文件分割和合并

public static void FileSplite(String filePath,int spliteSize) throws Exception{
/*filePath = "D:/xxxxx.docx";
spliteSize = 1000*1024;*/
File file = new File(filePath);

System.out.println(file.length());

long iPart= file.length()/spliteSize;   //分割
long leftNum = file.length()%spliteSize; //剩余部分

FileInputStream fis = new FileInputStream(file);

byte[] buff = new byte[spliteSize];
fileSpliteList = new ArrayList<String>();

for(int i=0 ;i<iPart; i++){
String fileSpliteName = file.getAbsolutePath()+".depart"+i;
fileSpliteList.add(fileSpliteName);
FileOutputStream writer=new FileOutputStream(fileSpliteName); 

int readInt = fis.read(buff);
writer.write(buff, 0, readInt);
writer.flush();
writer.close();
}

if(leftNum>0){
String fileSpliteName = file.getAbsolutePath()+".depart"+iPart;
fileSpliteList.add(fileSpliteName);
FileOutputStream writer=new FileOutputStream(fileSpliteName); 

int readInt = fis.read(buff);
writer.write(buff, 0, readInt);
writer.flush();
writer.close();
}
fis.close();

}

//文件追加

public static void  FileUnion() throws Exception{
if(fileSpliteList.size() <= 1){
return ;
}

String destFilePath =/*"D:/XXXdocx"*/ fileSpliteList.get(0);
File destFile = new File(destFilePath);
RandomAccessFile hFileWrite = new RandomAccessFile(destFile,"rw");
hFileWrite.seek(destFile.length());
//FileOutputStream fos = new FileOutputStream(destFile);
byte[] buff = new byte[1000];
int len = 0;
for(int i=1; i<fileSpliteList.size();i++){
String sourceFile = fileSpliteList.get(i);
File file = new File(sourceFile);
FileInputStream fis = new FileInputStream(file);

while((len = fis.read(buff))>0){
hFileWrite.write(buff, 0,len);  //追加

//fos.write(buff, 0,len);  //不是追加，是一个dest是新的文件
}

fis.close();
file.delete();
}


hFileWrite.close();

//rename


}