package com.gd.web.filter;

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 GdSetCharacterEncodingFilter implements Filter {
	//定義編碼方式
	protected String encoding = null;
    protected FilterConfig filterConfig = null;
    protected boolean ignore = true;
    /**
     * 初始化
     */
    public void init(FilterConfig filterConfig) throws ServletException {
    	//根據web.xml的設定獲取編碼方式
        this.filterConfig = filterConfig;
        this.encoding = filterConfig.getInitParameter("encoding");
        String value = filterConfig.getInitParameter("ignore");
        //假如沒有設定ignore，則表示使用設定的編碼方式
        if (value == null)
              this.ignore = true;
        else if (value.equalsIgnoreCase("true"))
              this.ignore = true;
        else if (value.equalsIgnoreCase("yes"))
              this.ignore = true;
        else
              this.ignore = false;
    }

    /**
     * 進行過濾，設定編碼
     */
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws ServletException, IOException {
		HttpServletRequest req = (HttpServletRequest)request;
          //加入設定了ignore，或設定了encoding，則使用設定編碼方式
          if (ignore || (request.getCharacterEncoding() == null)) {
                String encoding = selectEncoding(request);
                if (encoding != null) {
                	request.setCharacterEncoding(encoding);
                	System.out.println(" 使用web.xml中指定的編碼方式：" + encoding + " 進行編碼。");
                }
                      
          }
          chain.doFilter(request, response);
    }
    /**
     * 銷毀
     */
    public void destroy() {
        this.encoding = null;
        this.filterConfig = null;

    }
    /**
     * 獲取編碼方式
     * @param request
     * @return
     */
    protected String selectEncoding(ServletRequest request) {
          return (this.encoding);
    }

}