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package org.macrocloud.kernel.toolkit.jackson;

import com.fasterxml.jackson.core.JsonGenerator;
import com.fasterxml.jackson.databind.SerializerProvider;
import com.fasterxml.jackson.databind.annotation.JacksonStdImpl;
import com.fasterxml.jackson.databind.ser.std.NumberSerializer;

import java.io.IOException;


/**
 * 大数值序列化，避免超过js的精度，造成精度丢失.
 *
 * @author macro
 */
@JacksonStdImpl
public class BigNumberSerializer extends NumberSerializer {

	/**
	 * js 最大值为 Math.pow(2, 53)，十进制为：9007199254740992
	 */
	private static final long JS_NUM_MAX = 0x20000000000000L;
	/**
	 * js 最小值为 -Math.pow(2, 53)，十进制为：-9007199254740992
	 */
	private static final long JS_NUM_MIN = -0x20000000000000L;
	/**
	 * Static instance that is only to be used for {@link java.lang.Number}.
	 */
	public final static BigNumberSerializer instance = new BigNumberSerializer(Number.class);

	/**
	 * Instantiates a new big number serializer.
	 *
	 * @param rawType the raw type
	 */
	public BigNumberSerializer(Class rawType) {
		super(rawType);
	}

	/**
	 * Title: serialize
	 * Description: .
	 *
	 * @param value the value
	 * @param gen the gen
	 * @param provider the provider
	 * @throws IOException Signals that an I/O exception has occurred.
	 * @see com.fasterxml.jackson.databind.ser.std.NumberSerializer#serialize(java.lang.Number, com.fasterxml.jackson.core.JsonGenerator, com.fasterxml.jackson.databind.SerializerProvider)
	 */
	@Override
	public void serialize(Number value, JsonGenerator gen, SerializerProvider provider) throws IOException {
		long longValue = value.longValue();
		if (longValue < JS_NUM_MIN || longValue > JS_NUM_MAX) {
			gen.writeString(value.toString());
		} else {
			super.serialize(value, gen, provider);
		}
	}
}