Java – Read a file from resources folder

https://www.mkyong.com/java/java-read-a-file-from-resources-folder/

 this tutorial, we will show you how to read a file from a resources folder, in both Java and Unit Test environment. In simple, put files in a resources folder, and read the file with following code snippets :

ClassLoader classLoader = getClass().getClassLoader();
File file = new File(classLoader.getResource("file/test.xml").getFile());

1. Project Directory

Review a Maven project Structure.

2. Classic Example

Example to read a file “test.txt” from a resources folder.

main/resources/file/test.txt

This is line 1
This is line 2
This is line 3
This is line 4
This is line 5

Hello.java

package com.mkyong;

import java.io.File;
import java.io.IOException;
import java.util.Scanner;

public class Hello {

  public static void main(String[] args) {
 Hello obj = new Hello();
 System.out.println(obj.getFile("file/test.txt"));
  }

  private String getFile(String fileName) {

 StringBuilder result = new StringBuilder("");

 //Get file from resources folder
 ClassLoader classLoader = getClass().getClassLoader();
 File file = new File(classLoader.getResource(fileName).getFile());

 try (Scanner scanner = new Scanner(file)) {

  while (scanner.hasNextLine()) {
   String line = scanner.nextLine();
   result.append(line).append("\n");
  }

  scanner.close();

 } catch (IOException e) {
  e.printStackTrace();
 }

 return result.toString();

  }

}

Output

This is line 1
This is line 2
This is line 3
This is line 4
This is line 5

3. IOUtils Example

This example uses IOUtils to parse a file.

pom.xml

<dependency>
 <groupId>org.apache.directory.studio</groupId>
 <artifactId>org.apache.commons.io</artifactId>
 <version>2.4</version>
</dependency>

Hello.java

package com.mkyong;

import java.io.IOException;
import org.apache.commons.io.IOUtils;

public class Hello {

  public static void main(String[] args) {

 Hello obj = new Hello();
 System.out.println(obj.getFileWithUtil("file/test.txt"));

  }

  private String getFileWithUtil(String fileName) {

 String result = "";

 ClassLoader classLoader = getClass().getClassLoader();
 try {
     result = IOUtils.toString(classLoader.getResourceAsStream(fileName));
 } catch (IOException e) {
  e.printStackTrace();
 }

 return result;
  }

}

Output

This is line 1
This is line 2
This is line 3
This is line 4
This is line 5

4. Unit Test Example

A jUnit example.

test/resources/xml/test.xml

<test>
 <case id=1>
  <param>100</param>
  <expected>mkyong</expected>
 </case>
 <case id=2>
  <param>99</param>
  <expected>mkyong</expected>
 </case>
</test>

TestHello.java

package com.mkyong;

import java.io.IOException;
import org.apache.commons.io.IOUtils;
import org.junit.Test;

public class TestHello {

  @Test
  public void testHello() {

   String result = getFile("xml/test.xml");
   System.out.println(result);

  }

  private String getFile(String fileName){

   String result = "";

   ClassLoader classLoader = getClass().getClassLoader();
   try {
  result = IOUtils.toString(classLoader.getResourceAsStream(fileName));
   } catch (IOException e) {
  e.printStackTrace();
   }

   return result;

  }
}

Output

<test>
 <case id=1>
  <param>100</param>
  <expected>mkyong</expected>
 </case>
 <case id=2>
  <param>99</param>
  <expected>mkyong</expected>
 </case>
</test>