Java example source code file (TypeConverterBindingProcessor.java)

This example Java source code file (TypeConverterBindingProcessor.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

abstractmatcher, abstractprocessor, assertionerror, class, illegalaccessexception, matcher, nosuchmethodexception, object, override, reflection, string, suppresswarnings, typeconverter, typeconverterbindingprocessor, typeliteral

The TypeConverterBindingProcessor.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.TypeLiteral;
import com.google.inject.internal.util.SourceProvider;
import com.google.inject.matcher.AbstractMatcher;
import com.google.inject.matcher.Matcher;
import com.google.inject.matcher.Matchers;
import com.google.inject.spi.TypeConverter;
import com.google.inject.spi.TypeConverterBinding;

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

/**
 * Handles {@code Binder.convertToTypes} commands.
 *
 * @author crazybob@google.com (Bob Lee)
 * @author jessewilson@google.com (Jesse Wilson)
 */
final class TypeConverterBindingProcessor extends AbstractProcessor {

  TypeConverterBindingProcessor(Errors errors) {
    super(errors);
  }

  /** Installs default converters for primitives, enums, and class literals. */
  static void prepareBuiltInConverters(InjectorImpl injector) {
    // Configure type converters.
    convertToPrimitiveType(injector, int.class, Integer.class);
    convertToPrimitiveType(injector, long.class, Long.class);
    convertToPrimitiveType(injector, boolean.class, Boolean.class);
    convertToPrimitiveType(injector, byte.class, Byte.class);
    convertToPrimitiveType(injector, short.class, Short.class);
    convertToPrimitiveType(injector, float.class, Float.class);
    convertToPrimitiveType(injector, double.class, Double.class);

    convertToClass(injector, Character.class, new TypeConverter() {
      public Object convert(String value, TypeLiteral<?> toType) {
        value = value.trim();
        if (value.length() != 1) {
          throw new RuntimeException("Length != 1.");
        }
        return value.charAt(0);
      }

      @Override public String toString() {
        return "TypeConverter<Character>";
      }
    });

    convertToClasses(injector, Matchers.subclassesOf(Enum.class), new TypeConverter() {
      @SuppressWarnings("unchecked")
      public Object convert(String value, TypeLiteral<?> toType) {
          return Enum.valueOf((Class) toType.getRawType(), value);
        }

        @Override public String toString() {
          return "TypeConverter<E extends Enum";
        }
      });

    internalConvertToTypes(injector, new AbstractMatcher<TypeLiteral() {
        public boolean matches(TypeLiteral<?> typeLiteral) {
          return typeLiteral.getRawType() == Class.class;
        }

        @Override public String toString() {
          return "Class<?>";
        }
      },
      new TypeConverter() {
        @SuppressWarnings("unchecked")
        public Object convert(String value, TypeLiteral<?> toType) {
          try {
            return Class.forName(value);
          } catch (ClassNotFoundException e) {
            throw new RuntimeException(e.getMessage());
          }
        }

        @Override public String toString() {
          return "TypeConverter<Class";
        }
      }
    );
  }

  private static <T> void convertToPrimitiveType(InjectorImpl injector, Class primitiveType,
      final Class<T> wrapperType) {
    try {
      final Method parser = wrapperType.getMethod(
          "parse" + capitalize(primitiveType.getName()), String.class);

      TypeConverter typeConverter = new TypeConverter() {
        @SuppressWarnings("unchecked")
        public Object convert(String value, TypeLiteral<?> toType) {
          try {
            return parser.invoke(null, value);
          } catch (IllegalAccessException e) {
            throw new AssertionError(e);
          } catch (InvocationTargetException e) {
            throw new RuntimeException(e.getTargetException().getMessage());
          }
        }

        @Override public String toString() {
          return "TypeConverter<" + wrapperType.getSimpleName() + ">";
        }
      };

      convertToClass(injector, wrapperType, typeConverter);
    } catch (NoSuchMethodException e) {
      throw new AssertionError(e);
    }
  }

  private static <T> void convertToClass(InjectorImpl injector, Class type,
      TypeConverter converter) {
    convertToClasses(injector, Matchers.identicalTo(type), converter);
  }

  private static void convertToClasses(InjectorImpl injector,
      final Matcher<? super Class typeMatcher, TypeConverter converter) {
    internalConvertToTypes(injector, new AbstractMatcher<TypeLiteral() {
      public boolean matches(TypeLiteral<?> typeLiteral) {
        Type type = typeLiteral.getType();
        if (!(type instanceof Class)) {
          return false;
        }
        Class<?> clazz = (Class) type;
        return typeMatcher.matches(clazz);
      }

      @Override public String toString() {
        return typeMatcher.toString();
      }
    }, converter);
  }

  private static void internalConvertToTypes(InjectorImpl injector,
      Matcher<? super TypeLiteral typeMatcher,
      TypeConverter converter) {
    injector.state.addConverter(
        new TypeConverterBinding(SourceProvider.UNKNOWN_SOURCE, typeMatcher, converter));
  }

  @Override public Boolean visit(TypeConverterBinding command) {
    injector.state.addConverter(new TypeConverterBinding(
        command.getSource(), command.getTypeMatcher(), command.getTypeConverter()));
    return true;
  }
  
  private static String capitalize(String s) {
    if (s.length() == 0) {
      return s;
    }
    char first = s.charAt(0);
    char capitalized = Character.toUpperCase(first);
    return (first == capitalized)
        ? s
        : capitalized + s.substring(1);
  }

}