Updated at June 29, 2019
Sometimes, we need define a map constant in interface, but as interface can’t define initializer or static initializer block, how are we going to put values into the map and initialize it?
One way is to define an anonymous class that inherits from Hashmap, and initialize the map in the initialize block in the new anonymous class.
public class Activator extends AbstractUIPlugin
{
public static final String PLUGIN_ID = "org.codeexample.myrcp"; //$NON-NLS-1$
public Activator(){}
public void start(BundleContext context) throws Exception
{
LogConfigurer.configureLogging();
final Logger logger = Logger.getLogger(Activator.class.getName());
// test logger
logger.warning("hello logger: " + new Date());
logger.throwing(Activator.class.getName(), "start", new RuntimeException("thrown exception"));
super.start(context);
}
public void stop(BundleContext context) throws Exception
{
super.stop(context);
}
}
public class LogConfigurer {
public static String DATE_FOMAT = "yyyy-MM-dd hh:mm:ss.SSS";
public static String LOG_DIRECTORY = Platform.getLocation()
.toPortableString() + IConstants.FILE_SEPARATOR + "logs";
public static String LOG_PREFIX = "main";
public static boolean configured = false;
public synchronized static void configureLogging() {
if (!configured) {
configured = true;
try {
LogManager.getLogManager().readConfiguration(
LogConfigurer.class
.getResourceAsStream("logging.properties"));
File file = new File(LOG_DIRECTORY);
if (!file.exists()) {
file.mkdir();
}
FileHandler fileHandler = new FileHandler(LOG_DIRECTORY
+ IConstants.FILE_SEPARATOR + LOG_PREFIX + ".log", true);
fileHandler.setFormatter(new MySimpleFormatter());
fileHandler.setEncoding("UTF-8");
fileHandler.setLevel(Level.FINER);
ConsoleHandler consoleHandler = new ConsoleHandler();
consoleHandler.setFormatter(new MySimpleFormatter());
consoleHandler.setEncoding("UTF-8");
consoleHandler.setLevel(Level.ALL);
Logger parentLogger = Logger
.getLogger("com.ibm.storage.ess.cli.wrapper");
parentLogger.addHandler(fileHandler);
parentLogger.addHandler(consoleHandler);
parentLogger.setLevel(Level.ALL);
} catch (Exception e) {
Activator.logException(e);
}
}
}
}
/**
* The code is similar as JDK SimpleFormatter, just made a little change to
* record all message(including exception stack) in one line.
*/
public class MySimpleFormatter extends Formatter {
Date dat = new Date();
private final static String format = "{0,date," + LogConfigurer.DATE_FOMAT
+ "}";
private MessageFormat formatter;
private Object args[] = new Object[1];
public static final String LINE_SEPARATOR = System
.getProperty("line.separator");
private String separator = " ------ ";
public synchronized String format(LogRecord record) {
StringBuffer sb = new StringBuffer();
// Minimize memory allocations here.
dat.setTime(record.getMillis());
args[0] = dat;
StringBuffer text = new StringBuffer();
if (formatter == null) {
formatter = new MessageFormat(format);
}
formatter.format(args, text, null);
sb.append(text);
sb.append(" ");
if (record.getSourceClassName() != null) {
sb.append(record.getSourceClassName());
} else {
sb.append(record.getLoggerName());
}
if (record.getSourceMethodName() != null) {
sb.append(" ");
sb.append(record.getSourceMethodName());
}
sb.append(separator);
String message = formatMessage(record);
sb.append(record.getLevel().getLocalizedName());
sb.append(": ");
sb.append(message);
if (record.getThrown() != null) {
sb.append(separator);
try {
StringWriter sw = new StringWriter();
PrintWriter pw = new PrintWriter(sw);
record.getThrown().printStackTrace(pw);
pw.close();
String str = sw.toString();
String[] strs = str.split(IConstants.LINE_SEPARATOR);
for (int i = 0; i < strs.length; i++) {
sb.append(strs[i]);
if (i != strs.length - 1) {
sb.append(separator);
}
}
} catch (Exception ex) {
}
}
sb.append("\n");
return sb.toString();
}
}
public class LoggingConfig
{
/**
* This example demonstrate how to add a handler and filter
*/
public void setFilter()
{
try
{
FileHandler handler = new FileHandler("");
// Set the filter
handler.setFilter(new Filter()
{
public boolean isLoggable(LogRecord record)
{
// return true if the record should be logged, false otherwise.
// for example, only log if the method name starts with audit.
return (record.getSourceMethodName().startsWith("audit"));
}
});
// Add the handler to a logger
Logger logger = Logger.getLogger(LoggingConfig.class.getName());
logger.addHandler(handler);
}
catch (IOException e)
{
e.printStackTrace();
}
}
public void useMemeoryHandler()
{
// Create a memory handler with a memory of 100 records
// and dumps the records into the file my.log when a
// SEVERE message is logged
FileHandler fhandler;
try
{
fhandler = new FileHandler("my.log", true); // set append mode to true
int numRec = 100;
MemoryHandler mhandler = new MemoryHandler(fhandler, numRec, Level.SEVERE);
// Add to the desired logger
Logger logger = Logger.getLogger("com.mycompany");
logger.addHandler(mhandler);
}
catch (IOException e)
{
e.printStackTrace();
}
}
public static void main(String[] args)
{
Logger logger = Logger.getLogger(LoggingConfig.class.getName());
logger.setLevel(Level.SEVERE);
}
}
import java.text.DateFormat;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;
import java.util.GregorianCalendar;
import java.util.TimeZone;
public class DateCalendarTest {
public static void testSimpleDateFormat() throws ParseException {
// If no timezone is set, it would use the default timezone.
DateFormat df = new SimpleDateFormat("yyyy/MM/dd HH:mm");
// String to Date
Date date = df.parse("2011/04/16 26:65");
df.setLenient(true); // allow string like 26:65 etc, default is true
// Date to String
String sre = df.format(new Date());
// this would use the default format of the user's computer
df = DateFormat.getDateInstance();
// It also provides some alternative styles for dates.
df = DateFormat.getDateTimeInstance(DateFormat.SHORT, DateFormat.SHORT);
df = DateFormat.getDateInstance(DateFormat.LONG);
df = DateFormat.getTimeInstance();
}
public static void testCalendar() {
// this would create a calendar with current time and time zone.
Calendar calendar = Calendar.getInstance();
Date date = calendar.getTime();
// Be aware that months start with January equal to 0, month of the
// following time is May.
calendar = new GregorianCalendar(2011, 04, 16);
// A better way to create that date would be:
calendar = new GregorianCalendar(2011, Calendar.APRIL, 16, 23, 31, 00);
calendar.add(GregorianCalendar.DATE, 90);
calendar.add(GregorianCalendar.MONTH, 1);
// calculate difference between times
System.err.println(calendar.getTime());
}
public static void compareDate(Calendar calendar1, Calendar calendar2) {
long days, hours, minutes, seconds;
long diff = calendar1.getTimeInMillis() - calendar2.getTimeInMillis();
long millisADay = 24 * 60 * 60 * 1000;
days = diff / millisADay;
diff = diff - (days * millisADay);
hours = diff / 3600;
diff = diff - (hours * 3600);
minutes = diff / 60;
diff = diff - (minutes * 60);
seconds = diff;
System.out.println(days + " days(s) " + hours + " hour(s) " + minutes
+ " minute(s) " + seconds + " second(s)");
}
public static void testTimeZone() {
// displays the ID of the current default time zone
System.out.println(TimeZone.getDefault().getID()); // Asia/Shanghai
// You can change system property - user.timezone to alter the default time zone.
}
public static void testSqlTime() {
// convert a java.sql.timestamp to a java.util.Date
java.sql.Timestamp t = new java.sql.Timestamp(new Date().getTime());
// 1 Milli = 1x10^6 Nanos
Date d = new Date(t.getTime() + (t.getNanos() / 1000000));
DateFormat df = new SimpleDateFormat("MM/dd/yy hh:mm:ss.SSS a");
System.out.println(df.format(d)); // Right! At least we have the millis
}
/**
* This is a program to demonstrate how to group the days between startDate
* and endDate by week
*/
public static void runWeeklyReport(Date startDate, Date endDate) { Calendar startCalendar = Calendar.getInstance();
startCalendar.setTime(startDate);
Calendar endCalendar = Calendar.getInstance();
endCalendar.setTime(endDate);
while (startCalendar.before(endCalendar)) {
Date weekStartDate = startCalendar.getTime();
int dayOfWeek = startCalendar.get(Calendar.DAY_OF_WEEK);
if (dayOfWeek != Calendar.SUNDAY) {
startCalendar.add(Calendar.DAY_OF_WEEK, 7 - dayOfWeek + 1);
startCalendar.set(Calendar.HOUR, 23);
startCalendar.set(Calendar.MINUTE, 59);
startCalendar.set(Calendar.SECOND, 59);
}
if (startCalendar.before(endCalendar)) {
Date weekEndDate = startCalendar.getTime();
subrutine(weekStartDate, weekEndDate);
} else {
break;
}
// Go to next week
startCalendar.add(Calendar.SECOND, 1);
}
}
private static void subrutine(Date weekStartDate, Date weekEndDate) {
System.err.println(weekStartDate + ":" + weekEndDate);
}
}
Caveat
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>com.codeexample</groupId>
<artifactId>mvn-example-exclusion</artifactId>
<version>1.0-SNAPSHOT</version>
<packaging>jar</packaging>
<name>mvn-example-exclusion</name>
<properties>
<slf4j.version>1.6.1</slf4j.version>
</properties>
<dependencies>
<dependency>
<groupId>log4j</groupId>
<artifactId>log4j</artifactId>
<version>1.2.16</version>
</dependency>
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-log4j12</artifactId>
<version>${slf4j.version}</version>
</dependency>
<dependency>
<groupId>net.sf.dozer</groupId>
<artifactId>dozer</artifactId>
<version>5.3.2</version>
</dependency>
</dependencies>
</project>
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-api</artifactId>
<version>${slf4j.version}</version>
</dependency>
<dependency>
<groupId>net.sf.dozer</groupId>
<artifactId>dozer</artifactId>
<version>5.3.2</version>
<exclusions>
<exclusion>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-api</artifactId>
</exclusion>
</exclusions>
</dependency>
package org.codeexample.rs.client;
public class FriendWebServiceApacheHttpClient implements FriendWebServiceClient {
private String baseUrl;
@Required public void setBaseUrl(String baseUrl)
{ this.baseUrl = baseUrl; }
public List<PersonDTO> getFriends(Long userId) {
DefaultHttpClient httpClient = new DefaultHttpClient();
List<PersonDTO> friends = null;
HttpGet httpGet = new HttpGet(baseUrl + "/friends/" + userId);
httpGet.addHeader("accept", "application/xml");
ResponseHandler<List<PersonDTO>> responseHandler = new ResponseHandler<List<PersonDTO>>() {
public List<PersonDTO> handleResponse(HttpResponse response)
throws ClientProtocolException, IOException {
HttpEntity entity = response.getEntity();
if (entity != null) {
JAXBContext context;
try {
context = JAXBContext.newInstance(PersonDTO.class);
String str = EntityUtils.toString(entity);
StringReader sr = new StringReader(str);
// TODO this would cause UnmarshalException, fix it.
// javax.xml.bind.UnmarshalException: unexpected element
// (uri:"com.codeexample", local:"persons"). Expected
// elements are <{com.codeexample}person>
return (List<PersonDTO>) context.createUnmarshaller()
.unmarshal(sr);
} catch (JAXBException e) {
e.printStackTrace();
return null;
}
} else {
return new ArrayList<PersonDTO>();
}
}
};
try {
friends = httpClient.execute(httpGet, responseHandler);
} catch (ClientProtocolException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} finally {
httpClient.getConnectionManager().shutdown();
}
return friends;
}
public PersonDTO getFriend(Long userId, Long friendId) {
DefaultHttpClient httpClient = new DefaultHttpClient();
PersonDTO friend = null;
HttpGet httpGet = new HttpGet(baseUrl + "/friends/" + userId + "/"
+ friendId);
httpGet.addHeader("accept", "application/xml");
ResponseHandler<PersonDTO> responseHandler = new ResponseHandler<PersonDTO>() {
public PersonDTO handleResponse(HttpResponse response)
throws ClientProtocolException, IOException {
HttpEntity entity = response.getEntity();
if (entity != null) {
JAXBContext context;
try {
context = JAXBContext.newInstance(PersonDTO.class);
String str = EntityUtils.toString(entity);
StringReader sr = new StringReader(str);
return (PersonDTO) context.createUnmarshaller()
.unmarshal(sr);
} catch (JAXBException e) {
e.printStackTrace();
return null;
}
} else {
return null;
}
}
};
try {
friend = httpClient.execute(httpGet, responseHandler);
} catch (ClientProtocolException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} finally {
httpClient.getConnectionManager().shutdown();
}
return friend;
}
public Long addFriend(Long userId, PersonDTO friendDTO) {
Long friendId = null;
DefaultHttpClient httpClient = new DefaultHttpClient();
HttpPost httpPost = new HttpPost(baseUrl + "/friends/" + userId);
httpPost.addHeader("accept", "application/xml");
try {
StringWriter sw = new StringWriter();
JAXBContext context = JAXBContext.newInstance(PersonDTO.class);
context.createMarshaller().marshal(friendDTO, sw);
System.err.println(sw.toString());
StringEntity entity = new StringEntity(sw.toString());
entity.setContentType("application/xml");
httpPost.setEntity(entity);
ResponseHandler responseHandler = new BasicResponseHandler();
friendId = (Long) httpClient.execute(httpPost, responseHandler);
} catch (Exception e) {
e.printStackTrace();
}
return friendId;
}
public void removeFriend(Long userId, Long friendId) {
DefaultHttpClient httpClient = new DefaultHttpClient();
HttpDelete httpPost = new HttpDelete(baseUrl + "/friends/" + userId
+ "/" + friendId);
httpPost.addHeader("accept", "application/xml");
try {
httpClient.execute(httpPost);
} catch (Exception e) {
e.printStackTrace();
}
}
}
package org.codeexample.rs.client;
public class FriendWebServiceHttpClient implements FriendWebServiceClient {
private String baseUrl;
@Required public void setBaseUrl(String baseUrl) {
this.baseUrl = baseUrl;
}
@Override public List<PersonDTO> getFriends(Long userId) {
List<PersonDTO> friends = null;
try {
URL url = new URL(baseUrl + "/friends/" + userId);
HttpURLConnection connection = (HttpURLConnection) url
.openConnection();
connection.setRequestMethod("GET");
connection.setRequestProperty("Accept", "application/xml");
if (connection.getResponseCode() != 200) { throw new RuntimeException(
"Operation failed:” + connection.getResponseCode()); }
JAXBContext context = JAXBContext.newInstance(PersonDTO.class);
friends = (List<PersonDTO>) context.createUnmarshaller().unmarshal(
connection.getInputStream());
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} catch (JAXBException e) {
e.printStackTrace();
}
return friends;
}
@Override public PersonDTO getFriend(Long userId, Long friendId) {
PersonDTO friend = null;
try {
URL url = new URL(baseUrl + "/friends/" + userId + "/" + friendId);
HttpURLConnection connection = (HttpURLConnection) url
.openConnection();
connection.setRequestMethod("GET");
connection.setRequestProperty("Accept", "application/xml");
if (connection.getResponseCode() != 200) { throw new RuntimeException(
"Operation failed:” + connection.getResponseCode()); }
JAXBContext context = JAXBContext.newInstance(PersonDTO.class);
friend = (PersonDTO) context.createUnmarshaller().unmarshal(
connection.getInputStream());
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} catch (JAXBException e) {
e.printStackTrace();
}
return friend;
}
@Override public Long addFriend(Long userId, PersonDTO friendDTO) {
Long friendId = null;
HttpURLConnection connection = null;
try {
URL url = new URL(baseUrl + "/friends/" + userId);
connection = (HttpURLConnection) url.openConnection();
connection.setDoOutput(true);
connection.setInstanceFollowRedirects(false);
connection.setRequestMethod("POST");
connection.setRequestProperty("Content-Type", "application/xml");
connection.setRequestProperty("accept", "application/xml");
StringWriter sw = new StringWriter();
JAXBContext context = JAXBContext.newInstance(PersonDTO.class);
context.createMarshaller().marshal(friendDTO, sw);
System.err.println(sw.toString());
OutputStream os = connection.getOutputStream();
os.write(sw.toString().getBytes());
os.flush();
BufferedReader reader = new BufferedReader(new InputStreamReader(
connection.getInputStream()));
friendId = new Long(reader.readLine());
// this would cause org.xml.sax.SAXParseException: Content is not
// allowed in prolog.]
// context = JAXBContext.newInstance(PersonDTO.class);
// friendId = (Long) context.createUnmarshaller().unmarshal(
// connection.getInputStream());
} catch (IOException e) {
e.printStackTrace();
} catch (JAXBException e) {
e.printStackTrace();
} finally {
connection.disconnect();
}
return friendId;
}
@Override public void removeFriend(Long userId, Long friendId) {
try {
URL url = new URL(baseUrl + "/friends/" + userId + "/" + friendId);
HttpURLConnection connection = (HttpURLConnection) url
.openConnection();
connection.setRequestMethod("DELETE");
System.err.println(connection.getResponseCode());
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
}