Archive for the ‘Examples’ Category
Java CompletionService example
Friday, December 4th, 2020
Main.java
package com.lstierneyltd;
public class Main {
public static void main(String[] args) throws Exception {
final CompletionServiceExample completionServiceExample = new CompletionServiceExample();
completionServiceExample.runDemo();
}
}
CompletionServiceExample.java
package com.lstierneyltd;
import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.*;
public class CompletionServiceExample {
private static final int NUMBER_OF_THREADS = 3;
private final List<Callable<String>> callables = new ArrayList<>();
private final ThreadPoolExecutor threadPoolExecutor = (ThreadPoolExecutor) Executors.newFixedThreadPool(NUMBER_OF_THREADS);
public CompletionServiceExample() {
initCallables();
}
public void runDemo() throws Exception {
final long startTime = System.currentTimeMillis();
processCallableTasks();
System.out.println("That took " + (System.currentTimeMillis() - startTime)/1000 + " seconds");
shutdownThreadPoolExecutor();
}
private Callable<String> getCallable(int id) {
final Callable<String> callable = () -> {
System.out.println("Starting Callable " + id);
final long taskStartTime = System.currentTimeMillis();
TimeUnit.MILLISECONDS.sleep(10000);
System.out.println("CallableTask " + id + " took " + (System.currentTimeMillis() - taskStartTime)/1000 + " seconds");
return "Callable completed";
};
return callable;
}
private void initCallables() {
callables.add(getCallable(1));
callables.add(getCallable(2));
callables.add(getCallable(3));
}
private void processCallableTasks() throws InterruptedException, ExecutionException {
final CompletionService<String> completionService = new ExecutorCompletionService<String>(threadPoolExecutor);
for(Callable<String> callable : callables) {
completionService.submit(callable);
}
int received = 0;
while(received < NUMBER_OF_THREADS) {
Future<String> resultFuture = completionService.take(); // blocks if none available
String result = resultFuture.get();
System.out.println("Future done " + result);
received++;
}
}
private void shutdownThreadPoolExecutor() {
threadPoolExecutor.shutdown();
try {
if (!threadPoolExecutor.awaitTermination(800, TimeUnit.MILLISECONDS)) {
threadPoolExecutor.shutdownNow();
}
} catch (InterruptedException e) {
threadPoolExecutor.shutdownNow();
}
}
}
Output
Starting Callable 1 Starting Callable 2 Starting Callable 3 CallableTask 3 took 10 seconds CallableTask 1 took 10 seconds CallableTask 2 took 10 seconds Future done Callable completed Future done Callable completed Future done Callable completed That took 10 seconds
Tags: java, threads
Posted in Development, Examples | No Comments »
Oracle XML DB – Inserting XML
Friday, March 20th, 2015
Background
So following on from my previous post about creating XMLType tables in Oracle (either CLOB or schema based), here’s a few quick notes on getting data into the tables.
Inserting Data into XMLType Table
-- Create XMLType Table
CREATE TABLE XML_TABLE OF XMLType
-- create an Oracle directory to hold the XML (readable by Oracle)
CREATE OR REPLACE DIRECTORY XML as '/home/foo/bar/xml'
-- insert the record (reading from filesystem)
-- filename.xml would be in directory you created above
INSERT INTO XML_TABLE(SELECT XMLTYPE(bfilename('XML', 'filename.xml'), nls_charset_id('UTF8')) FROM dual);
Of course you could easily write some PL/SQL to iterate all files in the directory.
You can also insert XML directly via SQL:
INSERT INTO XML_TABLE VALUES(XMLType('<mxrecords>
<mxrecord>
<sysurn>sysurn1</sysurn>
<eventid>eventid1</eventid>
</mxrecord>
<mxrecord>
<sysurn>sysurn2</sysurn>
<eventid>eventid2</eventid>
</mxrecord>
</mxrecords>'
));
Tags: oracle, xml, xmldb, xmltype
Posted in Examples, How to's, Oracle | No Comments »
Oracle XML DB – XMLType table creation
Wednesday, March 18th, 2015
Background
So I’ve been doing some Oracle XML work again. I’d lost my notes from last time (nice touch) so here are my notes from this time:
XMLType Table Creation
CREATE TABLE xml_table OF XMLType
This will create “an xml table” into which you can insert XML. It will check that the XML is well formed before insertion. It will not validate that all documents inserted are the same or that elements contain valid data.
For that we need to create a table based upon an XML Schema/XSD
-- create an Oracle directory where the schema can be stored
create or replace directory XSD as '/home/foo/bar/oracle/xsd'
-- copy your Schema into the directory
-- then
BEGIN
DBMS_XMLSCHEMA.registerSchema(SCHEMAURL => 'http://www.foobar.com/xsd/my_schema.xsd', SCHEMADOC => bfilename('XSD','my_schema.xsd'));
END;
-- Note: the SCHEMAURL can be basically anything. Oracle uses it as a unique identifier
-- Create the table
CREATE TABLE matter OF xml_table XMLSCHEMA "http://www.foobar.com/xsd/my_schema.xsd" ELEMENT "nameOfTheRootXmlElement";
There are many overloaded versions of DBMS_XMLSCHEMA.registerSchema so you can shortcut some of the steps above. For example:
BEGIN
DBMS_XMLSCHEMA.registerSchema(
http://www.foobar.com/xsd/my_schema.xsd',
bfilename('XSD','my_schema.xsd'),
TRUE, -- generate required Oracle types. Default = true
TRUE, -- generate javabeans. Default = false
FALSE, -- generate errors when registering schema. True = do not
TRUE -- generate table
);
END;
Full docs for the DBMS_XMLSCHEMA package are here
here
Tags: oracle, schema, xml, xmldb, xmltype, xsd
Posted in Development, Examples, How to's | No Comments »
Java to XML, XML to Java (Marshalling and Unmarshalling)
Wednesday, July 13th, 2011
Introduction
JDK6 and JAXB2.x (which comes with JDK6) make marshalling Java to XML and unmarshalling XML to Java a snap, almost trivial.
Example
Java to XML
package foo.bar;
import java.math.BigDecimal;
import javax.xml.bind.JAXBContext;
import javax.xml.bind.Marshaller;
public class JavaToXML {
public static void main(String[] args) throws Exception {
JAXBContext context = JAXBContext.newInstance(Product.class);
Marshaller m = context.createMarshaller();
m.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);
Product object = new Product();
object.setCode("WI1");
object.setName("Widget Number One");
object.setPrice(BigDecimal.valueOf(300.00));
m.marshal(object, System.out);
}
}
XML to Java
package foo.bar;
import java.io.File;
import javax.xml.bind.JAXBContext;
import javax.xml.bind.JAXBException;
import javax.xml.bind.Unmarshaller;
public class XMLToJava {
public static void main(String[] args) {
try {
JAXBContext jc = JAXBContext.newInstance(Product.class);
Unmarshaller u = jc.createUnmarshaller();
File f = new File("product.xml");
Product product = (Product) u.unmarshal(f);
System.out.println(product.getCode());
System.out.println(product.getName());
System.out.println(product.getPrice());
} catch (JAXBException e) {
e.printStackTrace();
}
}
}
product.java
Note: the @XmlRootElement is vital here!
package foo.bar;
import java.math.BigDecimal;
import javax.xml.bind.annotation.XmlRootElement;
@XmlRootElement
public class Product {
private String code;
private String name;
private BigDecimal price;
public String getCode() {
return code;
}
public void setCode(String code) {
this.code = code;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public BigDecimal getPrice() {
return price;
}
public void setPrice(BigDecimal price) {
this.price = price;
}
}
product.xml
<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<product>
<code>WI1</code>
<name>Widget Number One</name>
<price>300.0</price>
</product>
Tags: java, jaxb, xml
Posted in Examples | 8 Comments »
Unit Testing Validation in Annotation Based Validating Spring Beans
Friday, April 22nd, 2011
Motivation
I added validation, via annotations, to a Spring “Model” bean. I needed someway to Unit Test this validation, without running the container and without initialising the Spring context.
The bean (simplified)
package foo.bar;
import javax.validation.constraints.NotNull;
import javax.validation.constraints.Pattern;
import javax.validation.constraints.Size;
public final class ProductModel {
@NotNull
@Size(max=100)
@Pattern(regexp="[^\n^\t^\r]+", message="Long Name must not contain New Lines, Carriage Returns or Tabs")
private String longName;
@Size(max=20)
private String shortName;
// rest snipped for brevity
}
The Unit Test
package foo.bar;
import java.util.Set;
import javax.validation.ConstraintViolation;
import junit.framework.Assert;
import org.hibernate.validator.HibernateValidator;
import org.junit.Before;
import org.junit.Test;
import org.springframework.validation.beanvalidation.LocalValidatorFactoryBean;
public class Temp {
private LocalValidatorFactoryBean localValidatorFactory;
@Before
public void setup() {
localValidatorFactory = new LocalValidatorFactoryBean();
localValidatorFactory.setProviderClass(HibernateValidator.class);
localValidatorFactory.afterPropertiesSet();
}
@Test
public void testLongNameWithInvalidCharCausesValidationError() {
final ProductModel productModel = new ProductModel();
productModel.setLongName("A long name with\t a Tab character");
Set<ConstraintViolation<ProductModel>> constraintViolations = localValidatorFactory.validate(productModel);
Assert.assertTrue("Expected validation error not found", constraintViolations.size() == 1);
}
}
More
It actually took me a few hours to work the above test out (simple as it is). If I hadn’t stumbled upon these Spring Unit Tests, I might never have got it.
Tags: annotations, java, junit, spring, testing
Posted in Spring | 3 Comments »