在jsp / java ee Web应用程序中加载images / css / javascript

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问题描述

今天我刚刚上了Java ee和动态网络项目的第一堂课......我有一个问题。

Today I just had my first class on Java ee and dynamic web project... and I have a question for you.

我的老师要求我们创建一个控制器在一个非常基本的mvc概念。

My teacher asked us to create a controller in an very basic mvc concept.

她给了我们一些代码示例，并要求我们从控制器调用一个视图。好的，它的确有效！
但是，如果我尝试添加图像< img src =images / img.jpg/> ，我认为我的控制器重新路由文件夹images / img.jpg以及我的图片/ img.jpg是文件标题中的类型文本...

She gave us some code example and asked us to call a view from the controller. Ok, it works!But then, if I try to add an image <img src="images/img.jpg" />, I think my controller re-route the folder images/img.jpg and well, my images/img.jpg is a type text in the file headers...

任何帮助将不胜感激...

Any help would be appreciated...

这是我的servlet
Controller.java

Here is my servletController.java

package ca.qc.lacmegantic.ville;

import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 * Servlet implementation class Controller
 */
@WebServlet("/Controller")
public class Controller extends HttpServlet
{
private static final long serialVersionUID = 1L;

/**
 * Processes requests for both HTTP <code>GET</code> and <code>POST</code>
 * methods.
 *
 * @param request servlet request
 * @param response servlet response
 * @throws ServletException if a servlet-specific error occurs
 * @throws IOException if an I/O error occurs
 */
protected void processRequest(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException
{
    String urlCP = request.getRequestURI();

    String url = urlCP.substring(request.getContextPath().length());

    if (url.equals("/") || url.equals(""))
    {
        request.getRequestDispatcher("WEB-INF/views/view.jsp").forward(request, response);
    }

}

/**
 * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse
 *      response)
 */
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException
{
    processRequest(request, response);
}

/**
 * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse
 *      response)
 */
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException
{
    processRequest(request, response);
}

}

这是我的网页.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns="http://java.sun.com/xml/ns/javaee" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
    xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
    version="2.5">
    <servlet>
        <servlet-name>Controller</servlet-name>
        <servlet-class>ca.qc.lacmegantic.ville.Controller</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>Controller</servlet-name>
        <url-pattern>/</url-pattern>
    </servlet-mapping>
    <session-config>
        <session-timeout>30</session-timeout>
    </session-config>
</web-app>

这是我的 view.jsp

<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
    pageEncoding="ISO-8859-1"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>Hello World!</title>
</head>
<body>
<h1>Hello World!</h1>
<img src="images/img.jpg" />
</body>
</html>

文件结构：

推荐答案

你不应该是将前端控制器servlet映射到 / 的URL模式。这将覆盖servletcontainer的默认servlet，它负责提供静态资源，如图像。这不是你想要的。

You should not be mapping a front controller servlet on an URL pattern of /. This would override servletcontainer's "default" servlet which is responsible for serving static resources such as images. This is not what you want.

将控制器映射到更具体的URL模式，例如 / pages / * 或者其他的东西。或者 / Controller ，就像你在 @WebServlet 注释中那样，实际上根本没有注册因为 web.xml 未声明为符合Servlet 3.0。

Map the controller on a more specific URL pattern such as /pages/* or something. Or maybe /Controller, exactly as you've there in the @WebServlet annotation which is actually not been registered at all because your web.xml is not declared conform Servlet 3.0.

<servlet-mapping>
    <servlet-name>Controller</servlet-name>
    <url-pattern>/Controller</url-pattern>
</servlet-mapping>

您的另一个问题是您已将图像放入 / WEB- INF 文件夹。此文件夹中的内容无法公开访问。它仅用于JSP文件，它们应该由前端控制器servlet或其他JSP转发或包含。将 / images 文件夹向上移动一级，位于 / WEB-INF 文件夹之外。

Your another problem is that you've placed the image in /WEB-INF folder. The content in this folder is not publicly accessible. It's intented for JSP files only which are supposed to be forwarded or included by a front controller servlet or another JSP. Move the /images folder one level up, outside the /WEB-INF folder.

- 包含一些hello world示例

Our servlets wiki page - contains some hello world examples as well
Difference between / and /* in servlet mapping url pattern
Browser can't access/find relative resources like CSS, images and links when calling a Servlet which forwards to a JSP
Moving resources under WEB-INF

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