1、我们知道让Servlet成功在服务端运行，就必须实现Servlet接口,而下面的这种方式没有直接实现Servlet接口，而是间接实现了Servlet接口：
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
@WebServlet(name = "MyServlet")
public class MyServlet extends HttpServlet {
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
response.setCharacterEncoding("UTF-8");//设置服务器的编码，默认是ISO-8859-1
response.setContentType("text/html; charset = utf-8");//告诉浏览器服务器的编码格式
response.getWriter().write("你好");
}
}
关系如下：
public class MyServlet extends HttpServlet//继承
public abstract class HttpServlet extends GenericServlet//继承
public abstract class GenericServlet implements Servlet, ServletConfig, Serializable//实现
2、表单登录与Servlet的联系
（1）get提交与doGet方法：
表单选择get提交：
<body bgcolor="#f5f5dc">
<center>
<h3>登录</h3>
<form action="http://localhost:8080/MyServlet_war_exploded/abc" method="get">
用户名：<input type="text" name="myname" size="12"><br>
密 码：<input type="password" name="password" size="6" ><br><br>
<input type="reset" value="取消">
<input type="submit" value="登录">
</form>
</center>
</body>
Servlet方法：
public class MyServlet extends HttpServlet {
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
response.setCharacterEncoding("UTF-8");//设置服务器的编码，默认是ISO-8859-1
response.setContentType("text/html; charset = utf-8");//告诉浏览器服务器的编码格式
response.getWriter().write("我是doPose方法！");
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
response.setCharacterEncoding("UTF-8");//设置服务器的编码，默认是ISO-8859-1
response.setContentType("text/html; charset = utf-8");//告诉浏览器服务器的编码格式
response.getWriter().write("我是doGet方法！");
}
(2)post提交与doPost方法：
将提交方式改为post：
<form action="http://localhost:8080/MyServlet_war_exploded/abc" method="post">
用户名：<input type="text" name="myname" size="12"><br>
密 码：<input type="password" name="password" size="6" ><br><br>
<input type="reset" value="取消">
<input type="submit" value="登录">
</form>
提交后调用doPost方法：
可以看出，表单提交方式中的get与doGet方法对应，而post提交与doPost方法对应。
3、在直接实现Servlet接口时，没有doGet与doPost方法，此时不管是get提交还是post提交，均调用service方法。