| ClientStateTag.java |
/* Copyright 2003 Sun Microsystems, Inc. All rights reserved.
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$Id: ClientStateTag.java,v 1.3 2003/07/11 22:55:58 gmurray Exp $ */
package com.sun.j2ee.blueprints.waf.view.taglibs.smart;
import java.io.IOException;
import java.io.ByteArrayOutputStream;
import java.io.ObjectOutputStream;
import java.io.ObjectOutput;
import java.util.Iterator;
import java.util.Map;
import java.util.Iterator;
import java.util.Enumeration;
import java.util.HashMap;
// Apache Commons- Tag-Lib Imports
import org.apache.commons.codec.base64.Base64;
// J2EE Imports
import javax.servlet.jsp.JspTagException;
import javax.servlet.jsp.JspWriter;
import javax.servlet.jsp.tagext.BodyContent;
import javax.servlet.jsp.tagext.BodyTagSupport;
import javax.servlet.http.HttpServletRequest;
// WAF imports
import com.sun.j2ee.blueprints.waf.controller.web.util.WebKeys;
/**
* This tag caches state in the page and provides a button or
* image link within a form with the current page parameters
* and the page request attributes by encoding them as hidden
* form variables that are serialized using Base 64 Encoded Strings.
*
* This tag when used along with a front controller such as the
* one provided in the WAF can utilize a flow handler to forward
* a request page to a page with the same attributes it recieved
* when the original request was made.
*/
public class ClientStateTag extends BodyTagSupport {
private String altText = "";
private String buttonText;
private String imageURL;
private String cacheId;
private String targetURL;
private boolean encodeRequestAttributes = true;
private boolean encodeRequestParameters = true;
private Class serializableClass = null;
private HashMap parameters;
public void setId(String cacheId) {
this.cacheId = cacheId;
}
public void setAlt(String altText) {
this.altText = altText;
}
public void setButtonText(String buttonText) {
this.buttonText = buttonText;
}
public void setImageURL(String imageURL) {
this.imageURL = imageURL;
}
public void setTargetURL(String targetURL) {
this.targetURL = targetURL;
}
public void setEncodeRequestAttributes(boolean encodeRequestAttributes) {
this.encodeRequestAttributes = encodeRequestAttributes;
}
public void setEncodeRequestParameters(boolean encodeRequestParameters) {
this.encodeRequestAttributes = encodeRequestParameters;
}
public int doStartTag() throws JspTagException {
if (imageURL == null && buttonText == null) {
throw new JspTagException("ClientStateTag error: either an " +
"imageURL or buttonText attribute must be specified.");
}
return EVAL_BODY_BUFFERED;
}
public int doEndTag() throws JspTagException {
HttpServletRequest request =
((HttpServletRequest) pageContext.getRequest());
StringBuffer buffer = new StringBuffer();
buffer.append("<form method=\"POST\" action=\"" + targetURL + "\">");
// insert any parameters that may have been added via sub tags
if (parameters != null) {
Iterator it = parameters.keySet().iterator();
// put the request attributes stored in the session in the request
while (it.hasNext()) {
String key = (String)it.next();
String value = (String)parameters.get(key);
buffer.append(" <input type=\"hidden\" name=\"" +
key + "\" value=\"" + value + "\" />");
}
}
String fullURL = request.getRequestURI();
// find the url that sent us this page
String targetURL = null;
int lastPathSeparator = fullURL.lastIndexOf("/") + 1;
if (lastPathSeparator != -1) {
targetURL = fullURL.substring(lastPathSeparator, fullURL.length());
}
buffer.append(" <input type=\"hidden\" name=\"referring_URL\"" +
"value=\"" + targetURL +
"\">");
String referringScreen =
(String)request.getSession().getAttribute(WebKeys.PREVIOUS_SCREEN);
buffer.append(" <input type=\"hidden\" name=\"referring_screen\"" +
"value=\"" + referringScreen +
"\">");
buffer.append(" <input type=\"hidden\" name=\"cacheId\"" +
"value=\"" + cacheId + "\">");
// check the request for previous parameters
Map params = (Map)request.getParameterMap();
if (!params.isEmpty() && encodeRequestParameters) {
Iterator it = params.keySet().iterator();
// copy in the request parameters stored
while (it.hasNext()) {
String key = (String)it.next();
if (!key.startsWith(cacheId)) {
String[] values = (String[])params.get(key);
String valueString = values[0];
buffer.append(" <input type=\"hidden\" name=\"" +
key + "\" value=\"" +
valueString +
"\" />");
}
}
}
/**
* Now serialize the request attributes into the page (only sealizable objects are going
* to be processed).
*/
if (encodeRequestAttributes) {
// put the request attributes into tattributres
Enumeration enum = request.getAttributeNames();
while (enum.hasMoreElements()) {
String key = (String)enum.nextElement();
// check if we have already serialized the items
// also don't serialize javax items because
if (!key.startsWith(cacheId) &&
!key.startsWith("javax.servlet")) {
Object value = request.getAttribute(key);
if (serializableClass == null) {
try {
serializableClass = getClass().forName("java.io.Serializable");
} catch (java.lang.ClassNotFoundException cnf) {
System.err.println("ClientStateTag caught: " + cnf);
}
}
// check if seralizable
if (serializableClass.isAssignableFrom(value.getClass())) {
try {
ByteArrayOutputStream bos = new ByteArrayOutputStream();
ObjectOutput out = new ObjectOutputStream(bos);
out.writeObject(value);
out.close();
buffer.append(" <input type=\"hidden\" name=\"" + cacheId +
"_attribute_" + key + "\" value=\"" +
new String(Base64.encode(bos.toByteArray()), "ISO-8859-1") + "\" />");
} catch (java.io.IOException iox) {
System.err.println("ClientStateTag caught: " + iox);
}
} else {
System.out.println(key + " not to Serializeable");
}
}
}
}// end get attributes
// now put the link in
if (imageURL != null) {
buffer.append(" <input alt=\"" + altText+ "\" type=\"image\" " +
"src=\"" + imageURL + "\"/>");
} else {
buffer.append(" <input alt=\"" + altText + "\" type=\"submit\" " +
"value=\"" + buttonText + "\"/>");
}
buffer.append("</form>");
// write the output to the output stream
try {
JspWriter out = pageContext.getOut();
out.print(buffer.toString());
} catch (IOException ioe) {
System.err.println("ClientStateTag: Problems with writing...");
}
parameters = null;
altText = "";
buttonText = null;
imageURL = null;
cacheId = null;
targetURL = null;
encodeRequestAttributes = true;
encodeRequestParameters = true;
serializableClass = null;
return EVAL_PAGE;
}
public void putParameter(String key, String value) {
if (parameters == null) parameters = new HashMap();
parameters.put(key,value);
}
}
| ClientStateTag.java |