Servlet&HTTP&Request8_Servlet1

1、Servlet的体系结构

　Servlet -- 接口

　Servlet接口的实现类：GenericServlet -- 抽象类，HttpServlet -- 抽象类（继承GenericServlet ）

GenericServlet：将Servlet接口中其他的方法做了默认空实现，只将service()方法作为抽象
- 将来定义Servlet类时，可以继承GenericServlet，实现service()方法即可。
HttpServlet：对http协议的一种封装，简化操作。推荐使用HttpServlet实现。步骤如下：
- 定义类继承HttpServlet
- 复写doGet/doPost方法

示例1：之前学习的方法

package cn.itcast.web.servlet;

import javax.servlet.*;
import javax.servlet.annotation.WebServlet;
import java.io.IOException;

@WebServlet("/demo1")
public class ServletDemo1 implements Servlet {
    @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("demo1...");
    }

    @Override
    public String getServletInfo() {
        return null;
    }

    @Override
    public void destroy() {

    }
}

　示例2：

package cn.itcast.web.servlet;

import javax.servlet.GenericServlet;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.annotation.WebServlet;
import java.io.IOException;

@WebServlet("/demo2")
public class ServletDemo2 extends GenericServlet {
    @Override
    public void service(ServletRequest servletRequest, ServletResponse servletResponse) throws ServletException, IOException {
        System.out.println("demo2...");
    }
}

　　把tomcat端口号改为80，浏览器访问http://localhost/demo2，则输出demo2...

　示例3：

package cn.itcast.web.servlet;

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("/demo3")
public class ServletDemo3 extends HttpServlet {

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
//        super.doGet(req, resp);
        System.out.println("doGet...");
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
//        super.doPost(req, resp);
        System.out.println("doPost...");
    }
}

　　浏览器访问http://localhost/demo3，则输出：doGet...。因为默认使用get方法提交。

　web目录下新建一个login.html文件：

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
    <form action="/demo3" method="post">
        <input name="username">
        <input type="submit" value="提交">
    </form>
</body>
</html>

　　浏览器访问http://localhost/login.html，在输入框中输入aaa，点击“提交”按钮，则idea控制台输出：doPost...。

2、Servlet相关配置

　1. urlpattern：Servlet访问路径

　　a. 一个Sevlet可以定义多个访问路径：@WebServlet({"/demo4","/dd","/ddd"})

　　b. 路径定义规则：

　　　　i. /xxx：路径匹配

　　　　ii. /xxx/xxx：多层路径，目录结构

　　　　iii. *.do：扩展名匹配，do可以替换为任意字母

　示例1：

package cn.itcast.web.servlet;

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({"/demo4","/dd","/ddd"})
public class ServletDemo4 extends HttpServlet {

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
//        super.doGet(req, resp);
        System.out.println("demo4...");
    }
}

　　浏览器访问http://localhost/demo4、http://localhost/dd、http://localhost/ddd，idea控制台都会输出：demo4...。

　示例2：

package cn.itcast.web.servlet;

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("/user/demo4")
public class ServletDemo4 extends HttpServlet {

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        System.out.println("demo4...");
    }
}

　　浏览器访问http://localhost/user/demo4，idea控制台输出demo4...。访问http://localhost/demo4则会报错。

　示例3：

package cn.itcast.web.servlet;

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("/user/*")
public class ServletDemo4 extends HttpServlet {

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
//        super.doGet(req, resp);
        System.out.println("demo4...");
    }
}

　　浏览器访问http://localhost/user/aaa，则会输出demo4，*表示不管访问/user/的任意路径都能输出demo4...

package cn.itcast.web.servlet;

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("/*")
public class ServletDemo4 extends HttpServlet {

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        System.out.println("demo4...");
    }
}

　　浏览器访问http://localhost/dddd，则输出demo4，但是访问http://localhost/demo3，则会输出doGet...。

　示例4：

package cn.itcast.web.servlet;

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("*.do")
public class ServletDemo4 extends HttpServlet {

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
//        super.doGet(req, resp);
        System.out.println("demo4...");
    }
}

　　浏览器访问http://localhost/aaa.do，则idea控制台会输出demo4...。访问http://localhost/aaa会报错。

posted on 2022-02-09 00:24 花溪月影阅读(28) 评论(0) 收藏举报