Chris Lacy's Software Engineering Blog
object translators
in the year 2000, the buzz will be object translators, aka, property editors, aka closures, aka un/marshallers, aka de/serializers, aka reflected methods, etc. and everyone will conform to a standard api
we'll have libraries of translators, too; and we'll define the rules by which a given translator is chosen for conversion between types. and we'll have translators that don't have return values, and translators that take multiple values, etc
and what we'll do, is, we'll pipe data between these translators and translator libraries. REST will be piping data from a web request to a translator that converts http messages to sql (with maybe JSON or XML or AMF in between, plus validation/exception handling and security)
but we'll add these "plus" features (exception handling, security, caching, etc) with aop and additional translators/libraries
Posted at 08:35PM Jun 26, 2010 by chris in General |
music test
package net.chrislacy.music.test;
import java.io.BufferedReader;
import java.io.ByteArrayInputStream;
import java.io.InputStreamReader;
import java.util.HashSet;
import java.util.LinkedList;
import java.util.List;
import java.util.Set;
import javax.sound.sampled.AudioFormat;
import javax.sound.sampled.AudioInputStream;
import javax.sound.sampled.AudioSystem;
import javax.sound.sampled.Clip;
public class MusicTest {
private static final double[] NOTES = { 261.626, 293.665, 329.628, 349.228, 391.995, 440.000, 493.883, 523.251 };
private static final Set<Integer> INCLUDE = new HashSet<Integer>();
private static final double VOLUME = 0.03;
private static final long LENGTH_MS = 1500;
static {
INCLUDE.add(1);
INCLUDE.add(3);
//INCLUDE.add(4);
INCLUDE.add(5);
//INCLUDE.add(8);
}
public static void main(String[] args) throws Throwable {
// TODO add fails to "more often test" list
// print solution after x (3) wrong guesses
while(true) {
List<Integer> notes = playRandomPhrase(3, VOLUME);
InputStreamReader converter = new InputStreamReader(System.in);
BufferedReader in = new BufferedReader(converter);
boolean shouldRepeat = true;
while(shouldRepeat) {
String line = in.readLine();
int index = 0;
boolean passed = true;
inner:
for(Integer n : notes) {
if(line.length() != notes.size() || Integer.parseInt(line.charAt(index++) + "") != n) {
System.out.println("nope");
playPhrase(VOLUME, createSimilarNotes(LENGTH_MS, 100, hertzFromOneBased(notes)));
passed = false;
break inner;
}
}
shouldRepeat = !passed;
}
}
}
private static double[] hertzFromOneBased(List<Integer> oneBased) {
double[] hertzs = new double[oneBased.size()];
int index = 0;
for(Integer oneB : oneBased) {
hertzs[index++] = NOTES[oneB - 1];
}
return hertzs;
}
private static List<Integer> playRandomPhrase(int length, double volume) {
List<Integer> result = new LinkedList<Integer>();
double[] hertzs = new double[length];
result.add(1);
hertzs[0] = NOTES[0];
for(int ii=1; ii<length; ii++) {
int cur = randomIntLessThan(NOTES.length);
int oneBasedCur = cur + 1;
while(!INCLUDE.contains(oneBasedCur)) {
cur = randomIntLessThan(NOTES.length);
oneBasedCur = cur + 1;
}
result.add(oneBasedCur);
hertzs[ii] = NOTES[cur];
}
playPhrase(volume, createSimilarNotes(LENGTH_MS, 100, hertzs));
return result;
}
private static int randomIntLessThan(int max) {
double r = Math.random();
return (int) Math.round(r * max);
}
private static ComplexNote[] createSimilarNotes(long length, int relativeVolume, double... hertz) {
ComplexNote[] result = new ComplexNote[hertz.length];
for(int ii=0; ii<hertz.length; ii++) {
result[ii] = new ComplexNote(hertz[ii], length, relativeVolume);
}
return result;
}
private static byte[] createOneWave(int numberOfBytes, double maxHeight) {
byte[] oneWave = new byte[numberOfBytes];
for(int i=0; i<numberOfBytes; i++) {
double fractionalPos = ((double)i*2) / numberOfBytes;
double angle = fractionalPos * Math.PI;
double sineVal = Math.sin(angle);
Double volSine = sineVal * maxHeight;
byte b = volSine.byteValue();
oneWave[i] = b;
}
return oneWave;
}
private static byte[] makeWaveTwoChannel(byte[] oneWave) {
byte[] stereoWave = new byte[oneWave.length * 2];
for(int i=0; i<oneWave.length; i++) {
int stereoPos = i*2;
stereoWave[stereoPos] = stereoWave[stereoPos+1] = oneWave[i];
}
return stereoWave;
}
private static byte[] repeatWave(byte[] original, int numberOfWaves) {
byte[] multipleStereoWaves = new byte[original.length * numberOfWaves];
for(int i=0; i < numberOfWaves; i++) {
System.arraycopy(original, 0, multipleStereoWaves, original.length * i, original.length);
}
return multipleStereoWaves;
}
private static byte[] createMultipleStereoWaves(int bytesPerWave, double volume, int numberOfWaves) {
byte[] oneWave = createOneWave(bytesPerWave, volume);
byte[] stereoWave = makeWaveTwoChannel(oneWave);
return repeatWave(stereoWave, numberOfWaves);
}
private static Clip createClip(AudioInputStream ais) {
Clip clip;
try {
clip = AudioSystem.getClip();
clip.open(ais);
clip.setFramePosition(0);
}
catch (Exception e) {
throw new RuntimeException(e);
}
return clip;
}
/**
* @param volume 1.000104 min vol headphones @ 220 hz
*/
private static AudioInputStream createAudioInputStream(double volume, ComplexNote... notes) {
float bytesPerSecond = 48000f;
AudioFormat af = new AudioFormat(bytesPerSecond,
8, // sample size in bits
2, // channels
true, // signed
false // bigendian
);
List<byte[]> waveList = new LinkedList<byte[]>();
int finalLength = 0;
for(ComplexNote note : notes) {
Double bpw = bytesPerSecond/note.getHertz();
int bytesPerWave = bpw.intValue();
int numberOfWaves = 800/bpw.intValue() + 5; // 763
byte[] multipleStereoWaves = createMultipleStereoWaves(bytesPerWave, note.getRelativeVolume() * volume, numberOfWaves);
int numBytesNeeded = ((Float) (bytesPerSecond * (note.getLength()/1000))).intValue();
byte[] noteBuffer = new byte[numBytesNeeded];
int repeatNum = numBytesNeeded / multipleStereoWaves.length;
int ii=0;
for(; ii<repeatNum; ii++) {
System.arraycopy(multipleStereoWaves, 0, noteBuffer, multipleStereoWaves.length * ii, multipleStereoWaves.length);
}
System.arraycopy(multipleStereoWaves, 0, noteBuffer, multipleStereoWaves.length * ii, numBytesNeeded % multipleStereoWaves.length);
waveList.add(noteBuffer);
finalLength += noteBuffer.length;
}
byte[] finalBa = new byte[finalLength];
int index = 0;
for(byte[] cur : waveList) {
System.arraycopy(cur, 0, finalBa, index, cur.length);
index = index + cur.length;;
}
return new AudioInputStream(new ByteArrayInputStream(finalBa), af, finalBa.length/2);
}
private static void playPhrase(double volume, ComplexNote... notes) {
Clip clip = createClip(createAudioInputStream(volume, notes));
clip.loop(0);
clip.drain();
clip.flush();
clip.close();
}
}
Posted at 12:31PM Jun 26, 2010 by chris in Java |
SingleResourceResolver
I don't know what others are doing for this, but try this for your rest implementations:
package net.chrislacy.webapp.util;
import java.util.Locale;
import org.springframework.web.servlet.View;
import org.springframework.web.servlet.ViewResolver;
public class SingleViewResolver implements ViewResolver {
private View view;
public SingleViewResolver(View view) {
this.view = view;
}
@Override
public View resolveViewName(String viewName, Locale locale) throws Exception {
return view;
}
}
for example:
<bean class="org.springframework.web.servlet.view.ContentNegotiatingViewResolver"> <property name="mediaTypes"> <map> <entry key="json" value="application/json" /> <entry key="xml" value="application/xml" /> <entry key="html" value="text/html" /> </map> </property> <property name="viewResolvers"> <list> <bean class="net.chrislacy.webapp.util.SingleViewResolver"> <constructor-arg name="view"> <bean class="org.springframework.web.servlet.view.json.MappingJacksonJsonView" /> </constructor-arg> </bean> <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver" p:prefix="/WEB-INF/jsp/" p:suffix=".jsp" /> </list> </property> </bean>
Posted at 02:20AM Jun 23, 2010 by chris in Java |
Integration Testing Spring Web Applications through DispatcherServlet
import static org.mockito.Matchers.anyString;
import static org.mockito.Mockito.*;
import static org.springframework.web.util.WebUtils.*;
import java.util.Enumeration;
import javax.servlet.RequestDispatcher;
import javax.servlet.ServletConfig;
import javax.servlet.ServletContext;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import net.chrislacy.utils.c.EasyEnumeration;
import org.springframework.web.context.WebApplicationContext;
import org.springframework.web.servlet.DispatcherServlet;
public class DispatcherTestHelper {
private DispatcherTestHelper() {}
@SuppressWarnings("unchecked")
public static HttpServletResponse test(String configLocation, String method, String path) throws Throwable {
DispatcherServlet ds = new DispatcherServlet();
ds.setContextConfigLocation(configLocation);
ServletConfig sc = mock(ServletConfig.class);
Enumeration e = mock(Enumeration.class);
when(sc.getInitParameterNames()).thenReturn(e);
ServletContext scon = mock(ServletContext.class);
when(scon.getInitParameterNames()).thenReturn(e);
when(scon.getAttributeNames()).thenReturn(e);
when(sc.getServletContext()).thenReturn(scon);
ds.init(sc);
WebApplicationContext wac = ds.getWebApplicationContext();
when(scon.getAttribute(WebApplicationContext.ROOT_WEB_APPLICATION_CONTEXT_ATTRIBUTE)).thenReturn(wac);
HttpServletRequest hsr = mock(HttpServletRequest.class);
when(hsr.getMethod()).thenReturn(method);
when(hsr.getAttribute(INCLUDE_REQUEST_URI_ATTRIBUTE)).thenReturn(path);
when(hsr.getAttribute(INCLUDE_CONTEXT_PATH_ATTRIBUTE)).thenReturn(path);
when(hsr.getAttribute(INCLUDE_SERVLET_PATH_ATTRIBUTE)).thenReturn(path);
when(hsr.getAttribute(WebApplicationContext.ROOT_WEB_APPLICATION_CONTEXT_ATTRIBUTE)).thenReturn(wac);
when(hsr.getAttributeNames()).thenReturn(new EasyEnumeration(INCLUDE_REQUEST_URI_ATTRIBUTE,
INCLUDE_CONTEXT_PATH_ATTRIBUTE, INCLUDE_SERVLET_PATH_ATTRIBUTE, WebApplicationContext.ROOT_WEB_APPLICATION_CONTEXT_ATTRIBUTE));
when(hsr.getRequestURI()).thenReturn(path);
RequestDispatcher rd = mock(RequestDispatcher.class);
when(hsr.getRequestDispatcher(anyString())).thenReturn(rd);
HttpServletResponse hsres = mock(HttpServletResponse.class);
ds.service(hsr, hsres);
verify(rd).include(hsr, hsres);
return hsres;
}
}
@Test
public void test() throws Throwable {
HttpServletResponse hsres = DispatcherTestHelper.test("file:src/main/webapp/WEB-INF/spring/*-config.xml", "GET", "/welcome");
System.out.println(hsres);
}
Posted at 11:32AM Jun 22, 2010 by chris in Java |
finite state machines, domain specific languages, and abstract resources
prediction: we're going to see a convergence around a domain specific language for constructing finite state machines that act on abstract resources. for example, web flow "languages", enterprise service buses, and enterprise integration technologies will eventually share a common tongue. we may see this vertically as well: how many (virtual) machine languages do we need? and since machine languages are themselves programming languages, can we consolidate? do we really need multiple data access technologies (rest, sql, no-sql, hql, jpql)? how many times are we going to re-invent distributed middleware (corba, rmi, rmi-iiop, soap)?
back to finite state machines, though. just as there are enterprise integration patterns, there will be semi-solid "strategies" which take pluggable abstract resources. those resources may be determined by the environment ala osgi di.
Posted at 12:19AM Jun 17, 2010 by chris in General |