student.java

用Java做的一个学生考试分析程序

/*
 * Student.java
 *
 * Created on 2007年12月12日, 下午6:00
 *
 * To change this template, choose Tools | Template Manager
 * and open the template in the editor.
 */

package 考试成绩分析程序;
import java.io.*;
/**
 *
 * @author drawen
 */
public class Student implements java.io.Serializable{
    public static final String STUDENT_FILE="studentFile.dat";
    private long id;
    private String name;
    /** Creates a new instance of Student */
    public Student(long id,String name) {
        setId(id);
        setName(name);
    }
    public Student(){}
    public void setId(long id){    
        this.id=id;
    }
    public long getId(){
        return id;
    }
    public void setName(String name){
        this.name=name;
    }
    public String getName(){
        return name;
    }
    public boolean equals(Object o){
        Student temp=(Student)(o);
        if(id==temp.id)
            return true;
        else
            return false;
    }
    public boolean saveToFile(){
        MainWindow.initDataFile(STUDENT_FILE);
        DataOutputStream output;     
        DataInputStream input;
        String name;
        long id;
        try{
            input=new DataInputStream(new FileInputStream(STUDENT_FILE));            
            while(input.available()>0){
                id=input.readLong();
                name=input.readUTF();
                if(id==this.id){
                    input.close();
                    return false;
                }
            }
            input.close();
            output=new DataOutputStream(new FileOutputStream(STUDENT_FILE,true));
            output.writeLong(this.id);
            output.writeUTF(this.name);
            output.close();
            return true;
        }catch(Exception e){      
            return false;
        }
    }   
    public static Student queryFromFile(long studentId){
        MainWindow.initDataFile(STUDENT_FILE);
        DataInputStream input;
        String name;
        long id;
        try{
            input=new DataInputStream(new FileInputStream(STUDENT_FILE));
            while(input.available()>0){
                id=input.readLong();
                name=input.readUTF();
                if(id==studentId){
                    input.close();
                    return new Student(id,name);                    
                }
            }
            input.close();
            return null;
        }catch(Exception e){
            return null;
        }
    }   
    public static Student[] loadFile(){
        Student[] student=new Student[20];
        int count=0;
        MainWindow.initDataFile(STUDENT_FILE);
        DataInputStream input;
        try{
            input=new DataInputStream(new FileInputStream(STUDENT_FILE));
            while(input.available()>0){
                if(count>=student.length){
                    Student[] temp=new Student[student.length*2];
                    for(int i=0;i<student.length;i++)
                        temp[i]=student[i];
                    student=temp;
                }
                student[count]=new Student();
                student[count].setId(input.readLong());
                student[count].setName(input.readUTF());
                count++;
            }
            input.close();
            return student;
        }catch(Exception e){
            return null;
        }
    }
}