第一种方法：通过实现servlet接口的方式来开发。
1、配置WEB-INF文件夹，内再建立classes和lib两个文件夹
2、开发servlet（引入servlet-api.jar）
1 //Hello.java
2
3 package com.keer2345;
4
5 import javax.servlet.*;
6 import java.io.*;
7 import javax.servlet.ServletConfig;
8 import javax.servlet.ServletException;
9 import javax.servlet.ServletRequest;
10 import javax.servlet.ServletResponse;
11 import java.io.IOException;
12
13 public class Hello implements Servlet{
14
15 public void init(ServletConfig parm1) throws ServletException {
16 // TODO: Add your code here
17 }
18
19 public ServletConfig getServletConfig() {
20 // TODO: Add your code here
21 return null;
22 }
23
24 public void service(ServletRequest request, ServletResponse response) throws ServletException, IOException {
25 // TODO: Add your code here
26 PrintWriter pw = response.getWriter();
27 pw.println("Hello World!");
28 }
29
30 public String getServletInfo() {
31 // TODO: Add your code here
32 return null;
33 }
34
35 public void destroy() {
36 // TODO: Add your code here
37 }
38
39 }
3、部署servlet（web.xml）
1 <?xml version="1.0" encoding="ISO-8859-1"?>
2
3 <web-app xmlns="http://java.sun.com/xml/ns/javaee"
4 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
5 xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
6 version="2.5">
7
8 <servlet>
9 <servlet-name>hello</servlet-name>
10 <servlet-class>com.keer2345.Hello</servlet-class>
11 </servlet>
12
13 <servlet-mapping>
14 <servlet-name>hello</servlet-name>
15 <url-pattern>/hello</url-pattern>
16 </servlet-mapping>
17
18 </web-app>
4、启动tomcat，访问http://127.0.0.1:8080/keer2345/hello。
第二种方法：通过继承GenericServle开发servlet
HelloGen.java
1 package com.keer2345;
2
3 import javax.servlet.*;
4 import javax.servlet.GenericServlet;
5 import java.io.*;
6
7 public class HelloGen extends GenericServlet {
8
9 public HelloGen() {
10 }
11
12 public void service(ServletRequest request, ServletResponse response) {
13 try {
14 PrintWriter pw = response.getWriter();
15 pw.println("Hello GenericServlet!");
16 }
17 catch(Exception ex) {
18 ex.printStackTrace();
19 }
20 }
21
22 }
第三种方法：通过继承HttpServlet开发Servlet
HelloHttp.java
1 package com.keer2345;
2
3 import javax.servlet.http.*;
4 import java.io.*;
5
6 public class HelloHttp extends HttpServlet {
7
8 public void doGet(HttpServletRequest request, HttpServletResponse response) {
9
10 try {
11 PrintWriter pw = response.getWriter();
12 pw.println("Hello HttpServlet!");
13 }
14 catch(Exception ex) {
15 ex.printStackTrace();
16 }
17
18 }
19
20 public void doPost(HttpServletRequest request, HttpServletResponse response) {
21
22 this.doGet(request, response);
23
24 }
25 }
web.xml
1 <?xml version="1.0" encoding="ISO-8859-1"?>
2
3 <web-app xmlns="http://java.sun.com/xml/ns/javaee"
4 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
5 xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
6 version="2.5">
7
8 <servlet>
9 <servlet-name>hello</servlet-name>
10 <servlet-class>com.keer2345.Hello</servlet-class>
11 </servlet>
12
13 <servlet-mapping>
14 <servlet-name>hello</servlet-name>
15 <url-pattern>/hello</url-pattern>
16 </servlet-mapping>
17
18 <servlet>
19 <servlet-name>helloGen</servlet-name>
20 <servlet-class>com.keer2345.HelloGen</servlet-class>
21 </servlet>
22
23 <servlet-mapping>
24 <servlet-name>helloGen</servlet-name>
25 <url-pattern>/helloGen</url-pattern>
26 </servlet-mapping>
27
28 <servlet>
29 <servlet-name>helloHttp</servlet-name>
30 <servlet-class>com.keer2345.HelloHttp</servlet-class>
31 </servlet>
32
33 <servlet-mapping>
34 <servlet-name>helloHttp</servlet-name>
35 <url-pattern>/helloHttp</url-pattern>
36 </servlet-mapping>
37
38
39 </web-app>