retrieveallmidlet.java

java移动通信程序设计

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

public class RetrieveAllMIDlet extends MIDlet
implements CommandListener {

  private Command exitCommand;
  private Display display;
  private String[] names = {"黄聪明","陈小筱","黄镇樟","郑雅文"};
  private int[] chineseScore = {74,98,89,76};
  private int[] englishScore = {67,89,89,78};
  private int[] mathScore = {80,76,80,78};

  public RetrieveAllMIDlet() {
    display = Display.getDisplay(this);
    exitCommand = new Command("离开", Command.EXIT, 1);
  }

  public void startApp() {
	TextBox aTextBox = new TextBox("主画面",null,256,TextField.ANY);

	RecordStore rs = null;
	byte[] nameEmail=null;
	boolean existingOrNot = false;
	boolean OK = true;

	existingOrNot = existing("aRS3");
	if(existingOrNot){
	   try{
		rs = RecordStore.openRecordStore("aRS3",false);
            }
            catch(Exception e){
		OK = false;
	   }
	   finally{
		 if(OK){
			 aTextBox.setString("aRS3已存在并且已打开");
	          }
	          else{
			aTextBox.setString("aRS3已存在但无法打开");
	          }
            }
        }
        else{
	try{
		rs = RecordStore.openRecordStore("aRS3",true);
	    }
             catch(Exception e){
		OK = false;
	    }
	    finally{
		if(OK){
	    	aTextBox.setString("aRS3虽未存在,但已创建并完成打开的操作!");
		}
		else{
	    	aTextBox.setString("aRS3虽未存在,但无法创建,打开文件失败!");
		}
	}
	}

    Student aStudent = null;

    if(OK)
       try{
		   for(int i=0;i<names.length;i++){
			  aStudent = new Student();
			  aStudent.write(names[i],
			                 chineseScore[i],
			                 englishScore[i],
			                 mathScore[i]
			                );
	    	  byte[] data = aStudent.changeToByteArray();
	    	  int recordID = aStudent.getRecordID();
	    	  if(recordID != -1){
	    	    rs.setRecord(recordID,data,0,data.length);
			  }
	    	  else{
				recordID = rs.addRecord(data,0,data.length);
			  	aStudent.setRecordID(recordID);
		  	  }
		  	  aStudent = null;
		    }
			aTextBox.setString("已完成新增记录的操作!");
		  }
	   catch(Exception e){
			aTextBox.setString("新增记录的操作失败!");
	   }

    String result="";
    aStudent = new Student();


    if(OK)
       try{
		   byte[] data;
		   int number = 0;
		   RecordFilter rf = new averageFilter();
		   RecordEnumeration re = rs.enumerateRecords(rf,null,false);
		   while(re.hasNextElement()){
			   int recordID = re.nextRecordId();
			   data = rs.getRecord(recordID);
			   aStudent.changeFromByteArray(data);
			   result += "第" + recordID + "笔\n" +
			             "姓名:" + aStudent.getName() + "\n" +
			   		"语文:" + aStudent.getChineseScore() + "\n" +
                                        "英语:" + aStudent.getEnglishScore() + "\n" +
	                                "数学:" + aStudent.getMathScore() + "\n";
	           number++;
	       }
 	        result += "共有" + number + "笔记录:\n";
	    	aTextBox.setString(result);
		  }
	   catch(Exception e){
		   aTextBox.setString("获取记录的操作失败!"  );
		   try{
				rs.closeRecordStore();
				System.out.println("1.Closed.");
		        RecordStore.deleteRecordStore("aRS3");
				System.out.println("delete OK");
			}
			catch(Exception x){
            }
	   }
    finally{
	   try{
		   if(rs != null) rs.closeRecordStore();
		   rs.deleteRecordStore("aRS3");
	   }
	   catch(Exception e){
	   }
	}

    aTextBox.setString(result);
    aTextBox.addCommand(exitCommand);
    aTextBox.setCommandListener(this);
    display.setCurrent(aTextBox);
  }

  public void pauseApp() {
  }
  public void destroyApp(boolean unconditional) {
  }

  public boolean existing(String recordStoreName) {
    boolean existingOrNot = false;
    RecordStore rs = null;
    if(recordStoreName.length() > 32) return false;
    try{
	    rs = RecordStore.openRecordStore(recordStoreName,false);
    }
    catch(RecordStoreNotFoundException e){
	    existingOrNot = false;
    }
    catch(Exception e){
    }
    finally{
    	try{
	        rs.closeRecordStore();
	    }
	    catch(Exception e){
	    }
    }
   return existingOrNot;
  }

  public void commandAction(Command c, Displayable s) {
     destroyApp(false);
     notifyDestroyed();
  }
}


class Student{
    private int ID = -1;
    private String name;
    private int chineseScore;
    private int englishScore;
    private int mathScore;
 
    public void write(string name,int chineseScore,int englishScore,int mathScore){
     this.name = name;
     this.chineseScore = chineseScore;
     this.englishScore = englishScore;
     this.mathScore = mathScore;
    }

    public void setRecordID(int ID){
      this.ID = ID;
    }
  
    public int getRecordID(){
      return ID;
    }
    
    public byte[] changeToByteArray(){
      byte[] data = null;

      try{
       ByteArrayOutputStream baos = new ByteArrayOutputStream();
       DataOutputStream dos = new DataOutputStream(baos);
       dos.writeUTF(name);
       dos.writeInt(chineseScore);
       dos.writeInt(englishScore);
       dos.writeInt(mathScore);
       data = baos.toByteArray();

       baos.close();
       dos.close();
       }
       catch(Exception e){
       }
       return data;
     }
    
    public void changeFromByteArray(byte[] data){
       try{
        ByteArrayInputStream bais = new ByteArrayInputStream(data);
        DataInputStream dis = new DataInputStream(bais);

        name = dis.readUTF();
        chineseScore = dis.readInt();
        englishScore = dis.readInt();
        mathScore = dis.readInt();

        bais.close();
        dis.close();
        }       
        catch(Exception e){
        }
       }

    public String getName(){
	return name;
    }

    public int getChineseScore(){
        return chineseScore;	   
    }
	
    public int getEnglishScore(){
        return englishScore;
    }

    public int getMathScore(){
        return mathScore;
    }
}