149 lines
7.5 KiB
HTML
149 lines
7.5 KiB
HTML
<?xml version="1.0" encoding="UTF-8"?>
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<!DOCTYPE html
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PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
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<html lang="en-us" xml:lang="en-us">
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<meta name="DC.Type" content="reference" />
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<meta name="DC.Title" content="Reading and writing records" />
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<meta name="abstract" content="" />
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<meta name="copyright" content="(C) Copyright IBM Corporation 2006" />
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<link rel="stylesheet" type="text/css" href="./ibmdita.css" />
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<link rel="stylesheet" type="text/css" href="./ic.css" />
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<title>Reading and writing records</title>
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</head>
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<body id="rlaread"><a name="rlaread"><!-- --></a>
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<!-- Java sync-link --><script language="Javascript" src="../rzahg/synch.js" type="text/javascript"></script>
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<h1 class="topictitle1">Reading and writing records</h1>
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<div><p></p>
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<div class="section"><p>You can use the <a href="javadoc/com/ibm/as400/access/AS400File.html#NAVBAR_TOP"> AS400File</a> class to read, write, update,
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and delete records in files on the server. The record is accessed through
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the <a href="dtadrec.htm#dtadrec">Record</a> class, which is described
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by a <a href="dtadrfmt.htm#dtadrfmt">RecordFormat</a> class. The record
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format must be set through the <a href="javadoc/com/ibm/as400/access/AS400File.html#SETRECORDFORMAT(INT)"> setRecordFormat()</a> method before the file
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is opened, unless the file was just created (without an intervening close())
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by one of the <a href="javadoc/com/ibm/as400/access/AS400File.html#CREATE(JAVA.LANG.STRING, JAVA.LANG.STRING)"> create()</a> methods, which sets the record
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format for the object.</p>
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</div>
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<div class="section"><p>Use the read() methods to read a record from the file. Methods
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are provided to do the following:</p>
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</div>
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<div class="section"><ul><li><a href="javadoc/com/ibm/as400/access/AS400File.html#READ()"> read()</a> - read the record at the current cursor position</li>
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<li><a href="javadoc/com/ibm/as400/access/AS400File.html#READFIRST()"> readFirst()</a> - read the first record of the file</li>
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<li><a href="javadoc/com/ibm/as400/access/AS400File.html#READLAST()"> readLast()</a> - read the last record of the file</li>
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<li><a href="javadoc/com/ibm/as400/access/AS400File.html#READNEXT()"> readNext()</a> - read the next record in the file</li>
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<li><a href="javadoc/com/ibm/as400/access/AS400File.html#READPREVIOUS()"> readPrevious()</a> - read the previous record
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in the file</li>
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</ul>
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</div>
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<div class="section"><p>The following example shows how to use the readNext() method:</p>
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</div>
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<div class="section"><div class="p"><pre> // Create an AS400 object, the file exists on this
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// server.
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AS400 sys = new AS400("mySystem.myCompany.com");
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// Create a file object that represents the file
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SequentialFile myFile = new SequentialFile(sys, "/QSYS.LIB/MYLIB.LIB/MYFILE.FILE/%FILE%.MBR");
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// Assume that the AS400FileRecordDescription class
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// was used to generate the code for a subclass of
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// RecordFormat that represents the record format
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// of file MYFILE in library MYLIB. The code was
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// compiled and is available for use by the Java
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// program.
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RecordFormat recordFormat = new MYFILEFormat();
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// Set the record format for myFile. This must
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// be done before invoking open()
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myFile.setRecordFormat(recordFormat);
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// Open the file.
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myFile.open(AS400File.READ_ONLY, 0, AS400File.COMMIT_LOCK_LEVEL_NONE);
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// Read each record in the file writing field
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// CUSTNAME to System.out
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System.out.println(" CUSTOMER LIST");
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System.out.println("____________________________________________");
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Record record = myFile.readNext();
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while(record != null)
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{
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System.out.println(record.getField("CUSTNAME"));
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record = myFile.readNext();
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}
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....
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// Close the file since I am done using it
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myFile.close();
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// Disconnect since I am done using
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// record-level access.
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sys.disconnectService(AS400.RECORDACCESS);</pre>
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</div>
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</div>
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<div class="section"><p>Use the <a href="javadoc/com/ibm/as400/access/AS400File.html#UPDATE(COM.IBM.AS400.ACCESS.RECORD)"> update()</a> method to update the record at
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the cursor position.</p>
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</div>
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<div class="section"><p>For example:</p>
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</div>
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<div class="section"><div class="p"><pre> // Create an AS400 object, the file exists on this
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// server.
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AS400 sys = new AS400("mySystem.myCompany.com");
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// Create a file object that represents the file
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SequentialFile myFile = new SequentialFile(sys, "/QSYS.LIB/MYLIB.LIB/MYFILE.FILE/%FILE%.MBR");
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// Assume that the AS400FileRecordDescription class
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// was used to generate the code for a subclass of
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// RecordFormat that represents the record format
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// of file MYFILE in library MYLIB. The code was
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// compiled and is available for use by the Java program.
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RecordFormat recordFormat = new MYFILEFormat();
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// Set the record format for myFile. This must
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// be done prior to invoking open()
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myFile.setRecordFormat(recordFormat);
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// Open the file for updating
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myFile.open(AS400File.READ_WRITE, 0, AS400File.COMMIT_LOCK_LEVEL_NONE);
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// Update the first record in the file. Assume
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// that newName is a String with the new name for
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// CUSTNAME
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Record updateRec = myFile.readFirst();
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updateRec.setField("CUSTNAME", newName);
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myFile.update(updateRec);
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....
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// Close the file since I am done using it
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myFile.close();
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// Disconnect since I am done using record-level access
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sys.disconnectService(AS400.RECORDACCESS);</pre>
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</div>
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</div>
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<div class="section"><p>Use the <a href="javadoc/com/ibm/as400/access/AS400File.html#WRITE(COM.IBM.AS400.ACCESS.RECORD)"> write()</a> method to append records to the
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end of a file. A single record or an array of records can be appended to the
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file.</p>
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</div>
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<div class="section"><p>Use the <a href="javadoc/com/ibm/as400/access/AS400File.html#DELETECURRENTRECORD()"> deleteCurrentRecord()</a> method to delete
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the record at the cursor position.</p>
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</div>
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</div>
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</body>
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</html> |