Converting the read data stream InputStreamReader

InputStreamReader(InputStream is):用默认编码读取数据
InputStreamReader(InputStream is,String charsetName):用指定编码读取数据
参数类型为inputStream抽象类，需要用FileInputStream子类来实现

//创建对象
		InputStreamReader isr=new InputStreamReader(new FileInputStream("a.txt"));
		
		//读数据，一次读取一个
		int len;
		while((len=isr.read())!=-1){
			System.out.print((char)len);
		}