Read resource text file to String in Java

Question

Is there a way to read a text file in the resource into a String?

I suppose this is a popular requirement, but I couldn't find any utility after Googling.

Answer 1

Yes, Guava provides this in the Resources class. For example:

URL url = Resources.getResource("foo.txt");
String text = Resources.toString(url, StandardCharsets.UTF_8);

Answer 2

You can use the old Stupid Scanner trick oneliner to do that without any additional dependency like guava:

String text = new Scanner(AppropriateClass.class.getResourceAsStream("foo.txt"), "UTF-8").useDelimiter("\\A").next();

Guys, don't use 3rd party stuff unless you really need that. There is a lot of functionality in the JDK already.

Answer 3

Pure and simple, jar-friendly, Java 8+ solution

This simple method below will do just fine if you're using Java 8 or greater:

/**
 * Reads given resource file as a string.
 *
 * @param fileName path to the resource file
 * @return the file's contents
 * @throws IOException if read fails for any reason
 */
static String getResourceFileAsString(String fileName) throws IOException {
    ClassLoader classLoader = ClassLoader.getSystemClassLoader();
    try (InputStream is = classLoader.getResourceAsStream(fileName)) {
        if (is == null) return null;
        try (InputStreamReader isr = new InputStreamReader(is);
             BufferedReader reader = new BufferedReader(isr)) {
            return reader.lines().collect(Collectors.joining(System.lineSeparator()));
        }
    }
}

And it also works with resources in jar files.

About text encoding: InputStreamReader will use the default system charset in case you don't specify one. You may want to specify it yourself to avoid decoding problems, like this:

new InputStreamReader(isr, StandardCharsets.UTF_8);

---

Avoid unnecessary dependencies

Always prefer not depending on big, fat libraries. Unless you are already using Guava or Apache Commons IO for other tasks, adding those libraries to your project just to be able to read from a file seems a bit too much.

Answer 4

For java 7:

new String(Files.readAllBytes(Paths.get(getClass().getResource("foo.txt").toURI())));

For Java 11:

Files.readString(Paths.get(getClass().getClassLoader().getResource("foo.txt").toURI()));

Answer 5

yegor256 has found a nice solution using Apache Commons IO:

import org.apache.commons.io.IOUtils;

String text = IOUtils.toString(this.getClass().getResourceAsStream("foo.xml"),
                               "UTF-8");

Answer 6

Guava has a "toString" method for reading a file into a String:

import com.google.common.base.Charsets;
import com.google.common.io.Files;

String content = Files.toString(new File("/home/x1/text.log"), Charsets.UTF_8);

This method does not require the file to be in the classpath (as in Jon Skeet previous answer).

Answer 7

apache-commons-io has a utility name FileUtils:

URL url = Resources.getResource("myFile.txt");
File myFile = new File(url.toURI());

String content = FileUtils.readFileToString(myFile, "UTF-8");  // or any other encoding

Answer 8

I like akosicki's answer with the Stupid Scanner Trick. It's the simplest I see without external dependencies that works in Java 8 (and in fact all the way back to Java 5). Here's an even simpler answer if you can use Java 9 or higher (since InputStream.readAllBytes() was added at Java 9):

String text = new String(AppropriateClass.class.getResourceAsStream("foo.txt")
    .readAllBytes());

If you're concerned about the filename being wrong and/or about closing the stream, you can expand this a little:

String text = null;
InputStream stream = AppropriateClass.class.getResourceAsStream("foo.txt");
if (null != stream) {
    text = stream.readAllBytes();
    stream.close()
}

Answer 9

You can use the following code form Java

new String(Files.readAllBytes(Paths.get(getClass().getResource("example.txt").toURI())));

Answer 10

I often had this problem myself. To avoid dependencies on small projects, I often write a small utility function when I don't need commons io or such. Here is the code to load the content of the file in a string buffer :

StringBuffer sb = new StringBuffer();

BufferedReader br = new BufferedReader(new InputStreamReader(getClass().getResourceAsStream("path/to/textfile.txt"), "UTF-8"));
for (int c = br.read(); c != -1; c = br.read()) sb.append((char)c);

System.out.println(sb.toString());   

Specifying the encoding is important in that case, because you might have edited your file in UTF-8, and then put it in a jar, and the computer that opens the file may have CP-1251 as its native file encoding (for example); so in this case you never know the target encoding, therefore the explicit encoding information is crucial. Also the loop to read the file char by char seems inefficient, but it is used on a BufferedReader, and so actually quite fast.

Answer 11

Here's a solution using Java 11's Files.readString:

public class Utils {
    public static String readResource(String name) throws URISyntaxException, IOException {
        var uri = Utils.class.getResource("/" + name).toURI();
        var path = Paths.get(uri);
        return Files.readString(path);
    }
}

Answer 12

If you want to get your String from a project resource like the file testcase/foo.json in src/main/resources in your project, do this:

String myString= 
 new String(Files.readAllBytes(Paths.get(getClass().getClassLoader().getResource("testcase/foo.json").toURI())));

Note that the getClassLoader() method is missing on some of the other examples.

Answer 13

I'm using the following for reading resource files from the classpath:

import java.io.IOException;
import java.io.InputStream;
import java.net.URISyntaxException;
import java.util.Scanner;

public class ResourceUtilities
{
    public static String resourceToString(String filePath) throws IOException, URISyntaxException
    {
        try (InputStream inputStream = ResourceUtilities.class.getClassLoader().getResourceAsStream(filePath))
        {
            return inputStreamToString(inputStream);
        }
    }

    private static String inputStreamToString(InputStream inputStream)
    {
        try (Scanner scanner = new Scanner(inputStream).useDelimiter("\\A"))
        {
            return scanner.hasNext() ? scanner.next() : "";
        }
    }
}

No third party dependencies required.

Answer 14

At least as of Apache commons-io 2.5, the IOUtils.toString() method supports an URI argument and returns contents of files located inside jars on the classpath:

IOUtils.toString(SomeClass.class.getResource(...).toURI(), ...)

Answer 15

Use Apache commons's FileUtils. It has a method readFileToString

Answer 16

With set of static imports, Guava solution can be very compact one-liner:

toString(getResource("foo.txt"), UTF_8);

The following imports are required:

import static com.google.common.io.Resources.getResource
import static com.google.common.io.Resources.toString
import static java.nio.charset.StandardCharsets.UTF_8

Answer 17

package test;

import java.io.InputStream;
import java.nio.charset.StandardCharsets;
import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        try {
            String fileContent = getFileFromResources("resourcesFile.txt");
            System.out.println(fileContent);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    //USE THIS FUNCTION TO READ CONTENT OF A FILE, IT MUST EXIST IN "RESOURCES" FOLDER
    public static String getFileFromResources(String fileName) throws Exception {
        ClassLoader classLoader = Main.class.getClassLoader();
        InputStream stream = classLoader.getResourceAsStream(fileName);
        String text = null;
        try (Scanner scanner = new Scanner(stream, StandardCharsets.UTF_8.name())) {
            text = scanner.useDelimiter("\\A").next();
        }
        return text;
    }
}

Answer 18

Here is my approach worked fine

public String getFileContent(String fileName) {
    String filePath = "myFolder/" + fileName+ ".json";
    try(InputStream stream = Thread.currentThread().getContextClassLoader().getResourceAsStream(filePath)) {
        return IOUtils.toString(stream, "UTF-8");
    } catch (IOException e) {
        // Please print your Exception
    }
}

Answer 19

If you include Guava, then you can use:

String fileContent = Files.asCharSource(new File(filename), Charset.forName("UTF-8")).read();

(Other solutions mentioned other method for Guava but they are deprecated)

Answer 20

The following cods work for me:

compile group: 'commons-io', name: 'commons-io', version: '2.6'

@Value("classpath:mockResponse.json")
private Resource mockResponse;

String mockContent = FileUtils.readFileToString(mockResponse.getFile(), "UTF-8");

Answer 21

I made NO-dependency static method like this:

import java.nio.file.Files;
import java.nio.file.Paths;

public class ResourceReader {
    public  static String asString(String resourceFIleName) {
        try  {
            return new String(Files.readAllBytes(Paths.get(new CheatClassLoaderDummyClass().getClass().getClassLoader().getResource(resourceFIleName).toURI())));
        } catch (Exception e) {
            throw new RuntimeException(e);
        }
    }
}
class CheatClassLoaderDummyClass{//cheat class loader - for sql file loading
}

Answer 22

I like Apache commons utils for this type of stuff and use this exact use-case (reading files from classpath) extensively when testing, especially for reading JSON files from /src/test/resources as part of unit / integration testing. e.g.

public class FileUtils {

    public static String getResource(String classpathLocation) {
        try {
            String message = IOUtils.toString(FileUtils.class.getResourceAsStream(classpathLocation),
                    Charset.defaultCharset());
            return message;
        }
        catch (IOException e) {
            throw new RuntimeException("Could not read file [ " + classpathLocation + " ] from classpath", e);
        }
    }

}

For testing purposes, it can be nice to catch the IOException and throw a RuntimeException - your test class could look like e.g.

    @Test
    public void shouldDoSomething () {
        String json = FileUtils.getResource("/json/input.json");

        // Use json as part of test ...
    }

Answer 23

Guava also has Files.readLines() if you want a return value as List<String> line-by-line:

List<String> lines = Files.readLines(new File("/file/path/input.txt"), Charsets.UTF_8);

Please refer to here to compare 3 ways (BufferedReader vs. Guava's Files vs. Guava's Resources) to get String from a text file.

Answer 24

public static byte[] readResoureStream(String resourcePath) throws IOException {
    ByteArrayOutputStream byteArray = new ByteArrayOutputStream();
    InputStream in = CreateBffFile.class.getResourceAsStream(resourcePath);

    //Create buffer
    byte[] buffer = new byte[4096];
    for (;;) {
        int nread = in.read(buffer);
        if (nread <= 0) {
            break;
        }
        byteArray.write(buffer, 0, nread);
    }
    return byteArray.toByteArray();
}

Charset charset = StandardCharsets.UTF_8;
String content = new   String(FileReader.readResoureStream("/resource/...*.txt"), charset);
String lines[] = content.split("\\n");