日志中获取request中请求参数（url参数和body参数）----get方式获取request请求参数（一）

在工作中我们有时会遇到需要在request中获取请求参数的场景。比如说用来记录追踪日志，排查问题等。
本篇文章主要介绍的是在springboot框架下输出到日志的使用场景。

一、当HTTP请求方式为get或delete时，有以下几种方式：

1.获取url中所有参数

request.getQueryString()；

2.获取指定某个参数：

String value=request.getparameter("key");

2.request.getParameterMap();

Enumeration enu=request.getParameterNames();  
while(enu.hasMoreElements()){  
String paraName=(String)enu.nextElement();  
System.out.println(paraName+": "+request.getParameter(paraName));  
}

3.request.getParameterNames();

Map map=request.getParameterMap();  
    Set keSet=map.entrySet();  
    for(Iterator itr=keSet.iterator();itr.hasNext();){  
        Map.Entry me=(Map.Entry)itr.next();  
        Object ok=me.getKey();  
        Object ov=me.getValue();  
        String[] value=new String[1];  
        if(ov instanceof String[]){  
            value=(String[])ov;  
        }else{  
            value[0]=ov.toString();  
        }  
  
        for(int k=0;k<value.length;k++){  
            System.out.println(ok+"="+value[k]);  
        }  
      }  

二、当HTTP请求方式为post、patch、put等时，有以下几种方式：

因为此时请求参数位于request中的body中，而java提供的requset中没有直接可以获取body信息的方法。那么我们可通过IO流的方式来获取，详情如下：
1.request.getReader()

//通过request.getReader()的方式来获取body
 public static String getBodyMsg(HttpServletRequest request)
    {
 
        BufferedReader br = null;
        StringBuilder sb = new StringBuilder("");
        try
        {
            br = request.getReader();
            String str;
            while ((str = br.readLine()) != null)
            {
                sb.append(str);
            }
            br.close();
        }
        catch (IOException e)
        {
            e.printStackTrace();
        }
        finally
        {
            if (null != br)
            {
                try
                {
                    br.close();
                }
                catch (IOException e)
                {
                    e.printStackTrace();
                }
            }
        }
        return sb.toString();
    }

2.request.getInputStream()
通过getInputStream()方法有两种方式：

//通过request.getInputStream()的方式来获取body信息
//方式一： IO流
public static void getBodyMsg(HttpServletRequest request)
    {
        InputStream is = null;
        try
        {
            is = request.getInputStream();
            StringBuilder sb = new StringBuilder();
            byte[] b = new byte[4096];
            for (int n; (n = is.read(b)) != -1;)
            {
                sb.append(new String(b, 0, n));
            }
        }
        catch (IOException e)
        {
            e.printStackTrace();
        }
        finally
        {
            if (null != is)
            {
                try
                {
                    is.close();
                }
                catch (IOException e)
                {
                    e.printStackTrace();
                }
            }
        }
     }
//方式二：二进制的方式
public static byte[] getBodyBytes(HttpServletRequest request)
    {
 
        int len = request.getContentLength();
        byte[] buffer = new byte[len];
        ServletInputStream in = null;
 
        try
        {
            in = request.getInputStream();
            in.read(buffer, 0, len);
            in.close();
        }
        catch (IOException e)
        {
            e.printStackTrace();
        }
        finally
        {
            if (null != in)
            {
                try
                {
                    in.close();
                }
                catch (IOException e)
                {
                    e.printStackTrace();
                }
            }
        }
        //也可以直接将byte[]转换为字符串返回
        return buffer;
    }

注意事项：

1.IO流使用完后记得关闭资源。
2.request中的body内容，通过流的方式只能调用一次。也就是request.getReader()，request.getInputStream()和request.getparameter(“key”)这三种方法，只能读取一次，如果再次读取就会报Stream closed的错误，错误信息如下：

org.springframework.http.converter.HttpMessageNotReadableException: I/O error while reading input message; nested exception is java.io.IOException: Stream closed
	at org.springframework.web.servlet.mvc.method.annotation.AbstractMessageConverterMethodArgumentResolver.readWithMessageConverters(AbstractMessageConverterMethodArgumentResolver.java:229)
	at org.springframework.web.servlet.mvc.method.annotation.RequestResponseBodyMethodProcessor.readWithMessageConverters(RequestResponseBodyMethodProcessor.java:150)
	at org.springframework.web.servlet.mvc.method.annotation.RequestResponseBodyMethodProcessor.resolveArgument(RequestResponseBodyMethodProcessor.java:128)
	at org.springframework.web.method.support.HandlerMethodArgumentResolverComposite.resolveArgument(HandlerMethodArgumentResolverComposite.java:121)
	at org.springframework.web.method.support.InvocableHandlerMethod.getMethodArgumentValues(InvocableHandlerMethod.java:158)
	at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:128)
	at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:97)
	at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:827)
	at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:738)
	at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:85)
	at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:967)
	at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:901)
	at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:970)
	at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:872)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:661)
	at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:846)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:742)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
	at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
	at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:197)
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
	at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:199)
	at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96)
	at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:478)
	at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:140)
	at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:81)
	at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:87)
	at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:342)
	at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:803)
	at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66)
	at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:868)
	at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1459)
	at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
	at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
	at java.lang.Thread.run(Thread.java:748)
Caused by: java.io.IOException: Stream closed
	at org.apache.catalina.connector.InputBuffer.readByte(InputBuffer.java:334)
	at org.apache.catalina.connector.CoyoteInputStream.read(CoyoteInputStream.java:93)
	at java.io.FilterInputStream.read(FilterInputStream.java:83)
	at java.io.PushbackInputStream.read(PushbackInputStream.java:139)
	at org.springframework.web.servlet.mvc.method.annotation.AbstractMessageConverterMethodArgumentResolver$EmptyBodyCheckingHttpInputMessage.<init>(AbstractMessageConverterMethodArgumentResolver.java:324)
	at org.springframework.web.servlet.mvc.method.annotation.AbstractMessageConverterMethodArgumentResolver.readWithMessageConverters(AbstractMessageConverterMethodArgumentResolver.java:189)
	... 41 common frames omitted

总结一下其实就是因为IO流关闭只能读取一次。读过之后，再来读取，就没有了。就像水流一样。这怎么办呢？
我们可以将读出来的内容保存起来后，再将它放回去，这样就不会影响下次使用了。
下一篇将着重介绍如何解决该方法。