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Dahua ICC Open API SDK for Java

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package com.dahuatech.hutool.core.io;

import com.dahuatech.hutool.core.util.CharsetUtil;

import java.io.IOException;
import java.io.OutputStream;
import java.nio.charset.Charset;

/**
 * 基于快速缓冲FastByteBuffer的OutputStream，随着数据的增长自动扩充缓冲区
 *
 * 可以通过{@link #toByteArray()}和 {@link #toString()}来获取数据
 *
 * 
{@link #close()}方法无任何效果，当流被关闭后不会抛出IOException
 *
 * 这种设计避免重新分配内存块而是分配新增的缓冲区，缓冲区不会被GC，数据也不会被拷贝到其他缓冲区。
 *
 * @author biezhi
 */
public class FastByteArrayOutputStream extends OutputStream {

  private final FastByteBuffer buffer;

  public FastByteArrayOutputStream() {
    this(1024);
  }

  /**
   * 构造
   *
   * @param size 预估大小
   */
  public FastByteArrayOutputStream(int size) {
    buffer = new FastByteBuffer(size);
  }

  @Override
  public void write(byte[] b, int off, int len) {
    buffer.append(b, off, len);
  }

  @Override
  public void write(int b) {
    buffer.append((byte) b);
  }

  public int size() {
    return buffer.size();
  }

  /** 此方法无任何效果，当流被关闭后不会抛出IOException */
  @Override
  public void close() throws IOException {
    // nop
  }

  public void reset() {
    buffer.reset();
  }

  /**
   * 写出
   *
   * @param out 输出流
   * @throws IORuntimeException IO异常
   */
  public void writeTo(OutputStream out) throws IORuntimeException {
    final int index = buffer.index();
    byte[] buf;
    try {
      for (int i = 0; i < index; i++) {
        buf = buffer.array(i);
        out.write(buf);
      }
      out.write(buffer.array(index), 0, buffer.offset());
    } catch (IOException e) {
      throw new IORuntimeException(e);
    }
  }

  /**
   * 转为Byte数组
   *
   * @return Byte数组
   */
  public byte[] toByteArray() {
    return buffer.toArray();
  }

  @Override
  public String toString() {
    return new String(toByteArray());
  }

  /**
   * 转为字符串
   *
   * @param charsetName 编码
   * @return 字符串
   */
  public String toString(String charsetName) {
    return toString(CharsetUtil.charset(charsetName));
  }

  /**
   * 转为字符串
   *
   * @param charset 编码
   * @return 字符串
   */
  public String toString(Charset charset) {
    return new String(toByteArray(), charset);
  }
}