co.cask.cdap.internal.io.ReflectionFieldAccessorFactory.java Source code

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Here is the source code for co.cask.cdap.internal.io.ReflectionFieldAccessorFactory.java

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/*
 * Copyright  2014 Cask Data, 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 co.cask.cdap.internal.io;

import com.google.common.base.Preconditions;
import com.google.common.base.Throwables;
import com.google.common.cache.CacheBuilder;
import com.google.common.cache.CacheLoader;
import com.google.common.cache.LoadingCache;
import com.google.common.reflect.TypeToken;

import java.lang.reflect.Field;

/**
 *
 */
public final class ReflectionFieldAccessorFactory implements FieldAccessorFactory {

    private final LoadingCache<FieldEntry, FieldAccessor> fieldAccessorCache;

    public ReflectionFieldAccessorFactory() {
        this.fieldAccessorCache = CacheBuilder.newBuilder().build(new CacheLoader<FieldEntry, FieldAccessor>() {
            @Override
            public FieldAccessor load(FieldEntry fieldEntry) throws Exception {
                Field field = null;
                for (TypeToken<?> type : fieldEntry.getType().getTypes().classes()) {
                    try {
                        field = type.getRawType().getDeclaredField(fieldEntry.getFieldName());
                    } catch (NoSuchFieldException e) {
                        // It's ok, keep searching.
                        continue;
                    }
                    break;
                }

                Preconditions.checkNotNull(field, "No such field in type. Type: %s, field: %s",
                        fieldEntry.getType(), fieldEntry.getFieldName());
                if (!field.isAccessible()) {
                    field.setAccessible(true);
                }
                final Field finalField = field;
                final TypeToken<?> fieldType = fieldEntry.getType().resolveType(finalField.getGenericType());
                return new FieldAccessor() {
                    @Override
                    public <T> void set(Object object, T value) {
                        try {
                            finalField.set(object, value);
                        } catch (Exception e) {
                            throw Throwables.propagate(e);
                        }
                    }

                    @SuppressWarnings("unchecked")
                    @Override
                    public <T> T get(Object object) {
                        try {
                            return (T) finalField.get(object);
                        } catch (Exception e) {
                            throw Throwables.propagate(e);
                        }
                    }

                    @Override
                    public boolean getBoolean(Object object) {
                        return (Boolean) get(object);
                    }

                    @Override
                    public byte getByte(Object object) {
                        return (Byte) get(object);
                    }

                    @Override
                    public char getChar(Object object) {
                        return (Character) get(object);
                    }

                    @Override
                    public short getShort(Object object) {
                        return (Short) get(object);
                    }

                    @Override
                    public int getInt(Object object) {
                        return (Integer) get(object);
                    }

                    @Override
                    public long getLong(Object object) {
                        return (Long) get(object);
                    }

                    @Override
                    public float getFloat(Object object) {
                        return (Float) get(object);
                    }

                    @Override
                    public double getDouble(Object object) {
                        return (Double) get(object);
                    }

                    @Override
                    public void setBoolean(Object object, boolean value) {
                        set(object, value);
                    }

                    @Override
                    public void setByte(Object object, byte value) {
                        set(object, value);
                    }

                    @Override
                    public void setChar(Object object, char value) {
                        set(object, value);
                    }

                    @Override
                    public void setShort(Object object, short value) {
                        set(object, value);
                    }

                    @Override
                    public void setInt(Object object, int value) {
                        set(object, value);
                    }

                    @Override
                    public void setLong(Object object, long value) {
                        set(object, value);
                    }

                    @Override
                    public void setFloat(Object object, float value) {
                        set(object, value);
                    }

                    @Override
                    public void setDouble(Object object, double value) {
                        set(object, value);
                    }

                    @Override
                    public TypeToken<?> getType() {
                        return fieldType;
                    }
                };
            }
        });
    }

    @Override
    public FieldAccessor getFieldAccessor(TypeToken<?> type, String fieldName) {
        return fieldAccessorCache.getUnchecked(new FieldEntry(type, fieldName));
    }
}