java如何在拦截器中取出post请求参数

！！！更推荐切面做这些操作，切面打印日志
get请求参数很好取出，但是对于post请求body里边的参数，因为是从流里边取，而这个流又只能取出来一次，如果你再拦截器里取出打印，后边的controller接口就无法在接受到请求参数，因此，你只能取出数据的同时，复制一份再放回去。
具体代码如下：

public class NewHttpRequestWrapper extends HttpServletRequestWrapper {
    private final String body;

    public NewHttpRequestWrapper(HttpServletRequest request) {
        super(request);
        StringBuilder stringBuilder = new StringBuilder();
        BufferedReader bufferedReader = null;
        InputStream inputStream = null;
        try {
            inputStream = request.getInputStream();
            if (inputStream != null) {
                bufferedReader = new BufferedReader(new InputStreamReader(inputStream));
                char[] charBuffer = new char[128];
                int bytesRead = -1;
                while ((bytesRead = bufferedReader.read(charBuffer)) > 0) {
                    stringBuilder.append(charBuffer, 0, bytesRead);
                }
            } else {
                stringBuilder.append("");
            }
        } catch (IOException ex) {

        } finally {
            if (inputStream != null) {
                try {
                    inputStream.close();
                }
                catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if (bufferedReader != null) {
                try {
                    bufferedReader.close();
                }
                catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
        body = stringBuilder.toString();
    }

    @Override
    public ServletInputStream getInputStream() throws IOException {
        final ByteArrayInputStream byteArrayInputStream = new ByteArrayInputStream(body.getBytes());
        return new ServletInputStream() {
            @Override
            public boolean isFinished() {
                return false;
            }
            @Override
            public boolean isReady() {
                return false;
            }
            @Override
            public void setReadListener(ReadListener readListener) {
            }
            @Override
            public int read() throws IOException {
                return byteArrayInputStream.read();
            }
        };
    }

    @Override
    public BufferedReader getReader() throws IOException {
        return new BufferedReader(new InputStreamReader(this.getInputStream()));
    }

    public String getBody() {
    //为了去除空格、换行符等
        return StringUtils.trimAllWhitespace(this.body);
    }
}

拦截器获取请求body参数：

NewHttpRequestWrapper requestWrapper = new NewHttpRequestWrapper(request);
        String body = requestWrapper.getBody();

通过filter将参数放回去：

@WebFilter(urlPatterns = "/*",filterName = "channelFilter")
public class RequestFilter implements Filter {

    @Override
    public void init(FilterConfig filterConfig) throws ServletException {

    }

    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
        ServletRequest requestWrapper = null;
        if(servletRequest instanceof HttpServletRequest) {
            requestWrapper = new NewHttpRequestWrapper((HttpServletRequest) servletRequest);
        }
        if(requestWrapper == null) {
            filterChain.doFilter(servletRequest, servletResponse);
        } else {
            filterChain.doFilter(requestWrapper, servletResponse);
        }
    }

    @Override
    public void destroy() {

    }
}

同时要在启动类上声明filter启用，加上下边的注解

@ServletComponentScan

这样就可以了。
！！！！注意事项：复制流这个操作仅限于body数据格式是JSON的情况。如果是form-urllencoded这种key-value格式的，不能走复制流，否则controller会拿不到参数，这种key-value直接在拦截器里边request.getParameter就可以了，不用复制~
如果既有form表单数据，又有key-value参数，取的时候就会麻烦，看到了一篇博客，但是没这个需求没有做，而且也没看太懂怎么做。。提取form表单数据
其他参考资料

参考资料：
另一种写法
本博客参考资料