文件的上传和下载
文件上传的介绍
<?xml version="1.0" encoding="UTF-8"?><web-app xmlns="/xml/ns/javaee"xmlns:xsi="/2001/XMLSchema-instance"xsi:schemaLocation="/xml/ns/javaee /xml/ns/javaee/web-app_4_0.xsd"version="4.0"><servlet><servlet-name>UploadServlet</servlet-name><servlet-class>com.atguigu.servlet.UploadServlet</servlet-class></servlet><servlet-mapping><servlet-name>UploadServlet</servlet-name><url-pattern>/uploadServlet</url-pattern></servlet-mapping></web-app>
package com.atguigu.servlet;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import java.io.IOException;public class UploadServlet extends HttpServlet {/*** 用来处理文件生成* @param req* @param resp* @throws ServletException* @throws IOException*/@Overrideprotected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {System.out.println("文件上传过来了");}}
<%@ page contentType="text/html;charset=UTF-8" language="java" %><html><head><title>Title</title></head><body><%-- form:post --%><form action="http://localhost:8080/jstl/uploadServlet" method="post" enctype="multipart/form-data">用户名 ：<input type="text" name="username"> <br>头像 ：<input type="file" name="photo"> <br><input type="submit" value="上传"></form></body></html>
上传的http协议介绍
以流的形式上传和接收所以如果用getPraramter没有用
package com.atguigu.servlet;import javax.servlet.ServletException;import javax.servlet.ServletInputStream;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import java.io.IOException;public class UploadServlet extends HttpServlet {/*** 用来处理文件生成* @param req* @param resp* @throws ServletException* @throws IOException*/@Overrideprotected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {ServletInputStream inputStream = req.getInputStream();byte[] buffer = new byte[1024000];int read = inputStream.read(buffer);System.out.println(new String(buffer, 0, read));}}
上传合用到的类和方法介绍
使用fileupload解析上传的数据
选中整行以后 command + option + t 快捷键
然后选择 try catch，然后手动改成Exception
package com.atguigu.servlet;import mons.fileupload.FileItem;import mons.fileupload.FileItemFactory;import mons.fileupload.FileUploadException;import mons.fileupload.disk.DiskFileItemFactory;import mons.fileupload.servlet.ServletFileUpload;import javax.servlet.ServletException;import javax.servlet.ServletInputStream;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import java.io.File;import java.io.IOException;import java.util.List;public class UploadServlet extends HttpServlet {@Overrideprotected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {// 1、先判断上传的数据是否为多段数据（只有是多段数据，才是文件上传的）if (ServletFileUpload.isMultipartContent((req))) {// 创建FileItemFactory工厂实现类FileItemFactory fileItemFactory = new DiskFileItemFactory();// 创建用于解析上传数据的工具类 ServletFileUpload类ServletFileUpload servletFileUpload = new ServletFileUpload(fileItemFactory);// 解析上传的数据，得到每一个表单项FileItemtry {List<FileItem> list = servletFileUpload.parseRequest(req);// 循环判断，每一个表单项，是普通类型，还是上传的文件for (FileItem fileItem : list) {if (fileItem.isFormField()) {// 普通表单项System.out.println("表单项的name属性值：" + fileItem.getFieldName());// 参数UTF-8，解决乱码问题System.out.println("表单的value属性值：" + fileItem.getString("UTF-8"));} else {// 上传的文件System.out.println("表单项的name属性值：" + fileItem.getFieldName());System.out.println("上传的文件名：" + fileItem.getName());// fileItem.write((new File(("e:\\" + fileItem.getName()))));}}} catch (Exception e) {e.printStackTrace();}}}}
文件下载的实现
package com.atguigu.servlet;import mons.io.IOUtils;import javax.servlet.ServletContext;import javax.servlet.ServletException;import javax.servlet.ServletOutputStream;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import java.io.IOException;import java.io.InputStream;public class Download extends HttpServlet {@Overrideprotected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {// 1、获取要下载的文件名String downloadFileName = "1.png";// 2、读取要下载的文件内容（通过ServletContext对象可以读取）ServletContext servletContext = getServletContext();// 获取要下载的文件类型String mimeType = servletContext.getMimeType("/file/" + downloadFileName);System.out.println("下载的文件类型：" + mimeType);// 4、在回传前，通过响应头告诉客户端返回的数据类型resp.setContentType(mimeType);// 5、还要告诉客户端收到的数据是用于下载使用（还是使用响应头）// Content-Disposition响应头，表示收到的数据怎么处理// attacjment表示附件，表示下载使用// filename= 表示指定下载的文件名resp.setHeader("Content-Disposition", "attachment;filename=" + downloadFileName);/*** /斜杠被服务器解析表示地址为http://ip:port/工程名/ 映射 到代码的web目录*/InputStream resourceAsStream = servletContext.getResourceAsStream("/file/" + downloadFileName);// 获取响应的输出流ServletOutputStream outputStream = resp.getOutputStream();// 3、把下载的文件内容回传给客户端// 读取输入流中全部的数据，复制给输出流，输出给客户端IOUtils.copy(resourceAsStream, outputStream);}}
输入后敲回车，直接就下载文件了
使用URLEncoder解决谷歌和IE浏览器中文下载名乱码问题
可以和原文件名不同，下载下来显示的名称就是filename
如果filename=中国.jpg，文件名会无法识别
因此，要对中文进行URL编码
Base64编解码操作
如果是火狐浏览器不支持上面这种方式
发现这个类和URLEncode类不同，不是静态方法，因此要先new
Base64编解码操作 解决 火狐浏览器的附近中文名问题
将原先那个setHeader换成resp.setHeader("Content-Disposition", "attachment; filename==?UTF-8?B?" + new BASE64Encoder().encode("中国.jpg".getBytes("UTF-8")) + "?=");
使用User-Agent请求头判断，动态切换不同的方案解决所有浏览器附件中文乱码问题
书城项目
command + shift + R可以查找替换（可以先选中目录）动态的base标签值
表单提交失败的错误回显
合并LoginServlet和RegistServlet程序为UserServlet程序
使用反射优化大量else if代码
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {String action = req.getParameter("action"); try {// 获取 action 业务鉴别字符串，获取相应的业务 方法反射对象 Method method = this.getClass().getDeclaredMethod(action, HttpServletRequest.class, HttpServletResponse.class); // System.out.println(method); // 调用目标业务 方法 method.invoke(this, req, resp); } catch (Exception e) {e.printStackTrace(); } }
抽取 BaseServlet 程序
public abstract class BaseServlet extends HttpServlet {protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {String action = req.getParameter("action"); try {// 获取 action 业务鉴别字符串，获取相应的业务 方法反射对象 Method method = this.getClass().getDeclaredMethod(action, HttpServletRequest.class, HttpServletResponse.class); // System.out.println(method); // 调用目标业务 方法 method.invoke(this, req, resp); } catch (Exception e) {e.printStackTrace(); } } }
数据的封装和抽取 BeanUtils 的使用
command + option + t选择代码的环绕方式MVC概念
Cookie
什么是Cookie
Cookie的创建
<!-- Cookie.html --><!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "/TR/html4/loose.dtd"><html><head><meta http-equiv="pragma" content="no-cache" /><meta http-equiv="cache-control" content="no-cache" /><meta http-equiv="Expires" content="0" /><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"><title>Cookie</title><!--因为是html页面--><base href="http://localhost:8080/cookie/"><style type="text/css">ul li {list-style: none;}</style></head><body><iframe name="target" width="500" height="500" style="float: left;"></iframe><div style="float: left;"><ul><li><a href="cookieServlet?action=createCookie" target="target">Cookie的创建</a></li><li><a href="cookieServlet?action=getCookie" target="target">Cookie的获取</a></li><li><a href="cookieServlet?action=updateCookie" target="target">Cookie值的修改</a></li><li>Cookie的存活周期</li><li><ul><li><a href="cookieServlet?action=defaultLife" target="target">Cookie的默认存活时间（会话）</a></li><li><a href="cookieServlet?action=deleteNow" target="target">Cookie立即删除</a></li><li><a href="cookieServlet?action=life3600" target="target">Cookie存活3600秒（1小时）</a></li></ul></li><li><a href="cookieServlet?action=testPath" target="target">Cookie的路径设置</a></li><li><a href="" target="target">Cookie的用户免登录练习</a></li></ul></div></body></html>
package com.atguigu.servlet;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import java.io.IOException;import java.lang.reflect.Method;public abstract class BaseServlet extends HttpServlet {@Overrideprotected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {doPost(req, resp);}protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {// 解决post请求中文乱码问题// 一定要在获取请求参数之前调用才有效req.setCharacterEncoding("UTF-8");// 解决响应中文乱码问题resp.setContentType("text/html; charset=UTF-8");String action = req.getParameter("action");try {// 获取action业务鉴别字符串，获取相应的业务 方法反射对象Method method = this.getClass().getDeclaredMethod(action, HttpServletRequest.class, HttpServletResponse.class);// System.out.println(method);// 调用目标业务 方法method.invoke(this, req, resp);} catch (Exception e) {e.printStackTrace();}}}
package com.atguigu.servlet;import javax.servlet.ServletException;import javax.servlet.http.Cookie;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import java.io.IOException;public class CookieServlet extends BaseServlet{protected void createCookie(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {// 1、创建Cookie对象Cookie cookie = new Cookie("key1", "value1");// 2、通知客户端保存Cookieresp.addCookie(cookie);resp.getWriter().write("Cookie创建成功");}}
Cookie的获取
package com.atguigu.servlet;import com.example.Cookie.CookieUtils;import javax.servlet.ServletException;import javax.servlet.http.Cookie;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import java.io.IOException;public class CookieServlet extends BaseServlet{protected void createCookie(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {// 1、创建Cookie对象Cookie cookie = new Cookie("key1", "value1");// 2、通知客户端保存Cookieresp.addCookie(cookie);resp.getWriter().write("Cookie创建成功");}protected void getCookie(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {Cookie[] cookies = req.getCookies();// getName方法// getValue方法for (Cookie cookie : cookies) {resp.getWriter().write("Cookie[" + cookie.getName() + " = " + cookie.getValue() + "] <br>");}Cookie iWantCookie = CookieUtils.findCookie("key1", cookies);if (iWantCookie != null) {resp.getWriter().write("找到了需要的Cookie");}}}
package com.atguigu.util;import javax.servlet.http.Cookie;public class CookieUtils {/*** 查找指定名称的cookie对象* @param name* @param cookies* @return*/public static Cookie findCookie(String name, Cookie[] cookies) {if (name == null || cookies == null || cookies.length == 0) {return null;}for (Cookie cookie : cookies) {if (name.equals(cookie.getName())) {return cookie;}}return null;}}
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "/TR/html4/loose.dtd"><html><head><meta http-equiv="pragma" content="no-cache" /><meta http-equiv="cache-control" content="no-cache" /><meta http-equiv="Expires" content="0" /><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"><title>Cookie</title><!--因为是html页面--><base href="http://localhost:8080/cookie/"><style type="text/css">ul li {list-style: none;}</style></head><body><iframe name="target" width="500" height="500" style="float: left;"></iframe><div style="float: left;"><ul><li><a href="cookieServlet?action=createCookie" target="target">Cookie的创建</a></li><li><a href="cookieServlet?action=getCookie" target="target">Cookie的获取</a></li><li><a href="cookieServlet?action=updateCookie" target="target">Cookie值的修改</a></li><li>Cookie的存活周期</li><li><ul><li><a href="cookieServlet?action=defaultLife" target="target">Cookie的默认存活时间（会话）</a></li><li><a href="cookieServlet?action=deleteNow" target="target">Cookie立即删除</a></li><li><a href="cookieServlet?action=life3600" target="target">Cookie存活3600秒（1小时）</a></li></ul></li><li><a href="cookieServlet?action=testPath" target="target">Cookie的路径设置</a></li><li><a href="" target="target">Cookie的用户免登录练习</a></li></ul></div></body></html><!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "/TR/html4/loose.dtd"><html><head><meta http-equiv="pragma" content="no-cache" /><meta http-equiv="cache-control" content="no-cache" /><meta http-equiv="Expires" content="0" /><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"><title>Cookie</title><!--因为是html页面--><base href="http://localhost:8080/cookie/"><style type="text/css">ul li {list-style: none;}</style></head><body><iframe name="target" width="500" height="500" style="float: left;"></iframe><div style="float: left;"><ul><li><a href="cookieServlet?action=createCookie" target="target">Cookie的创建</a></li><li><a href="cookieServlet?action=getCookie" target="target">Cookie的获取</a></li><li><a href="cookieServlet?action=updateCookie" target="target">Cookie值的修改</a></li><li>Cookie的存活周期</li><li><ul><li><a href="cookieServlet?action=defaultLife" target="target">Cookie的默认存活时间（会话）</a></li><li><a href="cookieServlet?action=deleteNow" target="target">Cookie立即删除</a></li><li><a href="cookieServlet?action=life3600" target="target">Cookie存活3600秒（1小时）</a></li></ul></li><li><a href="cookieServlet?action=testPath" target="target">Cookie的路径设置</a></li><li><a href="" target="target">Cookie的用户免登录练习</a></li></ul></div></body></html>
Cookie值的修改
protected void updateCookie(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {// 方案一 ：// 1、先创建一个要修改的同名的Cookie对象// 2、在构造器，同时赋于新的cookie值Cookie cookie = new Cookie("key1", "newValue1");// 3、调用resp.addCookie(cookie); ；通知 客户端 保存修改resp.addCookie(cookie);resp.getWriter().write("key1的cookie已经修改好了");}
protected void updateCookie(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {Cookie cookie = CookieUtils.findCookie("key1", req.getCookies());if (cookie != null) {cookie.setValue("newValue1");resp.addCookie(cookie);}}
中文也是
谷歌和火狐浏览器如何查看Cookie
Cookie的生命设置
protected void defaultLife(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {Cookie cookie = new Cookie("defaultLife", "defaultLife");cookie.setMaxAge(-1); // 设置存活时间resp.addCookie(cookie);}
protected void deleteNow(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {// 先找到要删除的cookie对象Cookie cookie = CookieUtils.findCookie(("key1"), req.getCookies());if (cookie != null) {// 调用setMaxAge（0）；cookie.setMaxAge(0); // 表示马上删除，都不需要等待浏览器关闭// 调用addCookieresp.addCookie(cookie);resp.getWriter().write("key1的cookie已经被删除");}}
Cookie 有效路径 Path 的设置
protected void testPath(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {Cookie cookie = new Cookie("path1", "path1");// getContextPath 得到工程路径cookie.setPath( req.getContextPath() + "/abc" ); // 工程路径/abcresp.addCookie(cookie);resp.getWriter().write("创建了一个带有Path路径的Cookie");}
Cookie 练习—免输入用户名登录
<%@ page contentType="text/html;charset=UTF-8" language="java" %><html><head><title>login.jsp</title></head><body><form action="http://localhost:8080/cookie/loginServlet" method="get">用户名：<input type="text" name="username" value="${ cookie.username.value }"> <br>密码：<input type="password" name="password"> <br><input type="submit" value="登陆"></form></body></html>
package com.atguigu.servlet;import javax.servlet.ServletException;import javax.servlet.http.Cookie;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import java.io.IOException;public class LoginServlet extends HttpServlet {@Overrideprotected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {String username = req.getParameter("username");String password = req.getParameter("password");if ("wzg168".equals(username) && "123456".equals(password)) {Cookie cookie = new Cookie("username", username);cookie.setMaxAge(60 * 60 * 24 * 7); // 当前Cookie一周内有效resp.addCookie(cookie);System.out.println("登陆成功");} else {System.out.println("登陆失败");}}}
在登陆成功一次，且在cookie消亡时间之前，再次访问login.jsp用户名会自动显示
