我正在尝试在Java Servlet过滤器中访问两个http请求参数，这里没什么新东西，但是很惊讶地发现参数已经被消耗了！因此，它在过滤器链中不再可用。
似乎只有在参数进入POST请求主体（例如表单提交）时才会出现这种情况。
有没有办法读取参数而不消耗它们？
到目前为止，我只找到了这个参考：Servlet Filter using request.getParameter loses Form data。
谢谢！
另外，解决此问题的另一种方法是不使用过滤器链而是构建自己的拦截器组件，可能使用可以在已解析的请求主体上操作的方面。它也可能更高效，因为您只需将请求InputStream转换为您自己的模型对象一次。
但是，我仍然认为想要多次读取请求体是合理的，特别是当请求通过过滤器链时。我通常会使用过滤器链来进行某些操作，我希望将这些操作保留在HTTP层，与服务组件分离。
正如Will Hartung所建议的，我通过扩展HttpServletRequestWrapper，消耗请求InputStream并基本上缓存字节来实现这一点。
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();
}
}
}
现在，通过在将原始请求传递给过滤器链之前包装原始请求，可以多次读取请求主体：
public class MyFilter implements Filter {
@Override
public void doFilter(ServletRequest request, ServletResponse response,
FilterChain chain) throws IOException, ServletException {
/* wrap the request in order to read the inputstream multiple times */
MultiReadHttpServletRequest multiReadRequest = new MultiReadHttpServletRequest((HttpServletRequest) request);
/* here I read the inputstream and do my thing with it; when I pass the
* wrapped request through the filter chain, the rest of the filters, and
* request handlers may read the cached inputstream
*/
doMyThing(multiReadRequest.getInputStream());
//OR
anotherUsage(multiReadRequest.getReader());
chain.doFilter(multiReadRequest, response);
}
}
此解决方案还允许您通过getParameterXXX方法多次读取请求体，因为底层调用是getInputStream()，当然会读取缓存的请求InputStream。
编辑
对于较新版本的ServletInputStream界面。您需要提供更多方法的实现，如isReady，setReadListener等。请参阅下面的评论中提供的question。
如果您可以控制请求，则可以将内容类型设置为binary / octet-stream。这允许在不消耗输入流的情况下查询参数。
但是，这可能是某些应用程序服务器特有的。我只测试了tomcat，根据https://stackoverflow.com/a/11434646/957103，码头似乎表现得一样。
首先，我们不应该读取过滤器中的参数。通常在过滤器中读取标头以执行一些身份验证任务。说过可以使用CharStreams在Filter或Interceptor中完全读取HttpRequest主体：
String body = com.google.common.io.CharStreams.toString(request.getReader());
这根本不会影响后续的读取。
你可以使用servlet过滤器链，但是使用原来的，你可以创建自己的请求yourownrequests扩展HttpServletRequestWrapper。
我知道我已经迟到了，但这个问题对我来说仍然很重要，而这篇帖子也是谷歌的热门歌曲之一。我要继续发布我的解决方案，希望别人可以节省几个小时。
在我的情况下，我需要记录所有请求和响应与他们的身体。使用Spring Framework的答案其实很简单，只需使用ContentCachingRequestWrapper和ContentCachingResponseWrapper。
import org.springframework.web.util.ContentCachingRequestWrapper;
import org.springframework.web.util.ContentCachingResponseWrapper;
import javax.servlet.*;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
public class LoggingFilter implements Filter {
@Override
public void init(FilterConfig filterConfig) throws ServletException {
}
@Override
public void destroy() {
}
@Override
public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
throws IOException, ServletException {
ContentCachingRequestWrapper requestWrapper = new ContentCachingRequestWrapper((HttpServletRequest) request);
ContentCachingResponseWrapper responseWrapper = new ContentCachingResponseWrapper((HttpServletResponse) response);
try {
chain.doFilter(requestWrapper, responseWrapper);
} finally {
String requestBody = new String(requestWrapper.getContentAsByteArray());
String responseBody = new String(responseWrapper.getContentAsByteArray());
// Do not forget this line after reading response content or actual response will be empty!
responseWrapper.copyBodyToResponse();
// Write request and response body, headers, timestamps etc. to log files
}
}
}
唯一的方法是让您自己在过滤器中使用整个输入流，从中获取所需的内容，然后为您读取的内容创建一个新的InputStream，并将该InputStream放入ServletRequestWrapper（或HttpServletRequestWrapper）。
缺点是您必须自己解析有效负载，标准不会使您可以使用该功能。
附录 -
正如我所说，你需要看看HttpServletRequestWrapper。
在过滤器中，您可以通过调用FilterChain.doFilter（请求，响应）继续。
对于普通过滤器，请求和响应与传递给过滤器的请求和响应相同。情况并非必须如此。您可以使用自己的请求和/或响应替换它们。
HttpServletRequestWrapper专门用于促进这一点。您将原始请求传递给它，然后您可以拦截所有呼叫。您可以创建自己的子类，并将getInputStream方法替换为您自己的子类。您无法更改原始请求的输入流，因此您可以使用此包装并返回自己的输入流。
最简单的情况是将原始请求输入流消耗到字节缓冲区中，对其执行任何魔术，然后从该缓冲区创建新的ByteArrayInputStream。这是包装器中返回的内容，它将传递给FilterChain.doFilter方法。
你需要继承ServletInputStream并为你的ByteArrayInputStream创建另一个包装器，但这也不是什么大问题。
以上答案非常有帮助，但在我的经验中仍然存在一些问题。在tomcat 7 servlet 3.0上，还必须覆盖getParamter和getParamterValues。这里的解决方案包括get-query参数和post-body。它允许轻松获取原始字符串。
与其他解决方案一样，它使用Apache commons-io和Googles Guava。
在此解决方案中，getParameter *方法不会抛出IOException，但它们使用super.getInputStream（）（来获取正文），这可能会抛出IOException。我抓住它并抛出runtimeException。这不太好。
import com.google.common.collect.Iterables;
import com.google.common.collect.ObjectArrays;
import org.apache.commons.io.IOUtils;
import org.apache.http.NameValuePair;
import org.apache.http.client.utils.URLEncodedUtils;
import org.apache.http.entity.ContentType;
import java.io.BufferedReader;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.UnsupportedEncodingException;
import java.nio.charset.Charset;
import java.util.Collections;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import javax.servlet.ServletInputStream;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletRequestWrapper;
/**
* Purpose of this class is to make getParameter() return post data AND also be able to get entire
* body-string. In native implementation any of those two works, but not both together.
*/
public class MultiReadHttpServletRequest extends HttpServletRequestWrapper {
public static final String UTF8 = "UTF-8";
public static final Charset UTF8_CHARSET = Charset.forName(UTF8);
private ByteArrayOutputStream cachedBytes;
private Map<String, String[]> parameterMap;
public MultiReadHttpServletRequest(HttpServletRequest request) {
super(request);
}
public static void toMap(Iterable<NameValuePair> inputParams, Map<String, String[]> toMap) {
for (NameValuePair e : inputParams) {
String key = e.getName();
String value = e.getValue();
if (toMap.containsKey(key)) {
String[] newValue = ObjectArrays.concat(toMap.get(key), value);
toMap.remove(key);
toMap.put(key, newValue);
} else {
toMap.put(key, new String[]{value});
}
}
}
@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);
}
@Override
public String getParameter(String key) {
Map<String, String[]> parameterMap = getParameterMap();
String[] values = parameterMap.get(key);
return values != null && values.length > 0 ? values[0] : null;
}
@Override
public String[] getParameterValues(String key) {
Map<String, String[]> parameterMap = getParameterMap();
return parameterMap.get(key);
}
@Override
public Map<String, String[]> getParameterMap() {
if (parameterMap == null) {
Map<String, String[]> result = new LinkedHashMap<String, String[]>();
decode(getQueryString(), result);
decode(getPostBodyAsString(), result);
parameterMap = Collections.unmodifiableMap(result);
}
return parameterMap;
}
private void decode(String queryString, Map<String, String[]> result) {
if (queryString != null) toMap(decodeParams(queryString), result);
}
private Iterable<NameValuePair> decodeParams(String body) {
Iterable<NameValuePair> params = URLEncodedUtils.parse(body, UTF8_CHARSET);
try {
String cts = getContentType();
if (cts != null) {
ContentType ct = ContentType.parse(cts);
if (ct.getMimeType().equals(ContentType.APPLICATION_FORM_URLENCODED.getMimeType())) {
List<NameValuePair> postParams = URLEncodedUtils.parse(IOUtils.toString(getReader()), UTF8_CHARSET);
params = Iterables.concat(params, postParams);
}
}
} catch (IOException e) {
throw new IllegalStateException(e);
}
return params;
}
public String getPostBodyAsString() {
try {
if (cachedBytes == null) cacheInputStream();
return cachedBytes.toString(UTF8);
} catch (UnsupportedEncodingException e) {
throw new RuntimeException(e);
} catch (IOException e) {
throw new RuntimeException(e);
}
}
/* 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();
}
}
@Override
public String toString() {
String query = dk.bnr.util.StringUtil.nullToEmpty(getQueryString());
StringBuilder sb = new StringBuilder();
sb.append("URL='").append(getRequestURI()).append(query.isEmpty() ? "" : "?" + query).append("', body='");
sb.append(getPostBodyAsString());
sb.append("'");
return sb.toString();
}
}
我也有同样的问题，我相信下面的代码更简单，它对我有用，
public class MultiReadHttpServletRequest extends HttpServletRequestWrapper {
private String _body;
public MultiReadHttpServletRequest(HttpServletRequest request) throws IOException {
super(request);
_body = "";
BufferedReader bufferedReader = request.getReader();
String line;
while ((line = bufferedReader.readLine()) != null){
_body += line;
}
}
@Override
public ServletInputStream getInputStream() throws IOException {
final ByteArrayInputStream byteArrayInputStream = new ByteArrayInputStream(_body.getBytes());
return new ServletInputStream() {
public int read() throws IOException {
return byteArrayInputStream.read();
}
};
}
@Override
public BufferedReader getReader() throws IOException {
return new BufferedReader(new InputStreamReader(this.getInputStream()));
}
}
在过滤器java类中，
HttpServletRequest properRequest = ((HttpServletRequest) req);
MultiReadHttpServletRequest wrappedRequest = new MultiReadHttpServletRequest(properRequest);
req = wrappedRequest;
inputJson = IOUtils.toString(req.getReader());
System.out.println("body"+inputJson);
如果您有任何疑问，请告诉我
所以这基本上是Lathy的答案，但更新了ServletInputStream的新要求。
即（对于ServletInputStream），必须实现：
public abstract boolean isFinished();
public abstract boolean isReady();
public abstract void setReadListener(ReadListener var1);
这是Lathy的编辑对象
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import javax.servlet.ServletInputStream;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletRequestWrapper;
public class RequestWrapper extends HttpServletRequestWrapper {
private String _body;
public RequestWrapper(HttpServletRequest request) throws IOException {
super(request);
_body = "";
BufferedReader bufferedReader = request.getReader();
String line;
while ((line = bufferedReader.readLine()) != null){
_body += line;
}
}
@Override
public ServletInputStream getInputStream() throws IOException {
CustomServletInputStream kid = new CustomServletInputStream(_body.getBytes());
return kid;
}
@Override
public BufferedReader getReader() throws IOException {
return new BufferedReader(new InputStreamReader(this.getInputStream()));
}
}
在某处（??）我发现了这个（这是一个处理“额外”方法的一流类。
import javax.servlet.ReadListener;
import javax.servlet.ServletInputStream;
import java.io.IOException;
import java.io.UnsupportedEncodingException;
public class CustomServletInputStream extends ServletInputStream {
private byte[] myBytes;
private int lastIndexRetrieved = -1;
private ReadListener readListener = null;
public CustomServletInputStream(String s) {
try {
this.myBytes = s.getBytes("UTF-8");
} catch (UnsupportedEncodingException ex) {
throw new IllegalStateException("JVM did not support UTF-8", ex);
}
}
public CustomServletInputStream(byte[] inputBytes) {
this.myBytes = inputBytes;
}
@Override
public boolean isFinished() {
return (lastIndexRetrieved == myBytes.length - 1);
}
@Override
public boolean isReady() {
// This implementation will never block
// We also never need to call the readListener from this method, as this method will never return false
return isFinished();
}
@Override
public void setReadListener(ReadListener readListener) {
this.readListener = readListener;
if (!isFinished()) {
try {
readListener.onDataAvailable();
} catch (IOException e) {
readListener.onError(e);
}
} else {
try {
readListener.onAllDataRead();
} catch (IOException e) {
readListener.onError(e);
}
}
}
@Override
public int read() throws IOException {
int i;
if (!isFinished()) {
i = myBytes[lastIndexRetrieved + 1];
lastIndexRetrieved++;
if (isFinished() && (readListener != null)) {
try {
readListener.onAllDataRead();
} catch (IOException ex) {
readListener.onError(ex);
throw ex;
}
}
return i;
} else {
return -1;
}
}
};
最终，我只是想记录请求。以上frankensteined合在一起帮助我创建了下面的内容。
import java.io.IOException;
import java.io.UnsupportedEncodingException;
import java.security.Principal;
import java.util.Enumeration;
import java.util.LinkedHashMap;
import java.util.Map;
import javax.servlet.FilterChain;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.apache.commons.io.IOUtils;
//one or the other based on spring version
//import org.springframework.boot.autoconfigure.web.ErrorAttributes;
import org.springframework.boot.web.servlet.error.ErrorAttributes;
import org.springframework.core.Ordered;
import org.springframework.http.HttpStatus;
import org.springframework.stereotype.Component;
import org.springframework.web.context.request.ServletRequestAttributes;
import org.springframework.web.context.request.WebRequest;
import org.springframework.web.filter.OncePerRequestFilter;
/**
* A filter which logs web requests that lead to an error in the system.
*/
@Component
public class LogRequestFilter extends OncePerRequestFilter implements Ordered {
// I tried apache.commons and slf4g loggers. (one or the other in these next 2 lines of declaration */
//private final static org.apache.commons.logging.Log logger = org.apache.commons.logging.LogFactory.getLog(LogRequestFilter.class);
private static final org.slf4j.Logger logger = org.slf4j.LoggerFactory.getLogger(LogRequestFilter.class);
// put filter at the end of all other filters to make sure we are processing after all others
private int order = Ordered.LOWEST_PRECEDENCE - 8;
private ErrorAttributes errorAttributes;
@Override
public int getOrder() {
return order;
}
@Override
protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain filterChain)
throws ServletException, IOException {
String temp = ""; /* for a breakpoint, remove for production/real code */
/* change to true for easy way to comment out this code, remove this if-check for production/real code */
if (false) {
filterChain.doFilter(request, response);
return;
}
/* make a "copy" to avoid issues with body-can-only-read-once issues */
RequestWrapper reqWrapper = new RequestWrapper(request);
int status = HttpStatus.INTERNAL_SERVER_ERROR.value();
// pass through filter chain to do the actual request handling
filterChain.doFilter(reqWrapper, response);
status = response.getStatus();
try {
Map<String, Object> traceMap = getTrace(reqWrapper, status);
// body can only be read after the actual request handling was done!
this.getBodyFromTheRequestCopy(reqWrapper, traceMap);
/* now do something with all the pieces of information gatherered */
this.logTrace(reqWrapper, traceMap);
} catch (Exception ex) {
logger.error("LogRequestFilter FAILED: " + ex.getMessage(), ex);
}
}
private void getBodyFromTheRequestCopy(RequestWrapper rw, Map<String, Object> trace) {
try {
if (rw != null) {
byte[] buf = IOUtils.toByteArray(rw.getInputStream());
//byte[] buf = rw.getInputStream();
if (buf.length > 0) {
String payloadSlimmed;
try {
String payload = new String(buf, 0, buf.length, rw.getCharacterEncoding());
payloadSlimmed = payload.trim().replaceAll(" +", " ");
} catch (UnsupportedEncodingException ex) {
payloadSlimmed = "[unknown]";
}
trace.put("body", payloadSlimmed);
}
}
} catch (IOException ioex) {
trace.put("body", "EXCEPTION: " + ioex.getMessage());
}
}
private void logTrace(HttpServletRequest request, Map<String, Object> trace) {
Object method = trace.get("method");
Object path = trace.get("path");
Object statusCode = trace.get("statusCode");
logger.info(String.format("%s %s produced an status code '%s'. Trace: '%s'", method, path, statusCode,
trace));
}
protected Map<String, Object> getTrace(HttpServletRequest request, int status) {
Throwable exception = (Throwable) request.getAttribute("javax.servlet.error.exception");
Principal principal = request.getUserPrincipal();
Map<String, Object> trace = new LinkedHashMap<String, Object>();
trace.put("method", request.getMethod());
trace.put("path", request.getRequestURI());
if (null != principal) {
trace.put("principal", principal.getName());
}
trace.put("query", request.getQueryString());
trace.put("statusCode", status);
Enumeration headerNames = request.getHeaderNames();
while (headerNames.hasMoreElements()) {
String key = (String) headerNames.nextElement();
String value = request.getHeader(key);
trace.put("header:" + key, value);
}
if (exception != null && this.errorAttributes != null) {
trace.put("error", this.errorAttributes
.getErrorAttributes((WebRequest) new ServletRequestAttributes(request), true));
}
return trace;
}
}
请把这个代码带上一粒盐。
最重要的“测试”是POST是否与有效载荷一起工作。这将揭示“双重阅读”问题。
伪示例代码
import org.springframework.web.bind.annotation.*;
@RestController
@RequestMapping("myroute")
public class MyController {
@RequestMapping(method = RequestMethod.POST, produces = "application/json")
@ResponseBody
public String getSomethingExample(@RequestBody MyCustomObject input) {
String returnValue = "";
return returnValue;
}
}
如果您只想测试，可以用普通的“对象”替换“MyCustomObject”。
这个答案是从几个不同的SOF帖子和例子中得到的，但是需要一段时间才能将它们整合在一起，所以我希望它能帮助未来的读者。
请在我之前提起Lathy的回答。没有它我可能没有这么远。
以下是我在解决这个问题时遇到的一个/一些例外情况。
已经为此请求调用了getReader（）
看起来我“借来”的一些地方在这里：
http://slackspace.de/articles/log-request-body-with-spring-boot/
https://howtodoinjava.com/servlets/httpservletrequestwrapper-example-read-request-body/
https://www.oodlestechnologies.com/blogs/How-to-create-duplicate-object-of-httpServletRequest-object
Spring使用AbstractRequestLoggingFilter内置支持：
@Bean
public Filter loggingFilter(){
final AbstractRequestLoggingFilter filter = new AbstractRequestLoggingFilter() {
@Override
protected void beforeRequest(final HttpServletRequest request, final String message) {
}
@Override
protected void afterRequest(final HttpServletRequest request, final String message) {
}
};
filter.setIncludePayload(true);
filter.setIncludeQueryString(false);
filter.setMaxPayloadLength(1000000);
return filter;
}
遗憾的是，您仍然无法直接从请求中读取有效负载，但String消息参数将包含有效负载，因此您可以从中获取有效负载，如下所示：
String body = message.substring(message.indexOf("{"), message.lastIndexOf("]"));
只是覆盖getInputStream()在我的情况下不起作用。我的服务器实现似乎解析参数而不调用此方法。我没有找到任何其他方法，但也重新实现了所有四个getParameter *方法。以下是getParameterMap的代码（使用Apache Http Client和Google Guava库）：
@Override
public Map<String, String[]> getParameterMap() {
Iterable<NameValuePair> params = URLEncodedUtils.parse(getQueryString(), NullUtils.UTF8);
try {
String cts = getContentType();
if (cts != null) {
ContentType ct = ContentType.parse(cts);
if (ct.getMimeType().equals(ContentType.APPLICATION_FORM_URLENCODED.getMimeType())) {
List<NameValuePair> postParams = URLEncodedUtils.parse(IOUtils.toString(getReader()), NullUtils.UTF8);
params = Iterables.concat(params, postParams);
}
}
} catch (IOException e) {
throw new IllegalStateException(e);
}
Map<String, String[]> result = toMap(params);
return result;
}
public static Map<String, String[]> toMap(Iterable<NameValuePair> body) {
Map<String, String[]> result = new LinkedHashMap<>();
for (NameValuePair e : body) {
String key = e.getName();
String value = e.getValue();
if (result.containsKey(key)) {
String[] newValue = ObjectArrays.concat(result.get(key), value);
result.remove(key);
result.put(key, newValue);
} else {
result.put(key, new String[] {value});
}
}
return result;
}
看看（或使用）Spring AbstractRequestLoggingFilter