Spring Framework example source code file (NestedPathTag.java)

This example Spring Framework source code file (NestedPathTag.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Spring Framework tags/keywords

eval_body_include, eval_body_include, eval_page, eval_page, http, jsp, jspexception, nested_path_variable_name, nested_path_variable_name, nestedpathtag, servlet, string, string, tagsupport, throwable, trycatchfinally

The Spring Framework NestedPathTag.java source code

/*
 * Copyright 2002-2007 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.PageContext;
import javax.servlet.jsp.tagext.TagSupport;
import javax.servlet.jsp.tagext.TryCatchFinally;

import org.springframework.beans.PropertyAccessor;
import org.springframework.web.util.ExpressionEvaluationUtils;

/**
 * <p>Nested-path tag, to support and assist with nested beans or bean properties
 * in the model. Exports a "nestedPath" variable of type String in request scope,
 * visible to the current page and also included pages, if any.
 *
 * <p>The BindTag will auto-detect the current nested path and automatically
 * prepend it to its own path to form a complete path to the bean or bean property.
 *
 * <p>This tag will also prepend any existing nested path that is currently set.
 * Thus, you can nest multiple nested-path tags.
 *
 * <p>Thanks to Seth Ladd for the suggestion and the original implementation!
 *
 * @author Juergen Hoeller
 * @since 1.1
 */
public class NestedPathTag extends TagSupport implements TryCatchFinally {

	/**
	 * Name of the exposed variable within the scope of this tag: "nestedPath".
	 */
	public static final String NESTED_PATH_VARIABLE_NAME = "nestedPath";


	private String path;

	/** Caching a previous nested path, so that it may be reset */
	private String previousNestedPath;


	/**
	 * Set the path that this tag should apply.
	 * <p>E.g. "customer" to allow bind paths like "address.street"
	 * rather than "customer.address.street".
	 * @see BindTag#setPath
	 */
	public void setPath(String path) {
		if (path == null) {
			path = "";
		}
		if (path.length() > 0 && !path.endsWith(PropertyAccessor.NESTED_PROPERTY_SEPARATOR)) {
			path += PropertyAccessor.NESTED_PROPERTY_SEPARATOR;
		}
		this.path = path;
	}

	/**
	 * Return the path that this tag applies to.
	 */
	public String getPath() {
		return this.path;
	}


	public int doStartTag() throws JspException {
		String resolvedPath = ExpressionEvaluationUtils.evaluateString("path", getPath(), pageContext);

		// Save previous nestedPath value, build and expose current nestedPath value.
		// Use request scope to expose nestedPath to included pages too.
		this.previousNestedPath =
				(String) pageContext.getAttribute(NESTED_PATH_VARIABLE_NAME, PageContext.REQUEST_SCOPE);
		String nestedPath =
				(this.previousNestedPath != null ? this.previousNestedPath + resolvedPath : resolvedPath);
		pageContext.setAttribute(NESTED_PATH_VARIABLE_NAME, nestedPath, PageContext.REQUEST_SCOPE);

		return EVAL_BODY_INCLUDE;
	}

	/**
	 * Reset any previous nestedPath value.
	 */
	public int doEndTag() {
		if (this.previousNestedPath != null) {
			// Expose previous nestedPath value.
			pageContext.setAttribute(NESTED_PATH_VARIABLE_NAME, this.previousNestedPath, PageContext.REQUEST_SCOPE);
		}
		else {
			// Remove exposed nestedPath value.
			pageContext.removeAttribute(NESTED_PATH_VARIABLE_NAME, PageContext.REQUEST_SCOPE);
		}

		return EVAL_PAGE;
	}

	public void doCatch(Throwable throwable) throws Throwable {
		throw throwable;
	}

	public void doFinally() {
		this.previousNestedPath = null;
	}

}