如何多次读取 request.getInputStream()
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【中文标题】如何多次读取 request.getInputStream()【英文标题】：How to read request.getInputStream() multiple times 【发布时间】：2011-05-25 20:19:57 【问题描述】：我有这个代码：
@Override
public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
throws IOException, ServletException
logger.info("Filter start...");
HttpServletRequest httpRequest = (HttpServletRequest) request;
HttpServletResponse httpResponse = (HttpServletResponse) response;
String ba = getBaId(getBody(httpRequest));
if (ba == null)
logger.error("Wrong XML");
httpResponse.setStatus(HttpServletResponse.SC_BAD_REQUEST);
else
if (!clients.containsKey(ba))
clients.put(ba, 1);
logger.info("Client map : init...");
else
clients.put(ba, clients.get(ba).intValue() + 1);
logger.info("Threads for " + ba + " = " + clients.get(ba).toString());
chain.doFilter(request, response);
还有这个 web.xml（包被缩短了，名字也变了，但是看起来一样）
<?xml version="1.0" encoding="ISO-8859-1"?>
<web-app>
<filter>
<filter-name>TestFilter</filter-name>
<filter-class>pkg.TestFilter</filter-class>
</filter>
<filter-mapping>
<filter-name>TestFilter</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>
<context-param>
<param-name>contextConfigLocation</param-name>
<param-value>WEB-INF/applicationContext.xml</param-value>
</context-param>
<listener>
<listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
</listener>
<servlet>
<servlet-name>Name</servlet-name>
<display-name>Name</display-name>
<servlet-class>pkg.Name</servlet-class>
<load-on-startup>1</load-on-startup>
</servlet>
<servlet-mapping>
<servlet-name>Name</servlet-name>
<url-pattern>/services/*</url-pattern>
</servlet-mapping>
</web-app>
我想在过滤器之后调用 Servlet。我希望chain.doFilter(...) 能做到这一点，但我总是在chain.doFilter(...) 上得到这个错误：
java.lang.IllegalStateException: getInputStream() can't be called after getReader()
at com.caucho.server.connection.AbstractHttpRequest.getInputStream(AbstractHttpRequest.java:1933)
at org.apache.cxf.transport.http.AbstractHTTPDestination.setupMessage(AbstractHTTPDestination.java:249)
at org.apache.cxf.transport.servlet.ServletDestination.invoke(ServletDestination.java:82)
at org.apache.cxf.transport.servlet.ServletController.invokeDestination(ServletController.java:283)
at org.apache.cxf.transport.servlet.ServletController.invoke(ServletController.java:166)
at org.apache.cxf.transport.servlet.AbstractCXFServlet.invoke(AbstractCXFServlet.java:174)
at org.apache.cxf.transport.servlet.AbstractCXFServlet.doPost(AbstractCXFServlet.java:152)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:153)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:91)
at com.caucho.server.dispatch.ServletFilterChain.doFilter(ServletFilterChain.java:103)
at pkg.TestFilter.doFilter(TestFilter.java:102)
at com.caucho.server.dispatch.FilterFilterChain.doFilter(FilterFilterChain.java:87)
at com.caucho.server.webapp.WebAppFilterChain.doFilter(WebAppFilterChain.java:187)
at com.caucho.server.dispatch.ServletInvocation.service(ServletInvocation.java:265)
at com.caucho.server.http.HttpRequest.handleRequest(HttpRequest.java:273)
at com.caucho.server.port.TcpConnection.run(TcpConnection.java:682)
at com.caucho.util.ThreadPool$Item.runTasks(ThreadPool.java:743)
at com.caucho.util.ThreadPool$Item.run(ThreadPool.java:662)
at java.lang.Thread.run(Thread.java:619)
【问题讨论】：
是的，它应该可以工作。 servlet 是否可以在没有过滤器的情况下工作？ 没有过滤器的 servlet 工作，没有chain.doFilter() 的过滤器也工作
如果..else 没有帮助就把它放在外面
另外，我注意到您正在尝试使用 Reader 读取 XML，根据我的经验，这通常是错误的。您应该在 InputStream 上使用 XML 解析器。我当然希望您不要使用正则表达式或类似的东西从 XML 中提取值？我们可以看看你的 getBaId() 和 getBody() 方法吗？
我只需要一个参数，我认为正则表达式可能比解析整个XML更快更有效。
【参考方案1】：
request.getInputStream() 只允许读取一次。为了多次使用此方法，我们需要对 HttpServletReqeustWrapper 类执行额外的自定义任务。请参阅下面的示例包装类。
public class MultiReadHttpServletRequest extends HttpServletRequestWrapper
private ByteArrayOutputStream cachedBytes;
public MultiReadHttpServletRequest(HttpServletRequest request)
super(request);
@Override
public ServletInputStream getInputStream() throws IOException
if (cachedBytes == null)
cacheInputStream();
return new CachedServletInputStream();
@Override
public BufferedReader getReader() throws IOException
return new BufferedReader(new InputStreamReader(getInputStream()));
private void cacheInputStream() throws IOException
/*
* Cache the inputstream in order to read it multiple times. For convenience, I use apache.commons IOUtils
*/
cachedBytes = new ByteArrayOutputStream();
IOUtils.copy(super.getInputStream(), cachedBytes);
/* An inputstream which reads the cached request body */
public class CachedServletInputStream extends ServletInputStream
private ByteArrayInputStream input;
public CachedServletInputStream()
/* create a new input stream from the cached request body */
input = new ByteArrayInputStream(cachedBytes.toByteArray());
@Override
public int read() throws IOException
return input.read();
就我而言，我将所有传入请求都跟踪到日志中。我创建了一个过滤器
public class TracerRequestFilter implements Filter
private static final Logger LOG = LoggerFactory.getLogger(TracerRequestFilter.class);
@Override
public void destroy()
@Override
public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException,
ServletException
final HttpServletRequest req = (HttpServletRequest) request;
try
if (LOG.isDebugEnabled())
final MultiReadHttpServletRequest wrappedRequest = new MultiReadHttpServletRequest(req);
// debug payload info
logPayLoad(wrappedRequest);
chain.doFilter(wrappedRequest, response);
else
chain.doFilter(request, response);
finally
LOG.info("end-of-process");
private String getRemoteAddress(HttpServletRequest req)
String ipAddress = req.getHeader("X-FORWARDED-FOR");
if (ipAddress == null)
ipAddress = req.getRemoteAddr();
return ipAddress;
private void logPayLoad(HttpServletRequest request)
final StringBuilder params = new StringBuilder();
final String method = request.getMethod().toUpperCase();
final String ipAddress = getRemoteAddress(request);
final String userAgent = request.getHeader("User-Agent");
LOG.debug(String.format("============debug request=========="));
LOG.debug(String.format("Access from ip:%s;ua:%s", ipAddress, userAgent));
LOG.debug(String.format("Method : %s requestUri %s", method, request.getRequestURI()));
params.append("Query Params:").append(System.lineSeparator());
Enumeration<String> parameterNames = request.getParameterNames();
for (; parameterNames.hasMoreElements();)
String paramName = parameterNames.nextElement();
String paramValue = request.getParameter(paramName);
if ("password".equalsIgnoreCase(paramName) || "pwd".equalsIgnoreCase(paramName))
paramValue = "*****";
params.append("---->").append(paramName).append(": ").append(paramValue).append(System.lineSeparator());
LOG.debug(params.toString());
/** request body */
if ("POST".equals(method) || "PUT".equals(method))
try
LOG.debug(IOUtils.toString(request.getInputStream()));
catch (IOException e)
LOG.error(e.getMessage(), e);
LOG.debug(String.format("============End-debug-request=========="));
@Override
public void init(FilterConfig arg0) throws ServletException
Servlet 2.5 和 3.0 都适用于我。我看到所有请求参数，包括表单编码和请求 json 正文。
【讨论】：
【参考方案2】：对于 Servlet 3.1
class MyHttpServletRequestWrapper extends HttpServletRequestWrapper
private byte[] body;
public MyHttpServletRequestWrapper(HttpServletRequest request)
super(request);
try
body = IOUtils.toByteArray(request.getInputStream());
catch (IOException ex)
body = new byte[0];
@Override
public ServletInputStream getInputStream() throws IOException
return new DelegatingServletInputStream(new ByteArrayInputStream(body));
public class DelegatingServletInputStream extends ServletInputStream
private final InputStream sourceStream;
private boolean finished = false;
/**
* Create a DelegatingServletInputStream for the given source stream.
*
* @param sourceStream the source stream (never @code null)
*/
public DelegatingServletInputStream(InputStream sourceStream)
this.sourceStream = sourceStream;
/**
* Return the underlying source stream (never @code null).
*/
public final InputStream getSourceStream()
return this.sourceStream;
@Override
public int read() throws IOException
int data = this.sourceStream.read();
if (data == -1)
this.finished = true;
return data;
@Override
public int available() throws IOException
return this.sourceStream.available();
@Override
public void close() throws IOException
super.close();
this.sourceStream.close();
@Override
public boolean isFinished()
return this.finished;
@Override
public boolean isReady()
return true;
@Override
public void setReadListener(ReadListener readListener)
throw new UnsupportedOperationException();
【讨论】：
异步请求会发生什么。因为您从 setReadListener 抛出 UnsupportedOperationException。 @MaheshBhuva 你可以自己实现setReadListener。
能否提供setReadListener的自定义实现参考？如果我将 setReadListener 实现留空，那么 servlet 异步功能将不起作用。我说的对吗？
我还有一个问题。如果我们通过添加一些字段来修改inputstream（如果是json body），在multipart request的情况下会不会导致任何问题？
@MaheshBhuva 您显示仅当请求是 json 请求时才修改 json 正文，您可以使用 content-type 标头来验证此请求是否为 json 请求【参考方案3】：
servlet请求中的inputStream因为是流，所以只能使用一次，可以存储，然后从字节数组中获取，这样可以解决。
public class HttpServletRequestWrapper extends javax.servlet.http.HttpServletRequestWrapper
private final byte[] body;
public HttpServletRequestWrapper(HttpServletRequest request)
throws IOException
super(request);
body = StreamUtil.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 byteArrayInputStream = new ByteArrayInputStream(body);
return new ServletInputStream()
@Override
public int read() throws IOException
return byteArrayInputStream.read();
@Override
public boolean isFinished()
return false;
@Override
public boolean isReady()
return false;
@Override
public void setReadListener(ReadListener arg0)
;
在过滤器中：
ServletRequest requestWrapper = new HttpServletRequestWrapper(request);
【讨论】：
但是当我们将 setReadListener 方法留空时，它是否适用于异步 servlet？。【参考方案4】：这对我有用。它实现了getInputStream。
private class MyHttpServletRequestWrapper extends HttpServletRequestWrapper
private byte[] body;
public MyHttpServletRequestWrapper(HttpServletRequest request)
super(request);
try
body = IOUtils.toByteArray(request.getInputStream());
catch (IOException ex)
body = new byte[0];
@Override
public ServletInputStream getInputStream() throws IOException
return new ServletInputStream()
ByteArrayInputStream bais = new ByteArrayInputStream(body);
@Override
public int read() throws IOException
return bais.read();
;
然后你在你的方法中使用：
//copy body
servletRequest = new MyHttpServletRequestWrapper(servletRequest);
【讨论】：
Request有Multipart文件上传请求怎么处理？ 这适用于任何内容。缺点是：所有内容都保存在内存中，因此内存限制可能是个问题。所以只在需要的地方创建包装器。例如如果是多部分，则传递原始请求并且不准备任何内容。【参考方案5】：基于接受的答案的工作代码。
public class CustomHttpServletRequestWrapper extends HttpServletRequestWrapper
private static final Logger logger = Logger.getLogger(CustomHttpServletRequestWrapper.class);
private final String body;
public CustomHttpServletRequestWrapper(HttpServletRequest request)
super(request);
StringBuilder stringBuilder = new StringBuilder();
BufferedReader bufferedReader = null;
try
InputStream 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)
logger.error("Error reading the request body...");
finally
if (bufferedReader != null)
try
bufferedReader.close();
catch (IOException ex)
logger.error("Error closing bufferedReader...");
body = stringBuilder.toString();
@Override
public ServletInputStream getInputStream () throws IOException
final ByteArrayInputStream byteArrayInputStream = new ByteArrayInputStream(body.getBytes());
ServletInputStream inputStream = new ServletInputStream()
public int read () throws IOException
return byteArrayInputStream.read();
;
return inputStream;
【讨论】：
谢谢。使用 Spring，我也需要覆盖getReader()：public BufferedReader getReader() throws IOException return new BufferedReader(new StringReader(body));
这是否也需要过滤器，或者我可以直接使用这个类并创建一个新对象然后转换为字符串？ PS：我对 java 很陌生，需要这样做才能从请求中打印我的 JSON。【参考方案6】：
您可能开始使用 getReader() 来使用 HttpServletRequest ：
String ba = getBaId(getBody(httpRequest));
您的 servlet 尝试在同一请求上调用 getInputStream()，这是不允许的。您需要做的是使用ServletRequestWrapper 制作请求正文的副本，以便您可以使用多种方法阅读它。我没有时间找到一个完整的例子知道...对不起...
【讨论】：
拥有请求的副本并使用getReader() 没有帮助。例外是getReader() has already been called for this request以上是关于如何多次读取 request.getInputStream()的主要内容，如果未能解决你的问题，请参考以下文章
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