AbstractJsonStringWriter.java

package com.firefly.utils.json.io;

import java.lang.ref.SoftReference;

import com.firefly.utils.json.JsonWriter;

abstract public class AbstractJsonStringWriter extends JsonWriter {

	protected char buf[];
	protected int count;
	protected final static ThreadLocal<SoftReference<char[]>> bufLocal = new ThreadLocal<SoftReference<char[]>>();
	public static final char[] NULL = "null".toCharArray();
	public static final char[] MIN_INT_VALUE = "-2147483648".toCharArray();
	public static final char[] MIN_LONG_VALUE = "-9223372036854775808"
			.toCharArray();
	public static final char[] TRUE_VALUE = "true".toCharArray();
	public static final char[] FALSE_VALUE = "false".toCharArray();

	public AbstractJsonStringWriter() {
		SoftReference<char[]> ref = bufLocal.get();

		if (ref != null) {
			buf = ref.get();
			bufLocal.set(null);
		}

		if (buf == null)
			buf = new char[1024];
	}

	public AbstractJsonStringWriter(int initialSize) {
		if (initialSize < 0) {
			throw new IllegalArgumentException("Negative initial size: "
					+ initialSize);
		}
		buf = new char[initialSize];
	}

	@Override
	public void write(int c) {
		int newcount = count + 1;
		if (newcount > buf.length) {
			expandCapacity(newcount);
		}
		buf[count] = (char) c;
		count = newcount;
	}

	@Override
	public void write(char[] c) {
		write(c, 0, c.length);
	}

	@Override
	public void write(char[] c, int off, int len) {
		if (off < 0 || off > c.length || len < 0 || off + len > c.length
				|| off + len < 0) {
			throw new IndexOutOfBoundsException();
		} else if (len == 0) {
			return;
		}

		int newcount = count + len;
		if (newcount > buf.length) {
			expandCapacity(newcount);
		}
		System.arraycopy(c, off, buf, count, len);
		count = newcount;
	}

	@Override
	public void write(String str) {
		write(str, 0, str.length());
	}

	@Override
	public void write(String str, int off, int len) {
		int newcount = count + len;
		if (newcount > buf.length) {
			expandCapacity(newcount);
		}
		str.getChars(off, off + len, buf, count);
		count = newcount;
	}

	@Override
	public AbstractJsonStringWriter append(CharSequence csq) {
		String str = csq.toString();
		write(str, 0, str.length());
		return this;
	}

	@Override
	public AbstractJsonStringWriter append(CharSequence csq, int start, int end) {
		String str = csq.subSequence(start, end).toString();
		write(str, 0, str.length());
		return this;
	}

	@Override
	public AbstractJsonStringWriter append(char c) {
		write(c);
		return this;
	}

	@Override
	public String toString() {
		return new String(buf, 0, count);
	}

	@Override
	public void flush() {
	}

	@Override
	public void close() {
		reset();
		bufLocal.set(new SoftReference<char[]>(buf));
	}

	@Override
	public void writeNull() {
		write(NULL);
	}

	@Override
	public void writeBoolean(boolean b) {
		if (b)
			write(TRUE_VALUE);
		else
			write(FALSE_VALUE);
	}

	@Override
	public void writeInt(int i) {
		if (i == Integer.MIN_VALUE) {
			write(MIN_INT_VALUE);
			return;
		}
		int size = (i < 0) ? IOUtils.stringSize(-i) + 1 : IOUtils.stringSize(i);
		int newcount = count + size;

		if (newcount > buf.length) {
			expandCapacity(newcount);
		}

		IOUtils.getChars(i, newcount, buf);
		count = newcount;
	}

	@Override
	public void writeShort(short i) {
		writeInt((int) i);
	}

	@Override
	public void writeByte(byte i) {
		writeInt((int) i);
	}

	@Override
	public void writeLong(long i) {
		if (i == Long.MIN_VALUE) {
			write(MIN_LONG_VALUE);
			return;
		}

		int size = (i < 0) ? IOUtils.stringSize(-i) + 1 : IOUtils.stringSize(i);

		int newcount = count + size;
		if (newcount > buf.length) {
			expandCapacity(newcount);
		}

		IOUtils.getChars(i, newcount, buf);
		count = newcount;
	}

	public void reset() {
		count = 0;
	}

	public int size() {
		return count;
	}

	protected void expandCapacity(int minimumCapacity) {
		int newCapacity = (buf.length * 3) / 2 + 1;

		if (newCapacity < minimumCapacity) {
			newCapacity = minimumCapacity;
		}
		char newValue[] = new char[newCapacity];
		System.arraycopy(buf, 0, newValue, 0, count);
		buf = newValue;
	}

}