最近有一个需要从接口请求参数后，打印日志，进行接口参数记录。
这里记录一下处理过程中出现的问题。
首先想到的就是request.getParameter(String )方法，但是这个方法只能在get请求中取到参数，post是不行的，后来想到了使用流的方式，调用request.getInputStream()获取流，然后从流中读取参数，如下代码所示：
String body = "";
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) {
e.printStackTrace();
} 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();
代码中的body就是request中的参数，我这里传的是JSON数据：{"page": 1, "pageSize": 10}，那么body就是：body = "{"page": 1, "pageSize": 10}"，一个JSON字符串。这样是可以成功获取到post请求的body，但是，经过过滤器后，参数经过@RequestBody注解赋值给controller中的方法的时候，却抛出了一个这样的异常：
org.springframework.http.converter.HttpMessageNotReadableException: Required request body is missing
在网上查找资料后发现，request的输入流只能读取一次，那么这是为什么呢？下面是答案：
那是因为流对应的是数据，数据放在内存中，有的是部分放在内存中。read 一次标记一次当前位置（mark position），第二次read就从标记位置继续读（从内存中copy）数据。 所以这就是为什么读了一次第二次是空了。 怎么让它不为空呢？只要inputstream 中的pos 变成0就可以重写读取当前内存中的数据。javaAPI中有一个方法public void reset() 这个方法就是可以重置pos为起始位置，但是不是所有的IO读取流都可以调用该方法！ServletInputStream是不能调用reset方法，这就导致了只能调用一次getInputStream()。
那么有什么办法可以用户解决呢？上面这篇博客中提到了解决方案，就是重写HttpServletRequestWrapper把request保存下来，然后通过过滤器把保存下来的request再填充进去，这样就可以多次读取request了。步骤如下所示：
①写一个类，继承HttpServletRequestWrapper
import javax.servlet.ReadListener;
import javax.servlet.ServletInputStream;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletRequestWrapper;
import java.io.*;
public class RequestWrapper extends HttpServletRequestWrapper {
private final String body;
public RequestWrapper(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());
ServletInputStream servletInputStream = 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();
}
};
return servletInputStream;
}
@Override
public BufferedReader getReader() throws IOException {
return new BufferedReader(new InputStreamReader(this.getInputStream()));
}
public String getBody() {
return this.body;
}
}
②过滤器Filter，用来把request传递下去
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.core.annotation.Order;
import org.springframework.web.filter.OncePerRequestFilter;
import com.cetc.common.utils.CommonUtils;
import javax.servlet.*;
import javax.servlet.annotation.WebFilter;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.BufferedReader;
import java.io.IOException;
import java.util.Date;
import java.util.Map;
/**
* @program: springboot
* @description:
* @author: Sid
* @date: 2018-11-19 09:21
* @since: 1.0
**/
@Order(0)
/**
* 注册过滤器
* */
@WebFilter(filterName = "RequestResponseLogFilter", urlPatterns = "/*")
public class RequestFilter extends OncePerRequestFilter {
private static final Logger logger = LoggerFactory.getLogger(RequestFilter.class);
@Override
protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain filterChain)
throws ServletException, IOException {
try {
RequestWrapper requestWrapper = new RequestWrapper(request);
String body = requestWrapper.getBody();
String parameterStr =
"接收到请求 时间:" + CommonUtils.DEFAULT_DTF.format(new Date()) + ". 地址:" + request.getRequestURI()
+ "request ContentType: " + request.getContentType() + ". 参数:" + body;
logger.debug(parameterStr);
filterChain.doFilter(requestWrapper, response);
} catch (Exception e) {
logger.error("权限判断出错", e);
}
}
}
③在启动类中注册过滤器
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.web.servlet.MultipartConfigFactory;
import org.springframework.boot.web.servlet.ServletComponentScan;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
@SpringBootApplication
@ServletComponentScan //注册过滤器注解
@Configuration
public class WebApplication {
public static void main(String[] args) {
SpringApplication.run(WebApplication.class, args);
}
}
经测试，问题解决