文章目录
1.Servlet整体框架
2.Servlet快速入门
1.创建项目配置基本环境
上个文件有详细介绍
2.添加jar包
1.在WEB-INF下创建目录lib，添加文件
2.添加到项目中
3.配置代码提示
3.src下创建文件
4.实现Servlet接口
package HelloServlet;
import javax.servlet.*;
import java.io.IOException;
/**
* @author 孙显圣
* @version 1.0
*/
public class HelloServlet implements Servlet {
/**
* 当创建HelloServlet会调用，且只会调用一次
* @param servletConfig
* @throws ServletException
*/
@Override
public void init(ServletConfig servletConfig) throws ServletException {
System.out.println("init()");
}
/**
* 返回ServletConfig,也就是servlet的配置
* @return
*/
@Override
public ServletConfig getServletConfig() {
return null;
}
/**
* 1.该方法处理浏览器的请求
* 2.当浏览器每次请求一次servlet时，就会调用一次
* 3.当tomcat调用该方法时，会把http请求的数据封装成实现ServletRequest接口的request对象
* 4.通过servletRequest对象，可以得到用户提交的数据
* 5.ServletResponsed对象可以用于返回数据给tomcat服务器
* @param servletRequest
* @param servletResponse
* @throws ServletException
* @throws IOException
*/
@Override
public void service(ServletRequest servletRequest, ServletResponse servletResponse) throws ServletException, IOException {
System.out.println("hi, helloServlet");
}
/**
* 返回servlet的信息，使用较少
* @return
*/
@Override
public String getServletInfo() {
return null;
}
/**
* 1.该方法是servlet销毁时调用的
* 2.只会调用一次
*/
@Override
public void destroy() {
}
}
5.在web.xml配置HelloServlet
6.通过浏览器访问HelloServlet
3.浏览器访问Servlet的流程分析
一共有三个容器
url-name
name-全类名
name-实例
Servlet的生命周期
初始化阶段
处理浏览器请求阶段
终止阶段
4.GET和POST的分发处理
代码示例
@Override
public void service(ServletRequest servletRequest, ServletResponse servletResponse) throws ServletException, IOException {
//GET和POST的分发处理
//1.首先需要知道，ServletRequest的运行类型其实是它的子类HttpServletRequest的实现类，而getMethod方法是这个子接口的，所以需要将这个父接口转换为子接口的类型
HttpServletRequest httpServletRequest = (HttpServletRequest) servletRequest; //现在就是他的子接口，指向它的实现类，封装了请求的方法
String method = httpServletRequest.getMethod();
if (method.equals("GET")) {
doGet();
}
else if (method.equals("POST")) {
doPost();
}
}
//编写doGet和doPost方法，用于分发处理
public void doGet() {
System.out.println("doGet被调用");
}
public void doPost() {
System.out.println("doPost被调用");
}
<%--
Created by IntelliJ IDEA.
User: 8615941515990
Date: 2024/1/24
Time: 16:38
To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>$Title$</title>
</head>
<body>
<form action="http://localhost:8080/servlet/helloServlet" method="post">
username: <input type="text" name="username">
</form>
</body>
</html>
5.继承HttpServlet来开发Servlet
1.创建文件
2.配置web.xml
3.实现doGet和doPost方法并编写
package HelloServlet;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
/**
* @author 孙显圣
* @version 1.0
*/
public class HiServlet extends HttpServlet {
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
System.out.println("hi HiServlet");
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
super.doPost(req, resp);
}
}
4.浏览器访问
5.过程解析
1.http://localhost:8080/servlet/hiServlet发送请求到Tomcat服务
2.Tomcat服务根据资源路径/hiServlet，找到HelloServlet.HiServlet
3.创建HiServlet的实例，并调用它的init()方法和service()方法
4.init()方法就是个空的，重点看service()方法，是它的父类HttpServlet的
6.debug方法
1.打断点
2.debug
3.输入网址
4.此时由于是get方式，所以程序会停在断点处
5.查看运行类型的确是HiServlet
6.Servlet注意事项
最简化的浏览器访问Servlet过程
- 浏览器向Tomcat服务发送请求
- Tomcat服务根据浏览器地址最后的路由/xxx去web.xml中找到对应的类并创建一个对象
- 调用init（）方法和service（）方法
- 第二次则直接调用service（）方法
7.Servlet注解方式
1.快速入门
1.代码实例
package annotation;
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;
/**
* @author 孙显圣
* @version 1.0
*/
//使用注解配置路由，一个servlet可以有多个路由，访问网址为http://localhost:8080/servlet/ok1 或者http://localhost:8080/servlet/ok2
@WebServlet(urlPatterns = {"/ok1", "/ok2"})
public class OkServlet extends HttpServlet {
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
System.out.println("注解的doGet");
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
System.out.println("注解的doPost");
}
}
2.结果
2.Servlet注解方式解密
1.与xml方式的区别
简要介绍
- 浏览器向Tomcat服务发送请求
- 服务扫描所有类的全路径并且通过反射获取注解对象，从而得到urlPatterns（路由）
- 将其与浏览器地址最后的/xxx比对，如果比对成功则调用init（）方法和service（）方法
- 第二次就直接调用service（）方法
2.Servlet注解的参数说明
3.注解URL的4种匹配方式
1.精确匹配
2.目录匹配
3.扩展名匹配
4.任意匹配
4.URL配置注意事项
8.课后练习
1.练习一
login.html
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
</head>
<body>
<form action="http://localhost:8080/servlet/cat" method="post">
username:<input name="username" type="text">
</form>
</body>
</html>
CatServlet.java
package HomeWork;
import javax.servlet.*;
import javax.servlet.http.HttpServletRequest;
import java.io.IOException;
/**
* @author 孙显圣
* @version 1.0
*/
public class CatServlet implements Servlet {
private int num = 0; //统计次数
@Override
public void init(ServletConfig servletConfig) throws ServletException {
}
@Override
public ServletConfig getServletConfig() {
return null;
}
@Override
public void service(ServletRequest servletRequest, ServletResponse servletResponse) throws ServletException, IOException {
System.out.println("访问次数：" + (++num));
//向下转型获取请求方式
HttpServletRequest httpServletRequest = (HttpServletRequest) servletRequest;
String method = httpServletRequest.getMethod();
if (method.equals("GET")) {
System.out.println("GET");
}
else if (method.equals("POST")) {
System.out.println("POST");
}
}
@Override
public String getServletInfo() {
return null;
}
@Override
public void destroy() {
}
}
web.xml
结果
2.练习二
login.html
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
</head>
<body>
<form action="http://localhost:8080/servlet/dog" method="post">
username:<input name="username" type="text">
</form>
</body>
</html>
DogServlet.java
package HomeWork;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
/**
* @author 孙显圣
* @version 1.0
*/
public class DogServlet extends HttpServlet {
//统计次数
private int get = 0;
private int post = 0;
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
System.out.println("GET:" + (++get));
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
System.out.println("POST:" + (++post));
}
}
web.xml
结果
3.练习三
PigServlet.java
package HomeWork;
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;
import java.net.InetAddress;
/**
* @author 孙显圣
* @version 1.0
*/
@WebServlet(urlPatterns = {"/pig1", "/pig2"})
public class PigServlet extends HttpServlet {
//统计次数
private int get = 0;
private int post = 0;
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
System.out.println("发出请求的浏览器的ip:" + req.getRemoteAddr());
System.out.println("GET:" + (++get));
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
System.out.println("发出请求的浏览器的ip:" + req.getRemoteAddr());
System.out.println("POST:" + (++post));
}
}
结果
![[StartingPoint][Tier1]Pennyworth](https://img-blog.csdnimg.cn/img_convert/9f2df5b5cc506b96ac695ef7b455968d.jpeg)
