装饰者模式

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package test.java.io;

import java.io.BufferedInputStream;
import java.io.FileInputStream;
import java.io.FilterInputStream;
import java.io.IOException;
import java.io.InputStream;

/**
* 装饰者模式
* 用LowerInputStream包装流，将经过该流的字母全部转换成小写的
*/
public class LowerInputStream extends FilterInputStream {

public LowerInputStream(InputStream in) {
super(in);
}

@Override
public int read() throws IOException {
int c = super.read();
return c == -1 ? c: Character.toLowerCase(c);
}

@Override
public int read(byte[] b, int offset, int len) throws IOException {
  int result = super.read(b, offset, len);
  for(int i=offset; i<offset+len; i++) {
   b[i] = (byte) Character.toLowerCase(b[i]);
  }

  return result;
}

public static void main(String[] args) {
  InputStream in = null;
  int c = 0;
  try {
   in = new LowerInputStream(new BufferedInputStream(new FileInputStream("test.txt")));

   while((c = in.read()) >= 0) {
    System.out.print((char)c);
   }

   in.close();
  } catch (Exception e) {
  }
}
}