J2ME从零开始（学习笔记7）

3 ImageItem

ImageItem主要应用于显示图片丢向，ImageItem很多用法与StringItem相似

有两个构造方法，ImageItem(String label, Image image, int layout, String altText )

ImageItem(String label, Image image, int layout , String altText, int appearranceMode)

两种构造方法的参数基本相同，其中Layout是布局参数：CENTER, DEFAULT, LEFT, NEWLINE_AFTER,（排在这一行后面） NEWLINE_BEFORE,（排在这一行前面） RIGHT（右对齐）。参数altText为可选信息。程序代码如下：

package J2ME001; import javax.microedition.lcdui.Command; import javax.microedition.lcdui.CommandListener; import javax.microedition.lcdui.Display; import javax.microedition.lcdui.Displayable; import javax.microedition.lcdui.Form; import javax.microedition.lcdui.Image; import javax.microedition.lcdui.ImageItem; import javax.microedition.lcdui.Item; import javax.microedition.lcdui.ItemCommandListener; import javax.microedition.midlet.MIDlet; import javax.microedition.midlet.MIDletStateChangeException; public class ImageItemMIDlet extends MIDlet implements ItemCommandListener, CommandListener { private Form form; private Command cmdImgItem1 = new Command("Plain", Command.ITEM, 1); private Command cmdImgItem2 = new Command("Button", Command.ITEM, 1); private Command cmdExit = new Command("Exit", Command.CANCEL, 1); public ImageItemMIDlet() { try { Image image1 = Image.createImage("/res/image.png"); ImageItem imageItem1 = new ImageItem("左上角", image1, Item.LAYOUT_LEFT, null, Item.PLAIN); imageItem1.setItemCommandListener(this); imageItem1.addCommand(cmdImgItem1); imageItem1.addCommand(cmdExit); Image image2 = Image.createImage("/res/rss.png"); ImageItem imageItem2 = new ImageItem("右下角", image2, Item.LAYOUT_RIGHT, null, Item.BUTTON); imageItem2.setItemCommandListener(this); imageItem2.addCommand(cmdImgItem2); imageItem2.addCommand(cmdExit); form = new Form("Photo显示"); form.append(imageItem1); form.append(imageItem2); form.addCommand(cmdExit); form.setCommandListener(this); } catch (Exception e) { e.printStackTrace(); } } protected void destroyApp(boolean unconditional) { // TODO Auto-generated method stub } protected void pauseApp() { // TODO Auto-generated method stub } protected void startApp() throws MIDletStateChangeException { Display.getDisplay(this).setCurrent(form); } public void commandAction(Command cmd, Item item) { if (cmd.equals(cmdImgItem1)) { System.out.println("This is left plain photo"); } else if (cmd.equals(cmdExit)) { notifyDestroyed(); destroyApp(true); } } public void commandAction(Command cmd, Displayable d) { // TODO Auto-generated method stub if (cmd.equals(cmdExit)) { notifyDestroyed(); destroyApp(true); } } }

 

ImageItem花费的时间最长了，主要是显示图片老显示不出来了！这一块郁闷了半天，大家在这块一定要注意图片的路径。我是在我的工程下的src下建了个res文件，将要显示的图片放在找个目录下，程序中用绝对路径