indexmanager.java

一个简单的数据库

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package indexManager;
import java.util.*;
import database.*;
import fileManager.*;
/**
 *
 * @author outlaw
 */
public class IndexManager {
    public static ArrayList<Index> indices=new ArrayList<Index>();
    public static final int IndexSize=10;
    public static final int BP_SIZE=50;
            
    public IndexManager()
    {
    }
    public static void open()
    {
    }
    public static ArrayList<Index> getIndices()
    {
        return indices;
    }
    public static Index getIndex(TableData tb)
    {
        return null;
    }
    public static Index readIndexIntoMemory(String fullName) throws Exception
    {
        Index index=FileManager.readIndexIntoMemory(fullName);
        addIndex(index);
        return index;
    }
    public static void addIndex(Index index) throws Exception
    {
        rearrange(index);
    }
    public static void rearrange(int index)
    {
        indices.add(indices.remove(index));
    }
    public static void rearrange(Index index) throws Exception
    {
        if(indices.size()>=IndexSize)
        {
            Index oldIndex=indices.get(0);
            if(oldIndex.isDirty())
            {
                FileManager.writeOutIndex(index);
            }
            indices.remove(0);
        }
        indices.add(index);
    }
    public static void close() throws Exception
    {
        FileManager.writeOutIndices();
    }
}