【转】Struts2 图形验证码

最新推荐文章于 2018-03-27 09:43:07 发布

原创最新推荐文章于 2018-03-27 09:43:07 发布 · 668 阅读

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本文介绍如何使用Struts2框架生成包含随机数字的验证码图片，并将其输出到客户端。该过程涉及随机数生成、图片绘制及Struts2配置。

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package com.gsj.action;

import java.io.*;
import javax.imageio.ImageIO;
import javax.imageio.stream.ImageOutputStream;

import org.apache.struts2.ServletActionContext;

import com.opensymphony.xwork2.ActionSupport;

import java.awt.*;
import java.awt.image.BufferedImage;
//DefaultAction类继承了ActionSupport 并定义了session变量
public class CreateValidateAction extends ActionSupport {

    /**
*
*/
private static final long serialVersionUID = 1L;
private ByteArrayInputStream inputStream;
    //产生四个0~9的随机数，放在一个字符串里
    public String createRandomString() {
        String str = "";
        for (int i = 0; i < 4; i++) {
            str += Integer.toString((new Double(Math.random() * 10)).intValue());
        }
        return str;
    }
    //随机产生一个颜色
    public Color createsRandomColor() {
        int r = (new Double(Math.random() * 256)).intValue();
        int g = (new Double(Math.random() * 256)).intValue();
        int b = (new Double(Math.random() * 256)).intValue();
        return new Color(r, g, b);
    }
    //生成一个内存图片，将四个随机数写在图片上
    public BufferedImage createImage(String str) {
        int width = 60;
        int height = 22;
        BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
        // 获取图形上下文
        Graphics g = image.getGraphics();
        // 设定背景色
        g.setColor(Color.WHITE);
        g.fillRect(0, 0, width, height);
        //画边框
        g.setColor(Color.black);
        g.drawRect(0, 0, width - 1, height - 1);
        // 将认证码显示到图象中
        g.setFont(new Font("Atlantic Inline", Font.PLAIN, 18));
        //使用随机颜色
        g.setColor(this.createsRandomColor());
        //将随机字符串的每个数字分别写到图片上
        g.drawString(Character.toString(str.charAt(0)), 8, 17);
        g.drawString(Character.toString(str.charAt(1)), 20, 17);
        g.drawString(Character.toString(str.charAt(2)), 33, 17);
        g.drawString(Character.toString(str.charAt(3)), 45, 17);
        // 图象生效
        g.dispose();
        return image;
    }
    //将图片的以字节形式写到InputStream里
    public ByteArrayInputStream createInputStream() throws Exception {
        //获取随机字符串
        String str=this.createRandomString();
        BufferedImage image = this.createImage(str);
        //将产生的字符串写入session，供校验时使用
        ServletActionContext.getRequest().getSession().setAttribute("validateCode", str);
        ByteArrayOutputStream output = new ByteArrayOutputStream();
        ImageOutputStream imageOut = ImageIO.createImageOutputStream(output);
        ImageIO.write(image, "JPEG", imageOut);
        imageOut.close();
        ByteArrayInputStream input = new ByteArrayInputStream(output.toByteArray());
        output.close();
        return input;
    }

    @Override
    public String execute() throws Exception {
        setInputStream(createInputStream());
        return SUCCESS;
    }

    public ByteArrayInputStream getInputStream() {
        return inputStream;
    }
    public void setInputStream(ByteArrayInputStream inputStream) {
        this.inputStream = inputStream;
    }
}

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struts.xml

<action name="createValidateAction" class="createValidateAction">
            <result type="stream">
                <param name="contentType">image/jpeg</param>
                <param name="inputName">inputStream</param>
            </result>
        </action>

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页面

<tr>
<td height="30" align="center">验证码</td>
<td><input name="yzm" type="text" id="yzm" size="10" />   <img src="createValidateAction.action" alt="看不清，再换一张？" style="cursor: hand;" align="absmiddle" onClick="changeValidateCode(this)"/></td>
</tr>
----------------------------------------------------------------------------------------------------------------------------------------------------------------

验证码在服务器端验证，所以不能在验证码所在页用JS验证 session中的验证码会和图片中的不一致。