SecureByteArrayInputStream.java

package hamaster.gradesgin.ibe.io;

import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.util.Arrays;

/**
 * 安全的字节数组输入流 操作完成后可以清理内存
 * @author Wang Ye
 */
public class SecureByteArrayInputStream extends ByteArrayInputStream {

	/**
	 * 将buf中内容复制并作为输入源
	 * @param buf 要处理的数组
	 */
	public SecureByteArrayInputStream(byte[] buf) {
		super(new byte[1]);
		super.buf = new byte[buf.length];
		System.arraycopy(buf, 0, super.buf, 0, buf.length);
		pos = 0;
		count = buf.length;
	}

	/**
	 * 将buf中内容复制并作为输入源
	 * @param buf 要处理的数组
	 * @param offset 开始读取的字节偏移量
	 * @param length 最多读取的长度
	 */
	public SecureByteArrayInputStream(byte[] buf, int offset, int length) {
		super(new byte[1], offset, length);
		super.buf = new byte[buf.length];
		System.arraycopy(buf, 0, super.buf, 0, buf.length);
		pos = offset;
		count = Math.min(offset + length, buf.length);
		mark = offset;
	}

	/**
	 * 擦出内存中数据并关闭输入流
	 * @throws IOException 清理内存中发生的任意异常都会被抛出
	 * @see java.io.ByteArrayInputStream#close()
	 */
	@Override
	public void close() throws IOException {
		try {
			Arrays.fill(buf, (byte) 0);
		} catch (Throwable t) {
			throw new IOException(t);
		}
		super.close();
	}
}