创建一个DrawImage Servlet,用来生成验证码图片:
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
|
package
gacl.response.study;
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.http.HttpServlet;
import
javax.servlet.http.HttpServletRequest;
import
javax.servlet.http.HttpServletResponse;
/**
* 生成随机图片,用来作为验证码
*/
public
class
DrawImage
extends
HttpServlet {
private
static
final
long
serialVersionUID = 3038623696184546092L;
public
static
final
int
WIDTH =
120
;
//生成的图片的宽度
public
static
final
int
HEIGHT =
30
;
//生成的图片的高度
public
void
doGet(HttpServletRequest request, HttpServletResponse response)
throws
ServletException, IOException {
this
.doPost(request, response);
}
public
void
doPost(HttpServletRequest request, HttpServletResponse response)
throws
ServletException, IOException {
String createTypeFlag = request.getParameter(
"createTypeFlag"
);
//接收客户端传递的createTypeFlag标识
//1.在内存中创建一张图片
BufferedImage bi =
new
BufferedImage(WIDTH, HEIGHT,BufferedImage.TYPE_INT_RGB);
//2.得到图片
Graphics g = bi.getGraphics();
//3.设置图片的背影色
setBackGround(g);
//4.设置图片的边框
setBorder(g);
//5.在图片上画干扰线
drawRandomLine(g);
//6.写在图片上随机数
//String random = drawRandomNum((Graphics2D) g,"ch");//生成中文验证码图片
//String random = drawRandomNum((Graphics2D) g,"nl");//生成数字和字母组合的验证码图片
//String random = drawRandomNum((Graphics2D) g,"n");//生成纯数字的验证码图片
//String random = drawRandomNum((Graphics2D) g,"l");//生成纯字母的验证码图片
String random = drawRandomNum((Graphics2D) g,createTypeFlag);
//根据客户端传递的createTypeFlag标识生成验证码图片
//7.将随机数存在session中
request.getSession().setAttribute(
"checkcode"
, random);
//8.设置响应头通知浏览器以图片的形式打开
response.setContentType(
"image/jpeg"
);
//等同于response.setHeader("Content-Type", "image/jpeg");
//9.设置响应头控制浏览器不要缓存
response.setDateHeader(
"expries"
, -
1
);
response.setHeader(
"Cache-Control"
,
"no-cache"
);
response.setHeader(
"Pragma"
,
"no-cache"
);
//10.将图片写给浏览器
ImageIO.write(bi,
"jpg"
, response.getOutputStream());
}
/**
* 设置图片的背景色
* @param g
*/
private
void
setBackGround(Graphics g) {
// 设置颜色
g.setColor(Color.WHITE);
// 填充区域
g.fillRect(
0
,
0
, WIDTH, HEIGHT);
}
/**
* 设置图片的边框
* @param g
*/
private
void
setBorder(Graphics g) {
// 设置边框颜色
g.setColor(Color.BLUE);
// 边框区域
g.drawRect(
1
,
1
, WIDTH -
2
, HEIGHT -
2
);
}
/**
* 在图片上画随机线条
* @param g
*/
private
void
drawRandomLine(Graphics g) {
// 设置颜色
g.setColor(Color.GREEN);
// 设置线条个数并画线
for
(
int
i =
0
; i <
5
; i++) {
int
x1 =
new
Random().nextInt(WIDTH);
int
y1 =
new
Random().nextInt(HEIGHT);
int
x2 =
new
Random().nextInt(WIDTH);
int
y2 =
new
Random().nextInt(HEIGHT);
g.drawLine(x1, y1, x2, y2);
}
}
/**
* 画随机字符
* @param g
* @param createTypeFlag
* @return
* String... createTypeFlag是可变参数,
* Java1.5增加了新特性:可变参数:适用于参数个数不确定,类型确定的情况,java把可变参数当做数组处理。注意:可变参数必须位于最后一项
*/
private
String drawRandomNum(Graphics2D g,String... createTypeFlag) {
// 设置颜色
g.setColor(Color.RED);
// 设置字体
g.setFont(
new
Font(
"宋体"
, Font.BOLD,
20
));
//常用的中国汉字
String baseChineseChar =
"\u7684\u4e00\u4e86\u662f\u6211\u4e0d\u5728\u4eba\u4eec\u6709\u6765\u4ed6\u8fd9\u4e0a\u7740\u4e2a\u5730\u5230\u5927\u91cc\u8bf4\u5c31\u53bb\u5b50\u5f97\u4e5f\u548c\u90a3\u8981\u4e0b\u770b\u5929\u65f6\u8fc7\u51fa\u5c0f\u4e48\u8d77\u4f60\u90fd\u628a\u597d\u8fd8\u591a\u6ca1\u4e3a\u53c8\u53ef\u5bb6\u5b66\u53ea\u4ee5\u4e3b\u4f1a\u6837\u5e74\u60f3\u751f\u540c\u8001\u4e2d\u5341\u4ece\u81ea\u9762\u524d\u5934\u9053\u5b83\u540e\u7136\u8d70\u5f88\u50cf\u89c1\u4e24\u7528\u5979\u56fd\u52a8\u8fdb\u6210\u56de\u4ec0\u8fb9\u4f5c\u5bf9\u5f00\u800c\u5df1\u4e9b\u73b0\u5c71\u6c11\u5019\u7ecf\u53d1\u5de5\u5411\u4e8b\u547d\u7ed9\u957f\u6c34\u51e0\u4e49\u4e09\u58f0\u4e8e\u9ad8\u624b\u77e5\u7406\u773c\u5fd7\u70b9\u5fc3\u6218\u4e8c\u95ee\u4f46\u8eab\u65b9\u5b9e\u5403\u505a\u53eb\u5f53\u4f4f\u542c\u9769\u6253\u5462\u771f\u5168\u624d\u56db\u5df2\u6240\u654c\u4e4b\u6700\u5149\u4ea7\u60c5\u8def\u5206\u603b\u6761\u767d\u8bdd\u4e1c\u5e2d\u6b21\u4eb2\u5982\u88ab\u82b1\u53e3\u653e\u513f\u5e38\u6c14\u4e94\u7b2c\u4f7f\u5199\u519b\u5427\u6587\u8fd0\u518d\u679c\u600e\u5b9a\u8bb8\u5feb\u660e\u884c\u56e0\u522b\u98de\u5916\u6811\u7269\u6d3b\u90e8\u95e8\u65e0\u5f80\u8239\u671b\u65b0\u5e26\u961f\u5148\u529b\u5b8c\u5374\u7ad9\u4ee3\u5458\u673a\u66f4\u4e5d\u60a8\u6bcf\u98ce\u7ea7\u8ddf\u7b11\u554a\u5b69\u4e07\u5c11\u76f4\u610f\u591c\u6bd4\u9636\u8fde\u8f66\u91cd\u4fbf\u6597\u9a6c\u54ea\u5316\u592a\u6307\u53d8\u793e\u4f3c\u58eb\u8005\u5e72\u77f3\u6ee1\u65e5\u51b3\u767e\u539f\u62ff\u7fa4\u7a76\u5404\u516d\u672c\u601d\u89e3\u7acb\u6cb3\u6751\u516b\u96be\u65e9\u8bba\u5417\u6839\u5171\u8ba9\u76f8\u7814\u4eca\u5176\u4e66\u5750\u63a5\u5e94\u5173\u4fe1\u89c9\u6b65\u53cd\u5904\u8bb0\u5c06\u5343\u627e\u4e89\u9886\u6216\u5e08\u7ed3\u5757\u8dd1\u8c01\u8349\u8d8a\u5b57\u52a0\u811a\u7d27\u7231\u7b49\u4e60\u9635\u6015\u6708\u9752\u534a\u706b\u6cd5\u9898\u5efa\u8d76\u4f4d\u5531\u6d77\u4e03\u5973\u4efb\u4ef6\u611f\u51c6\u5f20\u56e2\u5c4b\u79bb\u8272\u8138\u7247\u79d1\u5012\u775b\u5229\u4e16\u521a\u4e14\u7531\u9001\u5207\u661f\u5bfc\u665a\u8868\u591f\u6574\u8ba4\u54cd\u96ea\u6d41\u672a\u573a\u8be5\u5e76\u5e95\u6df1\u523b\u5e73\u4f1f\u5fd9\u63d0\u786e\u8fd1\u4eae\u8f7b\u8bb2\u519c\u53e4\u9ed1\u544a\u754c\u62c9\u540d\u5440\u571f\u6e05\u9633\u7167\u529e\u53f2\u6539\u5386\u8f6c\u753b\u9020\u5634\u6b64\u6cbb\u5317\u5fc5\u670d\u96e8\u7a7f\u5185\u8bc6\u9a8c\u4f20\u4e1a\u83dc\u722c\u7761\u5174\u5f62\u91cf\u54b1\u89c2\u82e6\u4f53\u4f17\u901a\u51b2\u5408\u7834\u53cb\u5ea6\u672f\u996d\u516c\u65c1\u623f\u6781\u5357\u67aa\u8bfb\u6c99\u5c81\u7ebf\u91ce\u575a\u7a7a\u6536\u7b97\u81f3\u653f\u57ce\u52b3\u843d\u94b1\u7279\u56f4\u5f1f\u80dc\u6559\u70ed\u5c55\u5305\u6b4c\u7c7b\u6e10\u5f3a\u6570\u4e61\u547c\u6027\u97f3\u7b54\u54e5\u9645\u65e7\u795e\u5ea7\u7ae0\u5e2e\u5566\u53d7\u7cfb\u4ee4\u8df3\u975e\u4f55\u725b\u53d6\u5165\u5cb8\u6562\u6389\u5ffd\u79cd\u88c5\u9876\u6025\u6797\u505c\u606f\u53e5\u533a\u8863\u822c\u62a5\u53f6\u538b\u6162\u53d4\u80cc\u7ec6"
;
//数字和字母的组合
String baseNumLetter =
"0123456789ABCDEFGHJKLMNOPQRSTUVWXYZ"
;
//纯数字
String baseNum =
"0123456789"
;
//纯字母
String baseLetter =
"ABCDEFGHJKLMNOPQRSTUVWXYZ"
;
//createTypeFlag[0]==null表示没有传递参数
if
(createTypeFlag.length >
0
&&
null
!= createTypeFlag[
0
]) {
if
(createTypeFlag[
0
].equals(
"ch"
)) {
// 截取汉字
return
createRandomChar(g, baseChineseChar);
}
else
if
(createTypeFlag[
0
].equals(
"nl"
)) {
// 截取数字和字母的组合
return
createRandomChar(g, baseNumLetter);
}
else
if
(createTypeFlag[
0
].equals(
"n"
)) {
// 截取数字
return
createRandomChar(g, baseNum);
}
else
if
(createTypeFlag[
0
].equals(
"l"
)) {
// 截取字母
return
createRandomChar(g, baseLetter);
}
}
else
{
// 默认截取数字和字母的组合
return
createRandomChar(g, baseNumLetter);
}
return
""
;
}
/**
* 创建随机字符
* @param g
* @param baseChar
* @return 随机字符
*/
private
String createRandomChar(Graphics2D g,String baseChar) {
StringBuffer sb =
new
StringBuffer();
int
x =
5
;
String ch =
""
;
// 控制字数
for
(
int
i =
0
; i <
4
; i++) {
// 设置字体旋转角度
int
degree =
new
Random().nextInt() %
30
;
ch = baseChar.charAt(
new
Random().nextInt(baseChar.length())) +
""
;
sb.append(ch);
// 正向角度
g.rotate(degree * Math.PI /
180
, x,
20
);
g.drawString(ch, x,
20
);
// 反向角度
g.rotate(-degree * Math.PI /
180
, x,
20
);
x +=
30
;
}
return
sb.toString();
}
}
|
二、在Form表单中使用验证码图片
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
|
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<
html
>
<
head
>
<
title
>在Form表单中使用验证码</
title
>
<
script
type
=
"text/javascript"
>
//刷新验证码
function changeImg(){
document.getElementById("validateCodeImg").src="${pageContext.request.contextPath}/servlet/DrawImage?"+Math.random();
}
</
script
>
</
head
>
<
body
>
<
form
action
=
"${pageContext.request.contextPath}/servlet/CheckServlet"
method
=
"post"
>
验证码:<
input
type
=
"text"
name
=
"validateCode"
/>
<
img
alt
=
"验证码看不清,换一张"
src
=
"${pageContext.request.contextPath}/servlet/DrawImage"
id
=
"validateCodeImg"
onclick
=
"changeImg()"
>
<
a
href
=
"javascript:void(0)"
onclick
=
"changeImg()"
>看不清,换一张</
a
>
<
br
/>
<
input
type
=
"submit"
value
=
"提交"
>
</
form
>
</
body
>
</
html
>
|
DrawImage Servlet除了可以生成的字母和数字的组合的验证码图片之外,还可以生成汉字,纯数字,纯字母的验证码图片,只需要向DrawImage Servlet传递约定好的生成标识符参数即可,如下所示
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
|
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<
html
>
<
head
>
<
title
>在Form表单中使用验证码</
title
>
<
script
type
=
"text/javascript"
>
//刷新验证码
function changeImg(obj,createTypeFlag){
document.getElementById(obj.id).src="${pageContext.request.contextPath}/servlet/DrawImage?createTypeFlag="+createTypeFlag+"&"+Math.random();
}
</
script
>
</
head
>
<
body
>
<
form
action
=
"${pageContext.request.contextPath}/servlet/CheckServlet"
method
=
"post"
>
数字字母混合验证码:<
input
type
=
"text"
name
=
"validateCode"
/>
<
img
alt
=
"验证码看不清,换一张"
src
=
"${pageContext.request.contextPath}/servlet/DrawImage"
id
=
"validateCodeImg1"
onclick
=
"changeImg(this,'nl')"
>
<
br
/>
中文验证码:<
input
type
=
"text"
name
=
"validateCode"
/>
<
img
alt
=
"验证码看不清,换一张"
src
=
"${pageContext.request.contextPath}/servlet/DrawImage?createTypeFlag=ch"
id
=
"validateCodeImg2"
onclick
=
"changeImg(this,'ch')"
>
<
br
/>
英文验证码:<
input
type
=
"text"
name
=
"validateCode"
/>
<
img
alt
=
"验证码看不清,换一张"
src
=
"${pageContext.request.contextPath}/servlet/DrawImage?createTypeFlag=l"
id
=
"validateCodeImg3"
onclick
=
"changeImg(this,'l')"
>
<
br
/>
数字验证码:<
input
type
=
"text"
name
=
"validateCode"
/>
<
img
alt
=
"验证码看不清,换一张"
src
=
"${pageContext.request.contextPath}/servlet/DrawImage?createTypeFlag=n"
id
=
"validateCodeImg4"
onclick
=
"changeImg(this,'n')"
>
<
br
/>
<
input
type
=
"submit"
value
=
"提交"
>
</
form
>
</
body
>
</
html
>
|
三、服务器端对form表单提交上来的验证码处理
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
|
package
gacl.response.study;
import
java.io.IOException;
import
javax.servlet.ServletException;
import
javax.servlet.http.HttpServlet;
import
javax.servlet.http.HttpServletRequest;
import
javax.servlet.http.HttpServletResponse;
/**
* @author gacl
* 服务器端接收到验证码后的处理
*/
public
class
CheckServlet
extends
HttpServlet {
public
void
doGet(HttpServletRequest request, HttpServletResponse response)
throws
ServletException, IOException {
String clientCheckcode = request.getParameter(
"validateCode"
);
//接收客户端浏览器提交上来的验证码
String serverCheckcode = (String) request.getSession().getAttribute(
"checkcode"
);
//从服务器端的session中取出验证码
if
(clientCheckcode.equals(serverCheckcode)) {
//将客户端验证码和服务器端验证比较,如果相等,则表示验证通过
System.out.println(
"验证码验证通过!"
);
}
else
{
System.out.println(
"验证码验证失败!"
);
}
}
public
void
doPost(HttpServletRequest request, HttpServletResponse response)
throws
ServletException, IOException {
doGet(request, response);
}
}
|
http://www.cnblogs.com/xdp-gacl/p/3798190.html
本文转自yunlielai51CTO博客,原文链接:http://blog.51cto.com/4925054/1723064,如需转载请自行联系原作者