charsetfilter.java

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package com.knt.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;
import javax.servlet.http.HttpServletResponse;

public class CharSetFilter implements Filter {
	private FilterConfig config;
	//当web应用重新启动或者销毁的时候才调用销毁方法

	public void destroy() {
		System.out.println("filter准备销毁...");

	}
	//filter主要目的就是为了过滤字符编码;
	//其次还可以做一些简单的应用逻辑;
	public void doFilter(ServletRequest arg0, ServletResponse arg1,
			FilterChain arg2) throws IOException, ServletException {
		//强制转换成Http的请求和响应
		HttpServletRequest request =(HttpServletRequest)arg0;
		HttpServletResponse response =(HttpServletResponse)arg1;
		//设置编码集
		//request.setCharacterEncoding("UTF-8");
		//response.setCharacterEncoding("UTF-8");
		//response.setContentType("text/html;charset=UTF-8");
		request.setCharacterEncoding(config.getInitParameter("charset"));
		response.setCharacterEncoding(config.getInitParameter("charset"));
		response.setContentType(config.getInitParameter("contentType"));
		
		
		//将请求发送到对应的目的地
		arg2.doFilter(request,response);
	}

	//初始化的时候会跟web应用一起启动
	//Filter不宜设置太多,否则过滤会变得臃肿,然后妨碍客户使用
	public void init(FilterConfig config) throws ServletException {
		this.config=config;
		System.out.println("filter已经初始化");

	}

}