rms_ex1.java

J2ME 无线通信技术应用开发源代码

//程序名RMS_Ex1.java，项目RMS_Ex1
//测试记录存储的生成、打开、关闭、删除、获取信息等。
import javax.microedition.midlet.*;
import javax.microedition.rms.*;

public class RMS_Ex1 extends MIDlet {

  public RMS_Ex1() {
    //删除当前套件中的所有记录存储，如果存在的话
    String[] RS_to_del = RecordStore.listRecordStores();
    if (RS_to_del != null) {
      System.out.println("All the RecordStore delected!");
      try {
        for (int i = 0;i<RS_to_del.length;i++) {
          RecordStore.deleteRecordStore(RS_to_del[i]);
        }
      } catch (RecordStoreException e) {
        System.out.println("Something error!");
        notifyDestroyed();
      }
    }
  }
  
  public void startApp() {
    RecordStore rs1 = null;
    RecordStore rs2 = null;
    RecordStore rs3 = null;
    RecordStore rs4 = null;
    //打开一个不存在的记录存储，参数createIfNecessary为false，因此要抛出异常RecordStoreNotFoundException
    try {
      rs1 = RecordStore.openRecordStore( "RecordStore1", false );
    } catch(RecordStoreNotFoundException rsnfe ){
      System.out.println("RecordStore1 is not exist,and createIfNecessary is false");
    } catch(RecordStoreException e ){
      System.out.println("Other Exception");
    } 
    
    //打开不存在的记录存储，参数createIfNecessary为true，因此生成新的记录存储
    try {
      rs2 = RecordStore.openRecordStore( "RecordStore2", true );
      rs3 = RecordStore.openRecordStore( "RecordStore3", true );
      System.out.println("Create RecordStore2 and RecordStore3");
    } catch(RecordStoreException e ){
    }
    
    //关闭一个记录存储
    try {
      rs3.closeRecordStore();
      System.out.println("close RecordStore3");
    } catch(RecordStoreException e ){
    }
    
    //列出套件中所有的记录存储
    String[] allRS = RecordStore.listRecordStores();
    if (allRS != null) {
      System.out.println("All the RecordStore :");
      for (int i = 0;i<allRS.length;i++) {
        System.out.println("  "+allRS[i]);
      }
    }
    
    //列出一个记录存储的名称、大小、可用大小
    try {
      System.out.println("rs2 is a reference of "+rs2.getName());
      System.out.println("The size of rs2 is "+rs2.getSize());
      System.out.println("The available size of rs2 is "+rs2.getSizeAvailable());
    } catch (RecordStoreNotOpenException e) {
    } catch (RecordStoreException e) {
    }
    
    //打开rs4，它和rs2指向同一个引用RecordStore2
    try {
      rs4 = RecordStore.openRecordStore( "RecordStore2", false );
      System.out.println("rs4 is a reference of "+rs4.getName());
    } catch (RecordStoreException e) {
    }
    
    //关闭一个记录存储，实际上关闭RecordStore2的一个引用
    try {
      rs2.closeRecordStore();
    } catch (RecordStoreException e) {
      System.out.println("Can not close rs2");
    }
    
    //打算删除RecordStore2，但它还有一个引用
    try {
      RecordStore.deleteRecordStore("RecordStore2");
    } catch (RecordStoreException e) {
      System.out.println("RecordStore2 has a reference exist ,can not delete");
    }
    
    //关闭RecordStore2的另一个引用//*
    try {
      System.out.println("////"+rs2.getName());
      rs2.closeRecordStore();
      System.out.println("Can close rs2 twice");
    } catch (RecordStoreException e) {
      System.out.println("Can not close rs2 twice");
    }

    //会捕获异常，因为RecordStore2已经关闭
    try {
      System.out.println("rs4 is a reference of"+rs4.getName());
    } catch (RecordStoreNotOpenException e) {
      System.out.println("RecordStore2 has closed");
    } catch (RecordStoreException e) {
    }
    
    //关闭应用程序
    notifyDestroyed();
  }

  public void pauseApp() {
  }

  public void destroyApp( boolean unconditional ) {
  }
}