filemanager.java

一个简单的数据库

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package fileManager;
import java.io.*;
import database.*;
import bufferedManager.*;
import catalogManager.*;
import java.util.ArrayList;
import indexManager.*;
import java.util.Date;
import javax.swing.JOptionPane;
/**
 *
 * @author outlaw
 */
public class FileManager {
    public static final String WORKPATH="d:/workspace/";
    public static final String DATABASE_INFO="d:/workspace/System.ini";
    public static final String LOG=WORKPATH+"db.log";
    
    public FileManager(){
    }
    public static void writeOutObject(Object obj,String fullName) throws Exception{
        try{
            //System.out.println(fullName);
            File parentDir=new File(new File(fullName).getParent());
            if(!parentDir.exists())
                parentDir.mkdirs();
            ObjectOutputStream oos=new ObjectOutputStream(
                    new FileOutputStream(fullName));
            oos.writeObject(obj);
            oos.close();
        }catch(Exception ex){
            throw new OperationInfo("File process error!:\nIn FileManager.writeOutObject.");
        }
    }
    public static TableData readInTable(String fullName) throws Exception
    {
        ObjectInputStream ois=new ObjectInputStream(new FileInputStream(fullName));
        TableData tb=(TableData) ois.readObject();
        ois.close();
        return tb;
    }
    public static DataBaseData readInDB(String fullName) throws Exception
    {
        ObjectInputStream ois=new ObjectInputStream(new FileInputStream(fullName));
        DataBaseData db=(DataBaseData)ois.readObject();
        ois.close();
        return db;
    }
    public static DataBaseData readInDBByName(String name) throws Exception
    {
        return readInDB(WORKPATH+name+"/"+name+".db");
    }
    public static void createFile(String fullName) throws Exception
    {
        File file=new File(fullName);
        File parent=new File(file.getParent());
        if(!parent.exists())
            parent.mkdirs();
        file.createNewFile();
    }
    public static void writeBlockBack(Block block) throws Exception
    {
        int blockID=block.getBlockID();
        String fullName=null;
        TableData tb=CatalogManager.getTableByName(block.getTBName());
        if(tb==null)
            throw new OperationInfo("Insert tuple error!Table not found!");
        fullName=tb.getFullName()+".tbl";
        try
        {
            RandomAccessFile raf=new RandomAccessFile(fullName,"rw");
            raf.seek(Block.BLOCKSIZE*block.getBlockID());
            /*System.out.println(block.getBlockID());
            Tuple[] tuples=block.getTuples();
            for(int i=0;i<tuples.length;i++)
            {
                if(tuples[i]!=null)
                {
                    System.out.println("--------------------------------");
                    String[] values=tuples[i].getValues();
                    for(int j=0;j<values.length;j++)
                        System.out.println(values[j]);
                }
            }*/
            //byte[] array=block.toBytes();
            //System.out.println("length: "+array.length);
            raf.write(block.toBytes());
            raf.close();
            tb.setBlockInFile(blockID);
        }catch(Exception ex)
        {
            ex.printStackTrace();
            throw new OperationInfo("Write block back error!");
        }
    }
    public static void writeOutIndex(Index index) throws Exception
    {
        String fullName=index.getFullName();
        FileOutputStream fos=new FileOutputStream(fullName);
        ObjectOutputStream oos=new ObjectOutputStream(fos);
        oos.writeObject(index);
        oos.close();
    }
    public static void makeDir(String path)
    {
        File file=new File(path);
        if(!file.exists())
        {
            file.mkdir();
        }
    }
    public static Index readInIndex(String fullName) throws Exception
    {
        FileInputStream fis=new FileInputStream(fullName);
        ObjectInputStream ois=new ObjectInputStream(fis);
        Index index=(Index) ois.readObject();
        
        return index;
    }
    public static void writeOutIndices() throws Exception
    {
        ArrayList<indexManager.Index> indices=IndexManager.indices;
        int len=indices.size();
        for(int i=0;i<len;i++)
        {
            if(indices.get(i).isDirty())
            {
                Index index=indices.get(i);
                index.clearDirty();
                writeOutIndex(index);
            }
        }
    }
    public static void writeOutTables() throws Exception
    {
        DataBaseData db=CatalogManager.getCurDB();
        ArrayList<TableData> tables=db.getTables();
        int len=tables.size();
        for(int i=0;i<len;i++)
        {
            writeOutTable(tables.get(i));
        }
    }
    public static void writeOutTable(TableData tb) throws Exception
    {
        String fullName=tb.getPath()+tb.getName()+".tbl";
        FileOutputStream fos=new FileOutputStream(fullName);
        ObjectOutputStream oos=new ObjectOutputStream(fos);
        oos.writeObject(tb);
        oos.close();
    }
    public static void writeOutDataBaseInfo() throws Exception
    {
        ArrayList<String> names=CatalogManager.getAllDBName();
        DataBaseInfo dbi=new DataBaseInfo(names);
        writeOutObject(dbi,DATABASE_INFO);
    }
    public static DataBaseInfo getDataBaseInfo() throws Exception
    {
        ObjectInputStream ois=new ObjectInputStream(new FileInputStream(DATABASE_INFO));
        DataBaseInfo dbi=(DataBaseInfo)ois.readObject();
        ois.close();
        return dbi;
    }
    public static void writeOutDataBase() throws Exception
    {
        DataBaseData db=CatalogManager.getCurDB();
        String fullName=db.getFullName()+".db";
        FileOutputStream fos=new FileOutputStream(fullName);
        ObjectOutputStream oos=new ObjectOutputStream(fos);
        oos.writeObject(db);
        oos.close();
    }
    public static void deleteFile(String fullName) throws Exception
    {
        File file=new File(fullName);
        if(file.exists())
            if(!file.delete())
                JOptionPane.showMessageDialog(null, "delete error!");
    }
    public static Index readIndexIntoMemory(String fullName) throws Exception
    {
        FileInputStream fis=new FileInputStream(fullName);
        ObjectInputStream ois=new ObjectInputStream(fis);
        Index index=(Index)ois.readObject();
        ois.close();
        return index;
    }
    public static void writeOutLog(String log) throws Exception
    {
        RandomAccessFile raf=new RandomAccessFile(LOG,"rw");
        long len=raf.length();
        raf.seek(len);
        Date date=new Date();
        String _date=date.toString();
        raf.write("==================================================================\n".getBytes());
        raf.write((_date+"\n").getBytes());
        raf.write("==================================================================\n".getBytes());
        raf.write(log.getBytes());
    }
}