一個開啟檔案具有一個游標。游標指向要讀取、更新或刪除的記錄。最先開啟某檔案之後,游標會指向該檔案的開頭。檔案的開頭是在第一筆記錄前面。
使用下列方法來設定游標位置:
下面範例說明如何使用 positionCursorToFirst() 方法來定位游標。
// Create an AS400 object, the file exists on this
// server.
AS400 sys = new AS400("mySystem.myCompany.com");
// Create a file object that represents the file
SequentialFile myFile = new SequentialFile(sys, "/QSYS.LIB/MYLIB.LIB/MYFILE.FILE/%FILE%.MBR");
// Assume that the AS400FileRecordDescription class
// was used to generate the code for a subclass of
// RecordFormat that represents the record format
// of file MYFILE in library MYLIB. The code was
// compiled and is available for use by the Java
// program.
RecordFormat recordFormat = new MYFILEFormat();
// Set the record format for myFile. This must
// be done before invoking open()
myFile.setRecordFormat(recordFormat);
// Open the file.
myFile.open(AS400File.READ_WRITE, 1, AS400File.COMMIT_LOCK_LEVEL_NONE);
// I want to delete the first record of the file.
myFile.positionCursorToFirst();
myFile.deleteCurrentRecord();
....
// Close the file since I am done using it
myFile.close();
// Disconnect since I am done using
// record-level access
sys.disconnectService(AS400.RECORDACCESS);