riad3.java

软件模拟RAID系统。。 。。 。

import java.io.IOException;
import java.io.RandomAccessFile;


 class Raid3 implements Raid {
	 String inFileName;
	 String outFileName;
	 RandomAccessFile in;
	 RandomAccessFile out[];
	 int startdisk=0;
	 int checkdisk;
	 int n;
	 int length;
	 int CAPACITY;
	 public int[] capRemain;
	 int[] waste;
	 byte[] cbuf;
	 int ReadAble;
	 public boolean Readable()
	 {
		 return(ReadAble!=-1);
	 }
	 public boolean Storeable()
	 {
		 boolean a=true;
		 for(int i=0;i<n;i++)
		 {
			 if(capRemain[i]-waste[i]<length)
			 {
				 a=false;

			 }
			 if(a==false)System.out.println ("磁盘"+i+"空间不足，整条将不再写入");
		 }
		 return a;
	 }
		public int Capcity()
		{
			return CAPACITY;
		}
		public void capcity_Remained(int[]a)
		{
			for(int i=0;i<n;i++)
			{
				a[i]=capRemain[i];
			}
		}
		public int Cap_available()
		{
			int a=0;
			for(int i=0;i<n;i++)
			{
				a+=capRemain[i]-waste[i];
			}
			return a*(n-1)/n;
		}
		public void ReadBlock() throws IOException
		{
			ReadAble=in.read(cbuf,0,(n-1)*length);
			if(ReadAble==-1){System.out.println("文件结束或不足一条，读入终止");}
			//这一行以后转为throw exception
		}
		public void StoreBlock()throws IOException{
			int id =startdisk;
			int begin=0;
			Cal ca=new Cal();	
			byte[] xor_check = new byte[length];
			ca.Init(xor_check, length);
			for (int i=0;i<n;i++)
			{
				if (capRemain[id]-waste[id] < length) {
					System.out.println("磁盘" + id + "容量不足，写入失败");
					break;
				}
				if (id == checkdisk) {
					out[id].write(xor_check);
					capRemain[id] -= length;
					System.out.println("磁盘" + id + "写入校验");
					//checkdisk = ((checkdisk==0)?n-1:(checkdisk - 1));
					ca.Init(xor_check, length);// 清为全零
					break;
				}
				out[id].write(cbuf,begin,length);
				System.out.println("磁盘" + id + "写入数据");
				capRemain[id] -= length;
				System.out.println("磁盘" + id + "剩余容量为" + capRemain[id]);
				begin += length;
				//startdisk=(startdisk+1)%n;
				xor_check = ca.Xor(cbuf,length,n-1);
				id = (id + 1) % n;
				//System.out.println("id:" + id + "begin:" + begin + "check" + check);
			}
		}
		
		public void Recover(int downID) throws IOException
		{
			int key=0;
			Cal cacu=new Cal();
			RandomAccessFile[] bac=new RandomAccessFile[n];
			byte[] temp=new byte[1];//防止恢复是出猥琐的错误 单字节恢复而不是单块恢复
			byte[] result =new byte[1];
			cacu.Init(result, 1);
			for(int i=0;i<n;i++)
			{
				if(i!=downID)
					bac[i]= new RandomAccessFile("" +i+ "_"+outFileName,"r");
			}
			
			RandomAccessFile rec= new RandomAccessFile("" +downID+ "_"+"RECOVER_"+outFileName,"rw");
			while(key!=-1)
			{
				for(int i=0;i<n;i++)
				{
					if(i!=downID)
					{
						key= bac[i].read(temp);
						if(key!=-1)
						result=cacu.Xor(result, temp, 1);
					}
				}
				if(key!=-1)	
					{
						rec.write(result);
						cacu.Init(result, 1);
					}
			}
		}
		public Raid3(String inf,String outf,int n,int l,int[]cap) throws IOException
		{
			Cal c=new Cal();
			int min=c.Min(cap, n);
			cbuf=new byte[(n-1)*l];
			inFileName=inf;
			outFileName=outf;
			checkdisk=n-1;
			this.n=n;
			capRemain=new int[n];
			for(int i=0;i<n;i++)
			{
				 capRemain[i]=cap[i];
				 System.out.println("磁盘"+i+"剩余容量为"+capRemain[i]);
			}
			length=l;
			in= new RandomAccessFile(inf,"r");
			out = new RandomAccessFile[n];
			for(int i=0;i<n;i++)
				out[i] = new RandomAccessFile ("" + i + "_" +outFileName,"rw");
			CAPACITY=min/length*length*(n-1);
			waste=new int[n];
			for(int i=0;i<n;i++)
			{
				waste[i]=cap[i]-min/length*length;
			}
		}
 }