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1   /*
2    * Copyright 2004-2009 the Seasar Foundation and the Others.
3    *
4    * Licensed under the Apache License, Version 2.0 (the "License");
5    * you may not use this file except in compliance with the License.
6    * You may obtain a copy of the License at
7    *
8    *     http://www.apache.org/licenses/LICENSE-2.0
9    *
10   * Unless required by applicable law or agreed to in writing, software
11   * distributed under the License is distributed on an "AS IS" BASIS,
12   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
13   * either express or implied. See the License for the specific language
14   * governing permissions and limitations under the License.
15   */
16  package org.seasar.cubby.plugins.guice;
17  
18  import java.util.ArrayList;
19  import java.util.List;
20  
21  import javax.servlet.ServletContext;
22  import javax.servlet.ServletContextEvent;
23  
24  import org.slf4j.Logger;
25  import org.slf4j.LoggerFactory;
26  
27  import com.google.inject.Guice;
28  import com.google.inject.Injector;
29  import com.google.inject.Module;
30  import com.google.inject.servlet.GuiceServletContextListener;
31  
32  /**
33   * {@link Injector} を初期化するための {@code Servlet} コンテキストのリスナです。
34   * <p>
35   * アプリケーションが使用するモジュールのクラス名を WEB 配備記述子の初期化パラメータ {@value #MODULE_INIT_PARAM_NAME}
36   * に指定してください。
37   * </p>
38   * <p>
39   * 例
40   * 
41   * <pre>
42   * &lt;context-param&gt;
43   *   &lt;param-name&gt;{@value #MODULE_INIT_PARAM_NAME}&lt;/paanm-name&gt;
44   *   &lt;param-value&gt;com.example.ApplicationModule&lt;/param-value&gt;
45   * &lt;/context-param&gt;
46   * </pre>
47   * 
48   * </p>
49   * 
50   * @author baba
51   */
52  public class CubbyGuiceServletContextListener extends
53  		GuiceServletContextListener {
54  
55  	private static final Logger logger = LoggerFactory
56  			.getLogger(CubbyGuiceServletContextListener.class.getName());
57  
58  	/** モジュールの WEB 配備記述子の初期化パラメータ名 */
59  	public static final String MODULE_INIT_PARAM_NAME = "cubby.guice.module";
60  
61  	/** インスタンス化するモジュールのクラス名 */
62  	private String[] moduleClassNames;
63  
64  	/**
65  	 * {@inheritDoc}
66  	 */
67  	@Override
68  	public void contextInitialized(ServletContextEvent servletContextEvent) {
69  		final ServletContext servletContext = servletContextEvent
70  				.getServletContext();
71  		final String moduleClassNamesString = servletContext
72  				.getInitParameter(MODULE_INIT_PARAM_NAME);
73  		if (moduleClassNamesString == null
74  				|| moduleClassNamesString.length() == 0) {
75  			throw new IllegalArgumentException("No context parameter \""
76  					+ MODULE_INIT_PARAM_NAME + "\", please set Module FQCN");
77  		}
78  		this.moduleClassNames = moduleClassNamesString.split(",");
79  
80  		super.contextInitialized(servletContextEvent);
81  	}
82  
83  	/**
84  	 * 指定されたクラス名のモジュールを生成します。
85  	 * 
86  	 * @param moduleClassName
87  	 *            モジュールのクラス名
88  	 * @return インジェクタ
89  	 */
90  	protected Module createModule(final String moduleClassName) {
91  		if (logger.isInfoEnabled()) {
92  			logger.info("Instantiates " + moduleClassName);
93  		}
94  
95  		final ClassLoader loader = Thread.currentThread()
96  				.getContextClassLoader();
97  		try {
98  			final Class<?> clazz = Class.forName(moduleClassName, true, loader);
99  			final Module module = Module.class.cast(clazz.newInstance());
100 			return module;
101 		} catch (final ClassNotFoundException e) {
102 			throw new IllegalArgumentException("Illegal module "
103 					+ moduleClassName, e);
104 		} catch (final InstantiationException e) {
105 			throw new IllegalArgumentException("Illegal module "
106 					+ moduleClassName, e);
107 		} catch (final IllegalAccessException e) {
108 			throw new IllegalArgumentException("Illegal module "
109 					+ moduleClassName, e);
110 		}
111 	}
112 
113 	/**
114 	 * {@inheritDoc}
115 	 */
116 	@Override
117 	protected Injector getInjector() {
118 		final List<Module> modules = new ArrayList<Module>();
119 		for (final String moduleClassName : this.moduleClassNames) {
120 			final Module module = createModule(moduleClassName.trim());
121 			modules.add(module);
122 		}
123 		return Guice.createInjector(modules);
124 	}
125 
126 }