知识大全 JavaME程序 Run Anywhere-- 利用反射机制来动态加载声

Posted 2022-07-14 知

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让JavaME程序 Run Anywhere 利用反射机制来动态加载声音API 欢迎指教 t cn Write once run anywhere 是JAVA的口号但在J ME平台上做的应用要想不改动代码就run anywhere 难度是很大的如果要把一个应用程序做到让大多数的机型都适用就让JavaME程序 Run Anywhere 利用反射机制来动态加载声音API Write once run anywhere 是JAVA的口号但在J ME平台上做的应用要想不改动代码就run anywhere 难度是很大的如果要把一个应用程序做到让大多数的机型都适用就要考虑到方方面面其难度是相当大的比如给百宝箱做游戏上线机型大多是MIDP 的机器感觉移植中最麻烦的还要数声音部分的API 必须根据各个机型来改动虽然图象还比较容易做成自适应的但声音部分就一般就只能根据各个机型来改动下面提供一种解决方案可以让J ME程序在运行时自动加载该机型支持的声音资源并用该机型的声音API来播放 关键问题 各机型提供的播放音乐的API都有所不同特别是较老的机型需要在运行时根据机型自动加载各机型支持的声音的资源文件也不同需要在运行时根据机型自动加载各机型的JVM不同多多少少有一些比较特别的BUG 解决方案 原则能用标准API就用标准API 不能用的话就用各个机型自身的API // Player types static final int STANDARD = ; //For MIDI static final int NOKIA = ; //For ott static final int SAMSUNG = ; //For mmf static final int NEC = ; //For MIDI static final String[] supportedPlayerTypes = jadia Player //STANDARD API nokia mid sound Sound // Nokia samsung util AudioClip //samsung dia AudioClip //nec ; 下面利用反射机制来动态加载 public void determinePlayerType() // use most > less use isSupportSound = true; for (int i = ; i < supportedPlayerTypes length; i ) // try to load a proper sound Player try Class forName(supportedPlayerTypes[i]); //加载当前的Player类型 playerType = i; //保存加载成功的类的类型 return; catch (Exception e) //加载不成功说明不支持继续加载下一种 e printStackTrace(); isSupportSound = false; 下面就可以根据在载成功的类型来加载可以播放的声音资源了 public void createPlayer(String name) if (!isSupportSound) return; switch (playerType) case STANDARD: // for MIDI case NEC: createPlayerFactory( / name mid ); break; case NOKIA: //for ott createPlayerFactory( / name ott ); break; case SAMSUNG: // for mmf createPlayerFactory( / name mmf ); break; 对各个机型特有的BUG 是没有什么特别好的办法的只能各个机型调试这只能怪厂商了该方案优点在移植的时候就不用改动代码只要在相应的机型JAR包中保留相关的资源就可以了这样就不用为了各个机型都折腾一遍了注意用 System getProperty( microedition platform )来确定机型是不保险的因为有的机型只是简单地返回J ME platform 遗留问题 NecN 在运行 Class forName( jadia Player );时候会立刻报应用程序出错而不是抛出 ClassNotFoundException 异常这是该机型JVM的特性（BUG）所以给NecN 的代码中必须注释掉jadia Player的一切信息这就得改动代码有违我们的初衷的确是个遗憾（估计NEC的机型都素这样的）这个类还有待扩展以支持更多机型并加入震动部分的API 理论上可以包含所有的机型但实际应用中只要包含需要用到的机型相关API就可以了测试机型在三星E MOTOV NOKIA NecN （注释掉jadia Player相关内容）上均测试通过 下面是源程序 /** * Created on * This class is mainly for the games on various mobile platform * If U have any good ideas about the J ME contact me at t cn * * Version */ import javax microedition lcdui *; import java io *; //********************* STANDARD *********************** import jadia *; //********************* NOKIA *********************** import nokia mid sound *; //********************* SAMSUNG *********************** import samsung util *; // ********************* NEC *********************** import dia *; //********************* SonyEricsson *********************** // the same as J ME standard API /** * @author IntoTheDream */ public class MyPlayer private static MyPlayer mp = null; //Sound types to be enlarged static final int MIDI = ; static final int MMF = ; static final int OTT = ; // Player types static final int STANDARD = ; //For MIDI static final int NOKIA = ; //For ott static final int SAMSUNG = ; //For mmf static final int NEC = ; //For MIDI static final String[] supportedSoundTypes = mid mmf ott ; private static int soundType; static final String[] supportedPlayerTypes = jadia Player //must be dimissed for NECN nokia mid sound Sound samsung util AudioClip dia AudioClip ; private static int playerType; // Note : first play sound to determine whether sound On or Off // Of course you can change it in the game static boolean isSupportSound; static boolean isSoundOn = true; // ********************* STANDARD *********************** Player player; // ********************* NOKIA *********************** Sound nokiaPlayer; // ********************* SAMSUNG *********************** samsung util AudioClip samsungPlayer; // ********************* NEC *********************** dia AudioClip necPlayer; // singleton private MyPlayer() public static MyPlayer getMyPlayer() if (mp == null) mp = new MyPlayer(); mp determinePlayerType(); return mp; // automatically run this first !! public void determinePlayerType() // use most > less use isSupportSound = true; for (int i = ; i < supportedPlayerTypes length; i ) // try to load a proper sound Player try Class forName(supportedPlayerTypes[i]); playerType = i; return; catch (Exception e) e printStackTrace(); isSupportSound = false; public void createPlayer(String name) if (!isSupportSound) return; switch (playerType) case STANDARD: // for MIDI case NEC: createPlayerFactory( / name mid ); break; case NOKIA: //for ott createPlayerFactory( / name ott ); break; case SAMSUNG: // for mmf createPlayerFactory( / name mmf ); break; private void createPlayerFactory(String url) if (isSupportSound && isSoundOn) try InputStream is; switch (playerType) case NEC: necPlayer = Media getAudioClip(url); break; case STANDARD: //must be dimissed for NECN is = this getClass() getResourceAsStream(url); player = Manager createPlayer(is audio/midi ); break; case NOKIA: is = this getClass() getResourceAsStream(url); ByteArrayOutputStream baos = new ByteArrayOutputStream(); for (int b = is read(); b >= ; b = is read()) baos write(b); nokiaPlayer = new nokia mid sound Sound(baos toByteArray() nokia mid sound Sound FORMAT_TONE); break; case SAMSUNG: samsungPlayer = new samsung util AudioClip( samsung util AudioClip TYPE_MMF url); break; catch (Exception e) e printStackTrace(); public void play(int loop) if (isSupportSound && isSoundOn) try switch (playerType) case NEC: if (necPlayer == null) break; necPlayer setLoopCount(loop); necPlayer play(); break; case STANDARD: //must be dimissed for NECN if (player == null) break; player setLoopCount(loop); player start(); break; case NOKIA: if (nokiaPlayer == null) break; nokiaPlayer play(loop); break; case SAMSUNG: if (samsungPlayer == null) break; samsungPlayer play(loop ); // is volume break; catch (Exception e) e printStackTrace(); public void stopSound() if (isSupportSound && isSoundOn) try switch (playerType) case STANDARD: //must be dimissed for NECN if (player == null) break; player deallocate(); player stop(); player close(); player = null; break; case NOKIA: if (nokiaPlayer == null) break; nokiaPlayer stop(); nokiaPlayer = null; break; case SAMSUNG: if (samsungPlayer == null) break; samsungPlayer stop(); samsungPlayer = null; break; case NEC: if (necPlayer == null) break; necPlayer stop(); necPlayer = null; break; System gc(); catch (Exception e) e printStackTrace(); cha138/Article/program/Java/hx/201311/26841