用清脆声铸建程序

package org.itrun.cnbrn.view.pageclass.system;

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.servlet.ServletContext;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.tapestry.IRequestCycle;
import org.apache.tapestry.engine.IEngineService;
import org.apache.tapestry.engine.ILink;
import org.apache.tapestry.web.WebSession;
import org.itrun.cnbrn.ConstantVar;

import com.sun.image.codec.jpeg.JPEGCodec;
import com.sun.image.codec.jpeg.JPEGImageEncoder;

public class ValidatorImageService implements IEngineService {

	Log logger=LogFactory.getLog(this.getClass());
	
	private HttpServletResponse response;
	private ServletContext context;
	private String TYPE="jpeg";

    public void setResponse(HttpServletResponse response){
        this.response = response;
    }
    
    public void setContext(ServletContext context){
    	this.context=context;
    }

	public ILink getLink(boolean arg0, Object arg1) {
		return null;
	}

	public String getName() {
		return "validatorImage";
	}

	public void service(IRequestCycle cycle) throws IOException {
		Random random = new Random();
		StringBuffer sb=new StringBuffer();
		for(int i=0;i<4;i++){
			int x=random.nextInt(25);
			x+=65;
			sb.append(String.valueOf((char)x));
			//sb.append(" ");
		}		
		String validateString=sb.toString();		
		WebSession sess=cycle.getInfrastructure().getRequest().getSession(true);
		sess.setAttribute(ConstantVar.VALIDATOR_SESSION_KEY, validateString);
		//画布大小
		int width = 60, height = 20;
		BufferedImage image = new BufferedImage(width, height,BufferedImage.TYPE_INT_RGB);
		Graphics g = image.getGraphics();
		// 以下填充背景颜色
		g.setColor(Color.decode("#FFFFFF"));
		g.fillRect(0, 0, width, height);
		//随机产生其他元素，使图象中的认证码不易被其它程序探测到
		g.setColor(getRandColor(160, 200));
		for (int i = 0; i < 300; i++) {
			int x = random.nextInt(width);
			int y = random.nextInt(height);
			int xl = random.nextInt(12);
			int yl = random.nextInt(12);
			g.drawLine(x, y, x + xl, y + yl);
		}
		
		//字的颜色
		g.setColor(Color.decode("#01556B"));
		//写的字的大小
		g.setFont(new Font(null, Font.BOLD, 18));
		//在画布上写字
		g.drawString(validateString, 2, 16);
		g.dispose();
		OutputStream os = response.getOutputStream();
		JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(os);
		encoder.encode(image);
		os.close();
	}
	
	private Color getRandColor(int fc,int bc){//给定范围获得随机颜色
        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);
    }
}

  	<service-point id="ValidatorImageService" interface="org.apache.tapestry.engine.IEngineService">
		<invoke-factory>
             <construct class="org.itrun.cnbrn.view.pageclass.system.ValidatorImageService"/>
		</invoke-factory>
    </service-point>

    <contribution configuration-id="tapestry.services.ApplicationServices">
      	<service name="validatorImage" object="service:ValidatorImageService"/>
    </contribution>

<img jwcid="@Any" src="ognl:cnbrnContextPath+'/app?service=validatorImage'" />