Javaweb开发之验证码制作

javaweb开发之制作简单验证码

使用xml对页面进行配置，验证码模块具体配置如下，code.jhtml为验证码存放位置

<servlet>
<servlet-name>CodeAction</servlet-name>
<servlet-class>campsg.qunawan.action.CodeAction</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>CodeAction</servlet-name>
<url-pattern>/code.jhtml</url-pattern>
</servlet-mapping>

html页面中，页面脚本如下（该页面为登录页面，不同于code.jhtml）

<li>
<span class="identifying">
<img width="120px" height="40px" src="/PRJ_WTP_JEE_005/code.jhtml" 
onclick="javascript:this.src='/PRJ_WTP_JEE_005/code.jhtml?id='+new Date().getMilliseconds()">
</span>
<input type="text" name="code" id="ident" class="text identify" value="验证码" />
</li>

其中的onclick()响应是为了保证每次刷新的能获取到正确可用的路径

制作验证码另外还需如下准备工作：制作字符库，颜色库，字体库（为了方便，统一成了一样），图像长、宽度等信息

在src目录下的包中，新建一个类，暂且命名为Constant，将所需信息写入

public class Constants {

// 验证码的字体库
public static Font[] codeFont = { new Font("Times New Roman", Font.PLAIN, 30),
new Font("Times New Roman", Font.PLAIN, 30), new Font("Times New Roman", Font.PLAIN, 30),
new Font("Times New Roman", Font.PLAIN, 30) };

// 验证码数字颜色库
public static Color[] color = { Color.BLACK, Color.RED, Color.DARK_GRAY, Color.BLUE };

// 验证码的字符库
public static final String IMAGE_CHAR = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";

// 验证码的宽度
public static final Integer IMAGE_WIDTH = 120;

// 验证码的高度
public static final Integer IMAGE_HEIGHT = 40;
}

在src目录的包下新建一个类，暂且命名为CodeAction，使其继承HttpServlet类，写入生成随机验证码代码

public class CodeAction extends HttpServlet{

private static final long serialVersionUID = -175449573736935176L;

private String codeNumbers="";

@Override
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

System.out.println("执行CodeAction方法");

BufferedImage image=new BufferedImage(
Constants.IMAGE_WIDTH, 
Constants.IMAGE_HEIGHT,
BufferedImage.TYPE_INT_RGB);

Graphics2D g=(Graphics2D) image.getGraphics();
g.setColor(createRandomColor(200,300));
g.fillRect(0, 0, Constants.IMAGE_WIDTH, Constants.IMAGE_HEIGHT);

/**
 * 画出验证码字符
 */
for(int i=0;i<4;i++)
{
drawString(g, i);
}

System.out.println("生成验证码："+this.codeNumbers);

//绘制干扰线
drawNoiseLine(g, 5);

this.codeNumbers="";
ServletOutputStream sos=response.getOutputStream();
ImageIO.write(image, "GIF", sos);
sos.close();
}


@Override
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
doGet(request,response);
}

/**
 * 绘制验证码字符串
 * @param g 图层
 * @param i 第几位字符
 */
private void drawString(Graphics2D g,int i) {
Random random=new Random();
Integer j=random.nextInt(Constants.IMAGE_CHAR.length());
String number=Constants.IMAGE_CHAR.substring(j, j+1);
g.setFont(Constants.codeFont[i]);
g.setColor(Constants.color[i]);
g.drawString(number, 15*i+20, 30);
this.codeNumbers+=number;
}


/**
 * 随机生成图片背景颜色
 * @param bcf 最小值
 * @param bcl 最大值
 * @return RGB颜色
 */
private Color createRandomColor(int bcf,int bcl ) {
Color color=null;
boolean flag=true;
while(flag)
{
int r=bcf+new Random().nextInt(bcl-bcf);
int g=bcf+new Random().nextInt(bcl-bcf);
int b=bcf+new Random().nextInt(bcl-bcf);
if((r>=0&&r<=255)&&(g>=0&&g<=255)&&(b>=0&&b<=255))
{
color=new Color(r,g,b);
flag=false;
}
}

return color;
}

/**
 * 绘制干扰线条
 * @param g 图层
 * @param NoiseLineNumber 干扰线数量
 */
private void drawNoiseLine(Graphics2D g,int NoiseLineNumber) {
g.setColor(createRandomColor(100,250));

int x1=0,y1=0,x2=0,y2=0;

for(int i=0;i<NoiseLineNumber;i++)
{
x1=(int) (1+(Math.random()*120));
y1=(int) (1+(Math.random()*40));
x2=(int) (1+(Math.random()*120));
y2=(int) (1+(Math.random()*40));
g.setStroke(new BasicStroke(2, BasicStroke.CAP_SQUARE, BasicStroke.JOIN_ROUND));
g.drawLine(x1, y1, x2, y2);
}

}
}

结果如下