I/O有关问题。代码没错，为何写入文件的都是乱码

import java.io.*;class PrimitiveIO {   public static void main(String args[]) {      try {         FileOutputStream fileOutStrm = new FileOutputStream("AAA.txt");         BufferedOutputStream bufOutStrm = new BufferedOutputStream(fileOutStrm);         DataOutputStream outStream = new DataOutputStream(bufOutStrm);         outStream.writeChar('A');         outStream.writeFloat((float)3.14);         outStream.writeInt(2012);         outStream.writeBoolean(false);         outStream.flush();         FileInputStream fileInStrm = new FileInputStream("AAA.txt");         BufferedInputStream bufInStrm = new BufferedInputStream(fileInStrm);         DataInputStream inStream = new DataInputStream(bufInStrm);         System.out.println(inStream.readChar());         System.out.println(inStream.readFloat());         System.out.println(inStream.readInt());         System.out.println(inStream.readBoolean());         inStream.close();       } catch (Exception ex) {         System.out.println("Exception: " + ex);      }   }}