JSP页面上引入：
<%@ taglib uri="/htdz-tag" prefix="htdz-tag"%>
使用自定义图形验证码标签自动生成验证码:
<htdz-tag:CheckCodeTag />
以下为详细定义过程：
<?xml version="1.0" encoding="UTF-8" ?>
<taglib xmlns="http://java.sun.com/xml/ns/j2ee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-jsptaglibrary_2_0.xsd"
version="2.0">
<description>htdz tag</description>
<display-name>htdz tag</display-name>
<tlib-version>1.0</tlib-version>
<short-name>htdz-tag</short-name>
<uri>/htdz-tag</uri>
<tag>
<!--
验证码控件
使用说明：
jsp中使用范例：
1.无参数：<htdz-tag:CheckCodeTag/>
2.全部参数：<htdz-tag:CheckCodeTag id="checkCodeImg" height="18" width="58"/>
如果用户未设置参数，则默认值分别为：height="18" width="58"
-->
<description>验证码控件</description>
<name>CheckCodeTag</name>
<tag-class>com.htdz.util.tag.CheckCodeTag</tag-class>
<body-content>JSP</body-content>
<attribute>
<description>id</description>
<name>id</name>
<required>false</required>
<rtexprvalue>true</rtexprvalue>
</attribute>
<attribute>
<description>高</description>
<name>height</name>
<required>false</required>
<rtexprvalue>true</rtexprvalue>
</attribute>
<attribute>
<description>宽</description>
<name>width</name>
<required>false</required>
<rtexprvalue>true</rtexprvalue>
</attribute>
</tag>
<taglib/>
CheckCodeTag.java:
public class CheckCodeTag extends TagSupport {
private String id;
private String height;
private String width;
public CheckCodeTag() {
}
@SuppressWarnings( { "unchecked", "static-access" })
public int doStartTag() throws JspException {
StringBuffer html = new StringBuffer();
if (height == null || height.length() == 0)
height = "18";
if (width == null || width.length() == 0)
width = "60";
html.append("<img alt=\"重新获取验证码\"");
if (id != null && id.length() > 0) {
html.append(" id=\"");
html.append(id);
html.append("\"");
}
html.append(" height=\"");
html.append(height);
html.append("\" width=\"");
html.append(width);
html.append("\" src=\"/checkCodeImg\" onclick=\"this.src='/checkCodeImg?now='+new Date();\" style=\"cursor: pointer\" />");
try {
pageContext.getOut().println(html.toString());
} catch (Exception e) {
throw new JspException(e.getMessage());
}
return this.SKIP_BODY;
}
public void setId(String id) {
this.id = id;
}
public void setHeight(String height) {
this.height = height;
}
public void setWidth(String width) {
this.width = width;
}
}
web.xml:
<servlet>
<servlet-name>img</servlet-name>
<servlet-class>com.htdz.util.CheckCodeImg</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>img</servlet-name>
<url-pattern>/checkCodeImg</url-pattern>
</servlet-mapping>
CheckCodeImg.java:
public class CheckCodeImg extends HttpServlet {
private Font mFont = new Font("Arial black", Font.PLAIN, 16);
public void init() throws ServletException {
super.init();
}
Color getRandColor(int fc, int bc) {
Random random = new Random();
if (fc > 255)
fc = 255;
if (bc > 255)
bc = 255;
int r = fc + random.nextInt(bc - fc);
int g = fc + random.nextInt(bc - fc);
int b = fc + random.nextInt(bc - fc);
return new Color(r, g, b);
}
public void service(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setHeader("Pragma", "No-cache");
response.setHeader("Cache-Control", "no-cache");
response.setDateHeader("Expires", 0);
response.setContentType("image/png");
int width = 60, height = 18;
BufferedImage image = new BufferedImage(width, height,
BufferedImage.TYPE_INT_RGB);
Graphics g = image.getGraphics();
Random random = new Random();
g.setColor(getRandColor(200, 250));
g.fillRect(1, 1, width - 1, height - 1);
g.setColor(new Color(102, 102, 102));
g.drawRect(0, 0, width - 1, height - 1);
g.setFont(mFont);
g.setColor(getRandColor(160, 200));
for (int i = 0; i < 155; i++) {
int x = random.nextInt(width - 1);
int y = random.nextInt(height - 1);
int xl = random.nextInt(6) + 1;
int yl = random.nextInt(12) + 1;
g.drawLine(x, y, x + xl, y + yl);
}
for (int i = 0; i < 70; i++) {
int x = random.nextInt(width - 1);
int y = random.nextInt(height - 1);
int xl = random.nextInt(12) + 1;
int yl = random.nextInt(6) + 1;
g.drawLine(x, y, x - xl, y - yl);
}
char[] codes = { // 'a','b','c','d','e','f','h','k','m','n','r','s','t','x','y',//15个
'0', '1', '2', '3', '4', '5', '6', '7', '8', '9'
// 'A','B','C','D','E','F','G','H','K','N','S','T','X','Y'//14
};
String sRand = "";
for (int i = 0; i < 4; i++) {
int j = random.nextInt(10);
String tmp = String.valueOf(codes[j]);
sRand += tmp;
g.setColor(new Color(20 + random.nextInt(110), 20 + random
.nextInt(110), 20 + random.nextInt(110)));
g.drawString(tmp, 15 * i + 2, 15);
}
HttpSession session = request.getSession(true);
session.setAttribute(MyConstant.SESSION_CHECKCODE, sRand);
g.dispose();
ImageIO.write(image, "PNG", response.getOutputStream());
}
}