我需要一个 servlet 过滤器来捕获所有输入，然后破坏该输入，在每种形式中插入一个特殊标记。想象一下，过滤器与所有请求（例如url-pattern=*）相关联。我有用于捕获内容的代码，但它似乎RequestWrapper不够强大，无法捕获所有输入。某些输入返回零字节，然后我无法将该内容“流式传输”回给用户。例如，我们仍在使用 Struts 1.3.10 并且任何 Struts 代码都不能正确“捕获”，我们得到零字节内容。我相信这是因为 Struts 处理前锋的方式。如果请求中涉及到转发，我想知道下面的捕获代码是否可以工作。这是所有代码，您是否有一种方法可以捕获旨在流式传输给用户的任何类型的内容。
<filter>
<filter-name>Filter</filter-name>
<filter-class>mybrokenCaptureHtml.TokenFilter</filter-class>
</filter>
<filter-mapping>
<filter-name>Filter</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>
package mybrokenCaptureHtml;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpServletResponseWrapper;
public class TokenFilter implements Filter {
@Override
public void destroy() {
}
public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain chain) throws IOException, ServletException {
HttpServletRequest request = (HttpServletRequest) servletRequest;
HttpServletResponse response = (HttpServletResponse) servletResponse;
try {
final MyResponseWrapper responseWrapper = new MyResponseWrapper((HttpServletResponse) response);
chain.doFilter(request, responseWrapper);
// **HERE DEPENDING ON THE SERVLET OR APPLICATION CODE (STRUTS, WICKET), the response returns an empty string //
// Especiall struts, is there something in their forwards that would cause an error?
final byte [] bytes = responseWrapper.toByteArray();
// For some applications that hit this filter
// ZERO BYTE DATA is returned, this is bad, but SOME
// CODE, the data is captured.
final String origHtml = new String(bytes);
final String newHtml = origHtml.replaceAll("(?i)</(\\s)*form(\\s)*>", "<input type=\"hidden\" name=\"zval\" value=\"fromSiteZ123\"/></form>");
response.getOutputStream().write(newHtml.getBytes());
} catch(final Exception e) {
e.printStackTrace();
}
return;
}
@Override
public void init(FilterConfig filterConfig) throws ServletException {
}
static class MyResponseWrapper extends HttpServletResponseWrapper {
private final MyPrintWriter pw = new MyPrintWriter();
public byte [] toByteArray() {
return pw.toByteArray();
}
public MyResponseWrapper(HttpServletResponse response) {
super(response);
}
@Override
public PrintWriter getWriter() {
return pw.getWriter();
}
@Override
public ServletOutputStream getOutputStream() {
return pw.getStream();
}
private static class MyPrintWriter {
private ByteArrayOutputStream baos = new ByteArrayOutputStream();
private PrintWriter pw = new PrintWriter(baos);
private ServletOutputStream sos = new MyServletStream(baos);
public PrintWriter getWriter() {
return pw;
}
public ServletOutputStream getStream() {
return sos;
}
byte[] toByteArray() {
return baos.toByteArray();
}
}
private static class MyServletStream extends ServletOutputStream {
ByteArrayOutputStream baos;
MyServletStream(final ByteArrayOutputStream baos) {
this.baos = baos;
}
@Override
public void write(final int param) throws IOException {
baos.write(param);
}
}
}
}
这是一个示例 Struts 应用程序可能看起来的样子，对于某些应用程序（不是 Struts），我们可能会捕获内容。但是对于像下面这样的应用程序，HTML 内容返回零字节，但应该有内容。
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<%@ taglib uri="/WEB-INF/struts-html.tld" prefix="html" %>
<%@ taglib uri="/WEB-INF/struts-bean.tld" prefix="bean" %>
<%@ taglib uri="/WEB-INF/c.tld" prefix="c" %>
<%@ taglib uri="/WEB-INF/struts-logic.tld" prefix="logic" %>
<%@ taglib uri="/WEB-INF/struts-tiles.tld" prefix="tiles" %>
<%@ taglib uri="/WEB-INF/struts-nested.tld" prefix="nested"%>
<html:html>
<head>
<title><bean:message key="myApp.customization.title" /></title>
<LINK rel="stylesheet" type="text/css" href="../theme/styles.css">
</head>
<body>
<html:form styleId="customizemyAppForm" method="post" action="/customizemyApp.do?step=submit">
<html:submit onclick="javascript:finish(this.form);" styleClass="input_small"> <bean:message key="myApp.customization.submit" /> </html:submit>
<input type="button" styleClass="input_small" width="80" style="WIDTH:80px" name="<bean:message key="myApp.customization.cancel" />" value="<bean:message key="myApp.customization.cancel" />" onclick="javascript:cancel();">
</html:form>
</body>
</html:html>
我怀疑MyResponseWrapper和MyPrintWriter不够健壮，无法捕获所有类型的内容。
可以工作的示例 servlet（a）：
response.getOutputStream().write(str.getBytes());
不起作用的示例 servlet ( b )：
response.getWriter().println("<html>data</html>");
示例a将获得捕获，示例b不会。
这是一个改进的包装类，大多数应用程序都可以工作，但现在一些 struts 应用程序，只有一些响应被发送到浏览器。
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 java.io.OutputStreamWriter;
import java.io.PrintWriter;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpServletResponseWrapper;
public class ByteArrayResponseWrapper extends HttpServletResponseWrapper {
private PrintWriter output = null;
private ServletOutputStream outStream = null;
private static final String NL = System.getProperty("line.separator");
public ByteArrayResponseWrapper(final HttpServletResponse response) {
super(response);
}
public String getDocument() {
InputStream in = null;
try {
in = this.getInputStream();
if (in != null) {
return getDocument(in);
}
} catch(final Exception ee) {
// ee.print;StackTrace();
} finally {
if (in != null) {
try {
in.close();
} catch (IOException e) {
//e.prin;tStackTrace();
}
}
}
return "";
}
protected String getDocument(final InputStream in) {
final StringBuffer buf = new StringBuffer();
BufferedReader br = null;
try {
String line = "";
br = new BufferedReader(new InputStreamReader(getInputStream(), this.getCharacterEncoding()));
while ((line = br.readLine()) != null) {
buf.append(line).append(NL);
}
} catch(final IOException e) {
//e.print;StackTrace();
} finally {
try {
if (br != null) {
br.close();
}
} catch (IOException ex) {
}
}
return buf.toString();
}
@Override
public PrintWriter getWriter() throws IOException {
if (output == null) {
output = new PrintWriter(new OutputStreamWriter(getOutputStream(), this.getCharacterEncoding()));
}
return output;
}
@Override
public ServletOutputStream getOutputStream() throws IOException {
if (outStream == null) {
outStream = new BufferingServletOutputStream();
}
return outStream;
}
public InputStream getInputStream() throws IOException {
final BufferingServletOutputStream out = (BufferingServletOutputStream) getOutputStream();
return new ByteArrayInputStream(out.getBuffer().toByteArray());
}
/**
* Implementation of ServletOutputStream that handles the in-memory
* buffering of the response content
*/
public static class BufferingServletOutputStream extends ServletOutputStream {
ByteArrayOutputStream out = null;
public BufferingServletOutputStream() {
this.out = new ByteArrayOutputStream();
}
public ByteArrayOutputStream getBuffer() {
return out;
}
public void write(int b) throws IOException {
out.write(b);
}
public void write(byte[] b) throws IOException {
out.write(b);
}
public void write(byte[] b, int off, int len) throws IOException {
out.write(b, off, len);
}
@Override
public void close() throws IOException {
out.close();
super.close();
}
@Override
public void flush() throws IOException {
out.flush();
super.flush();
}
}
}
我找到了一个可能的解决方案，在该getInputStream方法中，如果我在所有对象上调用“关闭”，例如outStream.flush()然后outStream.close()然后out.flush()...out.close()看起来最终字节被正确写入。它不直观，但看起来很有效。