Filter + 动态代理实现全局编码

本是古典何须时尚 2022-04-04 10:14 174阅读 0赞

html：

filter：

package web.filter;
    
    import java.io.IOException;
    import java.io.UnsupportedEncodingException;
    import java.lang.reflect.InvocationHandler;
    import java.lang.reflect.Method;
    import java.lang.reflect.Proxy;
    
    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 {
    		
    		
    		//被增强的对象
    		final HttpServletRequest req = (HttpServletRequest) request;
    
    		HttpServletRequest newProxyInstance = (HttpServletRequest) Proxy.newProxyInstance(req.getClass().getClassLoader(),
    								req.getClass().getInterfaces(), 
    								new InvocationHandler() {
    									
    									@Override
    									public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
    										String mothodName = method.getName();
    										if("getParameter".equals(mothodName)) {
    											String invoke = (String) method.invoke(req, args);
    											System.out.println("乱码"+invoke);
    											invoke = new String(invoke.getBytes("iso8859-1"),"UTF-8");
    											return invoke;
    										}
    										return method.invoke(req, args);
    									}
    								});
    		
    		chain.doFilter(newProxyInstance, response);
    		
    	}
    
    	@Override
    	public void destroy() {
    		
    	}
    	
    	@Override
    	public void init(FilterConfig filterConfig) throws ServletException {
    		
    	}
    
    }

servlet：

String parameter = request.getParameter("username");
    		System.out.println(parameter);
    		response.setContentType("text/html;charset=UTF-8"); 
    		response.getWriter().write(parameter);

web.xml

<filter>
        <filter-name>EncodingFilter</filter-name>
        <filter-class>web.filter.EncodingFilter</filter-class>
      </filter>
      <filter-mapping>
        <filter-name>EncodingFilter</filter-name>
        <url-pattern>/*</url-pattern>
      </filter-mapping>

![20181216152718787.png][]

[20181216152718787.png]: /images/20220404/868f81769ff74f7cba6ef29534f83ae3.png