singletonprovider.java

来自「resetful样式的ws样例,一种面向资源的webservices服务」· Java 代码 · 共 80 行

/*
 *
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
 * 
 * Copyright 1997-2007 Sun Microsystems, Inc. All rights reserved.
 * 
 * The contents of this file are subject to the terms of either the GNU
 * General Public License Version 2 only ("GPL") or the Common Development
 * and Distribution License("CDDL") (collectively, the "License").  You
 * may not use this file except in compliance with the License. You can obtain
 * a copy of the License at https://jersey.dev.java.net/CDDL+GPL.html
 * or jersey/legal/LICENSE.txt.  See the License for the specific
 * language governing permissions and limitations under the License.
 * 
 * When distributing the software, include this License Header Notice in each
 * file and include the License file at jersey/legal/LICENSE.txt.
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 * Header, with the fields enclosed by brackets [] replaced by your own
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 * only the GPL Version 2, indicate your decision by adding "[Contributor]
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 * its licensees as provided above.  However, if you add GPL Version 2 code
 * and therefore, elected the GPL Version 2 license, then the option applies
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 */

package com.sun.jersey.impl.resource;

import com.sun.jersey.api.container.ContainerException;
import com.sun.jersey.api.core.HttpContext;
import com.sun.jersey.api.model.AbstractResource;
import com.sun.jersey.spi.resource.InjectableProviderContext;
import com.sun.jersey.spi.resource.ResourceClassInjector;
import com.sun.jersey.spi.resource.ResourceProvider;
import com.sun.jersey.spi.service.ComponentProvider;
import com.sun.jersey.spi.service.ComponentProvider.Scope;
import javax.ws.rs.core.Context;

/**
 * A simple provider that maintains a singleton resource class instance
 */
public final class SingletonProvider implements ResourceProvider {
    @Context InjectableProviderContext ipc;

    private Object resource;
    
    public void init(ComponentProvider provider,
            AbstractResource abstractResource) {
        Class<?> c = abstractResource.getResourceClass();
        
        ResourceClassInjector rci = new ResourceClassInjector(
                ipc, 
                Scope.Singleton, 
                abstractResource);
        
        try {
            resource = provider.getInstance(Scope.Singleton, c);
            rci.inject(null, provider.getInjectableInstance(resource));
        } catch (InstantiationException ex) {
            throw new ContainerException("Unable to create resource", ex);
        } catch (IllegalAccessException ex) {
            throw new ContainerException("Unable to create resource", ex);
        }
    }

    public Object getInstance(ComponentProvider provider, HttpContext context) {
        return resource;
    }
}