package com;

import java.io.IOException;

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 javax.servlet.http.HttpServletRequest;

public class CharacterEncodingFilter implements Filter {
	protected String encoding = null;// 定义编码格式变量
	protected FilterConfig filterConfig = null;// 定义过滤器配置对象

	public void init(FilterConfig filterConfig) throws ServletException {
		this.filterConfig = filterConfig; // 初始化过滤器配置对象
		this.encoding = filterConfig.getInitParameter("encoding");// 获取配置文件中指定的编码格式
	}

	// 过滤器的接口方法，用于执行过滤业务
	public void doFilter(ServletRequest request, ServletResponse response,
			FilterChain chain) throws IOException, ServletException {
		if (encoding != null) {
			HttpServletRequest hsRequest = (HttpServletRequest) request;// 获取HttpServletRequest对象
			String requestedWith = hsRequest.getHeader("x-requested-with");// 获取请求的发出者，该信息由Ajax发送POST请求时设置
			String contentType = request.getContentType();// 获取请求的内容类型
			if (null != contentType
					&& contentType
							.equalsIgnoreCase("application/x-www-form-urlencoded")
					&& null != requestedWith && requestedWith.equals("ajax")) {
				request.setCharacterEncoding("UTF-8");// 设置编码为UTF-8

			} else {
				request.setCharacterEncoding(encoding); // 设置请求的编码
				response.setContentType("text/html; charset=" + encoding);// 设置应答对象的内容类型（包括编码格式）
			}
		}
		chain.doFilter(request, response); // 传递给下一个过滤器
	}

	public void destroy() {
		this.encoding = null;
		this.filterConfig = null;
	}
}