1、文件切割

public class SplitFile {

    private static final int SIZE = 1024*1024;

    public static void main(String[] args) throws IOException {
        //指定切割文件
        File file = new File("IMG_0215.JPG");

        //读取流
        FileInputStream fis = new FileInputStream(file);

        //写入流
        FileOutputStream fos = null;

        //缓冲区
        byte[] buf = new byte[SIZE];

        //存储目录
        File dir = new File("//Users//haojie//eclipse-workspace//hello world//partfiles");
        if(!dir.exists())
            dir.mkdir();

        //切割
        int length = 0;
        int count = 1;
        while((length = fis.read(buf)) != -1) {
            fos = new FileOutputStream(new File(dir,(count++)+".part"));
            fos.write(buf, 0, length);;
        }

        //关闭流
        fos.close();
        fis.close();
    }

}

2、文件合并

public class Merge {

    public static void main(String[] args) throws IOException {

        File dir = new File("//Users//haojie//eclipse-workspace//hello world//partfiles");
        mergeFile(dir);
    }

    public static void mergeFile(File dir) throws IOException {
        //读取流
        ArrayList<FileInputStream> al = new ArrayList<FileInputStream>();
        for(int x=1; x<3; x++) {
            al.add(new FileInputStream(new File(dir,x+".part")));
        }
        //合并流
        Enumeration<FileInputStream> en = Collections.enumeration(al);
        SequenceInputStream sis = new SequenceInputStream(en);
        //输出流
        FileOutputStream fos = new FileOutputStream(new File(dir,"1.JPG"));
        //缓冲区
        byte[] buf = new byte[1024];
        int length = 0;
        while((length = sis.read(buf)) != -1) {
            fos.write(buf, 0, length);
        }
        //关闭流
        fos.close();
        sis.close();
    }

}

3、文件切割合并+配置文件

public class FileSplitMergeUtil {

    private static final int SIZE = 1024*1024;

    public static void main(String[] args) throws IOException {

        //切割
        File file = new File("IMG_0215.JPG");
        splitFile(file);

        //合并
        File dir = new File("//Users//haojie//eclipse-workspace//hello world//partfiles");
        mergeFile(dir);
    }

    //切割传入的文件
    public static void splitFile(File file) throws IOException {

        //读取流
        FileInputStream fis = new FileInputStream(file);

        //写入流
        FileOutputStream fos = null;

        //缓冲区
        byte[] buf = new byte[SIZE];

        //存储目录
        File dir = new File("//Users//haojie//eclipse-workspace//hello world//partfiles");
        if(!dir.exists())
            dir.mkdir();

        //切割
        int length = 0;
        int count = 1;
        while((length = fis.read(buf)) != -1) {
            fos = new FileOutputStream(new File(dir,(count++)+".part"));
            fos.write(buf, 0, length);
            fos.close();
        }

        /**
         * 配置文件
         * partcount 碎片数量
         * filename 被切割文件名称
         */
        Properties prop = new Properties();

        //配置文件设置
        prop.setProperty("partcount", count+"");
        prop.setProperty("filename", file.getName());

        //配置文件输出流
        fos = new FileOutputStream(new File(dir,count+".properties"));

        //写入配置信息
        prop.store(fos, "fileinfo");

        //关闭流
        fos.close();
        fis.close();
    }

    public static void mergeFile(File dir) throws IOException {
        //过滤配置文件
        File[] files = dir.listFiles(new SuffixFilter(".properties"));
        if(files.length != 1)
            throw new RuntimeException(dir+"获取配置文件失败");
        File confile = files[0];

        //读取配置文件
        Properties prop = new Properties();
        FileInputStream fis = new FileInputStream(confile);
        prop.load(fis);
        String filename = prop.getProperty("filename");
        int count = Integer.parseInt(prop.getProperty("partcount"));

        //检查碎片文件个数
        File[] partFiles = dir.listFiles(new SuffixFilter(".part"));
        if(partFiles.length != (count-1)) {
            throw new RuntimeException("碎片文件与配置信息中的数量不符");            
        }

        //读取流
        ArrayList<FileInputStream> al = new ArrayList<FileInputStream>();
        for(int x=0; x<partFiles.length; x++) {
            al.add(new FileInputStream(partFiles[x]));
        }

        //合并流
        Enumeration<FileInputStream> en = Collections.enumeration(al);
        SequenceInputStream sis = new SequenceInputStream(en);

        //输出流
        FileOutputStream fos = new FileOutputStream(new File(dir,filename));

        //缓冲区
        byte[] buf = new byte[1024];
        int length = 0;
        while((length = sis.read(buf)) != -1) {
            fos.write(buf, 0, length);
        }

        //关闭流
        fos.close();
        sis.close();
    }
}

public class SuffixFilter implements FilenameFilter {

    private String suffix;

    public SuffixFilter(String suffix) {
        super();
        this.suffix = suffix;
    }

    public boolean accept(File dir, String name) {
        return name.endsWith(suffix);
    }

}