博主在學習《Head First Servlets & JSP》時，訪問Servlet出現404錯誤。但檔案中只有一個Servlet，所以問題就出在web.xml中。（因為重新學習，所以只用了編輯器，沒有使用IDE）

web.xml:

<?xml version="1.0" encoding="ISO-8851-1" ?>
<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_2_4.xsd"
	version="2.4">

	<servlet>
		<servlet-name>Chapter1 Servlet</servlet-name>
		<servlet-class>Ch1Servlet</servlet-class>
	</servlet>
	<servlet-mapping>
		<servlet-name>Chapter1 Servlet</servlet-name>
		<url-pattern>/Serv1</url-pattern>
	</servlet-mapping>
</web-app>
 

接著，在Eclipse中重新建立一個工程。生成的web.xml為：

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
	xmlns="http://xmlns.jcp.org/xml/ns/javaee" 
	xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee 
	http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd" 
	id="WebApp_ID" 
	version="3.1">
  <display-name>ch1</display-name>
  <welcome-file-list>
    <welcome-file>index.html</welcome-file>
    <welcome-file>index.htm</welcome-file>
    <welcome-file>index.jsp</welcome-file>
    <welcome-file>default.html</welcome-file>
    <welcome-file>default.htm</welcome-file>
    <welcome-file>default.jsp</welcome-file>
  </welcome-file-list>
  <servlet>
		<servlet-name>Chapter1 Servlet</servlet-name>
		<servlet-class>Ch1Servlet</servlet-class>
	</servlet>
	<servlet-mapping>
		<servlet-name>Chapter1 Servlet</servlet-name>
		<url-pattern>/Serv1</url-pattern>
	</servlet-mapping>
</web-app>
 

修改後的web.xml :

<?xml version="1.0" encoding="UTF-8" ?>
<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_2_4.xsd"
	version="2.4">

	<servlet>
		<servlet-name>Chapter1 Servlet</servlet-name>
		<servlet-class>Ch1Servlet</servlet-class>
	</servlet>
	<servlet-mapping>
		<servlet-name>Chapter1 Servlet</servlet-name>
		<url-pattern>/Serv1</url-pattern>
	</servlet-mapping>
</web-app>
 

接著去瀏覽器訪問試試

嗯，居然過了....然過了...過了...了

得出一個經驗：以後出現問題先看看編碼對不對