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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2022-03-10 12:10:06
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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