Servlet部分：
package servlet;
import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.io.OutputStream;
import java.util.Random;
import javax.imageio.ImageIO;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class LoginServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
// 产生随即的字体
private Font getFont() {
Random random = new Random();
Font font [] = new Font[5];
font [0] = new Font( "Ravie" , Font. PLAIN , 24);
font [1] = new Font( "Antique Olive Compact" , Font. PLAIN , 24);
font [2] = new Font( "Forte" , Font. PLAIN , 24);
font [3] = new Font( "Wide Latin" , Font. PLAIN , 24);
font [4] = new Font( "Gill Sans Ultra Bold" , Font. PLAIN , 24);
return font [ random .nextInt(5)];
}
@Override
protected void doGet(HttpServletRequest request , HttpServletResponse response )
throws ServletException, IOException {
doPost( request , response );
}
@Override
protected void doPost(HttpServletRequest request , HttpServletResponse response )
throws ServletException, IOException {
// 设置响应头 Content-type类型
response .setContentType( "image/jpeg" );
// 以下三句是用于设置页面不缓存
response .setHeader( "Pragma" , "No-cache" );
response .setHeader( "Cache-Control" , "No-cache" );
response .setDateHeader( "Expires" , 0);
OutputStream os = response .getOutputStream();
int width = 83, height = 30;
// 建立指定宽、高和BufferedImage对象
BufferedImage image = new BufferedImage( width , height , BufferedImage. TYPE_INT_RGB );
Graphics g = image .getGraphics(); // 该画笔画在image上
Color c = g .getColor(); // 保存当前画笔的颜色，用完画笔后要回复现场
g .fillRect(0, 0, width , height );
char [] ch = "abcdefghjkmnpqrstuvwxyz23456789" .toCharArray(); // 随即产生的字符串
// 不包括 i
// l(小写L)
// o（小写O）
// 1（数字1）0(数字0)
int length = ch . length ; // 随即字符串的长度
String sRand = "" ; // 保存随即产生的字符串
Random random = new Random();
for ( int i = 0; i < 4; i ++) {
// 设置字体
g .setFont(getFont());
// 随即生成0-9的数字
String rand = new Character( ch [ random .nextInt( length )]).toString();
sRand += rand ;
// 设置随机颜色
g .setColor( new Color( random .nextInt(255), random .nextInt(255), random .nextInt(255)));
g .drawString( rand , 20 * i + 6, 25);
}
// 产生随即干扰点
for ( int i = 0; i < 20; i ++) {
int x1 = random .nextInt( width );
int y1 = random .nextInt( height );
g .drawOval( x1 , y1 , 2, 2);
}
g .setColor( c ); // 将画笔的颜色再设置回去
g .dispose();
// 将验证码记录到session
request .getSession().setAttribute( "safecode" , sRand );
// 输出图像到页面
ImageIO. write( image , "JPEG" , os );
}
}
前端Jsp:
<%
String action = request.getParameter( "action" );
String safecodeText = request.getParameter( "safecodeTest" );
if ( "action" .equals(action)){
String safecode = (String)session.getAttribute( "safecode" );
if (safecode.equals(safecodeText)){
out.print( "验证码正确！" );
} else {
out.print( "验证码错误！请重新输入！" );
}
}
%>
< head >
< title > 验证码测试 </ title >
</ head >
< body >
< form action = "index.jsp" method = "post" >
< input type = "hidden" name = "action" value = "action" />
< img alt = "验证码" src = "login" >
< input type = "text" name = "safecodeTest" >
< input type = "submit" value = "go" >
</ form >
</ body >
</ html >
Servlet部分：
package servlet;
import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.io.OutputStream;
import java.util.Random;
import javax.imageio.ImageIO;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class LoginServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
// 产生随即的字体
private Font getFont() {
Random random = new Random();
Font font [] = new Font[5];
font [0] = new Font( "Ravie" , Font. PLAIN , 24);
font [1] = new Font( "Antique Olive Compact" , Font. PLAIN , 24);
font [2] = new Font( "Forte" , Font. PLAIN , 24);
font [3] = new Font( "Wide Latin" , Font. PLAIN , 24);
font [4] = new Font( "Gill Sans Ultra Bold" , Font. PLAIN , 24);
return font [ random .nextInt(5)];
}
@Override
protected void doGet(HttpServletRequest request , HttpServletResponse response )
throws ServletException, IOException {
doPost( request , response );
}
@Override
protected void doPost(HttpServletRequest request , HttpServletResponse response )
throws ServletException, IOException {
// 设置响应头 Content-type类型
response .setContentType( "image/jpeg" );
// 以下三句是用于设置页面不缓存
response .setHeader( "Pragma" , "No-cache" );
response .setHeader( "Cache-Control" , "No-cache" );
response .setDateHeader( "Expires" , 0);
OutputStream os = response .getOutputStream();
int width = 83, height = 30;
// 建立指定宽、高和BufferedImage对象
BufferedImage image = new BufferedImage( width , height , BufferedImage. TYPE_INT_RGB );
Graphics g = image .getGraphics(); // 该画笔画在image上
Color c = g .getColor(); // 保存当前画笔的颜色，用完画笔后要回复现场
g .fillRect(0, 0, width , height );
char [] ch = "abcdefghjkmnpqrstuvwxyz23456789" .toCharArray(); // 随即产生的字符串
// 不包括 i
// l(小写L)
// o（小写O）
// 1（数字1）0(数字0)
int length = ch . length ; // 随即字符串的长度
String sRand = "" ; // 保存随即产生的字符串
Random random = new Random();
for ( int i = 0; i < 4; i ++) {
// 设置字体
g .setFont(getFont());
// 随即生成0-9的数字
String rand = new Character( ch [ random .nextInt( length )]).toString();
sRand += rand ;
// 设置随机颜色
g .setColor( new Color( random .nextInt(255), random .nextInt(255), random .nextInt(255)));
g .drawString( rand , 20 * i + 6, 25);
}
// 产生随即干扰点
for ( int i = 0; i < 20; i ++) {
int x1 = random .nextInt( width );
int y1 = random .nextInt( height );
g .drawOval( x1 , y1 , 2, 2);
}
g .setColor( c ); // 将画笔的颜色再设置回去
g .dispose();
// 将验证码记录到session
request .getSession().setAttribute( "safecode" , sRand );
// 输出图像到页面
ImageIO. write( image , "JPEG" , os );
}
}
前端Jsp:
<%
String action = request.getParameter( "action" );
String safecodeText = request.getParameter( "safecodeTest" );
if ( "action" .equals(action)){
String safecode = (String)session.getAttribute( "safecode" );
if (safecode.equals(safecodeText)){
out.print( "验证码正确！" );
} else {
out.print( "验证码错误！请重新输入！" );
}
}
%>
< head >
< title > 验证码测试 </ title >
</ head >
< body >
< form action = "index.jsp" method = "post" >
< input type = "hidden" name = "action" value = "action" />
< img alt = "验证码" src = "login" >
< input type = "text" name = "safecodeTest" >
< input type = "submit" value = "go" >
</ form >
</ body >
</ html >