org.bbottema.javareflection.valueconverter.converters.StringConverters Maven / Gradle / Ivy

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Java Reflection provides a small package with nifty reflection features that will help with finding constructors, methods and value conversions
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package org.bbottema.javareflection.valueconverter.converters;

import lombok.NonNull;
import lombok.RequiredArgsConstructor;
import lombok.experimental.UtilityClass;
import org.bbottema.javareflection.util.Function;
import org.bbottema.javareflection.util.Function.Functions;
import org.bbottema.javareflection.util.commonslang25.NumberUtils;
import org.bbottema.javareflection.valueconverter.IncompatibleTypeException;
import org.bbottema.javareflection.valueconverter.ValueFunction;
import org.bbottema.javareflection.valueconverter.ValueFunction.ValueFunctionImpl;
import org.jetbrains.annotations.Nullable;
import org.slf4j.Logger;

import java.io.File;
import java.math.BigDecimal;
import java.math.BigInteger;
import java.util.ArrayList;
import java.util.Collection;

import static org.slf4j.LoggerFactory.getLogger;

/**
 * Conversions are as follows:
 * FIXME add non-Number conversions
 * 
 * Integer (or primitive int): Integer.parseInt(value)
 * Character: value.getCharAt(0)
 * Boolean: value equals {@code "true"} or {@code "1"}
 * Number: new BigDecimal(value) (simply attempt the widest number type)
 * Byte (or primitive byte): Byte.parseByte(value)
 * Short (or primitive short): Short.parseShort(value)
 * Long (or primitive long): Long.parseLong(value)
 * Float (or primitive float): Float.parseFloat(value)
 * Double (or primitive double): Double.parseDouble(value)
 * BigInteger: BigInteger.valueOf(Long.parseLong(value))
 * BigDecimal: new BigDecimal(value)
 * 
 */
@Nullable
@UtilityClass
public final class StringConverters {
	
	public static final Collection> STRING_CONVERTERS = produceStringConverters();
	
	private static Collection> produceStringConverters() {
		ArrayList> converters = new ArrayList<>();
		converters.add(new ValueFunctionImpl<>(String.class, String.class, Functions.identity()));
		converters.add(new ValueFunctionImpl<>(String.class, Character.class, new StringToCharacterFunction()));
		converters.add(new ValueFunctionImpl<>(String.class, Boolean.class, new StringToBooleanFunction()));
		converters.add(new ValueFunctionImpl<>(String.class, Number.class, new StringToNumberFunction()));
		converters.add(new ValueFunctionImpl<>(String.class, Byte.class, new StringToByteFunction()));
		converters.add(new ValueFunctionImpl<>(String.class, Short.class, new StringToShortFunction()));
		converters.add(new ValueFunctionImpl<>(String.class, Long.class, new StringToLongFunction()));
		converters.add(new ValueFunctionImpl<>(String.class, Float.class, new StringToFloatFunction()));
		converters.add(new ValueFunctionImpl<>(String.class, Double.class, new StringToDoubleFunction()));
		converters.add(new ValueFunctionImpl<>(String.class, BigInteger.class, new StringToBigIntegerFunction()));
		converters.add(new ValueFunctionImpl<>(String.class, BigDecimal.class, new StringToBigDecimalFunction()));
		converters.add(new ValueFunctionImpl<>(String.class, File.class, new StringToFileFunction()));
		return converters;
	}
	
	/**
	 * Creates a converter to convert a String to an Enum instance, by mapping to the enum's name using
	 * {@link Enum#valueOf(Class, String)}.
	 */
	public static > ValueFunction produceStringToEnumConverter(Class targetEnumClass) {
		return new ValueFunctionImpl<>(String.class, targetEnumClass, new StringToEnumFunction<>(targetEnumClass));
	}
	
	public static  ValueFunction produceTypeToStringConverter(Class fromType) {
		return new ValueFunctionImpl<>(fromType, String.class, Functions.simpleToString());
	}
	
	@RequiredArgsConstructor
	private static class StringToEnumFunction> implements Function {
		@NonNull
		private final Class targetEnumClass;
		
		@Override
		public T apply(String value) {
			// /CLOVER:OFF
			try {
				// /CLOVER:ON
				return Enum.valueOf(targetEnumClass, value);
				// /CLOVER:OFF
			} catch (final IllegalArgumentException | SecurityException e) {
				throw new IncompatibleTypeException(value, String.class, targetEnumClass, e);
			}
			// /CLOVER:ON
		}
	}
	
	private static class StringToCharacterFunction implements Function {
		@Override
		public Character apply(String value) {
			if (value.length() == 1) {
				return value.charAt(0);
			}
			throw new IncompatibleTypeException(value, String.class, Character.class);
		}
	}
	
	private static class StringToBooleanFunction implements Function {
		@Override
		public Boolean apply(String value) {
			if (value.equalsIgnoreCase("false") || value.equalsIgnoreCase("0")) {
				return false;
			} else if (value.equalsIgnoreCase("true") || value.equalsIgnoreCase("1")) {
				return true;
			}
			throw new IncompatibleTypeException(value, String.class, Boolean.class);
		}
	}
	
	private static class StringToNumberFunction implements Function {
		@Override
		public Number apply(String value) {
			if (NumberUtils.isNumber(value)) {
				return new BigDecimal(value);
			}
			throw new IncompatibleTypeException(value, String.class, Number.class);
		}
	}
	
	private static class StringToByteFunction implements Function {
		@Override
		public Byte apply(String value) {
			if (NumberUtils.isNumber(value)) {
				try {
					return Byte.parseByte(value);
				} catch (NumberFormatException e) {
					throw new IncompatibleTypeException(value, String.class, Byte.class, e);
				}
			}
			throw new IncompatibleTypeException(value, String.class, Byte.class);
		}
	}
	
	private static class StringToShortFunction implements Function {
		@Override
		public Short apply(String value) {
			if (NumberUtils.isNumber(value)) {
				try {
					return Short.parseShort(value);
				} catch (NumberFormatException e) {
					throw new IncompatibleTypeException(value, String.class, Short.class, e);
				}
			}
			throw new IncompatibleTypeException(value, String.class, Short.class);
		}
	}
	
	private static class StringToLongFunction implements Function {
		@Override
		public Long apply(String value) {
			if (NumberUtils.isNumber(value)) {
				return Long.parseLong(value);
			}
			throw new IncompatibleTypeException(value, String.class, Long.class);
		}
	}
	
	private static class StringToFloatFunction implements Function {
		@Override
		public Float apply(String value) {
			if (NumberUtils.isNumber(value)) {
				return Float.parseFloat(value);
			}
			throw new IncompatibleTypeException(value, String.class, Float.class);
		}
	}
	
	private static class StringToDoubleFunction implements Function {
		@Override
		public Double apply(String value) {
			if (NumberUtils.isNumber(value)) {
				return Double.parseDouble(value);
			}
			throw new IncompatibleTypeException(value, String.class, Double.class);
		}
	}
	
	private static class StringToBigIntegerFunction implements Function {
		@Override
		public BigInteger apply(String value) {
			if (NumberUtils.isNumber(value)) {
				return BigInteger.valueOf(Long.parseLong(value));
			}
			throw new IncompatibleTypeException(value, String.class, BigInteger.class);
		}
	}
	
	private static class StringToBigDecimalFunction implements Function {
		@Override
		public BigDecimal apply(String value) {
			if (NumberUtils.isNumber(value)) {
				return new BigDecimal(value);
			}
			throw new IncompatibleTypeException(value, String.class, BigDecimal.class);
		}
	}
	
	private static class StringToFileFunction implements Function {
		
		private static final Logger LOGGER = getLogger(StringToBigDecimalFunction.class);
		
		@Override
		public File apply(String value) {
			File file = new File(value);
			if (!file.exists()) {
				LOGGER.debug("file not found for [" + value + "]");
				throw new IncompatibleTypeException(value, String.class, File.class);
			}
			return file;
		}
	}
}