java IO中的乱码问题

　　 //文件拆分
    public void SplitFileStream(String src){
        //数据源
        File file = new File(src);
        //总长度
        long len = file.length();
        //块大小
        int blockSize = 500;
        //块个数
        int size = (int)Math.ceil(len*1.0/blockSize);

        //起始位置和实际大小
        int beginPos = 0;
        int actualSize = 0;
        for(int i= 0;i < size;++i){
            beginPos = i*blockSize;
            if(i == size -1){//最后一块另外处理
                actualSize = (int)len;
            }else{//剩余块数
                actualSize = blockSize;
                len-=actualSize;
            }
            Split(file,i,beginPos, actualSize);
        }
    }
    public void Split(File srcFile,int i,long beginPos,int actualSize){
        RandomAccessFile in = null;
        RandomAccessFile out = null;
        try {
            in = new RandomAccessFile((srcFile), "r");
            out = new RandomAccessFile(new File("D:\Test\split\"+i+"-"+srcFile.getName()), "rw");
            in.seek(beginPos);
            byte[] buffer = new byte[1024];
            int length = -1;
            while ((length = in.read(buffer, 0, buffer.length))!=-1){
                if (actualSize>length){
                    out.write(buffer, 0, length);
                    actualSize-=length;
                }else{
                    out.write(buffer, 0, actualSize);
                    break;
                }
            }
            System.out.println(i+"-->"+"已完成!");
        } catch (FileNotFoundException e) {
            System.out.println(i+"-->"+"有误！");
        } catch (IOException e) {
            System.out.println(i+"-->"+"有误！");
        }finally {
            if(out!=null){
                try {
                    out.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if (in!=null){
                try {
                    in.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }

执行上面的代码可以将某文件拆分成多个文件存储，但会出现部分正常，部分乱码的问题？？？