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Java example source code file (SingleMethodInjector.java)

This example Java source code file (SingleMethodInjector.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

assertionerror, errorsexception, illegalaccessexception, injectionpoint, internalcontext, invocationtargetexception, methodinvoker, object, reflection, singlememberinjector, singlemethodinjector, singleparameterinjector, throwable

The SingleMethodInjector.java Java example source code

/**
 * Copyright (C) 2008 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.internal;

import com.google.inject.internal.InjectorImpl.MethodInvoker;
import com.google.inject.spi.InjectionPoint;

import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;

/**
 * Invokes an injectable method.
 */
final class SingleMethodInjector implements SingleMemberInjector {
  private final MethodInvoker methodInvoker;
  private final SingleParameterInjector<?>[] parameterInjectors;
  private final InjectionPoint injectionPoint;

  SingleMethodInjector(InjectorImpl injector, InjectionPoint injectionPoint, Errors errors)
      throws ErrorsException {
    this.injectionPoint = injectionPoint;
    final Method method = (Method) injectionPoint.getMember();
    methodInvoker = createMethodInvoker(method);
    parameterInjectors = injector.getParametersInjectors(injectionPoint.getDependencies(), errors);
  }

  private MethodInvoker createMethodInvoker(final Method method) {

    /*if[AOP]*/
    try {
    final net.sf.cglib.reflect.FastClass fastClass =
        BytecodeGen.newFastClassForMember(method);
      if (fastClass != null) {
        final int index = fastClass.getMethod(method).getIndex();

        return new MethodInvoker() {
          public Object invoke(Object target, Object... parameters)
              throws IllegalAccessException, InvocationTargetException {
            return fastClass.invoke(index, target, parameters);
          }
        };
      }
    } catch (net.sf.cglib.core.CodeGenerationException e) {/* fall-through */}
    /*end[AOP]*/

    int modifiers = method.getModifiers();
    if (!Modifier.isPublic(modifiers) ||
        !Modifier.isPublic(method.getDeclaringClass().getModifiers())) {
      method.setAccessible(true);
    }

    return new MethodInvoker() {
      public Object invoke(Object target, Object... parameters)
          throws IllegalAccessException, InvocationTargetException {
        return method.invoke(target, parameters);
      }
    };
  }

  public InjectionPoint getInjectionPoint() {
    return injectionPoint;
  }

  public void inject(Errors errors, InternalContext context, Object o) {
    Object[] parameters;
    try {
      parameters = SingleParameterInjector.getAll(errors, context, parameterInjectors);
    } catch (ErrorsException e) {
      errors.merge(e.getErrors());
      return;
    }

    try {
      methodInvoker.invoke(o, parameters);
    } catch (IllegalAccessException e) {
      throw new AssertionError(e); // a security manager is blocking us, we're hosed
    } catch (InvocationTargetException userException) {
      Throwable cause = userException.getCause() != null
          ? userException.getCause()
          : userException;
      errors.withSource(injectionPoint).errorInjectingMethod(cause);
    }
  }
}

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