多次讀取ServletInputStream引發(fā)的問(wèn)題
因?yàn)榉?wù)器和app之間傳輸方式是JSON
格式如下
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{ head:nullbody:nulltoken:xxxxxxxxxxxxxxxxxxxxx} |
所以想在服務(wù)端寫個(gè)攔截器或者filter先讀取token，來(lái)驗(yàn)證身份.但是如果前置攔截，那么在springMVC里的參數(shù)控制器就會(huì)讀取不到，導(dǎo)致@RequestBody 這個(gè)注解的參數(shù)不起作用.
原因在于ServletInputStream已經(jīng)在前置攔截器里讀取過(guò)一次，在接下來(lái)的ArgumentHandler里讀取的時(shí)候就不能再讀了，導(dǎo)致取不到數(shù)據(jù)而無(wú)法賦值.
于是寫了下面的filter來(lái)讓ServletInputStream來(lái)多次讀取
先寫個(gè)request
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public class MyHttpRequest extends HttpServletRequestWrapper { private static Logger log=Logger.getLogger(MyHttpRequest.class); private byte[] bytes; /** * @param request {@link javax.servlet.http.HttpServletRequest} object. * @throws IOException */ public MyHttpRequest(HttpServletRequest request) throws IOException { super(request); bytes= IOUtils.toByteArray( request.getInputStream()); } @Override public ServletInputStream getInputStream() throws IOException { final ByteArrayInputStream byteArrayInputStream = new ByteArrayInputStream(bytes); return new DelegatingServletInputStream(byteArrayInputStream); } @Override public BufferedReader getReader() throws IOException { return new BufferedReader(new InputStreamReader(getInputStream())); } |
以上內(nèi)容是先讀取出來(lái)，然后放到一個(gè)byte[]里，以后每次拿流的時(shí)候就可以再新建一個(gè)關(guān)于Byte[]的流.
然后再寫一個(gè)filter
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public class MyFilter implements Filter{ @Override public void destroy() { } @Override public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain) throws IOException, ServletException { HttpServletRequest request=(HttpServletRequest) req; MyHttpRequest myrequest=new MyHttpRequest(request); chain.doFilter(myrequest, res); } @Override public void init(FilterConfig arg0) throws ServletException { } } |
在web.xml里配置一下，試試效果，非常不錯(cuò).可以多次讀取了，
但是，我去
在post請(qǐng)求下，request.getParamter這種東西又不起作用了.
原因在于我們重寫的那個(gè)request是默認(rèn)調(diào)用父類的super.getparamter方法，而super.getparamter又依賴于super.getInputStream，但是在我們重寫的request里的構(gòu)造方法里，第一句話就老request注入到super里，然后下一句話就把老的request的流給讀了，導(dǎo)致我們調(diào)用super.getparameter的時(shí)候遇到了一個(gè)空的流。
解決思路：自己解決
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package com.hrhs.jyj.filter; import java.io.BufferedReader;import java.io.ByteArrayInputStream;import java.io.IOException;import java.io.InputStreamReader;import java.io.UnsupportedEncodingException;import java.util.ArrayList;import java.util.Enumeration;import java.util.HashMap;import java.util.List;import java.util.Map; import javax.servlet.ServletInputStream;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletRequestWrapper; import org.apache.commons.io.IOUtils;import org.apache.log4j.Logger;import org.springframework.mock.web.DelegatingServletInputStream; public class MyHttpRequest extends HttpServletRequestWrapper { private static Logger log = Logger.getLogger(MyHttpRequest.class); private byte[] bytes; private String body; private Map<String, List<String>> map; private int readMap=0; private String queryString; /** * @param request * {@link javax.servlet.http.HttpServletRequest} object. * @throws IOException */ public MyHttpRequest(HttpServletRequest request) throws IOException { super(request); bytes = IOUtils.toByteArray(request.getInputStream()); queryString = request.getQueryString(); } @Override public ServletInputStream getInputStream() throws IOException { final ByteArrayInputStream byteArrayInputStream = new ByteArrayInputStream(bytes); return new DelegatingServletInputStream(byteArrayInputStream); } @Override public BufferedReader getReader() throws IOException { return new BufferedReader(new InputStreamReader(getInputStream())); } @Override public String getParameter(String name) { log.info("走了getParameter"); return super.getParameter(name); } @Override public Map<String, String[]> getParameterMap() { log.info("走了getParameterMap"); return super.getParameterMap(); } @Override public Enumeration<String> getParameterNames() { log.info("走了getParameterNames"); return super.getParameterNames(); } //暫時(shí)先改寫這一個(gè),其他的也可以修改 @Override public String[] getParameterValues(String name) { log.info("走了getParameterValues"); try { Map<String, List<String>> nameVals = doParameter(); List<String> list = nameVals.get(name); if(list!=null&&list.size()>0){ return list.toArray(new String[]{}); } } catch (UnsupportedEncodingException e) { e.printStackTrace(); } return new String[]{}; } //這里獲取所有參數(shù)值的map public Map<String, List<String>> doParameter() throws UnsupportedEncodingException { if(readMap==0){ //這里把post里的參數(shù)和地址欄參數(shù)結(jié)合到一起,然后解析 body = new String(bytes, getCharacterEncoding())+"&"+queryString; String[] nameVals = body.split("&"); map = new HashMap<String, List<String>>(); for (String nameVal : nameVals) { String name = nameVal.split("=")[0]; String val = nameVal.split("=")[1]; if (map.containsKey(name)) { List<String> vals = map.get(name); vals.add(val); map.put(name, vals); } else { List<String> vals = new ArrayList<String>(); vals.add(val); map.put(name, vals); } } readMap=1; } return map; }} |
ServletInputStream重復(fù)讀取問(wèn)題
本來(lái)是想實(shí)現(xiàn)tomcat的acess_log打印post請(qǐng)求參數(shù)。吐槽一下，tomcat功能和nginx差了好幾條街。網(wǎng)上找了個(gè)方法，用tomcat的filter來(lái)實(shí)現(xiàn)。
但是，寫filter的時(shí)候，發(fā)現(xiàn)了ServletInputStream重復(fù)讀取問(wèn)題。
網(wǎng)上找個(gè)幾個(gè)方法，都不能直接用。綜合網(wǎng)上的資料，根據(jù)自己的理解，終于能完美運(yùn)行了。
直接貼代碼了，親測(cè)能用
首先要寫個(gè)BufferHttpServletRequestWrapper類，用來(lái)復(fù)制HttpServletRequest request。
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import java.io.BufferedReader;import java.io.ByteArrayInputStream;import java.io.ByteArrayOutputStream;import java.io.IOException;import java.io.InputStream;import java.io.InputStreamReader; import javax.servlet.ServletInputStream;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletRequestWrapper; public class BufferHttpServletRequestWrapper extends HttpServletRequestWrapper { private final byte[] body; public BufferHttpServletRequestWrapper(HttpServletRequest request) throws IOException { super(request); InputStream is = request.getInputStream(); ByteArrayOutputStream baos = new ByteArrayOutputStream(); byte buff[] = new byte[ 1024 ]; int read; while( ( read = is.read( buff ) ) > 0 ) { baos.write( buff, 0, read ); } body = baos.toByteArray(); } @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 int read() throws IOException { return bais.read(); } }; } } |
然后filter實(shí)現(xiàn)如下：
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import java.io.ByteArrayOutputStream;import java.io.IOException;import java.io.InputStream;import javax.servlet.Filter;import javax.servlet.FilterChain;import javax.servlet.FilterConfig;import javax.servlet.ServletException;import javax.servlet.ServletRequest;import javax.servlet.ServletResponse;import javax.servlet.http.HttpServletRequest; /** * Servlet Filter implementation class PostDataDumperFilter */ public class PostDataDumperFilter implements Filter { private FilterConfig filterConfig = null; /** * Default constructor. */ public PostDataDumperFilter() { // TODO Auto-generated constructor stub } /** * @see Filter#destroy() */ public void destroy() { this.filterConfig = null; } /** * @see Filter#doFilter(ServletRequest, ServletResponse, FilterChain) */ public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException { if (filterConfig == null) return; //備份HttpServletRequest ServletRequest requestWrapper = null; if(request instanceof HttpServletRequest) { requestWrapper = new BufferHttpServletRequestWrapper((HttpServletRequest) request); } //使用流 InputStream reader = requestWrapper.getInputStream(); ByteArrayOutputStream byteOutput = new ByteArrayOutputStream(100); int i =0; byte [] b = new byte[100]; while((i = reader.read(b))!= -1){ byteOutput.write(b, 0, i); } request.setAttribute("post", new String(byteOutput.toByteArray())); // pass the request along the filter chain if(null == requestWrapper){ chain.doFilter(request, response); } else { chain.doFilter(requestWrapper, response); } } /** * @see Filter#init(FilterConfig) */ public void init(FilterConfig fConfig) throws ServletException { this.filterConfig = fConfig; } } |
好了，就寫到這里。以上為個(gè)人經(jīng)驗(yàn)，希望能給大家一個(gè)參考，也希望大家多多支持服務(wù)器之家。
原文鏈接：https://blog.csdn.net/dmw412724/article/details/79296345
