Servlet

简介

Servlet是sun公司开发的动态web的一门技术。提供的其中一个接口叫Servlet。把实现了Servlet接口的Java程序叫Servlet。

HelloServlet

Servlet在Sun公司有两个默认实现类，HttpServlet，GenericServlet。

import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.PrintWriter;

public class HttpServlet extends javax.servlet.http.HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        PrintWriter writer = resp.getWriter();
        writer.print("Hello Servlet");
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        this.doGet(req, resp);
    }
}

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd"
         version="4.0">

  <display-name>Archetype Created Web Application</display-name>

  <servlet>
    <servlet-name>helloServlet</servlet-name>
    <servlet-class>com.dawn.HttpServlet</servlet-class>
  </servlet>

  <servlet-mapping>
    <servlet-name>helloServlet</servlet-name>
    <url-pattern>/helloServlet</url-pattern>
  </servlet-mapping>
</web-app>

通过http://localhost:8080/s01/helloServlet访问刚刚配置的servlet。

Servlet原理