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Java example source code file (GuiceObjectFactory.java)

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

Learn more about this Java project at its project page.

Java - Java tags/keywords

annotation, class, classnotfoundexception, configurationexception, inject, injector, interceptor, log, logging, map, module, providedinterceptor, runtimeexception, set, string, suppresswarnings, throwable, util

The GuiceObjectFactory.java Java example source code

/**
 * Copyright (C) 2006 Google Inc.
 *
 * 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 com.google.inject.struts2;

import com.google.inject.AbstractModule;
import com.google.inject.Binder;
import com.google.inject.Guice;
import com.google.inject.Injector;
import com.google.inject.Module;
import com.google.inject.internal.Annotations;
import com.google.inject.servlet.ServletModule;

import com.opensymphony.xwork2.ActionInvocation;
import com.opensymphony.xwork2.ObjectFactory;
import com.opensymphony.xwork2.config.ConfigurationException;
import com.opensymphony.xwork2.config.entities.InterceptorConfig;
import com.opensymphony.xwork2.inject.Inject;
import com.opensymphony.xwork2.interceptor.Interceptor;

import java.lang.annotation.Annotation;
import java.util.ArrayList;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.logging.Logger;

/**
 * @deprecated Use {@link com.google.inject.struts2.Struts2Factory} instead.
 */
@Deprecated
public class GuiceObjectFactory extends ObjectFactory {

  static final Logger logger =
      Logger.getLogger(GuiceObjectFactory.class.getName());

  Module module;
  volatile Injector injector;
  boolean developmentMode = false;
  List<ProvidedInterceptor> interceptors
      = new ArrayList<ProvidedInterceptor>();

  @Override
  public boolean isNoArgConstructorRequired() {
    return false;
  }

  @Inject(value = "guice.module", required = false)
  void setModule(String moduleClassName) {
    try {
      // Instantiate user's module.
      @SuppressWarnings({"unchecked"})
      Class<? extends Module> moduleClass =
          (Class<? extends Module>) Class.forName(moduleClassName);
      this.module = moduleClass.newInstance();
    } catch (Exception e) {
      throw new RuntimeException(e);
    }
  }

  @Inject(value = "struts.devMode", required = false)
  void setDevelopmentMode(String developmentMode) {
    this.developmentMode = developmentMode.trim().equals("true");
  }

  Set<Class boundClasses = new HashSet>();

  public Class getClassInstance(String name) throws ClassNotFoundException {
    Class<?> clazz = super.getClassInstance(name);

    synchronized (this) {
      if (injector == null) {
        // We can only bind each class once.
        if (!boundClasses.contains(clazz)) {
          try {
            // Calling these methods now helps us detect ClassNotFoundErrors
            // early.
            clazz.getDeclaredFields();
            clazz.getDeclaredMethods();

            boundClasses.add(clazz);
          } catch (Throwable t) {
            // Struts should still work even though some classes aren't in the
            // classpath. It appears we always get the exception here when
            // this is the case.
            return clazz;
          }
        }
      }
    }

    return clazz;
  }

  @SuppressWarnings("unchecked")
  public Object buildBean(Class clazz, Map extraContext) {
    if (injector == null) {
      synchronized (this) {
        if (injector == null) {
          createInjector();
        }
      }
    }

    return injector.getInstance(clazz);
  }

  private void createInjector() {
    try {
      logger.info("Creating injector...");
      this.injector = Guice.createInjector(new AbstractModule() {
        protected void configure() {
          // Install default servlet bindings.
          install(new ServletModule());

          // Install user's module.
          if (module != null) {
            logger.info("Installing " + module + "...");
            install(module);
          }
          else {
            logger.info("No module found. Set 'guice.module' to a Module "
                + "class name if you'd like to use one.");
          }

          // Tell the injector about all the action classes, etc., so it
          // can validate them at startup.
          for (Class<?> boundClass : boundClasses) {
            // TODO: Set source from Struts XML.
            bind(boundClass);
          }

          // Validate the interceptor class.
          for (ProvidedInterceptor interceptor : interceptors) {
            interceptor.validate(binder());
          }
        }
      });

      // Inject interceptors.
      for (ProvidedInterceptor interceptor : interceptors) {
        interceptor.inject();
      }

    } catch (Throwable t) {
      t.printStackTrace();
      System.exit(1);
    }
    logger.info("Injector created successfully.");
  }

  @SuppressWarnings("unchecked")
  public Interceptor buildInterceptor(InterceptorConfig interceptorConfig,
      Map interceptorRefParams) throws ConfigurationException {
    // Ensure the interceptor class is present.
    Class<? extends Interceptor> interceptorClass;
    try {
      interceptorClass = getClassInstance(interceptorConfig.getClassName());
    } catch (ClassNotFoundException e) {
      throw new RuntimeException(e);
    }

    ProvidedInterceptor providedInterceptor = new ProvidedInterceptor(
        interceptorConfig, interceptorRefParams, interceptorClass);
    interceptors.add(providedInterceptor);
    return providedInterceptor;
  }

  Interceptor superBuildInterceptor(InterceptorConfig interceptorConfig,
      Map interceptorRefParams) throws ConfigurationException {
    return super.buildInterceptor(interceptorConfig, interceptorRefParams);
  }

  class ProvidedInterceptor implements Interceptor {

    final InterceptorConfig config;
    final Map params;
    final Class<? extends Interceptor> interceptorClass;
    Interceptor delegate;

    ProvidedInterceptor(InterceptorConfig config, Map params,
        Class<? extends Interceptor> interceptorClass) {
      this.config = config;
      this.params = params;
      this.interceptorClass = interceptorClass;
    }

    void validate(Binder binder) {
      // TODO: Set source from Struts XML.
      if (hasScope(interceptorClass)) {
        binder.addError("Scoping interceptors is not currently supported."
            + " Please remove the scope annotation from "
            + interceptorClass.getName() + ".");
      }

      // Make sure it implements Interceptor.
      if (!Interceptor.class.isAssignableFrom(interceptorClass)) {
        binder.addError(interceptorClass.getName() + " must implement "
          + Interceptor.class.getName() + ".");
      }
    }

    void inject() {
      delegate = superBuildInterceptor(config, params);
    }

    public void destroy() {
      if (null != delegate) {
        delegate.destroy();
      }
    }

    public void init() {
      throw new AssertionError();
    }

    public String intercept(ActionInvocation invocation) throws Exception {
      return delegate.intercept(invocation);
    }
  }

  /**
   * Returns true if the given class has a scope annotation.
   */
  private static boolean hasScope(Class<? extends Interceptor> interceptorClass) {
    for (Annotation annotation : interceptorClass.getAnnotations()) {
      if (Annotations.isScopeAnnotation(annotation.annotationType())) {
        return true;
      }
    }
    return false;
  }
}

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