Servlet——使用Filter设置全局的字符编码

r囧r小猫 2022-05-16 06:12 178阅读 0赞

### 使用包装设计模式对request进行增强 ###

Servlet API 中提供了一个request对象的Decorator设计模式的默认实现类++HttpServletRequestWrapper++，以避免用户在对request对象进行增强时需要实现request接口中的所有方法。

package com.kexin.web.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;
    import javax.servlet.http.HttpServletResponse;
    
    public class CharacterEncodingFilter1 implements Filter {
        
        private FilterConfig config;
        private String defaultCharset = "utf-8";
        @Override
        public void destroy() {
        }
    
        @Override
        public void doFilter(ServletRequest arg0, ServletResponse arg1, FilterChain chain)
                throws IOException, ServletException {
            String charset = this.config.getInitParameter("charset");
            if(charset==null){
                charset = defaultCharset;
            }
            HttpServletRequest request = (HttpServletRequest) arg0;
            HttpServletResponse response = (HttpServletResponse) arg1;
            request.setCharacterEncoding(charset);
            response.setCharacterEncoding(charset);
            response.setContentType("text/html;charset="+charset);
            chain.doFilter(request, response);
        }
    
        @Override
        public void init(FilterConfig arg0) throws ServletException {
            this.config = arg0;
        }
    
    }
    class MyRequest extends HttpServletRequestWrapper{
        private HttpServletRequest request;
        public MyRequest(HttpServletRequest request) {
            super(request);
            this.request = request;
        }
        @Override
        public String getParameter(String name) {
            String value = this.request.getParameter(name);
            if(!request.getMethod().equalsIgnoreCase("get")){
                return value;
            }
            if(value==null){
                return null;
            }
            try {
                return value = new String(value.getBytes("iso8859-1"),request.getCharacterEncoding());
            } catch (UnsupportedEncodingException e) {
                throw new RuntimeException(e);
            }
    
        }
    
    }