java中ByteArrayInputStream和ByteArrayOutputStream类用法

import java.io.*;

public class ByteArrayStreamTest {
public static void main(String [] args) {
String str = "abcdef";

ByteArrayInputStream in = new ByteArrayInputStream(str.getBytes());
ByteArrayOutputStream out = new ByteArrayOutputStream();

transform(in, out);

byte[] result = out.toByteArray();

System.out.println(out);
System.out.println(new String(result));

transform(System.in, System.out); // 从键盘读，输出到显示器
}

public static void transform(InputStream in, OutputStream out) {
int ch = 0;

try {
while ((ch = in.read()) != -1) {
int upperChar = Character.toUpperCase((char)ch);
out.write(upperChar);
} // close while
} catch (Exception e) {
e.printStackTrace();
}
}
}