I have a list of key/value pairs of configuration values I want to store as Java property files, and later load and iterate through.
Questions:
Do I need to store the file in the same package as the class which will load them, or is there any specific location where it should be placed?
Does the file need to end in any specific extension or is .txt OK?
How can I load the file in the code
And how can I iterate through the values inside?
You can pass an InputStream to the Property, so your file can pretty much be anywhere, and called anything.
Properties properties = new Properties();
try {
properties.load(new FileInputStream("path/filename"));
} catch (IOException e) {
...
}
Iterate as:
for(String key : properties.stringPropertyNames()) {
String value = properties.getProperty(key);
System.out.println(key + " => " + value);
}
You can store the file anywhere you like. If you want to keep it in your jar file, you'll want to use Class.getResourceAsStream() or ClassLoader.getResourceAsStream() to access it. If it's on the file system it's slightly easier.
Any extension is fine, although .properties is more common in my experience
Load the file using Properties.load, passing in an InputStream or a StreamReader if you're using Java 6. (If you are using Java 6, I'd probably use UTF-8 and a Reader instead of the default ISO-8859-1 encoding for a stream.)
Iterate through it as you'd iterate through a normal Hashtable (which Properties derives from), e.g. using keySet(). Alternatively, you can use the enumeration returned by propertyNames().
If you put the properties file in the same package as class Foo, you can easily load it with
new Properties().load(Foo.class.getResourceAsStream("file.properties"))
Given that Properties extends Hashtable you can iterate over the values in the same manner as you would in a Hashtable.
If you use the *.properties extension you can get editor support, e.g. Eclipse has a properties file editor.
There are many ways to create and read properties files:
Store the file in the same package.
Recommend .properties extension however you can choose your own.
Use theses classes located at java.util package => Properties, ListResourceBundle, ResourceBundle classes.
To read properties, use iterator or enumerator or direct methods of Properties or java.lang.System class.
ResourceBundle class:
ResourceBundle rb = ResourceBundle.getBundle("prop"); // prop.properties
System.out.println(rb.getString("key"));
Properties class:
Properties ps = new Properties();
ps.Load(new java.io.FileInputStream("my.properties"));
This load the properties file:
Properties prop = new Properties();
InputStream stream = ...; //the stream to the file
try {
prop.load(stream);
} finally {
stream.close();
}
I use to put the .properties file in a directory where I have all the configuration files, I do not put it together with the class that accesses it, but there are no restrictions here.
For the name... I use .properties for verbosity sake, I don't think you should name it .properties if you don't want.
Properties has become legacy. Preferences class is preferred to Properties.
A node in a hierarchical collection of preference data. This class allows applications to store and retrieve user and system preference and configuration data. This data is stored persistently in an implementation-dependent backing store. Typical implementations include flat files, OS-specific registries, directory servers and SQL databases. The user of this class needn't be concerned with details of the backing store.
Unlike properties which are String based key-value pairs, The Preferences class has several methods used to get and put primitive data in the Preferences data store. We can use only the following types of data:
String
boolean
double
float
int
long
byte array
To load the the properties file, either you can provide absolute path Or use getResourceAsStream() if the properties file is present in your classpath.
package com.mypack.test;
import java.io.*;
import java.util.*;
import java.util.prefs.Preferences;
public class PreferencesExample {
public static void main(String args[]) throws FileNotFoundException {
Preferences ps = Preferences.userNodeForPackage(PreferencesExample.class);
// Load file object
File fileObj = new File("d:\\data.xml");
try {
FileInputStream fis = new FileInputStream(fileObj);
ps.importPreferences(fis);
System.out.println("Prefereces:"+ps);
System.out.println("Get property1:"+ps.getInt("property1",10));
} catch (Exception err) {
err.printStackTrace();
}
}
}
xml file:
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE preferences SYSTEM 'http://java.sun.com/dtd/preferences.dtd'>
<preferences EXTERNAL_XML_VERSION="1.0">
<root type="user">
<map />
<node name="com">
<map />
<node name="mypack">
<map />
<node name="test">
<map>
<entry key="property1" value="80" />
<entry key="property2" value="Red" />
</map>
</node>
</node>
</node>
</root>
</preferences>
Have a look at this article on internals of preferences store
Example:
Properties pro = new Properties();
FileInputStream in = new FileInputStream("D:/prop/prop.properties");
pro.load(in);
String temp1[];
String temp2[];
// getting values from property file
String username = pro.getProperty("usernamev3");//key value in prop file
String password = pro.getProperty("passwordv3");//eg. username="zub"
String delimiter = ","; //password="abc"
temp1=username.split(delimiter);
temp2=password.split(delimiter);
In order:
You can store the file pretty much anywhere.
no extension is necessary.
Montecristo has illustrated how to load this. That should work fine.
propertyNames() gives you an enumeration to iterate through.
By default, Java opens it in the working directory of your application (this behavior actually depends on the OS used). To load a file, do:
Properties props = new java.util.Properties();
FileInputStream fis new FileInputStream("myfile.txt");
props.load(fis)
As such, any file extension can be used for property file. Additionally, the file can also be stored anywhere, as long as you can use a FileInputStream.
On a related note if you use a modern framework, the framework may provide additionnal ways of opening a property file. For example, Spring provide a ClassPathResource to load a property file using a package name from inside a JAR file.
As for iterating through the properties, once the properties are loaded they are stored in the java.util.Properties object, which offer the propertyNames() method.
Reading a properties file and loading its contents to Properties
String filename = "sample.properties";
Properties properties = new Properties();
input = this.getClass().getClassLoader().getResourceAsStream(filename);
properties.load(input);
The following is the efficient way to iterate over a Properties
for (Entry<Object, Object> entry : properties.entrySet()) {
System.out.println(entry.getKey() + " => " + entry.getValue());
}
In Java 8 to get all your properties
public static Map<String, String> readPropertiesFile(String location) throws Exception {
Map<String, String> properties = new HashMap<>();
Properties props = new Properties();
props.load(new FileInputStream(new File(location)));
props.forEach((key, value) -> {
properties.put(key.toString(), value.toString());
});
return properties;
}
1) It is good to have your property file in classpath but you can place it anywhere in project.
Below is how you load property file from classpath and read all properties.
Properties prop = new Properties();
InputStream input = null;
try {
String filename = "path to property file";
input = getClass().getClassLoader().getResourceAsStream(filename);
if (input == null) {
System.out.println("Sorry, unable to find " + filename);
return;
}
prop.load(input);
Enumeration<?> e = prop.propertyNames();
while (e.hasMoreElements()) {
String key = (String) e.nextElement();
String value = prop.getProperty(key);
System.out.println("Key : " + key + ", Value : " + value);
}
} catch (IOException ex) {
ex.printStackTrace();
} finally {
if (input != null) {
try {
input.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
2) Property files have the extension as .properties
Here is another way to iterate over the properties:
Enumeration eProps = properties.propertyNames();
while (eProps.hasMoreElements()) {
String key = (String) eProps.nextElement();
String value = properties.getProperty(key);
System.out.println(key + " => " + value);
}
I have written on this property framework for the last year.
It will provide of multiple ways to load properties, and have them strongly typed as well.
Have a look at http://sourceforge.net/projects/jhpropertiestyp/
JHPropertiesTyped will give the developer strongly typed properties.
Easy to integrate in existing projects.
Handled by a large series for property types.
Gives the ability to one-line initialize properties via property IO implementations.
Gives the developer the ability to create own property types and property io's.
Web demo is also available, screenshots shown above.
Also have a standard implementation for a web front end to manage properties, if you choose to use it.
Complete documentation, tutorial, javadoc, faq etc is a available on the project webpage.
Here ready static class
import java.io.*;
import java.util.Properties;
public class Settings {
public static String Get(String name,String defVal){
File configFile = new File(Variables.SETTINGS_FILE);
try {
FileReader reader = new FileReader(configFile);
Properties props = new Properties();
props.load(reader);
reader.close();
return props.getProperty(name);
} catch (FileNotFoundException ex) {
// file does not exist
logger.error(ex);
return defVal;
} catch (IOException ex) {
// I/O error
logger.error(ex);
return defVal;
} catch (Exception ex){
logger.error(ex);
return defVal;
}
}
public static Integer Get(String name,Integer defVal){
File configFile = new File(Variables.SETTINGS_FILE);
try {
FileReader reader = new FileReader(configFile);
Properties props = new Properties();
props.load(reader);
reader.close();
return Integer.valueOf(props.getProperty(name));
} catch (FileNotFoundException ex) {
// file does not exist
logger.error(ex);
return defVal;
} catch (IOException ex) {
// I/O error
logger.error(ex);
return defVal;
} catch (Exception ex){
logger.error(ex);
return defVal;
}
}
public static Boolean Get(String name,Boolean defVal){
File configFile = new File(Variables.SETTINGS_FILE);
try {
FileReader reader = new FileReader(configFile);
Properties props = new Properties();
props.load(reader);
reader.close();
return Boolean.valueOf(props.getProperty(name));
} catch (FileNotFoundException ex) {
// file does not exist
logger.error(ex);
return defVal;
} catch (IOException ex) {
// I/O error
logger.error(ex);
return defVal;
} catch (Exception ex){
logger.error(ex);
return defVal;
}
}
public static void Set(String name, String value){
File configFile = new File(Variables.SETTINGS_FILE);
try {
Properties props = new Properties();
FileReader reader = new FileReader(configFile);
props.load(reader);
props.setProperty(name, value.toString());
FileWriter writer = new FileWriter(configFile);
props.store(writer, Variables.SETTINGS_COMMENT);
writer.close();
} catch (FileNotFoundException ex) {
// file does not exist
logger.error(ex);
} catch (IOException ex) {
// I/O error
logger.error(ex);
} catch (Exception ex){
logger.error(ex);
}
}
public static void Set(String name, Integer value){
File configFile = new File(Variables.SETTINGS_FILE);
try {
Properties props = new Properties();
FileReader reader = new FileReader(configFile);
props.load(reader);
props.setProperty(name, value.toString());
FileWriter writer = new FileWriter(configFile);
props.store(writer,Variables.SETTINGS_COMMENT);
writer.close();
} catch (FileNotFoundException ex) {
// file does not exist
logger.error(ex);
} catch (IOException ex) {
// I/O error
logger.error(ex);
} catch (Exception ex){
logger.error(ex);
}
}
public static void Set(String name, Boolean value){
File configFile = new File(Variables.SETTINGS_FILE);
try {
Properties props = new Properties();
FileReader reader = new FileReader(configFile);
props.load(reader);
props.setProperty(name, value.toString());
FileWriter writer = new FileWriter(configFile);
props.store(writer,Variables.SETTINGS_COMMENT);
writer.close();
} catch (FileNotFoundException ex) {
// file does not exist
logger.error(ex);
} catch (IOException ex) {
// I/O error
logger.error(ex);
} catch (Exception ex){
logger.error(ex);
}
}
}
Here sample:
Settings.Set("valueName1","value");
String val1=Settings.Get("valueName1","value");
Settings.Set("valueName2",true);
Boolean val2=Settings.Get("valueName2",true);
Settings.Set("valueName3",100);
Integer val3=Settings.Get("valueName3",100);
You can load the property file suing the following way:
InputStream is = new Test().getClass().getClassLoader().getResourceAsStream("app.properties");
Properties props = new Properties();
props.load(is);
And then you can iterate over the map using a lambda expression like:
props.stringPropertyNames().forEach(key -> {
System.out.println("Key is :"+key + " and Value is :"+props.getProperty(key));
});
in my opinion other ways are deprecated when we can do it very simple as below:
#PropertySource("classpath:application.properties")
public class SomeClass{
#Autowired
private Environment env;
public void readProperty() {
env.getProperty("language");
}
}
it is so simple but i think that's the best way!!
Enjoy
Related
Getting NullPointerException when running all my script in the middle. I have xpath written in the property file and I'm loading the property file in BeforeSuite. The element will be present and the page is also present. Getting null in locator.
may be your property file is not giving the exact value of you element.
try calling this function by providing the property name.
public static String getProperty(String propertyname)
{
Properties prop = new Properties();
InputStream input = null;
try {
input = new FileInputStream(("path of your property file"));
// load a properties file
prop.load(input);
} catch (IOException ex) {
ex.printStackTrace();
} finally {
if (input != null) {
try {
input.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
System.out.println(prop.getProperty(propertyname));
//Return the property value
return prop.getProperty(propertyname);
}
I'm working on an Android application and I need to read my properties in assets folder in /app/src/main/assets/app.properties.
But when I use:
Properties properties = new Properties();
try {
properties.load(new FileInputStream("app.properties"));
} catch (IOException e) {
...
}
The inputStream seems to be null. I think I have to precise the filepath or something like that to access to my properties file.
I need to use my properties in this class: /app/src/main/java/mypackage/model/myclass.java
You can load the propertiy file using your android context like this :
context.getAssets().open("app.properties");
For example in a Fragment :
try{
Properties properties = new Properties();
properties.load(this.getActivity().getAssets().open("app.properties"));
}catch(Exception e){
e.printStackTrace();
}
As you seem to need this in a class where the context is not accessible you can create your own application class with a static access to the context and then use this context everywhere.
Create your application class :
public class MyApp extends Application {
private static MyApp instance;
public static MyApp getInstance() {
return instance;
}
public static Context getContext(){
return instance.getApplicationContext()
}
#Override
public void onCreate() {
instance = this;
super.onCreate();
}
}
Add your new created application into the manifest :
<application
android:name="com.example.yourapp.MyApp"
...
Once this done you can load your properties in your XMLParser :
try{
Properties properties = new Properties();
properties.load(MyApp.getContext().getAssets().open("app.properties"));
}catch(Exception e){
e.printStackTrace();
}
Try getting the asset and them reading it:
AssetFileDescriptor fileDescriptor = assetManager.openFd(fileName);
FileInputStream stream = fileDescriptor.createInputStream();
Properties properties = new Properties();
try {
properties.load(stream);
} catch (IOException e) {
...
}
In my unit tests "XMLParserTest" in /app/src/test/java/mypackage/XMLParserTest I tried with:
InputStream is = null;
Properties prop = null;
try {
prop = new Properties();
is = new FileInputStream(new File("C:/...fullpath.../app/src/main/assets/app.properties"));
prop.load(is);
} catch (FileNotFoundException e)
{
e.printStackTrace();
} catch (IOException e)
{
e.printStackTrace();
}
it works but when i put it in my XMLParser class my inputStream "is" is null.
It is like the class can't access to the file .properties. It works for tests only...
If you want to use a library: https://github.com/fernandodev/android-properties
I have tried in multiple ways to load the property file from the resource folder.
Every time, I'm getting a file not found exception. My code is as follows:
Properties prop = new Properties();
FileInputStream inputStream = new FileInputStream("/resource/excelfilepath.properties");
prop.load(inputStream);
String path = prop.getProperty("excelPath");
System.out.println("Excel File Path "+ path);
My project structure looks as follows,
What is the needed structure of the file path literal?
I don't think that you really want to read a ....properties file from web resources. That way the content is visible to all users that access your server - as long as you don't hide it explicitly in web.xml.
It's much more common to put it into the classpath next to your accessing class. That way you can access it with the classloader and it is not visible to the webusers anymore:
Properties prop = new Properties();
prop.load(CreateUser.class.getResourceAsStream("excelfilepath.properties"));
But as you are using Liferay, you should use its configuration as well. Just add the property UserCreationPortlet.excelPath to your portal-ext.properties and use:
String path = PrefsPropsUtil.getString("UserCreationPortlet.excelPath", defaultPath);
You need to tell to the server where your root folders are :
With Tomcat : in the catalina.properties
append the properties shared.loader with yours.
With Jboss : Edit jboss-service.xml in your conf folder
<classpath codebase="${jboss.home.url}/server/default/lib//proprietes/rootFolder" archives="*"/>
I would advice to create a classe to load your properties :
Like :
public static Properties charger(Class<?> pClass, String pFilename) {
Properties aProperties = null;
try {
InputStream aIs = null;
File aFile = new File(pFilename);
if (!aFile.isAbsolute()) {
aIs = pClass.getClassLoader().getResourceAsStream(pFilename);
if (aIs == null) {
return null;
}
} else if (!aFile.exists()) {
return null;
}
if (aIs == null)
aIs = new FileInputStream(aFile);
InputStreamReader reader = new InputStreamReader(aIs, "UTF-8");
aProperties = new Properties();
aProperties.clear();
aProperties.load(reader);
reader.close();
aIs.close();
} catch (FileNotFoundException e) {
LOG.error("Catch FileNotFoundException : ", e);
} catch (IOException e) {
LOG.error("Catch IOException : ", e);
}
return aProperties;
}
Then call your new class with the property that you wish :
protected static final Properties property = ChargeurProprietes.charger( .class,"PATH");
property.getProperty(NAME OF YOUR PROPERTY);
I have an issue.
I have a properties file. I want to store some values in that file and will implement in the code whenever it is required. Is there any way to do that?
I am using Properties class to do that..
Load the properties file using java.util.Properties.
Code snippet -
Properties prop = new Properties();
InputStream in = getClass().getResourceAsStream("xyz.properties");
prop.load(in);
It provides Properties#setProperty(java.lang.String, java.lang.String) which helps to add new property.
Code snippet -
prop.setProperty("newkey", "newvalue");
This new set you can save using Properties#store(java.io.OutputStream, java.lang.String)
Code Snippet -
prop.store(new FileOutputStream("xyz.properties"), null);
You can do it in following way:
Set the properties first in the Properties object by using object.setProperty(String obj1, String obj2).
Then write it to your File by passing a FileOutputStream to properties_object.store(FileOutputStream, String).
Here is the example code :
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.IOException;
import java.util.Arrays;
import java.util.Properties;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.File;
class Main
{
static File file;
static void saveProperties(Properties p) throws IOException
{
FileOutputStream fr = new FileOutputStream(file);
p.store(fr, "Properties");
fr.close();
System.out.println("After saving properties: " + p);
}
static void loadProperties(Properties p)throws IOException
{
FileInputStream fi=new FileInputStream(file);
p.load(fi);
fi.close();
System.out.println("After Loading properties: " + p);
}
public static void main(String... args)throws IOException
{
file = new File("property.dat");
Properties table = new Properties();
table.setProperty("Shivam","Bane");
table.setProperty("CS","Maverick");
System.out.println("Properties has been set in HashTable: " + table);
// saving the properties in file
saveProperties(table);
// changing the property
table.setProperty("Shivam", "Swagger");
System.out.println("After the change in HashTable: " + table);
// saving the properties in file
saveProperties(table);
// loading the saved properties
loadProperties(table);
}
}
Your problem is not clear since Writing/reading from properties files is something already available in java.
To write to properties file you can use the Properties class as you mentioned :
Properties properties = new Properties();
try(OutputStream outputStream = new FileOutputStream(PROPERTIES_FILE_PATH)){
properties.setProperty("prop1", "Value1");
properties.setProperty("prop2", "Value2");
properties.store(outputStream, null);
} catch (IOException e) {
e.printStackTrace();
}
Source and more examples here
This work for me.
Properties prop = new Properties();
try {
InputStream in = new FileInputStream("src/loop.properties");
prop.load(in);
} catch (IOException ex) {
System.out.println(ex);
}
//Setting the value to our properties file.
prop.setProperty("LOOP", "1");
//Getting the value from our properties file.
String value = prop.getProperty("LOOP").trim();
try {
prop.store(new FileOutputStream("src/loop.properties"), null);
} catch (IOException ex) {
System.out.println(ex);
}
I am creating a properties file and putting into my classpath folder Resources.
When I tried to read this file , i am not getting the expected result. i am getting the result of the previous values printed instead of the property values set now.
My class file is as follows :
public class App {
public static void main(String[] args) {
Properties prop = new Properties();
PrintWriter output = null;
try {
output = new PrintWriter("Resources/config.properties");
// set the properties value
prop.setProperty("database", "localhost");
prop.setProperty("dbuser", "mkyong");
prop.setProperty("dbpassword", "password");
// save properties to project root folder
prop.store(output, null);
if(output!=null) {
System.out.println("Output");
output.close();
}
} catch (IOException io) {
io.printStackTrace();
} finally {
if (output != null) {
output.close();
}
}
Properties prop1 = new Properties();
BufferedInputStream input = null;
try {
String filename = "config.properties";
input = (BufferedInputStream) AppCPLoad.class.getClassLoader().getResourceAsStream(filename);
if(input==null){
System.out.println("Sorry, unable to find " + filename);
return;
}
//load a properties file from class path, inside static method
prop1.load(input);
//get the property value and print it out
System.out.println(prop1.getProperty("database"));
System.out.println(prop1.getProperty("dbuser"));
System.out.println(prop1.getProperty("dbpassword"));
if(input!=null) {
System.out.println("Input");
input.close();
}
} catch (IOException ex) {
ex.printStackTrace();
} finally{
if(input!=null){
try {
input.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
}
Please help.
When you run the program, the properties file is loaded and the values are read. After you rewrite the properties file, that doesn't mean that the properties you have loaded already have be to rewritten. You need to reload the properties file and re-read the values. You are looking for an implementation like ReloadableResourceBundleMessageSource