package search;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.RandomAccessFile;
import java.nio.ByteBuffer;
import java.nio.channels.FileChannel;

public class Split {
    
    /**每个小文件大小*/
    static final int SIZE = 1024*1024*5;
    /**需要分割的文件*/
    static final String SOURCE = "E:/t_question.sql";
    /**分割后输出的目录*/
    static final String SOURCE_OUT = "E:/test/";
    /**合并后的文件*/
    static final String DST = "G:/quesion.sql";

    public static void main(String[] args) throws IOException{
        split();
    }
    /**
     * 文件分割
     * @throws IOException
     */
    public static void split() throws IOException{

        File file = new File(SOURCE);
        FileInputStream raf = new FileInputStream(file);
        FileChannel fc = raf.getChannel();
        long fileSize = fc.size();
        
        int count = (int) (fileSize/SIZE);
        ByteBuffer dst = ByteBuffer.allocate(SIZE);
        for(int i=0 ; i <=count  ; i++){
            FileOutputStream fs = new FileOutputStream(new File(SOURCE_OUT+i));
            if(i!=count){
                fc.read(dst,SIZE*i);
                fs.write(dst.array());
            }else{
                fileSize = fileSize -SIZE*count;
                System.out.println(fileSize);
                ByteBuffer dstTail = ByteBuffer.allocate((int) fileSize);
                fs.write(dstTail.array());
            }
            fs.flush();
            dst.clear();
        }
    
    }
    
    /**
     * 合并文件
     * @throws Exception
     */
    public static void merge()throws Exception{
        File parentFile = new File(SOURCE_OUT);
        File fileDst = new File(DST);
        FileChannel fs =  new FileOutputStream(fileDst, true).getChannel();
        try{
             for(File file :parentFile.listFiles()){
                 FileChannel fc = new FileInputStream(file).getChannel();
                 ByteBuffer by = ByteBuffer.allocate((int) fc.size());
                 fc.read(by);
                 by.position(0);
                 fs.write(by);
                 
             }
        }finally{
            fs.close();
        }
    }
}