在conf文件夹中读取属性文件

Question

I have a properties file which is located under conf folder. conf folder is under the project root directory. I am using the following code.

public class PropertiesTest {
 public static void main(String[] args) {
    InputStream inputStream = PropertiesTest.class
            .getResourceAsStream("/conf/sampleprop.conf");
    Properties prop = new Properties();
    try {
        prop.load(inputStream);
    } catch (IOException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }

    System.out.println(prop.getProperty("TEST"));
}
}

But I get nullpointer exception.

I have tried using

InputStream inputStream = PropertiesTest.class
        .getResourceAsStream("./conf/sampleprop.conf");

and

InputStream inputStream = PropertiesTest.class
        .getResourceAsStream("conf/sampleprop.conf");

But all result in nullpointer exception. Can anyone please help. Thanks in advance

Answer 1

Try to recover your working directory first:

String workingDir = System.getProperty("user.dir");
System.out.println("Current working dir: " + workingDir);

and then is simple:

Properties propertiesFile = new Properties();
propertiesFile.load(new FileInputStream(workingDir+ "/yourFilePath"));
    String first= propertiesFile.getProperty("myprop.first");

Regards, fabio

Answer 2

The getResourceAsStream() method tries to locate and load the resource using the ClassLoader of the class it is called on. Ideally it can locate the files only the class folders .. Rather you could use FileInputStream with relative path.

EDIT

if the conf folder is under src, then you still be able to access with getResourceAsStream()

 InputStream inputStream = Test.class
                    .getResourceAsStream("../conf/sampleprop.conf");

the path would be relative to the class from you invoke getRes.. method.

If not

 try {
                FileInputStream fis = new FileInputStream("conf/sampleprop.conf");
                Properties prop = new Properties();
                prop.load(fis);
                System.out.println(prop.getProperty("TEST"));
            } catch (Exception e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }

NOTE: this will only work if it is Stand alone application/in eclipse. This will not work if its web based (as the root will be Tomcat/bin, for eg)

I would suggest to copy the configuration file at designated place, then you can acess at ease. At certain extent 'System.getProperty("user.dir")' can be used if you are always copying the file 'tomcat` root or application root. But if the files to be used by external party, ideal to copy in a configurable folder (C:\\appconf)

Answer 3

Your code works like a charm! But you might have to add the project root dir to your classpath.

If you work with Maven, place your configuration in src/main/resources/conf/sampleprop.conf

When invoking java directly add the project root dir with the java -classpath parameter. Something like:

java -classpath /my/classes/dir:/my/project/root/dir my.Main