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经常看到有些很逗的项目，用AOP切Controller去打印日志，我只能说呵呵，aop是让你们这些人乱用的吗？不会用就不要用，是，我承认AOP切controller完全可以做到打印日志，但是，这种严重破坏对象封装并且完全不理解aop应用场景的做法完全不可取，如果什么事情都用aop，那么请问spring security项目为什么全都采用filter的方式，而非aop呢??

言归正传，打印日志的方式应该是我们自己定义一个过滤器，这个过滤器专门用来打印日志，打印完日志之后，再进行到下一个过滤器继续处理数据，但是从流中读取数据的难点在于，本次从流中读出了数据，那么下行程序链将无法再次读取流中数据，所以重点在于HttpServletRequestWrapper类

1.创建类RequestWrapper 继承 HttpServletRequestWrapper，然后重写

public class MyRequestWrapper extends HttpServletRequestWrapper {	public String body;	public MyRequestWrapper(HttpServletRequest request) throws IOException {		super(request);		StringBuilder sb = new StringBuilder();		String line;		InputStream stream = request.getInputStream();		BufferedReader br = new BufferedReader(new InputStreamReader(stream));		while ((line = br.readLine()) != null) {			sb.append(line);		}		body = sb.toString();	}	@Override	public ServletInputStream getInputStream() throws IOException {		final ByteArrayInputStream byteArrayInputStream = new ByteArrayInputStream(body.getBytes());		ServletInputStream servletInputStream = new ServletInputStream() {			@Override			public int read() throws IOException {				return byteArrayInputStream.read();			}			@Override			public boolean isFinished() {				return false;			}			@Override			public boolean isReady() {				return false;			}			@Override			public void setReadListener(ReadListener listener) {			}		};		return servletInputStream;	}	@Override	public BufferedReader getReader() throws IOException {		return new BufferedReader(new InputStreamReader(getInputStream()));	}}

2.创建类RequestFilter实现 Filter

@Order(0)//注意这里，无需再从web.xml中配置了@WebFilter(filterName = "MyFilter", urlPatterns = "/*")public class MyFilter implements Filter {	@Override	public void init(FilterConfig filterConfig) throws ServletException {	}	@Override	public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)			throws IOException, ServletException {		System.out.println("过滤器，开始打日志");		MyRequestWrapper wrapper = new MyRequestWrapper((HttpServletRequest) request);		System.out.println("body内容：" + wrapper.body);		chain.doFilter(wrapper, response);	}	@Override	public void destroy() {	}}

3.如果项目是spring boot,那么需要扫描到WebFilter注解，需要在启动类添加

@SpringBootApplication//扫描servlet相关注解@ServletComponentScanpublic class DemoApplication {	public static void main(String[] args) {		SpringApplication.run(DemoApplication.class, args);	}}

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