文件中(

我的代码如下：

loginservlet.java

    public class LoginServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;
    public LoginServlet() {
        super();
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        response.getWriter().append("Served at: ").append(request.getContextPath());
    }

    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doGet(request, response);
        String name = request.getParameter("name");
        String password = request.getParameter("password");
        String url = "/welcome.jsp";
        HttpSession session = request.getSession();
        session.setAttribute("name", name);
        getServletContext().getRequestDispatcher(url).forward(request, response);
    }
}

web.xml

    <!DOCTYPE web-app PUBLIC
 "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN"
 "http://java.sun.com/dtd/web-app_2_3.dtd" >
<web-app>
  <display-name>Archetype Created Web Application</display-name>
  <servlet>
    <servlet-name>LoginServlet</servlet-name>
    <display-name>LoginServlet</display-name>
    <description></description>
    <servlet-class>com.zurciu.servlet.LoginServlet</servlet-class>
  </servlet>
  <servlet-mapping>
    <servlet-name>LoginServlet</servlet-name>
    <url-pattern>/logmein</url-pattern>
  </servlet-mapping>
</web-app>

index.jsp

    <html>
<body>

<form action="logmein" method="post">
<pre>
Login :  <input type="text" name="name">  Password :  <input type="password" name="password">  <input type="submit" value="submit">
</pre>
</form>

</body>
</html>

欢迎。JSP

    <%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Welcome</title>
</head>
<body>
Welcome user!
${name}
${password}

</body>
</html>

pom.xml

    <project xmlns="http://maven.apache.org/POM/4.0.0"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <groupId>com.zurciu.maven</groupId>
    <artifactId>JSP_ACCESS_PARAMETER</artifactId>
    <packaging>war</packaging>
    <version>0.0.1-SNAPSHOT</version>
    <name>JSP_ACCESS_PARAMETER Maven Webapp</name>
    <url>http://maven.apache.org</url>
    <dependencies>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>3.8.1</version>
            <scope>test</scope>
        </dependency>
        <!-- https://mvnrepository.com/artifact/javax.servlet/javax.servlet-api -->
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>javax.servlet-api</artifactId>
            <version>3.1.0</version>
            <scope>provided</scope>
        </dependency>
        <!-- https://mvnrepository.com/artifact/javax.servlet/jsp-api -->
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>jsp-api</artifactId>
            <version>2.0</version>
            <scope>provided</scope>
        </dependency>
    </dependencies>
    <build>
        <finalName>JSP_ACCESS_PARAMETER</finalName>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>3.2</version>
                <configuration>
                    <verbose>true</verbose>
                    <source>1.8</source>
                    <target>1.8</target>
                    <showWarnings>true</showWarnings>
                </configuration>
            </plugin>
            <plugin>
                <groupId>org.apache.tomcat.maven</groupId>
                <artifactId>tomcat7-maven-plugin</artifactId>
                <version>2.2</version>
                <configuration>
                    <path>/</path>
                    <contextReloadable>true</contextReloadable>
                </configuration>
            </plugin>
        </plugins>
    </build>
</project>

我缺少什么？

您可以使用选项尝试使用JSTL而不是使用Direct EL。另外，未设置JSP页面范围，默认情况下，EL取决于请求范围，但是您可以通过基于$ {session.name}打印会话的值来单位测试代码的其余部分，请使用$ {request.name继续前进}，如果这也有效，则意味着您的EL不会将请求范围作为默认值。希望这可以帮助！

好吧，我想我有答案。我相信解决此问题的解决方案是将Servlet Web.xml声明为3.0

我将Web.xml修改为此，现在可以使用：(

<web-app
xmlns="http://java.sun.com/xml/ns/j2ee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-app_3_0.xsd"
version="3.0">

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