[Step-By-Step] How To Read a text file content in Spring Boot

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Reading text file content is a common task in software development, especially when working with Spring Boot applications. In this tutorial, we will guide you through a step-by-step process to read the content of a text file using Spring Boot. Whether you're a beginner or an experienced developer, by the end of this guide, you'll have a clear understanding of how to handle text file reading in a Spring Boot environment.

To read the content of a text file in a Spring Boot application, you can use the built-in utility classes provided by Java and Spring. Here's a step-by-step guide on how to do this:

1. Create the Text File: Make sure you have a text file placed in the resources directory of your Spring Boot project. For example, you can create a file named `sample.txt` inside the `src/main/resources` directory.

2. Create a Controller or Service: You can either create a controller to handle HTTP requests or a service to encapsulate the file reading logic. For this example, let's create a service.

3. Create the Service: Create a service class that will handle the file reading logic. Here's an example of how you can do this:

import org.springframework.core.io.ClassPathResource;

import org.springframework.stereotype.Service;

import org.springframework.util.StreamUtils;

import java.io.IOException;

import java.io.InputStream;

import java.nio.charset.StandardCharsets;

@Service

public class FileService {

    public String readFileContent(String filePath) throws IOException {

        ClassPathResource resource = new ClassPathResource(filePath);

        

        try (InputStream inputStream = resource.getInputStream()) {

            return StreamUtils.copyToString(inputStream, StandardCharsets.UTF_8);

        }

    }

}

4. Inject the Service: You can inject the `FileService` into your controller or any other component that needs to read the file content.

import org.springframework.beans.factory.annotation.Autowired;

import org.springframework.web.bind.annotation.GetMapping;

import org.springframework.web.bind.annotation.RequestMapping;

import org.springframework.web.bind.annotation.RestController;

import java.io.IOException;

@RestController

@RequestMapping("/file")

public class FileController {

    private final FileService fileService;

    @Autowired

    public FileController(FileService fileService) {

        this.fileService = fileService;

    }

    @GetMapping("/read")

    public String readFile() throws IOException {

        String content = fileService.readFileContent("sample.txt");

        return content;

    }

}

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5. Access the Content: Now, when you start your Spring Boot application and make a GET request to `/file/read`, it will read the content of the `sample.txt` file and return it as a response.

Remember to adapt the code according to your application's structure and needs. Also, handle exceptions appropriately in a production environment.

Keep in mind that the above example assumes the file is located in the classpath (`src/main/resources`). If your file is outside the classpath or in an external location, you might need to adjust the code accordingly.

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