OutputStream

package java.io;

public abstract class OutputStream implements Closeable, Flushable {

public abstract void write(int b) throws IOException;

//将指定字节数组写入(相当于往b数组写入b，起始点为0)
public void write(byte b[]) throws IOException {
write(b, 0, b.length);
}

/**
*往指定字节数组写入长度为len的数组，开始点为off
*/
public void write(byte b[], int off, int len) throws IOException {
//如果字节数组b为空
if (b == null) {
throw new NullPointerException();
//如果存在越界情况
} else if ((off < 0) || (off > b.length) || (len < 0) ||
((off + len) > b.length) || ((off + len) < 0)) {
throw new IndexOutOfBoundsException();
} else if (len == 0) {
return;
}
//从off+1开始写入长度为len的字节数组
for (int i = 0 ; i < len ; i++) {
write(b[off + i]);
}
}

/**

• 清空缓存中的输出字节
  */
  public void flush() throws IOException {
  }

/**

• 关闭输出流
  */
  public void close() throws IOException {
  }

}