这个问题在这里已有答案：
servlet是
import javax.servlet.*;
import javax.servlet.http.*;
import java.io.*;
public class ServletWriteHtml extends HttpServlet
{
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws IOException
{
PrintWriter out = response.getWriter();
java.util.Date today = new java.util.Date();
out.println("html" +
"<body>" +
"<h1 align = center>Write Html<h1>"
+ "<br>" + today + "<body>" + "</html>");
}
}
web.xml是
<?xml version="1.0" encoding="UTF-8"?>
<web-app id="file-upload" version="2.4"
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">
<servlet>
<servlet-name>And</servlet-name>
<servlet-class>ServletWriteHtml</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>ServletWriteHtml</servlet-name>
<url-pattern>/Alfa</url-pattern>
</servlet-mapping>
<welcome-file-list>
<welcome-file>index.html</welcome-file>
</welcome-file-list>
</web-app>
url是http://localhost:8080/JavaWeb/Alfa编译的servlet，类在WEB-INF文件夹中
HTTP状态404 - 未找到类型状态报告消息未找到描述所请求的资源不可用。 GlassFish Server开源版4.1.1
你的servlet-name在servlet和servlet-mapping中都应该相同
你需要在servlet-class中给出完整的类（包括包）路径
例如：
<servlet>
<servlet-name>ServletWriteHtml</servlet-name>
<servlet-class>my.packages.ServletWriteHtml</servlet-class>
</servlet>