使用动态代理实现对request和response的增强

最新推荐文章于 2020-12-21 19:19:15 发布

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本文介绍了一种通过自定义过滤器解决Web应用中中文乱码问题的方法，并实现了对HTTP响应内容的GZIP压缩，有效减少数据传输量。

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对request进行增强，解决提交时出现的中文乱码问题。

public class CharacterEncodingFilter implements Filter {
	
	public void doFilter(ServletRequest req, ServletResponse resp,
			FilterChain chain) throws IOException, ServletException {
		
		final HttpServletRequest request = (HttpServletRequest) req;
		HttpServletResponse response = (HttpServletResponse) resp;
		
		
		request.setCharacterEncoding("UTF-8");  //post
		response.setCharacterEncoding("UTF-8");
		response.setContentType("text/html;charset=UTF-8");
		
		
		//request.getParamter()  requestProxy.getParameter()
		chain.doFilter((ServletRequest) Proxy.newProxyInstance(CharacterEncodingFilter.class.getClassLoader(),request.getClass().getInterfaces(), new InvocationHandler(){

			public Object invoke(Object proxy, Method method, Object[] args)
					throws Throwable {
			
				if(!method.getName().equals("getParameter")){
					return method.invoke(request, args);
				}
				
				if(!request.getMethod().equalsIgnoreCase("get")){
					return method.invoke(request, args);
				}
				
				//getParameter get
				String value = (String) method.invoke(request, args);
				if(value==null){
					return null;
				}
				
				return new String(value.getBytes("iso8859-1"),"UTF-8");
			}
			
		}), response);  
		

	}
	

	public void destroy() {}
	public void init(FilterConfig filterConfig) throws ServletException {}

}

使用动态代理，实现对response响应文本内容进行压缩

public class GzipFilter implements Filter {

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

	}

	public void doFilter(ServletRequest req, ServletResponse resp,
			FilterChain chain) throws IOException, ServletException {

		
		final HttpServletRequest request = (HttpServletRequest) req;
		final HttpServletResponse response = (HttpServletResponse) resp;
		
		final ByteArrayOutputStream bout = new ByteArrayOutputStream();
		final PrintWriter pw = new PrintWriter(new OutputStreamWriter(bout,"UTF-8"));
		
		//response.getWriter().write("aaa");  responseProxy
		chain.doFilter(request, (ServletResponse) Proxy.newProxyInstance(GzipFilter.class.getClassLoader(), response.getClass().getInterfaces(), new InvocationHandler(){

			public Object invoke(Object proxy, Method method, Object[] args)
					throws Throwable {
				if(method.getName().equals("getWriter")){
					return pw; 
				}else if(method.getName().equals("getOutputStream")){  //servletOutputStream
					return new MyServletOutputStream(bout);
				}else{
					return method.invoke(response, args);
				}
			}
		}));
		
		
		pw.close();
		byte result[] = bout.toByteArray();  //拿到目标资源的输出
		System.out.println("原始大小：" + result.length);
		
		ByteArrayOutputStream bout2 = new ByteArrayOutputStream();
		GZIPOutputStream gout = new GZIPOutputStream(bout2);
		gout.write(result);
		gout.close();
		
		byte gzip[] = bout2.toByteArray();  //拿到目标资源输出的压缩数据
		System.out.println("压缩大小：" + gzip.length);
		
		response.setHeader("content-encoding", "gzip");
		response.setContentLength(gzip.length);
		response.getOutputStream().write(gzip);
		
		
		
		
		
		
	}

	public void init(FilterConfig filterConfig) throws ServletException {
		// TODO Auto-generated method stub

	}
}

class MyServletOutputStream extends ServletOutputStream{

	
	private ByteArrayOutputStream  bout = null;
	public MyServletOutputStream(ByteArrayOutputStream  bout){
		this.bout = bout;
	}
	@Override
	public void write(int b) throws IOException {
		bout.write(b);
	}
	
}