JSP验证码

很多人在JSP验证码上都迷糊，这里我介绍一下一种验证码（纯数字的），4位随机数（0-9）不多说了，我们就来看下代码吧！image.jsp

<%@ page contentType="image/jpeg" import="java.awt.*, 
java.awt.image.*,java.util.*,javax.imageio.*" pageEncoding="UTF-8"%> 
<%! 
	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); 
} 
%> 
<% 
	out.clear();//这句针对resin服务器，如果是tomcat可以不要这句 
	response.setHeader("Pragma","No-cache"); 
	response.setHeader("Cache-Control","no-cache"); 
	response.setDateHeader("Expires", 0); 
	int width=60, height=20; 
	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(0, 0, width, height); 
	g.setFont(new Font("Times New Roman",Font.PLAIN,18)); 
	g.setColor(getRandColor(160,200)); 
	for (int i=0;i<155;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); 
	} 
	String sRand=""; 
	for (int i=0;i<4;i++){ 
	String rand=String.valueOf(random.nextInt(10)); 
	sRand+=rand; 
	g.setColor(new Color(20+random.nextInt(110),20+random.nextInt(110),20+random.nextInt(110))); 
	g.drawString(rand,13*i+6,16); 
	} 
	// 将认证码存入SESSION 
	session.setAttribute("rand",sRand); 
	g.dispose(); 
	ImageIO.write(image, "JPEG", response.getOutputStream()); 
%>

 

引用的时候只要如下代码：（jsp文件中）-->这里还给了刷新验证码的作用

login.jsp

 

<script language="JavaScript">
      //刷新验证码
    function loadimage()
     {
           document.getElementById("randImage").src= "images.jsp?"+Math.random(); 
     } 
</script>

<a href="javascript:loadimage();" >
     <img alt="点击刷新" 
        name="randImage" id="randImage" 
        src="./images.jsp"
        width="60" 
        height="20" 
        border="1" 
       align="absmiddle">
</a>

 

这时候我们在业务控制端（如servlet、struts2 action类）

这里以struts2 action为例，代码如下：

LoginAction.java

 

public class LoginAction extends ActionSupport
{
	private String message="";
	private String verifycode;
	public String getMessage() {
		return message;
	}
	public void setMessage(String message) {
		this.message = message;
	}
	public String getVerifycode() {
		return verifycode;
	}
	public void setVerifycode(String verifycode) {
		this.verifycode = verifycode;
	}
	public String execute() throws Exception 
	{
		
		//this.INPUT;
		HttpServletRequest request = ServletActionContext.getRequest();
		HttpSession session=request.getSession();
		
		if("".equals(this.getVerifycode()))
		{
			this.setMessage("<font color='red'>验证码不能为空</font>");
			return this.INPUT;
		}
		else if(!session.getAttribute("rand").equals(this.getVerifycode()))
		{
			this.setMessage("<font color='red'>验证码出错！</font>");
			return this.INPUT;			
		}
		else
		{
			this.setMessage("<font color='red'>验证码输入正确！</font>");
						return this.SUCCESS;
		}
			
	}
}

 

希望对大家有用~