文件分割
1 import java.io.File; 2 import java.io.FileNotFoundException; 3 import java.io.IOException; 4 import java.io.RandomAccessFile; 5 6 public class FileSplitDemo { 7 public static void main(String[] args) throws IOException { 8 //分好块以后，调用方法读取每一块 9 File f=new File("src/com/hh/ThreadDemoe.java"); 10 long length=f.length();//文件大小 11 int blockSize=60;//块大小 12 int blockCount=(int)Math.ceil(length*1.0/blockSize);//块数 13 int beginPos=0; 14 int readSize=0; 15 for(int i=0;i<blockCount;i++){ 16 beginPos=i*blockSize; 17 if(i<blockCount-1){ 18 readSize=blockSize; 19 }else{ 20 readSize=(int)length%blockSize; 21 } 22 split(i,beginPos,readSize); 23 } 24 } 25 /* 26 * 块数，起始位置，读取长度 27 */ 28 private static void split(int i,int beginPos,int actualSize) throws IOException { 29 RandomAccessFile ras=new RandomAccessFile("src/com/hh/ThreadDemoe.java","r"); 30 31 ras.seek(beginPos);//随机读取 32 //读取操作 33 byte[] bys=new byte[10]; 34 int len=-1;//接收长度 35 while((len=ras.read(bys))!=-1){ 36 37 if(actualSize>len){//剩余长度大于接收长度 38 System.out.print(new String(bys,0,len)); 39 actualSize-=len; 40 }else{//剩余长度小于接收长度 41 System.out.print(new String(bys,0,actualSize)); 42 break; 43 } 44 } 45 ras.close(); 46 }
}
1 //将分块和读取放在一起，读取全部文件 2 private static void readFileSplit() throws FileNotFoundException, IOException { 3 RandomAccessFile ras=new RandomAccessFile("src/hh/ThreadDemoe.java","r"); 4 long len=ras.length();//文件长度 5 int blockSize=50;//块大小 6 int blockNum=(int) Math.ceil((len*1.0)/blockSize);//块数 7 8 byte[] bys=new byte[blockSize];//缓冲数组大小使用块大小 9 for(int i=0;i<blockNum;i++){ 10 ras.seek(i*blockSize); 11 if(i<blockNum-1){ 12 ras.read(bys); 13 System.out.print(new String(bys,0,blockSize)); 14 }else { 15 int size=ras.read(bys);//文件的最后一块，直接读取返回大小 16 System.out.print(new String(bys,0,size)); 17 } 18 } 19 ras.close(); 20 }
1 import java.io.File; 2 import java.io.FileNotFoundException; 3 import java.io.IOException; 4 import java.io.RandomAccessFile; 5 6 public class FileSplitDemo { 7 public static void main(String[] args) throws IOException { 8 //分好块以后，调用方法读取每一块 9 File f=new File("src/com/hh/ThreadDemoe.java"); 10 long length=f.length();//文件大小 11 int blockSize=60;//块大小 12 int blockCount=(int)Math.ceil(length*1.0/blockSize);//块数 13 int beginPos=0; 14 int readSize=0; 15 for(int i=0;i<blockCount;i++){ 16 beginPos=i*blockSize; 17 if(i<blockCount-1){ 18 readSize=blockSize; 19 }else{ 20 readSize=(int)length%blockSize; 21 } 22 split(i,beginPos,readSize); 23 } 24 } 25 /* 26 * 块数，起始位置，读取长度 27 * 28 * 跟字节流一样使，就是读写用的一个类new出来的对象 29 */ 30 private static void split(int i,int beginPos,int actualSize) throws IOException { 31 RandomAccessFile ras=new RandomAccessFile("src/com/hh/ThreadDemoe.java","r"); 32 RandomAccessFile ras2=new RandomAccessFile("ff/"+i+"Copy","rw"); 33 ras.seek(beginPos);//随机读取 34 //读取操作 35 byte[] bys=new byte[10]; 36 int len=-1;//接收长度 37 while((len=ras.read(bys))!=-1){ 38 39 if(actualSize>len){//剩余长度大于接收长度 40 ras2.write(bys,0,len); 41 actualSize-=len; 42 }else{//剩余长度小于接收长度 43 ras2.write(bys,0,actualSize); 44 break; 45 } 46 } 47 ras.close(); 48 } 49 }
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使用面向对象思想进行封装
1 import java.io.BufferedInputStream; 2 import java.io.File; 3 import java.io.FileInputStream; 4 import java.io.FileOutputStream; 5 import java.io.IOException; 6 import java.io.InputStream; 7 import java.io.OutputStream; 8 import java.io.RandomAccessFile; 9 import java.io.SequenceInputStream; 10 import java.util.ArrayList; 11 import java.util.Vector; 12 13 public class FileSplitDemo { 14 private File f; 15 private String dest;//父文件夹 16 private ArrayList<String> list=new ArrayList<String>(); 17 private int blockSize; 18 private long length;//文件大小 19 private int blockCount;//块数 20 public FileSplitDemo(String srcStr, String dest, int blockSize) { 21 super(); 22 this.f = new File(srcStr); 23 this.dest = dest; 24 this.blockSize = blockSize; 25 init(); 26 } 27 private void init(){ 28 length=f.length(); 29 blockCount=(int)Math.ceil(length*1.0/blockSize); 30 for(int i=0;i<blockCount;i++){ 31 list.add(dest+"/"+i+"-"+this.f.getName()); 32 System.out.println(list.get(i)); 33 } 34 35 } 36 37 38 39 public void split1() throws IOException { 40 //分好块以后，调用方法读取每一块 41 int beginPos=0; 42 int readSize=0; 43 for(int i=0;i<blockCount;i++){ 44 beginPos=i*blockSize; 45 if(i<blockCount-1){ 46 readSize=blockSize; 47 }else{ 48 readSize=(int)length%blockSize; 49 } 50 split(i,beginPos,readSize); 51 } 52 } 53 /* 54 * 块数，起始位置，读取长度 55 * 56 * 跟字节流一样使，就是读写用的一个类new出来的对象 57 */ 58 private void split(int i,int beginPos,int actualSize) throws IOException { 59 RandomAccessFile ras=new RandomAccessFile(f,"r"); 60 RandomAccessFile ras2=new RandomAccessFile(list.get(i),"rw"); 61 ras.seek(beginPos);//随机读取 62 //读取操作 63 byte[] bys=new byte[10]; 64 int len=-1;//接收长度 65 while((len=ras.read(bys))!=-1){ 66 67 if(actualSize>len){//剩余长度大于接收长度 68 ras2.write(bys,0,len); 69 actualSize-=len; 70 }else{//剩余长度小于接收长度 71 ras2.write(bys,0,actualSize); 72 break; 73 } 74 } 75 ras.close(); 76 } 77 //将多个文件合并到一个文件中，使用多个输入流和一个输出流 78 private void merge() throws IOException{ 79 OutputStream os=new FileOutputStream("ff/merge.txt",true); 80 byte[] bys=new byte[1024]; 81 int len; 82 for(int i=0;i<blockCount;i++){ 83 InputStream is=new FileInputStream(list.get(i)); 84 while((len=is.read(bys))!=-1){ 85 os.write(bys,0,len); 86 } 87 is.close(); 88 } 89 os.close(); 90 } 91 //将多个文件合并到一个文件中，使用序列流和一个输出流 92 private void merge2() throws IOException{ 93 OutputStream os=new FileOutputStream("ff/merge.txt",true); 94 Vector<InputStream> vi=new Vector<InputStream>();//集合对象 95 for(int i=0;i<blockCount;i++){ 96 vi.add(new BufferedInputStream(new FileInputStream(list.get(i)))); 97 } 98 SequenceInputStream sis=null;//序列流 99 sis=new SequenceInputStream(vi.elements()); 100 101 byte[] bys=new byte[1024]; 102 int len; 103 while((len=sis.read(bys))!=-1){ 104 os.write(bys,0,len); 105 } 106 sis.close(); 107 os.close(); 108 } 109 110 111 //测试 112 public static void main(String[] args) throws IOException { 113 FileSplitDemo fsd=new FileSplitDemo("src/com/hh/ThreadDemoe.java", "ff", 50); 114 fsd.split1(); 115 //fsd.merge(); 116 fsd.merge2(); 117 } 118 }
