HTML5 WebSocket-Server mit Java und Client mit JavaScript

0

16. Mai 2012

Zur Demonstration von HTML5-Websockets habe ich mit webbit einen einfachen WebSocket-Server geschrieben, der Nachrichten entgegen nimmt und diese Nachrichten wieder an den jeweiligen angemeldeten Client zurück schickt. Ein solches Beispiel nennt man auch Echo-Server.

Tags: Java, Client, HTML5, Java, JavaScript, JBoss, js, Netty, Server, webbit, WebSockets

How to get node attributes with Java SAX XML parser

0

8. Mai 2012

Code

import java.io.StringReader;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
import org.xml.sax.InputSource;
 
public class NewMain {
 
  public static void main(String[] args) throws Exception {
    String text = "<person number=\"72\"><name>Benny</name></person>";
 
    DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
    DocumentBuilder builder = factory.newDocumentBuilder();
    Document document = builder.parse(new InputSource(new StringReader(text)));
    NodeList elementsByTagName = document.getElementsByTagName("person");
    for (int i = 0; i < elementsByTagName.getLength(); i++) {
      Node node = elementsByTagName.item(i);
      Element element = (Element) node;
      String attribute = element.getAttribute("number");
      System.out.println(attribute);
    }
  }
}

Output

Tags: Java, attributes, Java, JSE, Parser, SAX, XML

How to use Iterator, for and foreach-loop in Java

0

7. Mai 2012

Here is a very good example on how to use the Iterator, for and foreach-loop in Java:

import java.io.IOException;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
 
public class JavaApplication {
 
  public static void main(String[] args) throws IOException {
    List<String> names = new ArrayList<>();
    names.add("Benny");
    names.add("Sarah");
    names.add("Daniel");
    names.add("Maria");
 
    // Iterator
    Iterator<String> iterator = names.iterator();
    while (iterator.hasNext()) {
      System.out.println(iterator.next());
    }
 
    // for
    for (int i = 0; i < names.size(); i++) {
      System.out.println(names.get(i));
    }
 
    // foreach
    for (String name : names) {
      System.out.println(name);
    }
  }
}

Tags: Java, Example, for, foreach, Iterator, Java, JSE, loop

Create GraphML XML files that can be used in the yEd Graph Editor

0

6. Mai 2012

In my article “Create GraphML XML file with Java” I showed how to write a Graph to a GraphML-compatible XML file. Now I want to show you how you can write a GraphML-compatible file that can be used in the yEd Graph Editor to get visualized later.

Tags: Java, editor, graph, GraphML, Java, XML, yEd

Parse some HTML tags with a Java SAX XML parser

1

5. Mai 2012

Parsing XML with Java is very simple. If you want to parse some HTML tags, then you just have to add a root element around those tags (to make it a valid XML structure) and then you can use the Java SAX XML parser.

Code

import java.io.StringReader;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import org.w3c.dom.Document;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
import org.xml.sax.InputSource;
 
public class NewMain {
 
  public static void main(String[] args) throws Exception {
    String html = "<h1>Headline</h1><p><b>Hello World.</b><b>This is a test.</b></p>";
    html = "<root>" + html + "</root>";
 
    DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
    DocumentBuilder builder = factory.newDocumentBuilder();
    Document document = builder.parse(new InputSource(new StringReader(html)));
    NodeList elementsByTagName = document.getElementsByTagName("b");
    for (int i = 0; i < elementsByTagName.getLength(); i++) {
      Node element = elementsByTagName.item(i);
      String text = element.getTextContent();
      System.out.println(text);
    }
  }
}

Result

Hello World.
This is a test.

Tags: Java, HTML, Java, Parser, SAX, XML

Create GraphML XML file with Java

0

4. Mai 2012

With Blueprints it is very easy to create a XML file following the GraphML standard. All you need is this:

import com.tinkerpop.blueprints.pgm.Vertex;
import com.tinkerpop.blueprints.pgm.impls.tg.TinkerGraph;
import com.tinkerpop.blueprints.pgm.util.io.graphml.GraphMLWriter;
import java.io.FileOutputStream;
import java.io.OutputStream;
 
public class App {
 
  private static final String OUTPUT_FILE = "./res/graph.graphml";
 
  public static void main(String[] args) throws Exception {
    OutputStream out = new FileOutputStream(OUTPUT_FILE);
    TinkerGraph graph = new TinkerGraph();
 
    Vertex source = graph.addVertex("1");
    Vertex target = graph.addVertex("2");
    graph.addEdge("3", source, target, "connection");
 
    GraphMLWriter writer = new GraphMLWriter(graph);
    writer.outputGraph(out);
  }
}

This is what you will get then:

graph.graphml

<?xml version="1.0" ?>
<graphml xmlns="http://graphml.graphdrawing.org/xmlns">
  <graph id="G" edgedefault="directed">
    <node id="2"></node>
    <node id="1"></node>
    <edge id="3" source="1" target="2" label="connection"></edge>
  </graph>
</graphml>

Tags: Java, create, graph, GraphML, Java, JSE, XML