【WEB小工具】EncodingFilter—设置全局编码

　　1.我们知道，如果是POST请求，我们需要调用request.setCharacterEncoding("utf-8")

方法来设计编码。

public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
         request.setCharacterEncoding("gbk");  //只适用于post提交，不适用于get
         response.setCharacterEncoding("gbk");
    }

　　2.如果是GET请求，我们需要自己手动来处理编码问题。

　　3.如果我们使用了EncodingFilter，那么就处理了POST和GET请求的编码问题。

修改web.xml:

<!-- 处理全站请求编码。无论是GET还是POST,默认是UTS-8 -->
<filter>
    <filter-name>EncodingFilter</filter-name>
    <filter-class>cn.itcast.filter.EncodingFilter</filter-class>
    <init-param>
        <param-name>charset</param-name>
        <param-value>utf-8</param-value>
    </init-param>
</filter>
<filter-mapping>
    <filter-name>EncodingFilter</filter-name>
    <url-pattern>/*</url-pattern>
</filter-mapping>

EncodingFilter() 类源代码：

package cn.itcast.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 EncodingFilter implements Filter {
    private String charset = "UTF-8";
    @Override
    public void destroy() {}

    @Override
    public void doFilter(ServletRequest request, ServletResponse response,
            FilterChain chain) throws IOException, ServletException {
        HttpServletRequest req = (HttpServletRequest) request;
        if(req.getMethod().equalsIgnoreCase("GET")) {
            if(!(req instanceof GetRequest)) {
                req = new GetRequest(req, charset);//澶勭悊get璇锋眰缂栫爜
            }
        } else {
            req.setCharacterEncoding(charset);//澶勭悊post璇锋眰缂栫爜
        }
        chain.doFilter(req, response);
    }

    @Override
    public void init(FilterConfig fConfig) throws ServletException {
        String charset = fConfig.getInitParameter("charset");
        if(charset != null && !charset.isEmpty()) {
            this.charset = charset;
        }
    }
}