拦截器中，request中getReader()和getInputStream()只能调用一次，构建可重复读取inputStream的request.

由于 request中getReader()和getInputStream()只能调用一次

在项目中，可能会出现需要针对接口参数进行校验等问题。

因此，针对这问题，给出一下解决方案

实现方法：先将RequestBody保存为一个byte数组，然后通过Servlet自带的HttpServletRequestWrapper类覆盖getReader()和getInputStream()方法，使流从保存的byte数组读取。然后再Filter中将ServletRequest替换为ServletRequestWrapper。代码如下：

BodyReaderHttpServletRequestWrapper类包装ServletRequest，将流保存为byte[]，然后将getReader()和getInputStream()方法的流的读取指向byte[]

http://zhangbo-peipei-163-com.iteye.com/blog/2022460

step 1:

添加RepeatedlyReadRequestWrapper 类并继承 HttpServletRequestWrapper 包装类

package com.config;

import org.apache.commons.lang3.StringUtils;

import javax.servlet.ReadListener;
import javax.servlet.ServletInputStream;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletRequestWrapper;
import java.io.BufferedReader;
import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.nio.charset.Charset;

public class RepeatedlyReadRequestWrapper extends HttpServletRequestWrapper {
    private final byte[] body;

    public RepeatedlyReadRequestWrapper(HttpServletRequest request)
            throws IOException {
        super(request);
        body = readBytes(request.getReader(), "utf-8");
    }

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

    @Override
    public ServletInputStream getInputStream() throws IOException {
        final ByteArrayInputStream bais = new ByteArrayInputStream(body);
        return new ServletInputStream() {

            @Override
            public boolean isFinished() {
            return false;
            }

            @Override
            public boolean isReady() {
            return false;
            }

            @Override
            public void setReadListener(ReadListener listener) {

            }

            @Override
            public int read() throws IOException {
            return bais.read();
            }
        };
    }

    /**
     * 通过BufferedReader和字符编码集转换成byte数组
     * @param br
     * @param encoding
     * @return
     * @throws IOException
     */
    private byte[] readBytes(BufferedReader br,String encoding) throws IOException{
        String str = null,retStr="";
        while ((str = br.readLine()) != null) {
            retStr += str;
        }
        if (StringUtils.isNotBlank(retStr)) {
            return retStr.getBytes(Charset.forName(encoding));
        }
        return null;
    }
}

step 2:

添加 RepeatedlyReadFilter 实现 filter 过滤器接口方法，当客户端的请求先过滤进入SpringMvc Dispatch 路由前先包装下

package com.filter;

import com.config.RepeatedlyReadRequestWrapper;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import javax.servlet.*;
import javax.servlet.http.HttpServletRequest;
import java.io.IOException;

/**
 * 复制请求数据包body
 * 以提供 拦截器下 可数次获取Body数据包*/
public class RepeatedlyReadFilter implements Filter {

    private static final Logger logger = LoggerFactory.getLogger(RepeatedlyReadFilter.class);

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

    }

    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
        logger.debug("复制request.getInputStream流");
        ServletRequest requestWrapper = null;
        if (request instanceof HttpServletRequest) {
            requestWrapper = new RepeatedlyReadRequestWrapper((HttpServletRequest) request);
        }
        if (null == requestWrapper) {
            chain.doFilter(request, response);
        } else {
            chain.doFilter(requestWrapper, response);
        }
    }

    @Override
    public void destroy() {

    }
}

step 3:

添加拦截器 RepeatedlyReadInterceptor 继承 HandlerInterceptorAdapter 拦截适配器

package com.interceptor;

import com.config.RepeatedlyReadRequestWrapper;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.web.servlet.ModelAndView;
import org.springframework.web.servlet.handler.HandlerInterceptorAdapter;

import javax.servlet.ServletInputStream;
import javax.servlet.ServletRequest;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.*;
import java.nio.charset.Charset;

public class RepeatedlyReadInterceptor extends HandlerInterceptorAdapter {

    private static final Logger logger = LoggerFactory.getLogger(RepeatedlyReadInterceptor.class);

    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        /**
         * 对来自后台的请求统一进行日志处理
         */
        RepeatedlyReadRequestWrapper requestWrapper;
        if (request instanceof RepeatedlyReadRequestWrapper) {
            // 签名处理过程 start.... 
            requestWrapper = (RepeatedlyReadRequestWrapper) request;
            logger.info("请求Body: {} ", getBodyString(requestWrapper));
            // 签名处理过程 end....
        }
        // 默认记录后台接口请求日志记录
        String url = request.getRequestURL().toString();
        String method = request.getMethod();
        String uri = request.getRequestURI();
        String queryString = request.getQueryString();
        logger.info(String.format("请求参数, url: %s, method: %s, uri: %s, params: %s ", url, method, uri, queryString));
        return super.preHandle(request, response, handler);
    }

    @Override
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
        RepeatedlyReadRequestWrapper requestWrapper;
        if (request instanceof RepeatedlyReadRequestWrapper) {
            // 测试再次获取Body start.... 
            requestWrapper = (RepeatedlyReadRequestWrapper) request;
            logger.info("请求Body: {} ", getBodyString(requestWrapper));
            // 测试再次获取Body end....
        }
    }

    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {

    }

    /**
     * 获取请求Body
     *
     * @param request
     *
     * @return
     */
    public static String getBodyString(final ServletRequest request) {
        StringBuilder sb = new StringBuilder();
        InputStream inputStream = null;
        BufferedReader reader = null;
        try {
            inputStream = cloneInputStream(request.getInputStream());
            reader = new BufferedReader(new InputStreamReader(inputStream, Charset.forName("UTF-8")));
            String line = "";
            while ((line = reader.readLine()) != null) {
            sb.append(line);
            }
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            if (inputStream != null) {
            try {
                inputStream.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
            }
            if (reader != null) {
            try {
                reader.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
            }
        }
        return sb.toString();
    }

    /**
     * Description: 复制输入流</br>
     *
     * @param inputStream
     *
     * @return</br>
     */
    public static InputStream cloneInputStream(ServletInputStream inputStream) {
        ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
        byte[] buffer = new byte[1024];
        int len;
        try {
            while ((len = inputStream.read(buffer)) > -1) {
            byteArrayOutputStream.write(buffer, 0, len);
            }
            byteArrayOutputStream.flush();
        } catch (IOException e) {
            e.printStackTrace();
        }
        InputStream byteArrayInputStream = new ByteArrayInputStream(byteArrayOutputStream.toByteArray());
        return byteArrayInputStream;
    }
}

step 4:

配置过滤器与拦截器 WebMvcConfig

package com.config;

import com.filter.RepeatedlyReadFilter;
import com.interceptor.MyInterceptor;
import org.springframework.boot.web.servlet.FilterRegistrationBean;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.*;

/**
 * SpringMVC 配置类*/
@Configuration
public class WebMvcConfig extends WebMvcConfigurerAdapter {

    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        registry.addInterceptor(new RepeatedlyReadInterceptor()).addPathPatterns("/**");
        super.addInterceptors(registry);
    }

    @Bean
    public FilterRegistrationBean repeatedlyReadFilter() {
        FilterRegistrationBean registration = new FilterRegistrationBean();
        RepeatedlyReadFilter repeatedlyReadFilter = new RepeatedlyReadFilter();
        registration.setFilter(repeatedlyReadFilter);
        registration.addUrlPatterns("/*");
        return registration;
    }
}

对于上述过滤器和拦截器的测试，可以得到如下结论：
（1）、Filter需要在web.xml中配置，依赖于Servlet；
（2）、Interceptor需要在SpringMVC中配置，依赖于框架；
（3）、Filter的执行顺序在Interceptor之前，具体的流程见下图；
这里写图片描述
（4）、两者的本质区别：拦截器（Interceptor）是基于Java的反射机制，而过滤器（Filter）是基于函数回调。从灵活性上说拦截器功能更强大些，Filter能做的事情，都能做，而且可以在请求前，请求后执行，比较灵活。Filter主要是针对URL地址做一个编码的事情、过滤掉没用的参数、安全校验（比较泛的，比如登录不登录之类），太细的话，还是建议用interceptor。不过还是根据不同情况选择合适的。

转自：https://www.cnblogs.com/alter888/p/8919865.html

https://blog.csdn.net/zxd1435513775/article/details/80556034

拦截器中，request中getReader()和getInputStream()只能调用一次，构建可重复读取inputStream的request.

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