移动Web服务项目解析

### 移动 Web 服务项目解析 在移动应用开发中，提供多样化的服务是吸引用户的关键。本文将详细解析一个移动 Web 服务项目，该项目包含多个功能模块，如天气查询、电影票务预订和新闻阅读等。我们将深入探讨项目中的各个类及其功能，包括 `MainClass`、`DataParser` 和 `Weather` 类。 #### 1. MainClass 类 `MainClass` 类是整个应用的入口点，负责启动移动服务并调用其他三个 MIDlets。以下是该类的主要功能和代码解析： ```java // © 2001 Dreamtech Software India, Inc. // All rights Reserved import javax.microedition.midlet.MIDlet; import javax.microedition.lcdui.List; import javax.microedition.lcdui.Display; import javax.microedition.lcdui.CommandListener; import javax.microedition.lcdui.Command; import javax.microedition.lcdui.Displayable; public class MainClass extends MIDlet implements CommandListener { private List menu = null; private Display displaymenu = null; MoviesList bookmovie = null; News readnews = null; Weather seeweather = null; Command exit; public MainClass() { displaymenu = Display.getDisplay(this); exit = new Command("EXIT", Command.EXIT, 1); } public void startApp() { menu = new List("Menu", List.IMPLICIT); menu.append("Weather", null); menu.append("Movies", null); menu.append("News", null); menu.setCommandListener(this); displaymenu.setCurrent(menu); menu.addCommand(exit); } public void pauseApp() { System.out.println("pause app called"); } public void destroyApp(boolean b) { menu = null; displaymenu = null; bookmovie = null; readnews = null; seeweather = null; } public void commandAction(Command c, Displayable d) { if (c == List.SELECT_COMMAND) { String menuselect = menu.getString(menu.getSelectedIndex()); if (menuselect.equals("Weather")) { seeweather = new Weather(displaymenu, this); seeweather.startApp(); } if (menuselect.equals("Movies")) { bookmovie = new MoviesList(displaymenu, this); bookmovie.startApp(); } if (menuselect.equals("News")) { readnews = new News(displaymenu, this); readnews.startApp(); } } if (c == exit) { destroyApp(true); notifyDestroyed(); } } public void getDisplayObject(Display dis) { displaymenu = dis; displaymenu.setCurrent(menu); } } ``` **代码解析**： - **导入语句**：导入了运行该应用所需的类。 - **类声明**：`MainClass` 继承自 `MIDlet` 并实现了 `CommandListener` 接口。 - **对象声明**：声明了 `List`、`Display`、`MoviesList`、`News`、`Weather` 和 `Command` 等对象。 - **构造函数**：获取 `Display` 对象并初始化退出命令。 - **startApp 方法**：初始化一个列表，显示可用的服务，并注册事件处理。 - **pauseApp 方法**：在应用暂停时打印信息。 - **destroyApp 方法**：将所有对象设置为 `null`，释放资源。 - **commandAction 方法**：处理用户事件，根据用户选择调用相应的 MIDlet。 - **getDisplayObject 方法**：获取 `Display` 对象并显示菜单列表。 #### 2. DataParser 类 `DataParser` 类用于处理 HTTP 请求、读取和解析 XML 数据。该类为应用中的三个 MIDlets 提供服务。以下是该类的主要功能和代码解析： ```java // © 2001 Dreamtech Software India, Inc. // All rights Reserved import java.io.InputStream; import java.io.IOException; import java.io.InputStreamReader; import org.kxml.*; import org.kxml.parser.XmlParser; import org.kxml.parser.*; import java.util.Vector; import java.util.Hashtable; import javax.microedition.io.HttpConnection; import javax.microedition.io.Connector; import java.lang.String; import javax.microedition.rms.*; public class DataParser { HttpConnection con = null; InputStream ins = null; ParseEvent event; AbstractXmlParser parser; Vector hall_id, hall_name, halldata, vnews; Hashtable htable; RecordStore recordStore = null; public DataParser() { hall_id = new Vector(); hall_name = new Vector(); halldata = new Vector(); vnews = new Vector(); htable = new Hashtable(); htable = new Hashtable(); } public void sourceurl(String url) { try { con = (HttpConnection) Connector.open(url); ins = con.openInputStream(); parser = new XmlParser(new InputStreamReader(ins)); } catch (IOException ex) { System.out.println("IOException occured"); } } void read_category() { boolean foundnews = false; do { try { event = parser.read(); if (event.getType() == Xml.START_TAG) { StartTag stag = (StartTag) event; if (stag.getName().equals("category")) { foundnews = true; } } if (event.getType() == Xml.TEXT) { TextEvent tevent = (TextEvent) event; if (foundnews) { vnews.addElement(tevent.getText()); foundnews = false; } } } catch (IOException ex) { System.out.println("Exception occured"); } } while (!(event instanceof EndDocument)); } void read_record() { int k, id; String state = "", data = ""; boolean founditem = false, foundstate = false; try { recordStore = RecordStore.openRecordStore("addresses", true); } catch (RecordStoreException rse) { rse.printStackTrace(); } do { try { event = parser.read(); if (event.getType() == Xml.START_TAG) { StartTag stag = (StartTag) event; if (stag.getName().equals("weather")) { founditem = true; } if (stag.getName().equals("state")) { foundstate = true; } } if (event.getType() == Xml.TEXT) { TextEvent tevent = (TextEvent) event; if (foundstate) { state = tevent.getText(); data = data + "?" + state; foundstate = false; } else { data = data + "?" + tevent.getText(); } } if (event.getType() == Xml.END_TAG) { EndTag etag = (EndTag) event; if (etag.getName().equals("weather")) { data = data + "?"; founditem = false; id = record_add(data); htable.put((Object) state, Integer.toString(id)); data = ""; } } } catch (IOException ex) { System.out.println("Exception occured"); } } while (!(event instanceof EndDocument)); try { recordStore.closeRecordStore(); } catc ```