httpimage.java

简单说明了一下http链接在j2me中的使用

import java.io.*;
import javax.microedition.io.*;
import javax.microedition.lcdui.*;
import javax.microedition.midlet.*;

public class HttpImage extends MIDlet implements CommandListener {
	//命令对象
	private Command exitCommand, loadCmd;

	private Form form;

	private ImageItem imgItem;

	private TextField tf; //通过TextField来显示信息

	private Ticker tker; //访问网络时显示滚动的标题

	public HttpImage() {
		form = new Form("imageLoad");
		tf = new TextField("URL", "http://192.168.1.238/board.png",
				120, TextField.URL);
		tf.setLayout(Item.LAYOUT_NEWLINE_AFTER);
		imgItem = new ImageItem("Image", null, Item.LAYOUT_CENTER, "image");
		imgItem.setPreferredSize(form.getWidth(), 180);//调整对象大小
		tker = new Ticker("Loading");
		form.append(tf);
		form.append(imgItem);

		exitCommand = new Command("Exit", Command.EXIT, 1);
		loadCmd = new Command("LoadImage", Command.SCREEN, 1);
		form.addCommand(exitCommand);
		form.addCommand(loadCmd);
		form.setCommandListener(this);
	}

	protected void startApp() throws MIDletStateChangeException {
		Display.getDisplay(this).setCurrent(form);
	}

	protected void pauseApp() {
	}

	protected void destroyApp(boolean p1) {
	}

	public void commandAction(Command c, Displayable d) {
		if (c == exitCommand) {
			destroyApp(false);
			notifyDestroyed();
		} else if (c == loadCmd) {
			form.setTicker(tker);
			new Loader(form, imgItem, tf.getString());
		}
	}

	private class Loader extends Thread {
		private String testUrl;

		private Form form; //在读入数据完成后停止窗口的滚动标题

		private ImageItem imgItem; //设置ImageItem 中的图像

		public Loader(Form f, ImageItem i, String url) {
			form = f;
			imgItem = i;
			testUrl = url;
			this.start();
		}

		public void run() {
			Image imgLoad = null;
			try {
				imgLoad = getPngImage(testUrl);
			} catch (Exception e) {
				System.out.println("error = " + e.getMessage());
			}
			form.setTicker(null);
			if (imgLoad != null)
				imgItem.setImage(imgLoad);//设置图像
		}

		public Image getPngImage(String url) throws IOException, Exception {//通过
																			// HttpConnection
																			// 对象来获取网页内容
			HttpConnection c = null;
			InputStream is = null;
			Image img = null;
			try {
				c = (HttpConnection) Connector.open(url); //创建 HttpConnection
														  // 对象
				//c.setRequestProperty("User-Agent", "MIDP/2.0");//设置客户方名称
				//c.setRequestProperty("Accept",
				//		"text/html, text/plain, text/xml, image/png, */*");//设置可接受的MIME类型

				int rc = c.getResponseCode(); //转换到Connected 状态
				if (rc != HttpConnection.HTTP_OK) {
					throw new Exception(c.getResponseMessage());
				}
				is = c.openInputStream();//打开输入流
				img = Image.createImage(is); //通过输入流创建图像
			} catch (IOException e) {
				System.out.println("error = " + e.getMessage());
			} finally {
				if (is != null)
					is.close();
				if (c != null)
					c.close();
			}
			return img;
		}
	}

}