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      1 /**
      2  * Copyright (C) 2010 Google, Inc.
      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, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 package com.google.inject.persist.jpa;
     18 
     19 import com.google.common.base.Preconditions;
     20 import com.google.common.collect.Lists;
     21 import com.google.inject.Inject;
     22 import com.google.inject.Provides;
     23 import com.google.inject.Singleton;
     24 import com.google.inject.TypeLiteral;
     25 import com.google.inject.persist.PersistModule;
     26 import com.google.inject.persist.PersistService;
     27 import com.google.inject.persist.UnitOfWork;
     28 import com.google.inject.persist.finder.DynamicFinder;
     29 import com.google.inject.persist.finder.Finder;
     30 import com.google.inject.util.Providers;
     31 
     32 import org.aopalliance.intercept.MethodInterceptor;
     33 import org.aopalliance.intercept.MethodInvocation;
     34 
     35 import java.lang.reflect.AccessibleObject;
     36 import java.lang.reflect.InvocationHandler;
     37 import java.lang.reflect.Method;
     38 import java.lang.reflect.Proxy;
     39 import java.util.List;
     40 import java.util.Map;
     41 
     42 import javax.persistence.EntityManager;
     43 import javax.persistence.EntityManagerFactory;
     44 
     45 /**
     46  * JPA provider for guice persist.
     47  *
     48  * @author dhanji (at) gmail.com (Dhanji R. Prasanna)
     49  */
     50 public final class JpaPersistModule extends PersistModule {
     51   private final String jpaUnit;
     52 
     53   public JpaPersistModule(String jpaUnit) {
     54     Preconditions.checkArgument(null != jpaUnit && jpaUnit.length() > 0,
     55         "JPA unit name must be a non-empty string.");
     56     this.jpaUnit = jpaUnit;
     57   }
     58 
     59   private Map<?,?> properties;
     60   private MethodInterceptor transactionInterceptor;
     61 
     62   @Override protected void configurePersistence() {
     63     bindConstant().annotatedWith(Jpa.class).to(jpaUnit);
     64 
     65     bind(JpaPersistService.class).in(Singleton.class);
     66 
     67     bind(PersistService.class).to(JpaPersistService.class);
     68     bind(UnitOfWork.class).to(JpaPersistService.class);
     69     bind(EntityManager.class).toProvider(JpaPersistService.class);
     70     bind(EntityManagerFactory.class)
     71         .toProvider(JpaPersistService.EntityManagerFactoryProvider.class);
     72 
     73     transactionInterceptor = new JpaLocalTxnInterceptor();
     74     requestInjection(transactionInterceptor);
     75 
     76     // Bind dynamic finders.
     77     for (Class<?> finder : dynamicFinders) {
     78       bindFinder(finder);
     79     }
     80   }
     81 
     82   @Override protected MethodInterceptor getTransactionInterceptor() {
     83     return transactionInterceptor;
     84   }
     85 
     86   @Provides @Jpa Map<?, ?> provideProperties() {
     87     return properties;
     88   }
     89 
     90   /**
     91    * Configures the JPA persistence provider with a set of properties.
     92    *
     93    * @param properties A set of name value pairs that configure a JPA persistence
     94    *     provider as per the specification.
     95    * @since 4.0 (since 3.0 with a parameter type of {@code java.util.Properties})
     96    */
     97   public JpaPersistModule properties(Map<?,?> properties) {
     98     this.properties = properties;
     99     return this;
    100   }
    101 
    102   private final List<Class<?>> dynamicFinders = Lists.newArrayList();
    103 
    104   /**
    105    * Adds an interface to this module to use as a dynamic finder.
    106    *
    107    * @param iface Any interface type whose methods are all dynamic finders.
    108    */
    109   public <T> JpaPersistModule addFinder(Class<T> iface) {
    110     dynamicFinders.add(iface);
    111     return this;
    112   }
    113 
    114   private <T> void bindFinder(Class<T> iface) {
    115     if (!isDynamicFinderValid(iface)) {
    116       return;
    117     }
    118 
    119     InvocationHandler finderInvoker = new InvocationHandler() {
    120       @Inject JpaFinderProxy finderProxy;
    121 
    122       public Object invoke(final Object thisObject, final Method method, final Object[] args)
    123           throws Throwable {
    124 
    125         // Don't intercept non-finder methods like equals and hashcode.
    126         if (!method.isAnnotationPresent(Finder.class)) {
    127           // NOTE(dhanji): This is not ideal, we are using the invocation handler's equals
    128           // and hashcode as a proxy (!) for the proxy's equals and hashcode.
    129           return method.invoke(this, args);
    130         }
    131 
    132         return finderProxy.invoke(new MethodInvocation() {
    133           public Method getMethod() {
    134             return method;
    135           }
    136 
    137           public Object[] getArguments() {
    138             return null == args ? new Object[0] : args;
    139           }
    140 
    141           public Object proceed() throws Throwable {
    142             return method.invoke(thisObject, args);
    143           }
    144 
    145           public Object getThis() {
    146             throw new UnsupportedOperationException("Bottomless proxies don't expose a this.");
    147           }
    148 
    149           public AccessibleObject getStaticPart() {
    150             throw new UnsupportedOperationException();
    151           }
    152         });
    153       }
    154     };
    155     requestInjection(finderInvoker);
    156 
    157     @SuppressWarnings("unchecked") // Proxy must produce instance of type given.
    158     T proxy = (T) Proxy
    159         .newProxyInstance(Thread.currentThread().getContextClassLoader(), new Class<?>[] { iface },
    160             finderInvoker);
    161 
    162     bind(iface).toInstance(proxy);
    163   }
    164 
    165   private boolean isDynamicFinderValid(Class<?> iface) {
    166     boolean valid = true;
    167     if (!iface.isInterface()) {
    168       addError(iface + " is not an interface. Dynamic Finders must be interfaces.");
    169       valid = false;
    170     }
    171 
    172     for (Method method : iface.getMethods()) {
    173       DynamicFinder finder = DynamicFinder.from(method);
    174       if (null == finder) {
    175         addError("Dynamic Finder methods must be annotated with @Finder, but " + iface
    176             + "." + method.getName() + " was not");
    177         valid = false;
    178       }
    179     }
    180     return valid;
    181   }
    182 }
    183