Database Feed

[Alessandro]

I modified the HelloWorldDataAdapter to poll a database, instead of generating the data internally.

Please consider this is just a five-minute effort and I've not tried to compile the code. Please let me know if you find any errors.

This Data Adapter uses JDBC to query an Access file ("C:/Data.mdb"). Every second, it reads the first record, extracts the "message" and "timestamp" fields and injects them into the Lightstreamer Kernel.

import java.util.*;<br /> import java.io.File;<br /> import java.sql.*;<br /> import com.lightstreamer.interfaces.data.*;<br /> <br /> public class HelloWorldDataAdapter implements SmartDataProvider {<br /> <br /> private ItemEventListener listener;<br /> private volatile GreetingsThread gt;<br /> private Statement command;<br /> <br /> public void init(Map params, File configDir) throws DataProviderException {<br /> try {<br /> Class.forName("sun.jdbc.odbc.JdbcOdbcDriver").newI nstance();<br /> String dbFile = "C:/Data.mdb";<br /> String database = "jdbc:odbc:Driver={Microsoft Access Driver (*.mdb)};DBQ="<br /> + dbFile.trim()+ ";DriverID=22;READONLY=true}";<br /> Connection conn = DriverManager.getConnection(database, "", "");<br /> command = conn.createStatement();<br /> } catch (Exception ex) {<br /> System.out.println(ex);<br /> throw new DataProviderException(ex.getMessage());<br /> }<br /> }<br /> <br /> public boolean isSnapshotAvailable(String itemName) throws SubscriptionException {<br /> return false;<br /> }<br /> <br /> public void setListener(ItemEventListener listener) {<br /> this.listener = listener;<br /> }<br /> <br /> public void subscribe(String itemName, Object itemHandle, boolean needsIterator)<br /> throws SubscriptionException, FailureException {<br /> if (itemName.equals("greetings")) {<br /> gt = new GreetingsThread(itemHandle);<br /> gt.start();<br /> }<br /> }<br /> <br /> public void subscribe(String itemName, boolean needsIterator)<br /> throws SubscriptionException, FailureException {<br /> } <br /> <br /> public void unsubscribe(String itemName) throws SubscriptionException,<br /> FailureException {<br /> if (itemName.equals("greetings") && gt != null) {<br /> gt.go = false;<br /> }<br /> }<br /> <br /> class GreetingsThread extends Thread {<br /> <br /> private final Object itemHandle;<br /> public volatile boolean go = true;<br /> <br /> public GreetingsThread(Object itemHandle) {<br /> this.itemHandle = itemHandle;<br /> }<br /> <br /> public void run() {<br /> int c = 0;<br /> Random rand = new Random();<br /> while(go) {<br /> try {<br /> ResultSet rs = command.executeQuery("select * from Data");<br /> if (rs.next()) {<br /> Map<String, String> data = new HashMap<String, String>();<br /> data.put("message", rs.getString("message"));<br /> data.put("timestamp", rs.getString("timestamp"));<br /> listener.smartUpdate(itemHandle, data, false);<br /> }<br /> } catch (Exception ex) {<br /> System.out.println(ex);<br /> } <br /> <br /> try {<br /> Thread.sleep(1000);<br /> } catch (InterruptedException e) {<br /> }<br /> }<br /> }<br /> }<br /> <br /> }