Available in Community Designer

Transformation required by the component must extend org.jetel.component.AbstractGenericTransform class.

The component has same java interface as CustomJavaComponent, but it provides different java template. See Java Interfaces for CustomJavaComponent.

Generate user-defined number of sequences of random bytes, each sequence is of 32 bytes.

Solution

Use CustomJavaReader to create a new user-defined component.

Add new custom attribute RecordCount to the component and set up a value to the attribute, e.g. to 5.

Define the transformation.

package jk;

import java.security.SecureRandom;
import org.jetel.component.AbstractGenericTransform;
import org.jetel.data.DataRecord;

/**
 * This is an example custom reader. It shows how you can create records using a
 * data source.
 */
public class CustomJavaReaderExample01 extends AbstractGenericTransform {

	@Override
	public void execute() {
		Integer recordCount = getProperties().getIntProperty("RecordCount");

		// Output record prepared for writing to output port 0.
		DataRecord record = outRecords[0];

		SecureRandom secureRandom = new SecureRandom();

		for (int i = 0; i < recordCount; ++i) {
			byte[] b = new byte[32];

			secureRandom.nextBytes(b);
			record.getField("field1").setValue(b);
			writeRecordToPort(0, record);
			record.reset();
		}
	}
}

Metadata on output port have need to have one field named field1. The field has byte data type.

Read binary data from a file. Each record has one byte header and variable length payload. The length of payload is defined by integer value of the header. Read length and payload from ech record. File to be read has to be configured by component attribute.

Example of source data:

!123456789012345678901234567890123"abcdefghijklmnopqrstuvwxyz78901234

Solution

Add attribute FileUrl to the component.

package jk;

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;

import org.jetel.component.AbstractGenericTransform;
import org.jetel.data.DataRecord;
import org.jetel.exception.JetelRuntimeException;

/**
 * This is an example custom reader. It shows how you can read data from file
 * with specific format.
 */
public class CustomJavaReaderExample02 extends AbstractGenericTransform {

	@Override
	public void execute() {
		DataRecord record = outRecords[0];
		String fileUrl = getProperties().getStringProperty("FileUrl");
		File file = getFile(fileUrl);

		try (FileInputStream inputStream = new FileInputStream(file)) {
			for (int length = inputStream.read(); length > 0; length = inputStream.read()) {
				byte[] b = new byte[length];
				inputStream.read(b, 0, length);

				record.getField("field1").setValue(length);
				record.getField("field2").setValue(b);
				writeRecordToPort(0, record);
				record.reset();
			}
		} catch (IOException e) {
			throw new JetelRuntimeException(e);
		}
	}
}

Note: input data is in binary format. First header contains character ! which corresponds to value 33. Thirty-three characters follow. Header of second record has value 34 which is displayed as character ". Thirty-four bytes follow.

Metadata on output port have need to have two fields named field1 and field2 with types integer and byte.