在 NetBeans IDE 中使用 Java Web Start(1)

Creating the Project

1. Choose File > New Project. Under Categories, select Samples > Mobile. Under Projects, select Currency Converter. Click Next.
2. The Project Name and Location page sets the name and location of the project folder, and gives you the option of setting the project as the main project. Click Next to accept the defaults.
3. The Platform selection page sets the default execution environment, the emulator platform, for the project. Note that the default emulator platform is the J2ME Wireless Toolkit, and the default device is the DefaultColorPhone, a generic mobile device. Click Finish to complete the wizard.
   The Currency Converter displays in the Projects window.

Running the Project

Choose Run > Run Main Project.
The Currency Converter displays in the DefaultColorPhone device emulator.

Now you're ready to test the application in the device emulator.

Testing the Application

1. In the DefaultColorPhone screen, click the button under the word "Launch."
2. Select the currency you want to convert by clicking the up and down arrow keys
   on the Select button. You can select Dollars, Euros, or Yen.
3. Enter the currency amount to convert by clicking the emulator’s numeric keys.
   The application makes the conversion calculations and displays the results.
4. Click the button underneath the word “Exit” to exit the application.
5. Click the red button in the upper right corner to close the emulator.

Changing the Default Emulator Device

You can create different project configurations to test your MIDlet on different emulator platforms, or simply change the device for the default configuration.

1. Choose File > "Currency Converter" Properties from the Main menu. In the Properties dialog, choose the Platform node. You can change the device for the default configuration.
2. Click the Device dropdown menu and choose QwertyDevice. Click OK.
3. Choose Run > Run Main Project Run the application again, and the application runs in the QwertyDevice emulator.

Creating the Project

1. Choose File > New Project. Under Categories, select Mobile. Under Projects, select Mobile Application. Click Next.
2. In the Project Name and Location page, name the project NewCurrencyConverter, and accept the default for Project Home. Leave the Set as Main Project check box checked, as you'll want this project to be your main project Click Next.
3. Accept the defaults on the Platform page by clicking Finish.
   The NewCurrencyConverter application displays in the Projects window.

Creating the converterMIDlet.java MIDlet

1. Choose File > New File. Under Categories, choose MIDP. Under File Types, choose MIDlet. Click Next.
2. In the Name and Location page, Enter Currency Converter for the MIDlet name, ConverterMIDlet for the MIDP Class Name, and myconverter for the package name.

Coding the ConverterMIDlet.java MIDlet

1. In the Source Editor, add the following import statements to ConverterMIDlet.java:
   

   import java.io.*;
   import javax.microedition.rms.*;

2. In the Projects Tab, expand the ConverterMIDlet node, right-click the ConverterMIDlet class and choose Add > Field.
   This next step will use the Add New Field dialog box to add the field storedDataStr to the MIDlet. The storedDataStr string contains the name of the RMS stored record.
3. Complete the Add New Field dialog box:
   • Enter the name of the new field, storedDataStr, in the Name box and select
     its type, String, from the Type combo box.
   • In the Modifiers box, select the type of access for the field, private, from the
     Access combo box.
   • Check the other modifiers for the field, which in this case is static.
   • Set the initial value for storedDataStr to "ConverterData".
   • Click OK to close the dialog box.

   The field is added to the code in the Source Editor window.

4. Add the following fields to the ConverterMIDlet.java class using the Source Editor.
   You can use the Add Field dialog box, copy the text from this page, or from the installed Currency Converter application, and paste it in the Source Editor. Be careful, however, not to change the package name from myconverter.

   public class ConverterMIDlet extends javax.microedition.midlet.MIDlet {
       private static String storedDataStr = "ConverterData";
       public String[] currencies = new String[] { "US $", "Yen \u00a5", "Euro \u20ac" };
       public boolean[] selected = new boolean[] { true, true, true, true };
       public long[][] rates = {{ 1000000, 117580000, 911079 },
                                { 8504, 1000000, 7749 },
                                { 1097600, 129056000, 1000000 }};
       private RecordStore storedData;

5. Add the following code to the method startApp(). This method is called when the application is started. It loads all the data (currencies, selected currencies, and exchange rates) from persistent storage and initially displays the Converter form. The method should look like this:
   

   public void startApp() {
       try {
           storedData = RecordStore.openRecordStore(storedDataStr, true);
           if (storedData.getNumRecords() > 0) {
               DataInputStream in = new DataInputStream(new ByteArrayInputStream(storedData.getRecord(1)));
               try {
                   int size = in.readInt();
                   currencies = new String[size];
                   selected = new boolean[size];
                   rates = new long[size][];
                   for (int i=0; i<size; i++) {
                        currencies[i] = in.readUTF();
                        selected[i] = in.readBoolean();
                        rates[i] = new long[size];
                        for (int j=0; j<size; j++) {
                            rates[i][j] = in.readLong();
                        }
                   }
                   in.close();
               } catch (IOException ioe) {
               }
            }
        } catch (RecordStoreException e) {
        }
        notifySettingsChanged();
     }

6. The destroyapp() method is called when the application is finished, or destroyed. Add the following code to complete the destroyApp() method:
   

   public void destroyApp(boolean unconditional) {
       try {
            ByteArrayOutputStream bytes = new ByteArrayOutputStream();
            DataOutputStream out = new DataOutputStream(bytes);
            try {
                out.writeInt(currencies.length);
                for (int i=0; i<currencies.length; i++) {
                    out.writeUTF(currencies[i]);
                    out.writeBoolean(selected[i]);
                    for (int j=0; j<currencies.length; j++) {
                        out.writeLong(rates[i][j]);
                    }
                }
                out.close();
                if (storedData.getNumRecords() > 0)
                    storedData.setRecord(1, bytes.toByteArray(), 0, bytes.size());
                else
                    storedData.addRecord(bytes.toByteArray(), 0, bytes.size());
            } catch (IOException ioe) {
                ioe.printStackTrace();
            }
        } catch (RecordStoreException e) {
            e.printStackTrace();
        }
        notifyDestroyed();
     }

7. Add the following three new methods:

• showSettings()
  This method creates and displays the CurrenciesSelector list.
  

    public void showSettings() {
       Display.getDisplay(this).setCurrent(new CurrenciesSelector(this));
    }

• notifySettingsChanged()
  This method displays a new Converter form after the settings are changed.
  

   public void notifySettingsChanged() {
      Display.getDisplay(this).setCurrent(new Converter(this));
   }

• longconvert()
  This method performs the currency conversion. The input value, frval, is multiplied by the exchange rate stored in the rates table and divided by 1,000,000. The fridx and toidx values are the indexes of the source and target currencies.
  

  public long convert(long frval, int fridx, int toidx) {
          return (frval * rates[fridx][toidx]) / 1000000;

  8. Save the ConverterMIDlet by choosing File > Save.