JavaWeb實現登入驗證碼
阿新 • • 發佈：2019-01-07
在登入介面中使用圖片驗證碼, 對於現在的web應用到處可見.
話不多說, 開始寫程式碼了!
首先, 新建一個JSP, 表示登入介面:
login3.jsp檔案:
<%--
User: menglanyingfei
Date: 2018/1/12
Time: 16:16
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html> 介面就是這樣, 當然, 你肯定現在出來不了這個效果! 沒事, 接著往下看吧!
然後, 新建一個Servlet:
VerifyCodeServlet.java檔案, 因為這裡配置了@WebServlet註解, 所以無需在web.xml中配置!
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.awt.image.BufferedImage;
import java.io.IOException;
/**
* 用來生成圖片驗證碼
* Created by menglanyingfei on 2018/1/12.
*/
@WebServlet(name = "VerifyCodeServlet", value = "/VerifyCodeServlet")
public class VerifyCodeServlet extends HttpServlet {
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//建立物件
VerifyCode vc = new VerifyCode();
//獲取圖片物件
BufferedImage bi = vc.getImage();
//獲得圖片的文字內容
String text = vc.getText();
// 將系統生成的文字內容儲存到session中
request.getSession().setAttribute("text", text);
//向瀏覽器輸出圖片
vc.output(bi, response.getOutputStream());
}
}在同一包下, 新建一個Java檔案VerifyCode.java(具體的程式碼意思, 可以看註釋, 已經寫得非常清楚了!):
import java.awt.BasicStroke;
import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics2D;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.io.OutputStream;
import java.util.Random;
import javax.imageio.ImageIO;
public class VerifyCode {
private int w = 70;
private int h = 35;
private Random r = new Random();
// {"宋體", "華文楷體", "黑體", "華文新魏", "華文隸書", "微軟雅黑", "楷體_GB2312"}
private String[] fontNames = {"宋體", "華文楷體", "黑體", "微軟雅黑", "楷體_GB2312"};
// 可選字元
private String codes = "0123456789abcdefghjkmnopqrstuvwxyzABCDEFGHJKMNPQRSTUVWXYZ";
// 背景色
private Color bgColor = new Color(255, 255, 255);
// 驗證碼上的文字
private String text ;
// 生成隨機的顏色
private Color randomColor () {
int red = r.nextInt(150);
int green = r.nextInt(150);
int blue = r.nextInt(150);
return new Color(red, green, blue);
}
// 生成隨機的字型
private Font randomFont () {
int index = r.nextInt(fontNames.length);
String fontName = fontNames[index];//生成隨機的字型名稱
int style = r.nextInt(4);//生成隨機的樣式, 0(無樣式), 1(粗體), 2(斜體), 3(粗體+斜體)
int size = r.nextInt(5) + 24; //生成隨機字號, 24 ~ 28
return new Font(fontName, style, size);
}
// 畫干擾線
private void drawLine (BufferedImage image) {
int num = 3;//一共畫3條
Graphics2D g2 = (Graphics2D)image.getGraphics();
for(int i = 0; i < num; i++) {//生成兩個點的座標，即4個值
int x1 = r.nextInt(w);
int y1 = r.nextInt(h);
int x2 = r.nextInt(w);
int y2 = r.nextInt(h);
g2.setStroke(new BasicStroke(1.5F));
g2.setColor(Color.BLUE); //干擾線是藍色
g2.drawLine(x1, y1, x2, y2);//畫線
}
}
// 隨機生成一個字元
private char randomChar () {
int index = r.nextInt(codes.length());
return codes.charAt(index);
}
// 建立BufferedImage
private BufferedImage createImage () {
BufferedImage image = new BufferedImage(w, h, BufferedImage.TYPE_INT_RGB);
Graphics2D g2 = (Graphics2D)image.getGraphics();
g2.setColor(this.bgColor);
g2.fillRect(0, 0, w, h);
return image;
}
// 呼叫這個方法得到驗證碼
public BufferedImage getImage () {
BufferedImage image = createImage();//建立圖片緩衝區
Graphics2D g2 = (Graphics2D)image.getGraphics();//得到繪製環境
StringBuilder sb = new StringBuilder();//用來裝載生成的驗證碼文字
// 向圖片中畫4個字元
for(int i = 0; i < 4; i++) {//迴圈四次，每次生成一個字元
String s = randomChar() + "";//隨機生成一個字母
sb.append(s); //把字母新增到sb中
float x = i * 1.0F * w / 4; //設定當前字元的x軸座標
g2.setFont(randomFont()); //設定隨機字型
g2.setColor(randomColor()); //設定隨機顏色
g2.drawString(s, x, h-5); //畫圖
}
this.text = sb.toString(); //把生成的字串賦給了this.text
drawLine(image); //新增干擾線
return image;
}
// 返回驗證碼圖片上的文字
public String getText () {
return text;
}
// 儲存圖片到指定的輸出流
public static void output (BufferedImage image, OutputStream out)
throws IOException {
ImageIO.write(image, "JPEG", out);
}
}
處理登入邏輯的Servlet(LoginServlet3.java):
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
/**
* Created by menglanyingfei on 2018/1/12.
*/
@WebServlet(name = "LoginServlet3", value = "/LoginServlet3")
public class LoginServlet3 extends HttpServlet {
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// 編碼
request.setCharacterEncoding("utf-8");
// 獲取請求引數
/*
拿到頁面傳過來的手動輸入的驗證碼, 該驗證碼要和生成圖片上的
文字驗證碼比較, 如果相同, 驗證碼輸入成功!
*/
String imageText = request.getParameter("image");
// 圖片的驗證碼
String text = (String) request.getSession().getAttribute("text");
if (!text.equalsIgnoreCase(imageText)) {
request.setAttribute("imageMess", "驗證碼輸入錯誤!");
request.getRequestDispatcher("/jsp/login3.jsp").forward(request, response);
}
// 獲取使用者名稱和密碼
String username = request.getParameter("username");
String password = request.getParameter("password");
if ("haha".equals(username) && "123".equals(password)) {
// 將使用者資訊儲存到session中
request.getSession().setAttribute("username", username);
// 使用cookie實現回寫使用者名稱
Cookie cookie = new Cookie("username", username);
cookie.setMaxAge(60 * 60);
// 通過響應頭髮送cookie
response.addCookie(cookie);
// 重定向登入成功介面
response.sendRedirect(request.getContextPath() + "/jsp/success2.jsp");
} else {
request.setAttribute("error", "使用者名稱或密碼錯誤!");
request.getRequestDispatcher("/jsp/login3.jsp").forward(request, response);
}
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
}
}
登入成功後的介面:(success2.jsp)
<%--
User: menglanyingfei
Date: 2018/1/12
Time: 16:44
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<title>成功登入</title>
</head>
<body>
<%
// 獲取使用者資訊
String username = (String) session.getAttribute("username");
if (username == null) {
// 儲存錯誤資訊到request中, 然後轉發到login3.jsp中, 提醒登入
request.setAttribute("message", "請登入!");
// 轉發到登入頁面
request.getRequestDispatcher("/jsp/login3.jsp").forward(request, response);
}
%>
<h2>歡迎登入:${sessionScope.username}!!!</h2>
</body>
</html>
最後, 演示登入:
因為, 使用者名稱haha和密碼123已經寫死在程式碼裡了!
