J2ME中面向对象方式实现数据管理(RMS)

本例实现的功能：

1.MVC结构

2.数据存储

3.数据筛选

4.数据排序

相关代码如下：

/** * @作者 Jcuckoo * @创建日期 2009-4-21 * @版本 V 1.0 */public class MyFilter implements RecordFilter {private String search=null;public MyFilter(String search) {this.search = search.toLowerCase();}public boolean matches(byte[] reference) {String temp=new String(reference).toLowerCase();if(temp!=null&&temp.indexOf(search)!=-1){return true;}else{return false;}}}

package chapter08;import java.io.ByteArrayInputStream;import java.io.DataInputStream;import javax.microedition.rms.RecordComparator;/** * @作者 Jcuckoo * @创建日期 2009-4-22 * @版本 V 1.0 * 按照学生年龄进行排序 */public class MyComparator implements RecordComparator {private ByteArrayInputStream bais=null;private DataInputStream dis=null;public int compare(byte[] rec1, byte[] rec2) {int recInt1, recInt2;try {bais = new ByteArrayInputStream(rec1);dis = new DataInputStream(bais);dis.readUTF();recInt1 = dis.readInt();bais = new ByteArrayInputStream(rec2);dis = new DataInputStream(bais);dis.readUTF();recInt2 = dis.readInt();System.out.println(recInt1+" "+recInt2);if (recInt1 > recInt2) {return RecordComparator.FOLLOWS;} else if (recInt1 < recInt2) {return RecordComparator.PRECEDES;} else {return RecordComparator.EQUIVALENT;}} catch (Exception e) {return 3;}}}

package chapter08;/** * @作者 Jcuckoo * @创建日期 2009-4-9 * @版本 V 1.0 */public class Student {private String name;private int age;private boolean sex;public Student() {}public Student(String name,int age, boolean sex) {this.age = age;this.name = name;this.sex = sex;}public String getName() {return name;}public void setName(String name) {this.name = name;}public int getAge() {return age;}public void setAge(int age) {this.age = age;}public boolean isSex() {return sex;}public void setSex(boolean sex) {this.sex = sex;}}

package chapter08;import java.io.ByteArrayInputStream;import java.io.ByteArrayOutputStream;import java.io.DataInputStream;import java.io.DataOutputStream;import javax.microedition.rms.RecordEnumeration;import javax.microedition.rms.RecordStore;/** * @作者 Jcuckoo * @创建日期 2009-4-9 * @版本 V 1.0 */public class StudentDao {private RecordStore recordstore=null;private String recordName="myRecordStore";public StudentDao() {openRecordStore(recordName);}public void openRecordStore(String recordName){try {recordstore=RecordStore.openRecordStore(recordName,true);} catch (Exception e) {System.out.println("创建记录存储器失败。");e.printStackTrace();} }public void closeRecordStore(){try {recordstore.closeRecordStore();} catch (Exception e) {System.out.println("关闭记录存储器失败。");e.printStackTrace();} }public void deleteRecordStore(){if(RecordStore.listRecordStores()!=null){try {closeRecordStore();RecordStore.deleteRecordStore(recordName);} catch (Exception e) {System.out.println("删除记录存储器失败。");e.printStackTrace();}}}public boolean saveStudent(Student student){byte[]object;ByteArrayOutputStream bos=new ByteArrayOutputStream();DataOutputStream dos=new DataOutputStream(bos);try {dos.writeUTF(student.getName());dos.writeInt(student.getAge());dos.writeBoolean(student.isSex());System.out.println("写入数据成功");dos.flush();object=bos.toByteArray();recordstore.addRecord(object, 0, object.length);bos.reset();bos.close();dos.close();return true;} catch (Exception e) {System.out.println("对象写入失败。");e.printStackTrace();return false;}}public Student[] getAllStudent(){byte[]object=new byte[1];Student []students;try {ByteArrayInputStream bis=null;DataInputStream dis=null;students=new Student[recordstore.getNumRecords()];for(int i=1;i<=recordstore.getNumRecords();i++){if(recordstore.getRecordSize(i)>object.length){object=new byte[recordstore.getRecordSize(i)];}recordstore.getRecord(i,object,0);bis=new ByteArrayInputStream(object);dis=new DataInputStream(bis);//数组的下标是从0开始，而RMS是从1开始，故需要i-1students[i-1]=new Student(dis.readUTF(),dis.readInt(),dis.readBoolean());//重新定位“标识”在数据流中的位置 dis.reset();}bis.close();dis.close();return students;} catch (Exception e) {System.out.println("读取数据失败。");return null;}}public Student[] getStudentByFilter(){byte[]object=new byte[(new Student()).toString().length()];Student []students;try {MyFilter myFilter=new MyFilter("jcuckoo");RecordEnumeration recEnumeration=recordstore.enumerateRecords(myFilter, null, false);ByteArrayInputStream bis=null;DataInputStream dis=null;students=new Student[recEnumeration.numRecords()];for(int i=0;i<recEnumeration.numRecords();i++){int id = recEnumeration.nextRecordId();if (recordstore.getRecordSize(id) > object.length) {object = new byte[recordstore.getRecordSize(id)];}recordstore.getRecord(id, object, 0);bis=new ByteArrayInputStream(object);dis=new DataInputStream(bis);students[i]=new Student(dis.readUTF(),dis.readInt(),dis.readBoolean());//重新定位“标识”在数据流中的位置 dis.reset(); }bis.close();dis.close();return students;} catch (Exception e) {System.out.println("error");return null;}}public Student[] getStudentByComparator(){byte[]object=new byte[(new Student()).toString().length()];Student []students;try {MyComparator myComparator=new MyComparator();RecordEnumeration recEnumeration=recordstore.enumerateRecords(null, myComparator, false);ByteArrayInputStream bis=null;DataInputStream dis=null;students=new Student[recEnumeration.numRecords()];for(int i=0;i<recEnumeration.numRecords();i++){int id = recEnumeration.nextRecordId();if (recordstore.getRecordSize(id) > object.length) {object = new byte[recordstore.getRecordSize(id)];}recordstore.getRecord(id, object, 0);bis=new ByteArrayInputStream(object);dis=new DataInputStream(bis);students[i]=new Student(dis.readUTF(),dis.readInt(),dis.readBoolean());//重新定位“标识”在数据流中的位置 dis.reset(); }bis.close();dis.close();return students;} catch (Exception e) {System.out.println("error");return null;}}public Student[] getStudentByFilterComparator(){byte[]object=new byte[(new Student()).toString().length()];Student []students;try {MyFilter myFilter=new MyFilter("jcuckoo");MyComparator myComparator=new MyComparator();RecordEnumeration recEnumeration=recordstore.enumerateRecords(myFilter, myComparator, false);ByteArrayInputStream bis=null;DataInputStream dis=null;students=new Student[recEnumeration.numRecords()];for(int i=0;i<recEnumeration.numRecords();i++){int id = recEnumeration.nextRecordId();if (recordstore.getRecordSize(id) > object.length) {object = new byte[recordstore.getRecordSize(id)];}recordstore.getRecord(id, object, 0);bis=new ByteArrayInputStream(object);dis=new DataInputStream(bis);students[i]=new Student(dis.readUTF(),dis.readInt(),dis.readBoolean());//重新定位“标识”在数据流中的位置 dis.reset(); }bis.close();dis.close();return students;} catch (Exception e) {System.out.println("error");return null;}}}

package chapter08;import javax.microedition.lcdui.Alert;import javax.microedition.lcdui.AlertType;import javax.microedition.lcdui.ChoiceGroup;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.Item;import javax.microedition.lcdui.StringItem;import javax.microedition.lcdui.TextField;import javax.microedition.midlet.MIDlet;import javax.microedition.midlet.MIDletStateChangeException;/** * @作者 Jcuckoo * @创建日期 2009-4-9 * @版本 V 1.0 */public class ComplexOjbectRecord extends MIDlet implements CommandListener{private Display display;private Form mainForm;private Alert alert;private StringItem st;private Command add;private Command show;private Command search;private Command comparator;private Command sea_comp;private Command exit;private StudentDao studao;public ComplexOjbectRecord() {display=Display.getDisplay(this);//用到的按钮exit=new Command("退出",Command.SCREEN,1);add=new Command("添加学生信息",Command.SCREEN,1);show=new Command("显示学生信息",Command.SCREEN,1);search=new Command("选择显示学生信息",Command.SCREEN,1);comparator=new Command("按年龄排序显示",Command.SCREEN,1);sea_comp=new Command("筛选并排序",Command.SCREEN,1);//主界面mainForm=new Form("记录存储器演示");mainForm.addCommand(add);mainForm.addCommand(search);mainForm.addCommand(comparator);mainForm.addCommand(sea_comp);mainForm.addCommand(show);mainForm.addCommand(exit);mainForm.setCommandListener(this);studao=new StudentDao();}protected void destroyApp(boolean arg0) {studao.deleteRecordStore();}protected void pauseApp() {}protected void startApp() throws MIDletStateChangeException {display.setCurrent(mainForm);}public void commandAction(Command c, Displayable d) {//退出if(c==exit){destroyApp(true);notifyDestroyed();}//输入学生信息界面的add按钮if(c==add){studao.saveStudent(new Student("jcuckoo",30,true));studao.saveStudent(new Student("Jerry",30,true));studao.saveStudent(new Student("cuckoo",20,false));studao.saveStudent(new Student("jCuckoo",23,true));studao.saveStudent(new Student("Jcuckoo",32,true));studao.saveStudent(new Student("JCuckoo",30,false));alert=new Alert("提示信息","学生信息添加成功",null,AlertType.INFO);alert.setTimeout(Alert.FOREVER);display.setCurrent(alert);}//显示过滤后的学生信息if(c==search){showStudents(studao.getStudentByFilter());}//显示排序后学生信息if(c==comparator){showStudents(studao.getStudentByComparator());}//筛选并排序if(c==sea_comp){showStudents(studao.getStudentByFilterComparator());}//显示所有学生信息if(c==show){showStudents(studao.getAllStudent());}}public void showStudents(Student[] students){mainForm.deleteAll();//如果返回的集合不为空，则循环显示。st=new StringItem("姓名 年龄 性别","");mainForm.append(st);if(students!=null){for(int i=0;i<students.length;i++){Student student=students[i];st=new StringItem(student.getName()+" "+student.getAge()+" "+student.isSex(),"");mainForm.append(st);}}else{mainForm.deleteAll();st=new StringItem("没有找到学生信息","");mainForm.append(st);}}}