Servlet中请求参数的编码处理Filter

由于GET请求参数的编码和POST请求的BODY编码原理不一样，而且这个处理几乎在所有请求中都要处理，因此可以将其放在Filter中进行统一处理。

 

基本的原理是：POST请求与body的编码一致，因此在读取参数前，直接通过setCharacterEncoding会覆盖http头中的设置；GET请求会比较复杂一点，一般都是在请求URL中指定URLENCODE的编码类型，而服务器对应的进行解码。可以有两种方式，一种是tomcat设置Connector中的URIEncoding，一种就是通过filter了。

下面代码均参考至《JSP&Servlet学习笔记》

 

 

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.annotation.WebInitParam;
import javax.servlet.http.HttpServletRequest;

@WebFilter(urlPatterns = { "/*" }, initParams = { @WebInitParam(name = "ENCODING", value = "UTF-8") })
public class EncodingFilter implements Filter {
	private String ENCODING;

	public void init(FilterConfig config) throws ServletException {
		ENCODING = config.getInitParameter("ENCODING");
	}

	public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
		HttpServletRequest req = (HttpServletRequest) request;
		/**
		 * GET请求参数中的解码，tomcat默认使用ISO-8859-1。因此需要对GET参数进行解码
		 * */
		if ("GET".equals(req.getMethod())) {
			req = new EncodingWrapper(req, ENCODING);
		} else {
			/**
			 * POST请求中body部分直根据指定编码方式进行
			 * */
			req.setCharacterEncoding(ENCODING);
		}
		chain.doFilter(req, response);
	}

	public void destroy() {
	}

}

 request的wrapper对象

 

 

import java.io.UnsupportedEncodingException;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletRequestWrapper;

public class EncodingWrapper extends HttpServletRequestWrapper {
    private String ENCODING;
    public EncodingWrapper(HttpServletRequest request, String ENCODING) {
        super(request);
        this.ENCODING = ENCODING;
    }
    
    @Override
    public String getParameter(String name) {
        String value = getRequest().getParameter(name);
        if(value != null) {
            try {
                byte[] b = value.getBytes("ISO-8859-1");
                value = new String(b, ENCODING);
            } catch (UnsupportedEncodingException e) {
                throw new RuntimeException(e);   
            }
        }
        return value;
    }
    
    

}