servlet_1

时间：2023-03-09 14:24:54
servlet_1 
HttpServlet超类在java构建路径中没有找到

https://jingyan.baidu.com/article/6c67b1d69a37a02787bb1ee2.html

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servlet处理http请求1

	客户端发送http请求的方式

	HttpServletRequest接口概述

	获取http请求参数的方法

	客户端发送http请求的方式

		地址栏直接输入URL

		超链接的href指定的URL

		表单标签form的action指定的URL

		javascript的location.href指定URL

	HttpServletRequest接口

		继承自ServletRequest接口，处理http请求

		封装了http请求的请求url，请求参数，请求报文等信息

		由容器实现，开发中直接从doMethod的参数中获取其实例

	获取http请求参数的方法

		从以do开头的方法中直接获取。

servlet处理http请求2

	获取表单控件中的参数

	处理console乱码，临时地加入下面一行

	request.setCharacterEncoding("utf-8");

	空字符串	用户名与密码未填写时

	null	单选框未选中时

	空指针	复选框一个都不选时
<%@ page language="java" contentType="text/html; charset=UTF-8"

    pageEncoding="UTF-8"%>

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">

<html>

<head>

<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">

<title>Insert title here</title>

</head>

<body>

    <a href="Servlet1?name=tom&name=jack&gender=male">请求1</a>

    <form action="Servlet2" method="post">

        <input type="text" name="username"/><br />

        <input type="password" name="userpwd"/><br />

        <input type="radio" name="gender" value="f"  />女

        <input type="radio" name="gender" value="m" />男<br />

        <input type="checkbox" name="favors" value="football" />足球

        <input type="checkbox" name="favors" value="music" />音乐

        <input type="checkbox" name="favors" value="swim" />游泳<br />

        <select name="cities">

            <option value="1">内蒙</option>

            <option value="2">河南</option>

            <option value="3">河北</option>

        </select><br />

        <textarea rows="3" cols="3" name="description"></textarea>

        <br /> <input type="submit" value="提交" />

    </form>

</body>

</html>
package com.fgy;

import java.io.IOException;

import javax.servlet.ServletException;

import javax.servlet.annotation.WebServlet;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

@WebServlet("/Servlet2")

public class Servlet2 extends HttpServlet {

    private static final long serialVersionUID = 1L;

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        System.out.println("============================");

        //临时地解决一下控制台中文乱码问题

        request.setCharacterEncoding("utf-8");

        String userName=request.getParameter("username");

        System.out.println(userName);

        System.out.println(request.getParameter("userpwd"));

        System.out.println(request.getParameter("gender"));

        String[] favors=request.getParameterValues("favors");

        if (favors != null) {

            for (String s : favors) {

                System.out.println(s);

            }

        }

        System.out.println(request.getParameter("cities"));

        System.out.println(request.getParameter("description"));

    }

    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        doGet(request, response);

    }

}
servlet处理文件上传-1

	文件上传方式概述

	客户端编程要点

	servlet内置的文件上传配置

	使用part处理文件上传

	part接口及获取其实例

		在multipart请求中，每一个表单控件，都会被转换成一个part

		使用HttpServletRequest获取Part:

			getPart：返回指定名称的part，一个文件

			getParts：返回请求中所有的part，多个文件

		part接口的方法

		part接口方法2

			write

			delete

			getInputStream
servlet处理文件上传-2

	文件上传的相关配置

	服务器端处理文件上传要点

	@MultipartConfig注解及属性

	maxRequestSize

	maxFileSize

	location

	fileSizeThreshold

	如果location没有指定的话，就在下面这个路径，

	全局属性的值javax.servlet.context.tmpdir

	apache-tomcat-8.5.15\work\Catalina\localhost\project3

	如果在web.xml中配置，就要用到multipart的子标签，就是上面几个属性
前端展示页面

<!DOCTYPE html>

<html>

<head>

<meta charset="UTF-8">

<title>Insert title here</title>

</head>

<body>

<form action="Upload2" method="post" enctype="multipart/form-data">

<input type="file" name="file1"><br>

<input type="file" name="file2"><br>

<input type="text" name="name"><br>

<input type="submit" value="上传">

</form>

</body>

</html>

==================================

后端处理逻辑

package com.fgy;

import java.io.IOException;

import java.util.Collection;

import javax.servlet.ServletException;

import javax.servlet.annotation.MultipartConfig;

import javax.servlet.annotation.WebServlet;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

import javax.servlet.http.Part;

/**

 * Servlet implementation class UploadServlet

 */

@WebServlet("/Upload2")

@MultipartConfig(maxRequestSize=1024*1024*10,maxFileSize=1024*1024*9,location="d:\\")

public class UploadServlet2 extends HttpServlet {

    private static final long serialVersionUID = 1L;

    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        System.out.println("=========================");

        System.out.println(request.getParameter("name"));

        Collection<Part> parts=request.getParts();

        for (Part part : parts) {

            if (part.getContentType() != null) {

                String fileName=part.getSubmittedFileName();

                if (!fileName.equals("")) {

                    part.write(fileName);

                }

            }

        }

    }

}