keycodefilter.java

struts spring ibatis

package com.struts2.framework.filter;

import java.io.IOException;
import java.util.Random;

import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;

import com.struts2.framework.util.ImageServlet;





public class KeyCodeFilter implements Filter{
	public void init(FilterConfig config) {
	}

	public void doFilter(ServletRequest request, ServletResponse response,
			FilterChain chain) throws IOException, ServletException {
		String randomCode = randomInt(4) + "";
		request.setAttribute("randomCode",randomCode);
		 String key = ImageServlet.encode(randomCode);
		 request.setAttribute("key",key);
		 request.setCharacterEncoding("UTF-8");
		 chain.doFilter(request, response);
	}

	public void destroy() {
		try {
			this.finalize();
		} catch (Throwable e) {
			
			e.printStackTrace();
		}
	}
	public static final int randomInt(int length) {
		if (length < 1 && length > 9)
			throw new ArithmeticException(
					"the length of random int must be between 0 and 9");
		int sum = 0;
		int n = 1;
		int r = 0;
		for (int i = 1; i < length; i++) {
			r = randGen.nextInt(10);
			sum += r * n;
			n *= 10;
		}

		r = 1 + randGen.nextInt(9);
		sum += r * n;
		return sum;
	}
	private static Random randGen = new Random();
}