org.springframework.context.support.SimpleThreadScope.java Source code

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Here is the source code for org.springframework.context.support.SimpleThreadScope.java

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/*
 * Copyright 2002-2019 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.context.support;

import java.util.HashMap;
import java.util.Map;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import org.springframework.beans.factory.ObjectFactory;
import org.springframework.beans.factory.config.Scope;
import org.springframework.core.NamedThreadLocal;
import org.springframework.lang.Nullable;

/**
 * A simple thread-backed {@link Scope} implementation.
 *
 * <p><b>NOTE:</b> This thread scope is not registered by default in common contexts.
 * Instead, you need to explicitly assign it to a scope key in your setup, either through
 * {@link org.springframework.beans.factory.config.ConfigurableBeanFactory#registerScope}
 * or through a {@link org.springframework.beans.factory.config.CustomScopeConfigurer} bean.
 *
 * <p>{@code SimpleThreadScope} <em>does not clean up any objects</em> associated with it.
 * It is therefore typically preferable to use a request-bound scope implementation such
 * as {@code org.springframework.web.context.request.RequestScope} in web environments,
 * implementing the full lifecycle for scoped attributes (including reliable destruction).
 *
 * <p>For an implementation of a thread-based {@code Scope} with support for destruction
 * callbacks, refer to
 * <a href="https://www.springbyexample.org/examples/custom-thread-scope-module.html">Spring by Example</a>.
 *
 * <p>Thanks to Eugene Kuleshov for submitting the original prototype for a thread scope!
 *
 * @author Arjen Poutsma
 * @author Juergen Hoeller
 * @since 3.0
 * @see org.springframework.web.context.request.RequestScope
 */
public class SimpleThreadScope implements Scope {

    private static final Log logger = LogFactory.getLog(SimpleThreadScope.class);

    private final ThreadLocal<Map<String, Object>> threadScope = new NamedThreadLocal<Map<String, Object>>(
            "SimpleThreadScope") {
        @Override
        protected Map<String, Object> initialValue() {
            return new HashMap<>();
        }
    };

    @Override
    public Object get(String name, ObjectFactory<?> objectFactory) {
        Map<String, Object> scope = this.threadScope.get();
        Object scopedObject = scope.get(name);
        if (scopedObject == null) {
            scopedObject = objectFactory.getObject();
            scope.put(name, scopedObject);
        }
        return scopedObject;
    }

    @Override
    @Nullable
    public Object remove(String name) {
        Map<String, Object> scope = this.threadScope.get();
        return scope.remove(name);
    }

    @Override
    public void registerDestructionCallback(String name, Runnable callback) {
        logger.warn("SimpleThreadScope does not support destruction callbacks. "
                + "Consider using RequestScope in a web environment.");
    }

    @Override
    @Nullable
    public Object resolveContextualObject(String key) {
        return null;
    }

    @Override
    public String getConversationId() {
        return Thread.currentThread().getName();
    }

}