创建顺序存取文件

package  com.hz.FileandIO;

import  java.awt.BorderLayout;
import  java.awt.GridLayout;

import  javax.swing.JButton;
import  javax.swing.JLabel;
import  javax.swing.JPanel;
import  javax.swing.JTextField;

public   class  BankUI  extends  JPanel ... {
    
    protected final static String names[] = ...{"Account number","First name","Last name","Balance","Transaction Amount"    };
    
    protected JLabel labels[];
    protected JTextField fields[];
    protected JButton doTask1,doTask2;
    protected JPanel innerPanelCenter,innerPanelSouth;
    
    protected int size;
    
    public static final int ACCOUNT = 0,FIRSTNAME = 1, LASTNAME =2,BALANCE=3,TRANSACTION=4;
    
    public BankUI(int mySize)
    ...{
        size = mySize;
        labels = new JLabel[size];
        fields = new JTextField[size];
        
        for(int i=0;i<labels.length;i++)
            labels[i] = new JLabel(names[i]);
        
        for(int i=0;i<fields.length;i++)
            fields[i] = new JTextField();
        
        innerPanelCenter = new JPanel();
        innerPanelCenter.setLayout(new GridLayout(size,2));
        
        for(int i=0;i<size;i++)...{
            innerPanelCenter.add(labels[i]);
            innerPanelCenter.add(fields[i]);
        }
        
        doTask1 =new JButton();
        doTask2 = new JButton();
        
        innerPanelSouth = new JPanel();
        innerPanelSouth.add(doTask1);
        innerPanelSouth.add(doTask2);
        
        setLayout(new BorderLayout());
        add(innerPanelCenter,BorderLayout.CENTER);
        add(innerPanelSouth,BorderLayout.SOUTH);
        
        validate();
    }
    
    public JButton getDoTask1Button()...{
        return doTask1;
    }
    
    public JButton getDoTask2Button()...{
        return doTask2;
    }
    public JTextField[] getFields()...{
        return fields;
    }
    public void clearFields()...{
        for(int i=0;i<size;i++)
            fields[i].setText("");
    }
    public void setFieldValues(String strings[])throws IllegalArgumentException...{
        if(strings.length != size)
            throw new IllegalArgumentException("There must be" +
                    size + "Strings in the array");
        for(int i=0;i<size;i++)
            fields[i].setText(strings[i]);
    }
    public String[] getFieldValues()...{
        String values[] = new String[size];
        for(int i=0;i<size;i++)
            values[i] = fields[i].getText();
        return values;
    }
    
    
}

 

BankUI包含一个可以在多个程序中重用的GUI

 

package  com.hz.FileandIO;

// AccountRecord方法主要是维护一个帐号的信息。
import  java.io.Serializable;
// Serializable是一个标记接口。（标记接口不含任何方法）实现该接口能使ObjectOutputStream和
// ObjectInputStream使用AccountRecord对象。
public   class  AccountRecord  implements  Serializable ... {

    private int account;
    private String firstName;
    private String lastName;
    private double balance;
    
    public AccountRecord()
    ...{
        this(0,"","",0.0);
    }

    public AccountRecord(int acct, String first, String last, double bal) ...{
        // TODO 自动生成构造函数存根
        setAccount(acct);
        setFirstName(first);
        setFirstName(last);
        setBalance(bal);
    }

    public int getAccount() ...{
        return account;
    }

    public void setAccount(int account) ...{
        this.account = account;
    }

    public String getFirstName() ...{
        return firstName;
    }

    public void setFirstName(String firstName) ...{
        this.firstName = firstName;
    }

    public String getLastName() ...{
        return lastName;
    }

    public void setLastName(String lastName) ...{
        this.lastName = lastName;
    }

    public double getBalance() ...{
        return balance;
    }

    public void setBalance(double balance) ...{
        this.balance = balance;
    }

    
    
}

 

AccountRecord此类主要是维护一个帐号的信息

 

package  com.hz.FileandIO;


// 创建顺序存取文件
import  java.awt.BorderLayout;
import  java.awt.event.ActionEvent;
import  java.awt.event.ActionListener;
import  java.awt.event.WindowAdapter;
import  java.awt.event.WindowEvent;
import  java.io.File;
import  java.io.FileNotFoundException;
import  java.io.FileOutputStream;
import  java.io.IOException;
import  java.io.ObjectOutputStream;

import  javax.swing.JButton;
import  javax.swing.JFileChooser;
import  javax.swing.JFrame;
import  javax.swing.JOptionPane;

public   class  CreateSequentialFile  extends  JFrame  ... {

    private ObjectOutputStream output;
    private BankUI userInterface;
    private JButton enterButton,openButton;
    
    public CreateSequentialFile()
    ...{
        super("Creating a Swquential File of Objects");
        
        userInterface  = new BankUI(4);
        getContentPane().add(userInterface,BorderLayout.CENTER);
        openButton = userInterface.getDoTask1Button();
        openButton.setText("保存文件！！");
        openButton.addActionListener(
                new ActionListener()...{
                    public void actionPerformed(ActionEvent event)
                    ...{
                        openFile();
                    }
                }
            );
        enterButton = userInterface.getDoTask2Button();
        enterButton.setText("Enter");
        enterButton.setEnabled(false);
        
        enterButton.addActionListener(
                new ActionListener()...{
                    public void actionPerformed(ActionEvent event)
                    ...{
                        addRecord();
                    }
                }
            );
        
        addWindowListener(
                new WindowAdapter()...{
                    public void windowClosing(WindowEvent event)
                    ...{
                        if(output != null)
                            addRecord();
                        closeFile();
                    }
                }
        );
        
        setSize(300,200);
        setVisible(true);
    }
    
    
    private void openFile()
    ...{
        //创建了一个fileChooser对象
        JFileChooser fileChooser = new JFileChooser();
        
        //调用serFileSelectionMode方法以指定用户是否可以从fileChooser中选择文件目录。
        //JFileCooser类的静态常量FILES_ONLY，指出用户只能选择文件。
        fileChooser.setFileSelectionMode(JFileChooser.FILES_ONLY);
        
        /**//*调用fileChooser中的showOpenDialog方法来显示标题为“save”的JFileChooser对话框。
            this指定JfileChooser对话框的父窗口确定屏幕上的显示位置
        */
        int result = fileChooser.showOpenDialog(this);
        
        //通过比较result和静态常量CANCEL_OPTION，来判断用户是否单击了“Cancel”按钮。
        if(result == JFileChooser.CANCEL_OPTION)
            return;
        
        //getSwlectedFile()方法来获得用户所选择的文件。
        File fileName = fileChooser.getSelectedFile();
        
        if(fileName == null || fileName.getName().equals(""))
            JOptionPane.showMessageDialog(this,"Invalid File Name",
                    "Invalid File Name",JOptionPane.ERROR_MESSAGE);
        else...{
            try ...{
                //输出文件
                FileOutputStream fos = new FileOutputStream(fileName);
                output = new ObjectOutputStream(fos);
                openButton.setEnabled(false);
                enterButton.setEnabled(true);
                
            } catch (FileNotFoundException e) ...{
                // TODO 自动生成 catch 块
                e.printStackTrace();
            } catch (IOException e) ...{
                // TODO 自动生成 catch 块
                JOptionPane.showMessageDialog(this, "Error Opening file",
                        "Error",JOptionPane.ERROR_MESSAGE);
            }
        }
        
    }
    
    private void closeFile()
    ...{
        try ...{
            output.close();
            System.exit(0);
        } catch (IOException ioException) ...{
            // TODO 自动生成 catch 块
            JOptionPane.showMessageDialog(this, "Error closing file",
                    "Error",JOptionPane.ERROR_MESSAGE);
            System.exit(1);
        }
        
    }
    
    private void addRecord()
    ...{
        int accountNumber = 0;
        AccountRecord record;
        String fieldValues[] = userInterface.getFieldValues();
        
        if( ! fieldValues[BankUI.ACCOUNT].equals(""))
        ...{
            try...{
                accountNumber = Integer.parseInt(fieldValues[BankUI.ACCOUNT]);
                
                if(accountNumber > 0)
                ...{
                    record = new AccountRecord(accountNumber,fieldValues[BankUI.FIRSTNAME],fieldValues[BankUI.LASTNAME],Double.parseDouble(fieldValues[BankUI.BALANCE]));
                    
                    output.writeObject(record);
                    output.flush();
                }
                else
                ...{
                    JOptionPane.showMessageDialog(this, "Account number must be greater than 0","Bad accountnumber",JOptionPane.ERROR_MESSAGE);
                    
                }
                
                userInterface.clearFields();
            }catch(NumberFormatException formatException)...{
                JOptionPane.showMessageDialog(this, "Bad account number or balance","Invalid Number Format",JOptionPane.ERROR_MESSAGE);
            }catch(IOException io)...{
                JOptionPane.showConfirmDialog(this, "Error writing to file","IO exception",JOptionPane.ERROR_MESSAGE);
                closeFile();
            }
        }
    }
    
    public static void main(String args[])...{
        new CreateSequentialFile();
    }
}

 

 使用ObjectOutputStream创建顺序文件