planemodeldaofromfile.java

航空售票系统的代码

package com.tarena.abs.dao;

import java.util.*;
import java.io.*;
import com.tarena.abs.model.PlaneModel;

public class PlaneModelDaoFromFile implements PlaneModelDAO {

	private File file;
	
	public PlaneModelDaoFromFile(String fileName){
		file=new File(fileName);
		FileOutputStream fos=null;
		ObjectOutputStream oos=null;
		FileInputStream fis=null;
		ObjectInputStream ois=null;
		Object obj=null;
		
		try {//试着读取文件中的对象
			fis=new FileInputStream(file);
			ois=new ObjectInputStream(fis);
			obj=ois.readObject();
		} catch (Exception e) {
			//e.printStackTrace();
			System.out.println("没有找到"+fileName+"文件");
		}finally{
			if(ois!=null)try{ois.close();}catch(IOException e){}
			if(fis!=null)try{fis.close();}catch(IOException e){}
		}
		
		//如果读到的对象为null，或者不是HashSet
		if(obj==null || !(obj instanceof HashSet)){
			try {//就向文件中写入一个空的HashSet
				fos=new FileOutputStream(file);
				oos=new ObjectOutputStream(fos);
				oos.writeObject(new HashSet());
				oos.flush();
				System.out.println("创建了"+fileName+"文件");
			} catch (Exception e) {
				e.printStackTrace();
			}finally{
				if(oos!=null)try{oos.close();}catch(IOException e){}
				if(fos!=null)try{fos.close();}catch(IOException e){}
			}
		}
	}
	

	public Set getAllPlaneModel() {
		FileInputStream fis=null;
		ObjectInputStream ois=null;
		HashSet hs=null;
		
		try {
			fis=new FileInputStream(file);
			ois=new ObjectInputStream(fis);
			hs=(HashSet)ois.readObject();
			return hs;
		} catch (Exception e) {
			e.printStackTrace();
		}finally{
			if(ois!=null)try{ois.close();}catch(IOException e){}
			if(fis!=null)try{fis.close();}catch(IOException e){}
		}
		return null;
	}

	public boolean addPlaneModel(PlaneModel plane) {
		FileInputStream fis=null;
		ObjectInputStream ois=null;
		FileOutputStream fos=null;
		ObjectOutputStream oos=null;
		HashSet hs=null;
		boolean b=false;
		try {
			fis=new FileInputStream(file);
			ois=new ObjectInputStream(fis);
			hs=(HashSet)ois.readObject();
		} catch (Exception e) {
			e.printStackTrace();
		} finally{
			if(ois!=null)try{ois.close();}catch(IOException e){}
			if(fis!=null)try{fis.close();}catch(IOException e){}
		}
		b = hs.add(plane);
		try {
			fos=new FileOutputStream(file);
			oos=new ObjectOutputStream(fos);
			oos.writeObject(hs);
			return b;
		} catch (Exception e) {
			e.printStackTrace();
		} finally{
			if(oos!=null)try{oos.close();}catch(IOException e){}
			if(fos!=null)try{fos.close();}catch(IOException e){}
		}

		return false;
	}

	public boolean removePlaneModel(String model) {
		FileInputStream fis=null;
		ObjectInputStream ois=null;
		FileOutputStream fos=null;
		ObjectOutputStream oos=null;
		HashSet hs=null;
		boolean b = false;
		try {
			fis=new FileInputStream(file);
			ois=new ObjectInputStream(fis);
			hs=(HashSet)ois.readObject();
		} catch (Exception e) {
			e.printStackTrace();
		} finally{
			if(ois!=null)try{ois.close();}catch(IOException e){}
			if(fis!=null)try{fis.close();}catch(IOException e){}
		}
		
		Iterator it=hs.iterator();
		while(it.hasNext()){
			PlaneModel pm=(PlaneModel)it.next();
			if(pm.getModel().equals(model) ){
				b = hs.remove(pm);
			}
		}
		try {
			fos=new FileOutputStream(file);
			oos=new ObjectOutputStream(fos);
			oos.writeObject(hs);
			return b;
		} catch (Exception e) {
			e.printStackTrace();
		} finally{
			if(oos!=null)try{oos.close();}catch(IOException e){}
			if(fos!=null)try{fos.close();}catch(IOException e){}
		}
		
		return false;
	}

}