(20)IO流之SequenceInputStream 序列流

序列流，对多个流进行合并。

SequenceInputStream 表示其他输入流的逻辑串联。它从输入流的有序集合开始，并从第一个输入流开始读取，直到到达文件末尾，接着从第二个输入流读取，依次类推，直到到达包含的最后一个输入流的文件末尾为止。

序列流，对多个流进行合并。

SequenceInputStream 表示其他输入流的逻辑串联。它从输入流的有序集合开始，并从第一个输入流开始读取，直到到达文件末尾，接着从第二个输入流读取，依次类推，直到到达包含的最后一个输入流的文件末尾为止。

合并两个流

使用构造函数SequenceInputStream(InputStream s1, InputStream s2)

//使用SequenceInputStream合并两个文件
    public static void merge2() throws IOException{
        //找到目标文件
        File inFile1 = new File("d:\a.txt");
        File inFile2 = new File("d:\b.txt");
        File outFile = new File("D:\c.txt");
        //建立数据通道
        FileOutputStream fileOutputStream = new FileOutputStream(outFile);
        FileInputStream fileInputStream1 = new FileInputStream(inFile1);
        FileInputStream fileInputStream2 = new FileInputStream(inFile2);
        
        //建立序列流对象
        SequenceInputStream inputStream = new SequenceInputStream(fileInputStream1,fileInputStream2);
        byte[] buf = new byte[1024];
        int length = 0;
        while((length = inputStream.read(buf))!=-1)
        {
            fileOutputStream.write(buf, 0, length);
        }
        inputStream.close();
//        fileInputStream1.close();    //查看上面inputStream.close（）的源码就可以看到，它穿起来的流一块关闭了
//        fileInputStream2.close();
        fileOutputStream.close();
}

合并多个文件

//把三个文件合并成一个文件
    public static void merge3() throws IOException
    {
        //找到目标文件
        File file1 = new File("d:\a.txt");
        File file2 = new File("d:\b.txt");
        File file3 = new File("D:\c.txt");
        File file4 = new File("d:\d.txt");
        //建立对应的输入输出流对象
        FileInputStream fileInputStream1 = new FileInputStream(file1);
        FileInputStream fileInputStream2 = new FileInputStream(file2);
        FileInputStream fileInputStream3 = new FileInputStream(file3);
        FileOutputStream fileOutputStream = new FileOutputStream(file4);
        
        //创建序列流对象
        Vector<FileInputStream> vector = new Vector<FileInputStream>();
        vector.add(fileInputStream1);
        vector.add(fileInputStream2);
        vector.add(fileInputStream3);
        Enumeration<FileInputStream> e = vector.elements();
        
        SequenceInputStream inputStream = new SequenceInputStream(e);
        
        //读取文件的数据
        int length =0;
        byte[] buf = new byte[1024];
        while((length = inputStream.read(buf))!=-1)
        {
            fileOutputStream.write(buf, 0, length);
        }
        inputStream.close();
        fileOutputStream.close();
    }

下面是一个例子把一个mp3文件切割合并的过程：

public class Demo2
{
    public static void main(String[] args) throws IOException
    {
        cutFile();
        mergeFile();
    }
    
    //合并
    public static void mergeFile() throws IOException
    {
        //找到目标文件
        File dir = new File("D:\part");
        Vector<FileInputStream> vector = new Vector<FileInputStream>();
        //通过目标文件夹找到所有的mmp3并添加到Vector中
        File[] files =  dir.listFiles();
        for (File file : files)
        {
            if(file.getName().endsWith("mp3"))
            {
                vector.add(new FileInputStream(file));
            }
        }
        
        //通过vector获取迭代器对象
        Enumeration<FileInputStream> e =  vector.elements();
        
        SequenceInputStream inputStream = new SequenceInputStream(e);
        
        //建立文件的输出通道
        FileOutputStream fileOutputStream = new FileOutputStream("D:\merge.mp3");
        //建立缓冲数组
        int length = 0;
        byte[] buf = new byte[1024*1024];
        while((length = inputStream.read(buf))!=-1)
        {
            fileOutputStream.write(buf, 0, length);
        }
    }
    
    
    //切割
    public static void cutFile() throws IOException
    {
        File file = new File("D:\1.mp3");
        //目标文件夹
        File dir = new File("D:\part");
        //建立数据的输入通道
        FileInputStream fileInputStream = new FileInputStream(file);
        //建立缓存数组存储
        byte[] buf = new byte[1024*1024];
        int length = 0;
        for(int i = 1 ; (length = fileInputStream.read(buf))!=-1; i ++)
        {
            FileOutputStream fileOutputStream = new FileOutputStream(new File(dir, "part"+i+".mp3"));
            fileOutputStream.write(buf, 0, length);
            fileOutputStream.close();
        }
        //关闭资源
        fileInputStream.close();
    }
}