Add <spring:argument> subtag for message/theme

Add a new <spring:argument> tag that cab be nested within
<spring:message> and <spring:theme>. The tag is based on the <fmt:param>
tag and uses conventions found throughout other Spring tags.

Issue: SPR-9678

Author: beamerblvd

spring-webmvc/src/main/java/org/springframework/web/servlet/tags/ArgumentAware.java

@@ -0,0 +1,36 @@
+/*
+ * Copyright 2002-2013 the original author or authors.
+ *
+ * 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.springframework.web.servlet.tags;
+
+import javax.servlet.jsp.JspTagException;
+
+/**
+ * Allows implementing tag to utilize nested {@code spring:argument} tags.
+ *
+ * @author Nicholas Williams
+ * @since 4.0
+ * @see ArgumentTag
+ */
+public interface ArgumentAware {
+
+	/**
+	 * Callback hook for nested spring:argument tags to pass their value
+	 * to the parent tag.
+	 * @param argument the result of the nested {@code spring:argument} tag
+	 */
+	void addArgument(Object argument) throws JspTagException;
+}

spring-webmvc/src/main/java/org/springframework/web/servlet/tags/ArgumentTag.java

@@ -0,0 +1,88 @@
+/*
+ * Copyright 2002-2013 the original author or authors.
+ *
+ * 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.springframework.web.servlet.tags;
+
+import javax.servlet.jsp.JspException;
+import javax.servlet.jsp.tagext.BodyTagSupport;
+
+/**
+ * JSP tag for collecting arguments and passing them to an {@link ArgumentAware} ancestor
+ * in the tag hierarchy.
+ *
+ * <p>This tag must be nested under an argument aware tag.
+ *
+ * @author Nicholas Williams
+ * @since 4.0
+ * @see MessageTag
+ * @see ThemeTag
+ */
+@SuppressWarnings("serial")
+public class ArgumentTag extends BodyTagSupport {
+
+	private Object value;
+
+	private boolean valueSet;
+
+	// tag lifecycle
+
+	@Override
+	public int doEndTag() throws JspException {
+		Object argument = null;
+		if (this.valueSet) {
+			argument = this.value;
+		}
+		else if (getBodyContent() != null) {
+			// get the value from the tag body
+			argument = getBodyContent().getString().trim();
+		}
+
+		// find a param aware ancestor
+		ArgumentAware argumentAwareTag = (ArgumentAware) findAncestorWithClass(this,
+				ArgumentAware.class);
+		if (argumentAwareTag == null) {
+			throw new JspException(
+					"The argument tag must be a descendant of a tag that supports arguments");
+		}
+
+		argumentAwareTag.addArgument(argument);
+
+		return EVAL_PAGE;
+	}
+
+	// tag attribute mutators
+
+	/**
+	 * Sets the value of the argument
+	 *
+	 * <p>
+	 * Optional. If not set, the tag's body content is evaluated.
+	 *
+	 * @param value the parameter value
+	 */
+	public void setValue(Object value) {
+		this.value = value;
+		this.valueSet = true;
+	}
+
+	@Override
+	public void release() {
+		super.release();
+		this.value = null;
+		this.valueSet = false;
+	}
+
+}

spring-webmvc/src/main/java/org/springframework/web/servlet/tags/MessageTag.java

@@ -18,6 +18,9 @@
 
 import java.io.IOException;
 import java.util.Collection;
+import java.util.LinkedList;
+import java.util.List;
+
 import javax.servlet.jsp.JspException;
 import javax.servlet.jsp.JspTagException;
 
@@ -40,17 +43,22 @@
  * <p>If "code" isn't set or cannot be resolved, "text" will be used as default
  * message. Thus, this tag can also be used for HTML escaping of any texts.
  *
+ * <p>Message arguments can be specified via the {@link #setArguments(Object) arguments}
+ * attribute or by using nested {@code &lt;spring:argument&gt;} tags.
+ *
  * @author Rod Johnson
  * @author Juergen Hoeller
+ * @author Nicholas Williams
  * @see #setCode
  * @see #setText
  * @see #setHtmlEscape
  * @see #setJavaScriptEscape
  * @see HtmlEscapeTag#setDefaultHtmlEscape
  * @see org.springframework.web.util.WebUtils#HTML_ESCAPE_CONTEXT_PARAM
+ * @see ArgumentTag
  */
 @SuppressWarnings("serial")
-public class MessageTag extends HtmlEscapingAwareTag {
+public class MessageTag extends HtmlEscapingAwareTag implements ArgumentAware {
 
 	/**
 	 * Default separator for splitting an arguments String: a comma (",")
@@ -66,6 +74,8 @@ public class MessageTag extends HtmlEscapingAwareTag {
 
 	private String argumentSeparator = DEFAULT_ARGUMENT_SEPARATOR;
 
+	private List<Object> nestedArguments;
+
 	private String text;
 
 	private String var;
@@ -109,6 +119,11 @@ public void setArgumentSeparator(String argumentSeparator) {
 		this.argumentSeparator = argumentSeparator;
 	}
 
+	@Override
+	public void addArgument(Object argument) throws JspTagException {
+		this.nestedArguments.add(argument);
+	}
+
 	/**
 	 * Set the message text for this tag.
 	 */
@@ -146,6 +161,12 @@ public void setJavaScriptEscape(boolean javaScriptEscape) throws JspException {
 	}
 
 
+	@Override
+	protected final int doStartTagInternal() throws JspException, IOException {
+		this.nestedArguments = new LinkedList<Object>();
+		return EVAL_BODY_INCLUDE;
+	}
+
 	/**
 	 * Resolves the message, escapes it if demanded,
 	 * and writes it to the page (or exposes it as variable).
@@ -155,7 +176,7 @@ public void setJavaScriptEscape(boolean javaScriptEscape) throws JspException {
 	 * @see #writeMessage(String)
 	 */
 	@Override
-	protected final int doStartTagInternal() throws JspException, IOException {
+	public int doEndTag() throws JspException {
 		try {
 			// Resolve the unescaped message.
 			String msg = resolveMessage();
@@ -172,13 +193,22 @@ protected final int doStartTagInternal() throws JspException, IOException {
 				writeMessage(msg);
 			}
 
-			return EVAL_BODY_INCLUDE;
+			return EVAL_PAGE;
+		}
+		catch (IOException ex) {
+			throw new JspTagException(ex.getMessage(), ex);
 		}
 		catch (NoSuchMessageException ex) {
 			throw new JspTagException(getNoSuchMessageExceptionDescription(ex));
 		}
 	}
 
+	@Override
+	public void release() {
+		super.release();
+		this.arguments = null;
+	}
+
 	/**
 	 * Resolve the specified message into a concrete message String.
 	 * The returned message String should be unescaped.
@@ -198,6 +228,11 @@ protected String resolveMessage() throws JspException, NoSuchMessageException {
 		if (this.code != null || this.text != null) {
 			// We have a code or default text that we need to resolve.
 			Object[] argumentsArray = resolveArguments(this.arguments);
+			if(!this.nestedArguments.isEmpty()) {
+				argumentsArray = appendArguments(argumentsArray,
+						this.nestedArguments.toArray());
+			}
+
 			if (this.text != null) {
 				// We have a fallback text to consider.
 				return messageSource.getMessage(
@@ -214,6 +249,16 @@ protected String resolveMessage() throws JspException, NoSuchMessageException {
 		return this.text;
 	}
 
+	private Object[] appendArguments(Object[] sourceArguments, Object[] additionalArguments) {
+		if(ObjectUtils.isEmpty(sourceArguments)) {
+			return additionalArguments;
+		}
+		Object[] arguments = new Object[sourceArguments.length + additionalArguments.length];
+		System.arraycopy(sourceArguments, 0, arguments, 0, sourceArguments.length);
+		System.arraycopy(additionalArguments, 0, arguments, sourceArguments.length, additionalArguments.length);
+		return arguments;
+	}
+
 	/**
 	 * Resolve the given arguments Object into an arguments array.
 	 * @param arguments the specified arguments Object

spring-webmvc/src/main/java/org/springframework/web/servlet/tags/ThemeTag.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2012 the original author or authors.
+ * Copyright 2002-2013 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -30,6 +30,9 @@
  * <p>If "code" isn't set or cannot be resolved, "text" will be used
  * as default message.
  *
+ * <p>Message arguments can be specified via the {@link #setArguments(Object) arguments}
+ * attribute or by using nested {@code &lt;spring:argument&gt;} tags.
+ *
  * @author Jean-Pierre Pawlak
  * @author Juergen Hoeller
  * @see org.springframework.ui.context.Theme
@@ -39,6 +42,7 @@
  * @see #setHtmlEscape
  * @see HtmlEscapeTag#setDefaultHtmlEscape
  * @see org.springframework.web.util.WebUtils#HTML_ESCAPE_CONTEXT_PARAM
+ * @see ArgumentTag
  */
 @SuppressWarnings("serial")
 public class ThemeTag extends MessageTag {

spring-webmvc/src/main/resources/META-INF/spring.tld

@@ -83,7 +83,8 @@
 			<description>Set optional message arguments for this tag, as a
 			(comma-)delimited String (each String argument can contain JSP EL),
 			an Object array (used as argument array), or a single Object (used
-			as single argument).</description>
+			as single argument). You can additionally use nested spring:argument
+			tags.</description>
 			<name>arguments</name>
 			<required>false</required>
 			<rtexprvalue>true</rtexprvalue>
@@ -160,7 +161,8 @@
 			<description>Set optional message arguments for this tag, as a
 			(comma-)delimited String (each String argument can contain JSP EL),
 			an Object array (used as argument array), or a single Object (used
-			as single argument).</description>
+			as single argument). You can additionally use nested spring:argument
+			tags.</description>
 			<name>arguments</name>
 			<required>false</required>
 			<rtexprvalue>true</rtexprvalue>
@@ -211,6 +213,22 @@
 		</attribute>
 	</tag>
 
+	<tag>
+		<description>Argument tag based on the JSTL fmt:param tag.  The purpose is to
+			support arguments inside the spring:message and spring:theme
+			tags.</description>
+		<name>argument</name>
+		<tag-class>org.springframework.web.servlet.tags.ArgumentTag</tag-class>
+		<body-content>JSP</body-content>
+		<attribute>
+			<description>The value of the argument.</description>
+			<name>value</name>
+			<required>false</required>
+			<rtexprvalue>true</rtexprvalue>
+			<type>java.lang.Object</type>
+		</attribute>
+	</tag>
+
 	<tag>
 		<description>
 			Provides Errors instance in case of bind errors.