/*
* Copyright 1999,2004 The Apache Software Foundation.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.taglibs.standard.tag.common.core;
import java.lang.reflect.Method;
import java.net.URLEncoder;
import java.util.LinkedList;
import java.util.List;
import javax.servlet.jsp.JspException;
import javax.servlet.jsp.JspTagException;
import javax.servlet.jsp.tagext.BodyTagSupport;
import javax.servlet.jsp.tagext.Tag;
import org.apache.taglibs.standard.resources.Resources;
/**
* <p>Support for tag handlers for <param>, the URL parameter
* subtag for <import> in JSTL 1.0.</p>
*
* @see ParamParent, ImportSupport, URLEncodeSupport
* @author Shawn Bayern
*/
public abstract class ParamSupport extends BodyTagSupport {
//*********************************************************************
// Private constants
private static final Class[] URL_ENCODER_PARAM_TYPES =
new Class[] { String.class, String.class };
//*********************************************************************
// Protected state
protected String name; // 'name' attribute
protected String value; // 'value' attribute
/**
* There used to be an 'encode' attribute; I've left this as a
* vestige in case custom subclasses want to use our functionality
* but NOT encode parameters.
*/
protected boolean encode = true;
//*********************************************************************
// Private state
private static Method encodeMethod1_4 = null;
//*********************************************************************
// Constructor and initialization
// URLEncoder.encode(String) has been deprecated in J2SE 1.4.
// Take advantage of the new method URLEncoder.encode(String, enc)
// if J2SE 1.4 is used.
static {
try {
Class urlEncoderClass = Class.forName("java.net.URLEncoder");
encodeMethod1_4 =
urlEncoderClass.getMethod(
"encode",
new Class[] {String.class, String.class});
} catch (Exception ex) {} // encodeMethod1_4 will be null if exception
}
public ParamSupport() {
super();
init();
}
private void init() {
name = value = null;
}
//*********************************************************************
// Tag logic
// simply send our name and value to our appropriate ancestor
public int doEndTag() throws JspException {
Tag t = findAncestorWithClass(this, ParamParent.class);
if (t == null)
throw new JspTagException(
Resources.getMessage("PARAM_OUTSIDE_PARENT"));
// take no action for null or empty names
if (name == null || name.equals(""))
return EVAL_PAGE;
// send the parameter to the appropriate ancestor
ParamParent parent = (ParamParent) t;
String value = this.value;
if (value == null) {
if (bodyContent == null || bodyContent.getString() == null)
value = "";
else
value = bodyContent.getString().trim();
}
if (encode) {
if (encodeMethod1_4 != null) {
Object[] methodArgsName = new Object[2];
methodArgsName[0] = name;
methodArgsName[1] = pageContext.getResponse().getCharacterEncoding();
Object[] methodArgsValue = new Object[2];
methodArgsValue[0] = value;
methodArgsValue[1] = pageContext.getResponse().getCharacterEncoding();
try {
parent.addParameter(
(String)encodeMethod1_4.invoke(null, methodArgsName),
(String)encodeMethod1_4.invoke(null, methodArgsValue));
} catch (Exception ex) {
throw new JspException("System error invoking URLEncoder.encode() by reflection.", ex);
}
} else {
// must use J2SE 1.3 version
parent.addParameter(
URLEncoder.encode(name), URLEncoder.encode(value));
}
} else {
parent.addParameter(name, value);
}
return EVAL_PAGE;
}
// Releases any resources we may have (or inherit)
public void release() {
init();
}
//*********************************************************************
// Support for parameter management
/**
* Provides support for aggregating query parameters in URLs.
* Specifically, accepts a series of parameters, ensuring that
* - newer parameters will precede older ones in the output URL
* - all supplied parameters precede those in the input URL
*/
public static class ParamManager {
//*********************************
// Private state
private List names = new LinkedList();
private List values = new LinkedList();
private boolean done = false;
//*********************************
// Public interface
/** Adds a new parameter to the list. */
public void addParameter(String name, String value) {
if (done)
throw new IllegalStateException();
if (name != null) {
names.add(name);
if (value != null)
values.add(value);
else
values.add("");
}
}
/**
* Produces a new URL with the stored parameters, in the appropriate
* order.
*/
public String aggregateParams(String url) {
/*
* Since for efficiency we're destructive to the param lists,
* we don't want to run multiple times.
*/
if (done)
throw new IllegalStateException();
done = true;
//// reverse the order of our two lists
// Collections.reverse(this.names);
// Collections.reverse(this.values);
// build a string from the parameter list
StringBuffer newParams = new StringBuffer();
for (int i = 0; i < names.size(); i++) {
newParams.append(names.get(i) + "=" + values.get(i));
if (i < (names.size() - 1))
newParams.append("&");
}
// insert these parameters into the URL as appropriate
if (newParams.length() > 0) {
int questionMark = url.indexOf('?');
if (questionMark == -1) {
return (url + "?" + newParams);
} else {
StringBuffer workingUrl = new StringBuffer(url);
workingUrl.insert(questionMark + 1, (newParams + "&"));
return workingUrl.toString();
}
} else {
return url;
}
}
}
}