装饰者模式实际应用

Java IO类采用了装饰者模式：

利用装饰者模式会产生很多的小类。

InputStream

子类:FileInputStream StringBufferInputStream ByteArrayInputStream FilterInputStream

FilterInputStream子类:PushbackInputStream BufferedInputStream DataInputStream LineNumberInputStream

下面利用装饰者模式，写一个IO类自己的装饰者:

将输入流的大写字符全部转换小写字符。

import java.io.FilterInputStream;

import java.io.IOException;

import java.io.InputStream;

public class LowerCaseInputStream extends FilterInputStream{

protected LowerCaseInputStream(InputStream in) {
super(in);

}

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

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

}

测试运行类:

package com.gac.zsz;

import java.io.BufferedInputStream;

import java.io.FileInputStream;

import java.io.FileNotFoundException;

import java.io.InputStream;

public class InputTest {

public static void main(String[] args){

int c;

try {

InputStream in = new LowerCaseInputStream(new BufferedInputStream(

new FileInputStream(“test.txt”)));

while((c = in.read())>=0){

System.out.println((char)c);

}

in.close();

} catch (Exception e) {

// TODO Auto-generated catch block

e.printStackTrace();

}

}

}