rms_ex4.java

J2ME 无线通信技术应用开发源代码

//程序名RMS_Ex4.java，项目RMS_Ex4
//测试记录存储的版本号和时间戳
import javax.microedition.midlet.*;
import javax.microedition.rms.*;

public class RMS_Ex4 extends MIDlet {
  RecordStore rs1 = null;
  RecordStore rs2 = null;

  public RMS_Ex4() {
    //这个例子需要使用一个新的记录存储进行测试，所以要删除旧的文件。
    try {
      RecordStore.deleteRecordStore("rs_test");
    } catch( Exception e ){
      // ignore any errors...
    }
    //生成一个新的记录存储rs_test，并有两个引用
    try {
      rs1 = RecordStore.openRecordStore("rs_test", true );
      rs2 = RecordStore.openRecordStore("rs_test", true );
    } catch( Exception e ){
      // ignore any errors...
    }
  }

  public void startApp() {
    byte[] b_test = "A meeting at GreatWall Hotel, 8:00AM".getBytes();
    try {
      System.out.println("@create a new record store.");
      test_print(rs1);

      rs1.addRecord(b_test, 0, b_test.length);
      System.out.println("@rs1 add 1 record :");
      test_print(rs1);

      rs1.addRecord(b_test, 0, b_test.length);
      rs1.addRecord(b_test, 0, b_test.length);
      System.out.println("@rs1 add 2 records :");
      test_print(rs1);

      byte[] temp = rs1.getRecord(1);
      System.out.println("@rs1 look 1 record, and not modity :");
      test_print(rs1);
      
      try {
        rs1.addRecord(b_test, 0, b_test.length+1);//这里会出现错误
      } catch (Exception e) {
        System.out.println("@rs1 add 1 records, and a error occurred, not modified :");
        test_print(rs1);
      }

      rs2.addRecord(b_test, 0, b_test.length);
      System.out.println("@rs2 add 1 record :");
      test_print(rs1);

      rs2.deleteRecord(2);
      System.out.println("@rs2 delete 1 record :");
      test_print(rs1);

      rs1.setRecord(1,b_test, 0, b_test.length);
      System.out.println("@rs1 modify 1 records :");
      test_print(rs1);

      rs2.closeRecordStore();
      System.out.println("@rs1 closed :");
      test_print(rs1);
    } catch(RecordStoreException e ){
      System.out.println("error , program exist.");
      notifyDestroyed();//发生错误，关闭应用程序
    }
    notifyDestroyed();//运行结束即关闭应用程序
  }

  public void pauseApp() {
  }

  public void destroyApp( boolean unconditional ) {
  }
  
  private void test_print(RecordStore rs) {
    try {
      int version = rs.getVersion();
      java.util.Calendar calendar = java.util.Calendar.getInstance();
      calendar.setTime(new java.util.Date(rs.getLastModified()));
      System.out.println("    version: "+version+" , last modified: "+calendar);
    } catch (Exception e) {
      System.out.println("error.");
    }
  }
}