对多个流进行合并

1、构造方法

SequenceInputStream(Enumeration<? extends InputStream> e)

public class demo1 {

    public static void main(String[] args) throws IOException {
        /**
         * 将1.txt，2.txt，3.txt文件中的数据合并到一个文件4.txt中
         */
        Vector<FileInputStream> v = new Vector<FileInputStream>();
        v.add(new FileInputStream("1.txt"));
        v.add(new FileInputStream("2.txt"));
        v.add(new FileInputStream("3.txt"));

        Enumeration<FileInputStream> en = v.elements();

        SequenceInputStream sis = new SequenceInputStream(en);

        FileOutputStream fos = new FileOutputStream("4.txt");

        byte[] buf = new byte[1024];

        int length = 0;

        while((length = sis.read(buf)) != -1 ) {
            fos.write(buf,0,length);
        }

        fos.close();
        sis.close();
    }

}

2、枚举和迭代

//Vctor集合效率低。

Vector<FileInputStream> v = new Vector<FileInputStream>();
v.add(new FileInputStream("1.txt"));
v.add(new FileInputStream("2.txt"));
v.add(new FileInputStream("3.txt"));

Enumeration<FileInputStream> en = v.elements();

//ArrayList集合代替
ArrayList<FileInputStream> al = new ArrayList<FileInputStream>();
//用集合工具类中的方法，返回Enumeration类对象
Enumeration<FileInputStream> en = Collections.enumeration(al);