Struts2生成验证码小例子

众所周知，验证码在互联网中应用非常之广泛，作用也很明确，防止机器人。下面我将详细讲解如何利用struts2来生成验证码：

Struts2生成验证码小例子

step1：ImageUtil.java

工具类，生产指定大小的图片

package image;

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.io.ByteArrayOutputStream;
import java.util.Random;

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

public class ImageUtil {
	public static byte[] getInstance(int width,int height,int num,String number) throws Exception{
		byte[] codeArr = null;
		 /* 
         * 一,绘图 
         */  
        //step1,内存映像对象(画布)  
        BufferedImage image =   
            new BufferedImage(width,height,  BufferedImage.TYPE_INT_RGB); 
        
        //step2,获得画笔  
        Graphics g = image.getGraphics();  
        
        //step3,给画笔设置颜色  
        Random r = new Random();  
        g.setColor(new Color(r.nextInt(255),  r.nextInt(255),r.nextInt(255)));  
        
        //step4,给画布设置背景颜色  
        g.fillRect(0, 0, width, height); 
        
        //step5,重新给笔设置颜色  
        g.setColor(new Color(255,255,255));  
        g.setFont(new Font(null,Font.ITALIC,height-height/5)); 
        
        //step6,将验证码转换成图片  
        g.drawString(number, width/10, height-height/5);  
        //step7,加一些干扰线  
        for(int i = 0; i < 8; i ++){  
            g.setColor(new Color(r.nextInt(255),  
                    r.nextInt(255),r.nextInt(255)));  
            g.drawLine(r.nextInt(width),  r.nextInt(height),
            		r.nextInt(width),  r.nextInt(height));  
        }  
        /* 
         * 二,压缩图片并输出 
         */  
        //1.字节数组输出流，向字节数组中输出信息
        ByteArrayOutputStream baos = new ByteArrayOutputStream();
        
        //2.压缩图片
        JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(baos);
        
        //图片中的二进制信息输出到内存中
        encoder.encode(image);
        
        codeArr = baos.toByteArray();
        
        return codeArr;
	}
          
      
	//获取随机数
    public static String getNumber(int num) {  
        String number = "";  
        String chars = "0123456789";  
        Random r = new Random();  
        for(int i = 0; i < num; i ++){  
            number += chars.charAt(  
                    r.nextInt(chars.length()));  
        }  
        return number;  
    }  
		
}

step2：VerifyAction.java

生成验证码Action，将生成的验证码的字节数组连接到InputStream流上，传给VS，以便jsp页面使用

package image;

import java.io.ByteArrayInputStream;
import java.io.InputStream;

public class VerifyAction {
	public InputStream inputStream;
	
	public InputStream getInputStream() {
		return inputStream;
	}

	public void setInputStream(InputStream inputStream) {
		this.inputStream = inputStream;
	}

	public String execute() throws Exception{
		String number = ImageUtil.getNumber(4);
		try {
			byte[] arr = ImageUtil.getInstance(100, 30,4, number);
			inputStream = new ByteArrayInputStream(arr);
		} catch (Exception e) {
			e.printStackTrace();
			throw e;
		}
		return "success";
	}
}

struts.xml文件

	<package name="image" namespace="/image" extends="struts-default">
		<!--stream类型负责输出二进制信息  -->
		<action name="img" class="image.VerifyAction">
			<result name="success" type="stream">
				<!-- inputName是一个OGNL表达式，该表达式可以从VS中获取相应的属性值 -->
				<!-- StreamResult就是从InputStream对象中读取输入流 -->
				<param name="inputName">inputStream</param>
			</result>
		</action>
	</package>

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Struts2生成验证码小例子

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