用J2ME實現簡單電子郵件發送功能(1)

這裡一個非常重要的思想就是代理。我們知道GCF提供給我們進行聯網的能力了，比如通過Http聯網。在MIDP2.0中甚至提供了socket聯網的API。那麼我們可以通過他們連接服務器端的程序比如servlet，然後servlet可以通過JavaMail提供的接口發送郵件。那麼我們需要做的只是通過Http協議或者其他協議把郵件的標題、內容、收件人等發送給servlet。就是這個簡單的思想卻是非常靈活非常有用。

首先我們構造一個Message類來代表發送的消息。它包括主題、收件人和內容三個字段。

package com.J2MEdev.mail;
public class Message
{    private String to;
    private String subject;
    private String content;
    public Message()
    {
    }
    public Message(String to, String subject, String content)
    {
        this.to = to;
        this.subject = subject;
        this.content = content;
    }
    public String getContent()
    {
        return content;
    }
    public void setContent(String content)
    {
        this.content = content;
    }
    public String getSubject()
    {
        return subject;
    }
    public void setSubject(String subject)
    {
        this.subject = subject;
    }  
    public String getTo()
    {
        return to;
    }
    public void setTo(String to)
    {
        this.to = to;
    }
    
    public String toString()
    {
        return to+subject+content; 
    }
}

在用戶界面的設計上，我們需要兩個界面。一個讓用戶輸入收件人和主題，另一個用於收集用戶輸入的內容。由於TextBox要獨占一個屏幕的，因此我們不能把他們放在一起。

/*
 * Created on 2004-12-8
 *
 * TODO To change the template for this generated file go to
 * Window - Preferences - Java - Code Style - Code Templates
 */
package com.J2MEdev.mail;
import Javax.microedition.lcdui.Form;
import Javax.microedition.lcdui.Item;
import Javax.microedition.lcdui.*;
import Javax.microedition.midlet.MIDlet;
/**
 * @author P2800
 * 
 * TODO To change the template for this generated type comment go to Window -
 * Preferences - Java - Code Style - Code Templates
 */
public class MainForm extends Form implements CommandListener
{
private MailClIEnt midlet;
    private TextField toFIEld;
    private TextField subFIEld;    
    private boolean first = true;
    public static final Command nextCommand = new Command("NEXT", Command.OK, 1);
public MainForm(MailClIEnt midlet, String arg0)
    {
        super(arg0);
        this.midlet = midlet;
        if(first)
        {
            first = false;
            init();
        }
        
    }
public void init()
    {
        toField = new TextField("To:", null, 25, TextFIEld.ANY);
        subField = new TextField("Subject:", null, 30, TextFIEld.ANY);
        this.append(toFIEld);
        this.append(subFIEld);
        this.addCommand(nextCommand);
        this.setCommandListener(this);        
    }
    
    public void commandAction(Command cmd,Displayable disp)
    {
        if(cmd == nextCommand)
        {
            String to = toFIEld.getString();
            String subject = subFIEld.getString();
            if(to == "" && subject == "")
            {
                midlet.displayAlert("Null to or sub",AlertType.WARNING,this);
            }
            else
            {
                midlet.getMessage().setTo(to);
                midlet.getMessage().setSubject(subject);
                midlet.getDisplay().setCurrent(midlet.getContentForm());
            }
        }
    }
}
package com.J2MEdev.mail;
import Javax.microedition.lcdui.Command;
import Javax.microedition.lcdui.CommandListener;
import Javax.microedition.lcdui.Displayable;
import Javax.microedition.lcdui.TextBox;
import Javax.microedition.midlet.MIDlet;
public class ContentForm extends TextBox implements CommandListener
{
    private MailClIEnt midlet;
    private boolean first = true;
    public static final Command sendCommand = new Command("SEND", Command.ITEM,
            1);
public ContentForm(String arg0, String arg1, int arg2, int arg3,
            MailClIEnt midlet)
    {
        super(arg0, arg1, arg2, arg3);
        this.midlet = midlet;
        if (first)
        {
            first = false;
            init();
        }
}
public void init()
    {
        this.addCommand(sendCommand);
        this.setCommandListener(this);
    }
public void commandAction(Command cmd, Displayable disp)
    {
        if (cmd == sendCommand)
        {
            String content = this.getString();
            midlet.getMessage().setContent(content);
            System.out.println(midlet.getMessage());
            try
            {
                synchronized (midlet)
                {
                    midlet.notify();
                }
} catch (Exception e)
            {
            }
        }
    }
}