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Open a properties file from a class in a Dynamic Web Project

I'm using Eclipse for EE Developer.
I need to access to a properties file (db.properties) from a class's method (DBQuery.java).
The class is located inside a package inside the src folder.
For the properties file i tried almost everything that i could find over the net to make it work, but looks like i can't.
The properties file is located inside the WebContent folder, and i'll add the code with which i'm trying to load this file:
public class DBQuery {
public static String create_DB_string(){
//the db connection string
String connString = "";
try{
Properties props = new Properties();
FileInputStream fis = new FileInputStream("db.properties");
props.load(fis);
fis.close();
/* creating connString using props.getProperty("String"); */
}
catch (Exception e) {
System.out.println(e.getClass());
}
return connString;
}
}
So my question is, where to put the properties file, and which is the correct way to load it?

You can put this propertie file within your java package for example com/test and use following:
getClass().getResourceAsStream( "com/test/myfile.propertie");
Hope it helps.

Unable to load external files in java while running in terminal

I have created a executable jar package (called myjar.jar) which has a class for reading config file(called config_reader) .There is another class file outside myjar.jar which uses the config_reader. But the config file for config_reader is placed outside the myjar.jar ( in local filesystem) .Now when i try to execute the executable jar along with another file that uses it i get an error saying config file not found :
I tried to :
java -classpath config myclass.class
can Anyone help out on this ?
The code of config_reader is :
public class config_reader()
{
public static ArrayList<String> get_prop()
{
Properties prop = new Properties();
ArrayList<String> s= new ArrayList<String>();
try {
//load a properties file
prop.load(new FileInputStream("config"));
//get the property value and print it out
s.add(prop.getProperty("source_folder_dir"));
s.add(prop.getProperty("dest_folder_dir"));
s.add(prop.getProperty("file_type"));
s.add(prop.getProperty("username"));
s.add(prop.getProperty("userpwd"));
s.add(prop.getProperty("exclusion_list"));
} catch (IOException ex) {
ex.printStackTrace();
}
return s;
}
}

prop.load(new FileInputStream("config"));
Instead of just saying config use absolute path to the file. Infact it is better to do
File configFile = new File("absolute path to config file");
if(configFile.exists()){
//continue with your logic
}

Where to keep `java.util.Properties` file and how to access it?

I am adding email sending capability to my web app. SMTP server settings will be read from a java.util.Properties file. I wouldn't like to hardcode path to this file.
Where should I keep this file?
How should I access this file?

A good pattern to follow is to keep your static resources (like property files) under your WEB-INF/classes/ directory.
That way they can be read from the classpath and not accessed by the browser:
for example, put your settings file under WEB-INF/classes/mail-settings.properties, and use the following to read it:
InputStream is = MyClass.class.getResourceAsStream("mail-settings.properties");
Properties p = new Properties();
p.load(is);
is.close();

Keep property file in classpath location like in folder : WEB-INF/classes/mail.properties
Here property file is - mail.properties. To read this file you can use below code
import java.util.Locale;
import java.util.MissingResourceException;
import java.util.ResourceBundle;
public class EmailPropertyReader {
private static ResourceBundle myResources;
public static String FILENAME = "mail";
static{
initialize(FILENAME);
}
public static void initialize(String propertyFile) throws MissingResourceException
{
try{
myResources = ResourceBundle.getBundle(FILENAME, Locale.getDefault());
}catch(Exception ex){
//Logger
}
}
private static String getParameter(String parmName)
{
String param = null;
try
{
param = myResources.getString(parmName) ;
}catch(Exception e){
param = null;
//Logger
}
if (param != null)
return param.trim();
else
return param;
}
}
You just create object and enter code here use method getParameter() ->
For example:
mail.properties :
EMAILID=a#a.com
then
String strEmailid=EmailPropertyReader.getParameter("EMAILID");

if you want to keep it with your code you may just as well create the Properties instance programmatically.
Properties mailProperties = new Properties();
mailProperties.setProperty("mail.transport.protocol", "smtp");
mailProperties.setProperty("mail.smtp.host", "localhost");
mailProperties.setProperty("mail.smtp.port", "587");
mailProperties.setProperty("mail.smtp.auth", "false");
javax.mail.Session.getInstance(mailProperties);
If you want to have it in a properties file anyway you can load it as a classpath resource. Have a look at getResourceAsStream in java.lang.Class. Update: see epochs answer for how to do this!

Here is a solution:
I have placed EmailSettings.properties file into WebContent\WEB-INF\classes. This code now works:
InputStream inputFile = this.getClass().getClassLoader().getResourceAsStream("EmailSettings.properties");
Properties emailConfig = new Properties();
emailConfig.load( inputFile );
.
.
.

If the settings are stage dependent ,you could set the path to the File via a vm Enviorment varibable.
-DmyPropertyFilePath=....
Also there is a good artikel about loading property files (even so it is a bit Dated) on Java World

java.util.Properties$LineReader.readLine

I need to read a config file
I get this error while running the following code:
java.util.Properties$LineReader.readLine
The file config.cfg is present and has r/w permissions.
import java.util.*;
import java.util.Properties;
public class Config
{
Properties configFile;
public Config()
{
configFile = new java.util.Properties();
try {
configFile.load(this.getClass().getClassLoader().
getResourceAsStream("config.cfg"));
}catch(Exception eta){
eta.printStackTrace();
}
}
public String getProperty(String key)
{
String value = this.configFile.getProperty(key);
return value;
}
}
EDIT - Full Error
[java] java.lang.NullPointerException
[java] at java.util.Properties$LineReader.readLine(Properties.java:418)
[java] at java.util.Properties.load0(Properties.java:337)
[java] at java.util.Properties.load(Properties.java:325)
[java] at Config.<init>(Unknown Source)
[java] at ClosureBuilder.<clinit>(Unknown Source)
EDIT - Directory Structure
src
-> config.java
-> config.cfg

You have to put your config.cfg in the same folder where your .class file lies.

The resource stream is being returned as null. The resource isn't where you think it is in the classpath.

It seems your program is not able to find the config.cfg file.
this.getClass().getClassLoader().getResourceAsStream("config.cfg")
The above call is returning null.
Try the below:
InputStream is = this.getClass().getClassLoader().getResourceAsStream("config.cfg")
if(is !=null){
configFile.load(is);
}
This change will not let your program fail. But also, if the file is not located, your property object configFile will not have any property from the file.

Check the path what you are getting for your config using this.getClass().getResource("/");

How to read a properties file in Java? [duplicate]

This question already has answers here:
Where to place and how to read configuration resource files in servlet based application?
(6 answers)
Closed 7 years ago.
I am using servlets where I hard-code the database connection details, so if make any change I have to recompile the code. So instead I'd like to use a .properties file (which I can modify later) and use that as the source for my database connection.
The problem is I don't know how to read the property file. Could someone please help me to read the file?

. . .
// create and load default properties
Properties defaultProps = new Properties();
FileInputStream in = new FileInputStream("defaultProperties");
defaultProps.load(in);
in.close();
// create application properties with default
Properties applicationProps = new Properties(defaultProps);
// now load properties from last invocation
in = new FileInputStream("appProperties");
applicationProps.load(in);
in.close();
. . .
Example is coming from here Properties (Java)
The methods of Properties can throw exceptions.
- When the file path is not valid (FileNotFoundException). Please try to create a File object and check, whether the File is existing.
- ...

You may take a look at Apache Commons Configuration. Using it you can read properties file like that:
Configuration config = new PropertiesConfiguration("user.properties");
String connectionUrl = config.getString("connection.url");
This information regarding file location may be also important:
If you do not specify an absolute
path, the file will be searched
automatically in the following
locations:
in the current directory
in the user home directory
in the classpath
So in case of reading properties file in a servlet you should put properties file in a classpath (e.g. in WEB-INF/classes).
You can find more examples at their website.

You can use java.util.Properties

The biggest problem in reading a property file in web application is that you actually don't know about the actaul path of the file. So we have to use the relative path and for that we have to use various functions and classes like getresourceAsStream(), InputStream, FileinputStream etc.
And the method getReourceAsStream behaves differently in static and non static methogs..
you can do this in below way
Non Static
InputStream input = getClass().getClassLoader().getResourceAsStream("config.properties");
Static
InputStream input = ReadPropertyFile.class.getClassLoader().getResourceAsStream("config.properties");
For complete reference you can follow these links..
http://www.codingeek.com/java/using-getresourceasstream-in-static-method-reading-property-files
http://www.codingeek.com/java/read-and-write-properties-file-in-java-examples/

InputStream in = Thread.currentThread().getContextClassLoader().getResourceAsStream("my.properties");
Properties p = new Properties();
p.load(in);
in.close();

The below code, will add a Listener which checks for file configured with dbprops system property. For every given interval it will look if the file is modified, if it is modified it will load the Properties from the file.
package com.servlets;
import java.io.File;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.Timer;
import java.util.TimerTask;
import javax.servlet.ServletContext;
import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;
public class DBPropsWatcherListener
implements ServletContextListener
{
public void contextInitialized(ServletContextEvent event)
{
ServletContext servletContext = event.getServletContext();
Timer timer = new Timer("ResourceListener");
timer.schedule(new MyWatcherTask(servletContext), 15);
}
public void contextDestroyed(ServletContextEvent event)
{
}
private class MyWatcherTask extends TimerTask
{
private final ServletContext servletContext;
private long lastModifiedTime = -1;
public MyWatcherTask(ServletContext servletContext)
{
this.servletContext = servletContext;
}
public void run()
{
try {
File resourceFile = new File(System.getProperty("dbProps"));
long current = resourceFile.lastModified();
if (current > lastModifiedTime) {
java.io.InputStream dbPropsStream = new FileInputStream(resourceFile );
java.util.Properties dbProps = new java.util.Properites();
dbProps.load(dbPropsStream);
realoadDBProps();
}
lastModifiedTime = current;
} catch (MalformedURLException e) {
e.printStackTrace();
}
}
}
}

Below program read the properties file a display using key value pair
File f1 = new File("abcd.properties");
FileReader fin = new FileReader(f1);
Properties pr = new Properties();
pr.load(fin);
Set<String> keys = pr.stringPropertyNames();
Iterator<String> it = keys.iterator();
String key, value;
while (it.hasNext())
{
key = it.next();
value = pr.getProperty(key);
System.out.println(key+":"+value);
}
}

If your application is small enough with only a handful of properties coming from just one or two property files, then I would suggest to use the JDK's own Properties class which load the properties from a file and use it just like the way you use a hashtable. Properties class itself inherits from Hashtable. But, your application is significantly large with sizable number of properties coming from different sources like property files, xml files, system properties then I would suggest to use Apache commons configuration. It presents a unified view of properties from across different configuration sources and allows you to define an override and preference mechanism for common properties appearing in different sources. Refer this article http://wilddiary.com/reading-property-file-java-using-apache-commons-configuration/ for a quick tutorial on using the commons configuration.

This may work::
Properties prop = new Properties();
FileReader fr = new FileReader(filename);
prop.load(fr);
Set<String> keys = pr.stringPropertyNames();
//now u can get the values from keys.

The Properties class has a convenient load method. That's the easiest way to read a java properties file.

That is a good idea to read the database values from properties file
You can use a properties class from Util package. The important thing to keep in mind is closing the stream after reading the file or writing the file to disk. Otherwise it causes problems. Here is an example for your reference:
import java.io.FileInputStream;
import java.io.IOException;
import java.util.Properties;
public class App
{
public static void main( String[] args )
{
Properties prop = new Properties();
try {
//load a properties file
prop.load(new FileInputStream("config.properties"));
//get the property value and print it out
System.out.println(prop.getProperty("database"));
System.out.println(prop.getProperty("dbuser"));
System.out.println(prop.getProperty("dbpassword"));
} catch (IOException ex) {
ex.printStackTrace();
}
}
}
Output
localhost
mkyong
password

ResourceBundle rb = ResourceBundle.getBundle("mybundle");
String propertyValue = rb.getString("key");
assuming mybundle.properties file is in classpath

Read this.Usually the properties file is kept in the classpath so that this method can read it.