org.springframework.web.servlet.tags.NestedPathTag.java Source code

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Here is the source code for org.springframework.web.servlet.tags.NestedPathTag.java

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/*
 * Copyright 2002-2018 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
 *
 *      https://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.lang.Nullable;

/**
 * <p>The {@code <nestedPath>} tag supports and assists 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.
 *
 * <table>
 * <caption>Attribute Summary</caption>
 * <thead>
 * <tr>
 * <th>Attribute</th>
 * <th>Required?</th>
 * <th>Runtime Expression?</th>
 * <th>Description</th>
 * </tr>
 * </thead>
 * <tbody>
 * <tr>
 * <td>path</td>
 * <td>true</td>
 * <td>true</td>
 * <td>Set the path that this tag should apply. E.g. 'customer' to allow bind
 * paths like 'address.street' rather than 'customer.address.street'.</td>
 * </tr>
 * </tbody>
 * </table>
 *
 * @author Juergen Hoeller
 * @since 1.1
 */
@SuppressWarnings("serial")
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";

    @Nullable
    private String path;

    /** Caching a previous nested path, so that it may be reset. */
    @Nullable
    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(@Nullable 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.
     */
    @Nullable
    public String getPath() {
        return this.path;
    }

    @Override
    public int doStartTag() throws JspException {
        // Save previous nestedPath value, build and expose current nestedPath value.
        // Use request scope to expose nestedPath to included pages too.
        this.previousNestedPath = (String) this.pageContext.getAttribute(NESTED_PATH_VARIABLE_NAME,
                PageContext.REQUEST_SCOPE);
        String nestedPath = (this.previousNestedPath != null ? this.previousNestedPath + getPath() : getPath());
        this.pageContext.setAttribute(NESTED_PATH_VARIABLE_NAME, nestedPath, PageContext.REQUEST_SCOPE);

        return EVAL_BODY_INCLUDE;
    }

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

        return EVAL_PAGE;
    }

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

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

}