【javaweb:Filter】通过过滤器和装饰设计模式解决request的全局乱码

最新推荐文章于 2020-11-29 00:52:05 发布

原创最新推荐文章于 2020-11-29 00:52:05 发布 · 421 阅读

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本文介绍了一个使用装饰者模式实现的编码过滤器，该过滤器能够对HTTP请求参数进行编码转换，解决因编码不一致导致的数据乱码问题。通过创建一个自定义的HttpServletRequest包装类来增强原始请求对象的功能。

package indi.filter;

import java.io.IOException;
import java.io.UnsupportedEncodingException;

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.HttpServletRequestWrapper;

public class EncodingFilter implements Filter{

	
	@Override
	public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
			throws IOException, ServletException {
			
		//在传递request之前对request的getParameter方法进行增强
		/*
		 * 装饰者模式(包装)
		 * 
		 * 1、增强类与被增强的类要实现统一接口
		 * 2、在增强类中传入被增强的类
		 * 3、需要增强的方法重写 不需要增强的方法调用被增强对象的
		 * 
		 */
		
		//被增强的对象
		HttpServletRequest req = (HttpServletRequest) request;
		//增强对象
		EnhanceRequest enhanceRequest = new EnhanceRequest(req);
		//放行
		chain.doFilter(enhanceRequest, response);
	}

	@Override
	public void destroy() {
		
	}
	
	@Override
	public void init(FilterConfig filterConfig) throws ServletException {
		
	}

}

class EnhanceRequest extends HttpServletRequestWrapper{
	
	private HttpServletRequest request;

	public EnhanceRequest(HttpServletRequest request) {
		super(request);
		this.request = request;
	}
	
	//对getParaameter增强
	@Override
	public String getParameter(String name) {
		String parameter = request.getParameter(name);//乱码
		try {
			parameter = new String(parameter.getBytes("iso8859-1"),"UTF-8");
		} catch (UnsupportedEncodingException e) {
			e.printStackTrace();
		}
		return parameter;
	}
	
}