[Java知识库]处理全站编码乱码问题

package day31_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.annotation.WebFilter;
import javax.servlet.http.HttpServletRequest;
/**
 * 处理全站乱码--Filter(过滤器)
 *2022年3月30日下午5:10:24
 * @author tao
 */
@WebFilter("/*")
public class EncodingFilter implements Filter {

	public void destroy() {
		// TODO Auto-generated method stub
	}

	public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
			throws IOException, ServletException {
		//处理post请求
		request.setCharacterEncoding("utf-8");
		HttpServletRequest req = (HttpServletRequest) request;
		/**
		 * 处理get请求
		 * 
		 */
//		String userName = request.getParameter("userName");
//		userName = new String(userName.getBytes("ISO-8859-1"),"utf-8");
		/**
		 * 调包request
		 * 1.写一个request的装饰类
		 * 2.在放行时，使用我们的request
		 */
		if(req.getMethod().equalsIgnoreCase("GET")) {
			EncodingRequest er = new EncodingRequest(req);
			chain.doFilter(er, response);
		}else if(req.getMethod().equalsIgnoreCase("POST")) {
			chain.doFilter(request, response);
	}
	}
	public void init(FilterConfig fConfig) throws ServletException {
		// TODO Auto-generated method stub
	}

}

?下面是需要用到的装饰类

装饰器模式（Decorator Pattern）允许向一个现有的对象添加新的功能，同时又不改变其结构。这种类型的设计模式属于结构型模式，它是作为现有的类的一个包装。

这种模式创建了一个装饰类，用来包装原有的类，并在保持类方法签名完整性的前提下，提供了额外的功能。

装饰类是为扩展类的功能

package day31_Filter;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.UnsupportedEncodingException;
import java.security.Principal;
import java.util.Collection;
import java.util.Enumeration;
import java.util.Locale;
import java.util.Map;

import javax.servlet.AsyncContext;
import javax.servlet.DispatcherType;
import javax.servlet.RequestDispatcher;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.ServletInputStream;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletRequestWrapper;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import javax.servlet.http.HttpUpgradeHandler;
import javax.servlet.http.Part;

/**
 * 装饰request
 *2022年3月30日下午5:12:38
 * @author tao
 * HttpServletRequestWrapper类 -->实现了HttpServletRequest接口
 */
public class EncodingRequest extends HttpServletRequestWrapper{
	private HttpServletRequest request;
	public EncodingRequest(HttpServletRequest request) {
		super(request);
		// TODO Auto-generated constructor stub
		this.request = request; 
	}
	public String getParameter(String name) {
		// TODO Auto-generated method stub
		String value = request.getParameter(name);
		//处理编码问题
		try {
			value = new String(value.getBytes("ISO-8859-1"),"utf-8");
		} catch (UnsupportedEncodingException e) {
			// TODO Auto-generated catch block
			throw new RuntimeException(e);
		}
		return value;
	}
}