saveandquery.java

用java实现的一个随机抽查学生回答问题的一个软件

package speech;

import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.FileReader;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.util.ArrayList;

public class SaveAndQuery {
	private static SaveAndQuery saq = new SaveAndQuery();
	
	public static SaveAndQuery getInstance(){
		return saq;
	}
	
	private SaveAndQuery(){
		
	}
	
	public void saveStudentHistory(Student stu){
		Student[] stus = queryStudentHistory();
		try {
			FileOutputStream fos = new FileOutputStream("history.dat");
			ObjectOutputStream oos = new ObjectOutputStream(fos);
			if(stus != null){
				for(int i = 0;i < stus.length;i ++){
					oos.writeObject(stus[i]);
				}				
			}
			oos.writeObject(stu);
			oos.close();
		} catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}
	
	
	public Student[] queryStudentHistory(){
		ArrayList list = new ArrayList();
		ObjectInputStream ois = null;
		try {
			FileInputStream fis = new FileInputStream("history.dat");
			ois = new ObjectInputStream(fis);
			
			while(true){				
				try {
					list.add((Student)ois.readObject());
				} catch (Exception e) {
					// TODO Auto-generated catch block
//					e.printStackTrace();
					break;
				} 
			}

		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}finally{
			try {
				if(ois != null){					
					ois.close();
				}
			} catch (IOException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
		}
		
		if(list.size() == 0){
			return null;
		}
		return (Student[])list.toArray(new Student[list.size()]);
	}
	
	
	public Student[] loadStudent(){
		Student[] stus = null;
		try {
			File f = new File("student.txt");
			FileReader fr = new FileReader(f);
			BufferedReader br = new BufferedReader(fr);
			String readStr = null;
			ArrayList list = new ArrayList();
			while((readStr = br.readLine()) != null){
				String[] info = readStr.split(","); 
				boolean sex = Boolean.valueOf(info[1]).booleanValue();
				Student stu = new Student(info[0],sex);
				list.add(stu);
			}
			if(list.size() != 0){
				stus = (Student[])list.toArray(new Student[list.size()]);
			}
			
		} catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		return stus;
		
	}
	



}