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案例：登录注册实现

案例概述

案例知识点分析

开发框架

注册功能的实现流程

  • 监听器初始化数据
  • 实现表单提交
  • Servlet接收
  • Servlet封装
  • Servlet处理数据（解耦）
  • Servlet转发，JSP显示

文件上传功能的实现

文件上传要点

文件上传原理

文件上传参考案例

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
</head>
<body>
    <h1>文件上传</h1>
    <form action="${pageContext.request.contextPath }/uploadservlet" method="post"  enctype="multipart/form-data">
        <input type="text" name= "name"><br/>
        <input type="file" name= "upload"><br/>
        <input type="submit" value= "上传">
    </form>
</body>
</html>

package com.jesse.servlet;

import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.List;

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 org.apache.commons.fileupload.FileItem;
import org.apache.commons.fileupload.FileUploadException;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;


@WebServlet("/uploadservlet")
public class UploadServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // 1.创建磁盘文件项工厂
        DiskFileItemFactory diskFileItemFactory = new DiskFileItemFactory();
        // 2.创建核心解析类
        ServletFileUpload fileUpload = new ServletFileUpload(diskFileItemFactory);
        // 3.解析请求对象，将请求分成几个部分（FileItem）
        try {
            List<FileItem> list = fileUpload.parseRequest(request);
            // 4. 遍历集合获得每个部分的对象
            for(FileItem fileItem:list) {
                // 判断是普通项还是文件上传项
                if(fileItem.isFormField()) {
                    // 普通项
                    //获得普通项的名称：
                    String name = fileItem.getFieldName();
                    //获得普通项的值：
                    String value = fileItem.getString("UTF-8");
                    System.out.println(name + "-" + value);
                }else {
                    // 文件上传项
                    // 获得文件的名称：
                    String fileName  = fileItem.getName();
                    // 获得文件的输入流：
                    InputStream is = fileItem.getInputStream();
                    // 需要将文件写入到服务器的某个路径即可：
                    String path = getServletContext().getRealPath("/upload");
                    System.out.println(path);
                    // 创建输出流与输入流进行对接
                    OutputStream os = new FileOutputStream(path+ "\\" + fileName);
                    int len = 0;
                    byte[] b = new byte[1024];
                    while((len = is.read(b)) != -1) {
                        os.write(b, 0, len);
                    }
                    is.close();
                    os.close();
                }
            }
        } catch (FileUploadException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

    }


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

}

登陆功能和验证码

登陆功能的实现

验证码

验证码生成的流程

验证码参考案例

package com.jesse.web.servlet;

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.util.Random;

import javax.imageio.ImageIO;
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 com.sun.prism.Image;

@WebServlet("/check1")
public class CheckImgServlet1 extends HttpServlet {
    private static final long serialVersionUID = 1L;

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        int width = 120;
        int height = 30;
        // 步骤一：在内存中生成一张图片
        BufferedImage bufferedImage = new BufferedImage(width,height,BufferedImage.TYPE_INT_RGB);

        // 步骤二：操作该图片，设置背景色及绘制边框
        Graphics graphics = bufferedImage.getGraphics();
        // 设置背景色
        graphics.setColor(Color.YELLOW);
        graphics.fillRect(0, 0, width, height);
        // 绘制边框
        graphics.setColor(Color.BLUE);
        graphics.drawRect(0, 0, width-1, height-1);

        // 步骤三：生成随机的四个字母，写入到图片中
        Graphics2D g2d = (Graphics2D)graphics;
        g2d.setColor(Color.BLACK);
        g2d.setFont(new Font("宋体", Font.BOLD, 18)); // a 4 3 r

        String words = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";
        Random random = new Random();
        int x = 10;
        for(int i = 0; i < 4; i++) {
            int idx = random.nextInt(words.length());
            // 获得指定位置的字符
            char ch = words.charAt(idx);
            // 旋转的角度 -30到30之间
            int angle = random.nextInt(60) - 30;
            // 将角度转化为弧度：
            double theta = angle * Math.PI / 180;
            g2d.rotate(theta, x, 20);
            g2d.drawString(String.valueOf(ch), x, 20);
            g2d.rotate(-theta, x, 20);
            x += 30;
        }

        // 步骤四：将内存中的图片，进行输出
        ImageIO.write(bufferedImage, "jpg", response.getOutputStream());
    }

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

}

项目实现展示

posted @ 2020-04-27 21:06  JesseKkk  阅读(257)  评论(0)    收藏  举报