Java ，IO流，文件的分割与合并

package fileSplitAndBination;import java.io.BufferedOutputStream;import java.io.DataOutputStream;import java.io.File;import java.io.FileOutputStream;import java.io.IOException;import java.io.OutputStream;import java.io.RandomAccessFile;/** * 文件的分割 * @author 风潇潇 * */public class FileSplit {//文件路径private String srcPath;//文件对象private File src;//源文件大小private long fileSize;//源文件名private String name;//分割块数private int blocks;//每块大小private long blockSize;//分割后存储路径public FileSplit(String srcPath){this(srcPath,10);//默认分割为十块}/** * 默认为读取源文件目录，和分割块数 * @param srcPath * @param blocks */public FileSplit(String srcPath,int blocks){this.srcPath = srcPath;this.blocks=blocks;initial();}/** * 读取文件名，文件大小，计算分割后每块大小 */public void initial(){this.src=new File(srcPath);if(!src.isFile()){System.out.println("传入文件夹只能分割文件,或文件不存在");return;}this.fileSize=src.length();//文件大小this.name=src.getName();//文件名this.blockSize = fileSize/blocks;//分割块大小}/** * 指定输出目录 * @param destPath * @throws IOException */public void split(String destPath) throws IOException{File dest = new File(destPath);if(dest.isFile()||dest.isDirectory()){System.out.println("无法存储到已有文件或文件夹中中，请指定未建立的文件夹路劲");//为方便合并，限定必须为未建立的文件夹路径return;}if(!dest.exists()){dest.mkdirs();}long head=0;long size=this.blockSize;for(int i=0;i<blocks;i++){if(i==blocks-1){size=this.fileSize-head;}splitDtails(i,dest,head,size);head+=size;}/** * 输出分割信息 * 由于分割信息名制定 * 所以限定未建立的文件夹 * 以便合并时读取 */File info = new File(dest,"splitInfo");DataOutputStream dos = new DataOutputStream(   new BufferedOutputStream(       new FileOutputStream(info)));dos.writeUTF(this.name);dos.writeInt(this.blocks);dos.flush();dos.close();}private void splitDtails(int idx,File dest,long head,long size) throws IOException{File destSplit = new File(dest,this.name+"第"+idx+"部分");if(destSplit.exists()){destSplit.delete();}//避免重复写入RandomAccessFile is = new RandomAccessFile(src,"r");OutputStream os = new BufferedOutputStream(new FileOutputStream(destSplit,true));is.seek(head);byte[] flush =new byte[1024];int len=0;long sum=0;//此处要尤为注意，应按实际size写入，最后一次//同文件复制不同，此处无法通过返回-1来推出循环//因为文件分割所以在size边界外还是有字节存在//若直接使用len，就无法正确读取！while(-1!=(len=is.read(flush))){if(size-len>=0){os.write(flush, 0, len);size-=len;}else{os.write(flush,0,(int)size);break;}}os.flush();os.close();is.close();}/**、 * 通过制定大小来分割文件 * @param destPath * @param blockSize * @throws IOException */public void splitBySize(String destPath,long blockSize) throws IOException{if(blockSize>fileSize){blockSize = fileSize;}this.blockSize=blockSize;this.blocks = (int)(Math.ceil((fileSize*1.0/blockSize)));split(destPath);}public static void main(String[] args) {FileSplit fs = new FileSplit("G:/《Java核心技术 卷1 基础知识（原书第9版）》（完整中文版）.pdf");try {fs.split("G:/test");} catch (IOException e) {e.printStackTrace();}}}

文件的合并

package fileSplitAndBination;import java.io.BufferedInputStream;import java.io.BufferedOutputStream;import java.io.DataInputStream;import java.io.File;import java.io.FileInputStream;import java.io.FileOutputStream;import java.io.IOException;import java.io.InputStream;import java.io.OutputStream;public class FileBination {private String srcPath;private String destPath;private String fileName;private int blocks;public FileBination(String srcPath, String destPath) throws IOException {this.srcPath = srcPath;this.destPath = destPath;binationIntial();}public void binationIntial() throws IOException{File src = new File(srcPath);File splitInfo = new File(src,"splitInfo");if(!src.isDirectory()){System.out.println("请提供分割文件绝对路径！");return;}else if(!splitInfo.exists()||!splitInfo.isFile()){System.out.println("分割信息文件不存在或损坏");return;}else{DataInputStream dis = new DataInputStream(      new BufferedInputStream(      new FileInputStream(splitInfo)));this.fileName=dis.readUTF();this.blocks = dis.readInt();}}public void bination() throws IOException{File bFile = new File(destPath, fileName);for(int i=0 ;i<blocks;i++){if(!binationDtail(bFile,i)){bFile.delete();break;}}}private boolean binationDtail(File bFile,int i) throws IOException{File inFile = new File(srcPath,fileName+"第"+i+"部分");OutputStream os = new BufferedOutputStream(new FileOutputStream(bFile,true));InputStream is=null;boolean ok=true;if(!inFile.exists()){System.out.println("第"+i+"个分割文件损坏");ok=false;}else{is = new BufferedInputStream(new FileInputStream(inFile));int len =0;byte[] flush = new byte[1024];while(-1!=(len=is.read(flush))){os.write(flush, 0, len);}}os.flush();os.close();is.close();return ok;}public static void main(String[] args) {try {FileBination fb =new FileBination("G:/test","D:/");fb.bination();} catch (IOException e) {e.printStackTrace();}}}