面向过程核心版
package com.yishan.io3;
import java.io.File;
import java.io.IOException;
import java.io.RandomAccessFile;
/**
* 随机读取和写入流 RandomAccessFile
* @author : yishan
* @date : 2020-09-15 14:06
*/
public class RandTest01 {
public static void main(String[] args) throws IOException {
//分多少块
File src = new File("F:/My direction/java SE/copy.txt");
//总长度
long len = src.length();
//没块大小
int blockSize = 100;
//多少块
int size = (int) Math.ceil(len*1.0/blockSize);
System.out.println(size);
//起始位置和大小
int beginPos = 0;
int actualSize = (int)(blockSize>len?len:blockSize);
for(int i = 0;i < size; i++){
beginPos = i * blockSize;
if(i==size-1){//最后一块
actualSize = (int)len;
}else{
actualSize = blockSize;
len -= actualSize;//剩余量
}
System.out.println(i+"--"+beginPos+"--"+actualSize);
split(i,beginPos,actualSize);
}
}
/**
* 指定第i快的起始位置和实际长度
* @param i
* @param beginPos
* @param actualSize
* @throws IOException
*/
// 分块思想：起始、实际大小
public static void split(int i,int beginPos,int actualSize ) throws IOException {
RandomAccessFile raf = new RandomAccessFile("F:/My direction/java SE/copy.txt","r" );
raf.seek(beginPos);
//读取
//操作
byte[] flush = new byte[1024];
int len = -1;
while ((len=raf.read(flush))!=-1){
if(actualSize>len){
System.out.println(new String(flush,0,len));
}else{
System.out.println(new String(flush,0,actualSize));
break;
}
}
raf.close();
}
//指定起始位置，读取剩余所有内容
public static void test01()throws IOException{
RandomAccessFile raf = new RandomAccessFile("F:/My direction/java SE/copy.txt","r" );
//随机读取
raf.seek(2);
//读取
//操作
byte[] flush = new byte[1024];
int len = -1;
while ((len=raf.read(flush))!=-1){
System.out.println(new String(flush,0,len));
}
raf.close();
}
}
面向对象终极版（合并流）
package com.yishan.io3;
import java.io.*;
import java.util.ArrayList;
import java.util.List;
import java.util.Vector;
/**
* 面向对象思想封装 分割
* @author : yishan
* @date : 2020-09-15 14:06
*/
public class SplitFile {
//源头
private File src;
//目的地（文件夹）
private String desrDir;
//所有分割后的文件存储路径
private List<String> destPaths;
//每块大小
private int blockSize;
//块数：多少块
private int size;
public SplitFile(String srcPath, String desrDir, int blockSize) {
this.src = new File(srcPath);
this.desrDir = desrDir;
this.blockSize = blockSize;
this.destPaths = new ArrayList<>();
//初始化
init();
}
//初始化
private void init(){
//总长度
long len = this.src.length();
//多少块
this.size = (int) Math.ceil(len*1.0/blockSize);
//路径
for(int i = 0; i < size;i++){
this.destPaths.add(this.desrDir+"/"+i+this.src.getName());
}
}
public void split() throws IOException {
//总长度
long len = src.length();
//起始位置和大小
int beginPos = 0;
int actualSize = (int)(blockSize>len?len:blockSize);
for(int i = 0;i < size; i++){
beginPos = i * blockSize;
if(i==size-1){//最后一块
actualSize = (int)len;
}else{
actualSize = blockSize;
len -= actualSize;//剩余量
}
System.out.println(i+"--"+beginPos+"--"+actualSize);
splitDetail(i,beginPos,actualSize);
}
}
/**
* 指定第i快的起始位置和实际长度
* @param i
* @param beginPos
* @param actualSize
* @throws IOException
*/
// 分块思想：起始、实际大小
private void splitDetail(int i,int beginPos,int actualSize ) throws IOException {
RandomAccessFile raf = new RandomAccessFile(this.src,"r" );
RandomAccessFile raf2 = new RandomAccessFile(this.destPaths.get(i),"rw" );
raf.seek(beginPos);
//读取
//操作
byte[] flush = new byte[1024];
int len = -1;
while ((len=raf.read(flush))!=-1){
if(actualSize>len){
raf2.write(flush,0,len);
actualSize-=len;
}else{
raf2.write(flush,0,actualSize);
break;
}
}
raf.close();
}
/**
* 文件的合并
*/
public void merge(String destPath) throws IOException {
//输出流
OutputStream os = new BufferedOutputStream(new FileOutputStream(destPath,true));
Vector<InputStream> vi = new Vector<>();
SequenceInputStream sis = null;
//输入流
for(int i=0;i<destPaths.size();i++){
vi.add(new BufferedInputStream(new FileInputStream(destPaths.get(i))));
}
sis = new SequenceInputStream(vi.elements());
//拷贝
//操作（分段读取）
byte[] flush = new byte[1024];
int len = -1;
while((len=sis.read(flush))!=-1){
os.write(flush,0,len);
}
os.flush();
sis.close();
os.close();
}
public static void main(String[] args) throws IOException {
SplitFile sf= new SplitFile("F:\\My direction\\java SE\\IO\\src\\com\\yishan\\io3\\SplitFile.java", "dest", 1024);
sf.split();
sf.merge("aaa.java");
}
}