Class FileUtils

java.lang.Object

io.fluxzero.common.FileUtils

public class FileUtils
extends Object

Utility class for reading and writing files and classpath resources.

Supports:

• Reading text files from file system, URL, URI, or classpath
• Writing string content to files
• Graceful resolution of paths in JAR and non-JAR environments
• Loading and merging Properties from multiple modules
• Safe fallbacks using Optional

Default character encoding is StandardCharsets.UTF_8.

Constructor Summary

Constructors

Constructor	Description
FileUtils()

Method Summary

Modifier and Type	Method	Description
static URI	getFile(Class<?> referencePoint, String fileName)	Gets a file from a classpath location using a reference class.
static URI	getResourceBaseUri(@NonNull String resourcePath)	Retrieves the base URI of a given resource path.
static URI	getResourceBaseUri(@NonNull String resourcePath, ClassLoader classLoader)	Retrieves the base URI of a given resource path.
static String	loadFile(File file)	Loads file contents from a File.
static String	loadFile(File file, Charset charset)	Loads file contents from a File using a specific charset.
static String	loadFile(Class<?> referencePoint, String fileName)	Loads a classpath resource relative to a given reference class.
static String	loadFile(Class<?> referencePoint, String fileName, Charset charset)	Loads a file from a classpath location using a reference class and charset.
static String	loadFile(String fileName)	Loads the contents of a file located relative to the calling class.
static String	loadFile(String fileName, Charset charset)	Loads a file with a specified charset, using the calling class as reference point.
static String	loadFile(URI uri)	Loads file contents from a URI.
static String	loadFile(URI uri, Charset charset)	Loads file contents from a URI using a specific charset.
static String	loadFile(URL url, Charset charset)	Loads file contents from a URL using a specific charset.
static Properties	loadProperties(String fileName)	Loads properties from the classpath, merging from all available matching resources.
static URI	safeResolve(URI base, String relativePath)	Safely resolves a relative path against a base URI, including JAR URLs.
static Optional<String>	tryLoadFile(File file)	Attempts to load file content from a File.
static Optional<String>	tryLoadFile(File file, Charset charset)	Attempts to load file content from a File with specified charset.
static Optional<String>	tryLoadFile(Class<?> referencePoint, String fileName)	Attempts to load file content relative to a reference class.
static Optional<String>	tryLoadFile(Class<?> referencePoint, String fileName, Charset charset)	Attempts to load file content with specified reference class and charset.
static Optional<String>	tryLoadFile(String fileName)	Attempts to load file content relative to the caller class, returns empty if not found.
static Optional<String>	tryLoadFile(String fileName, Charset charset)	Attempts to load file content with specified charset.
static void	writeFile(String fileName, String content)	Writes a string to a file using UTF-8 encoding.

Methods inherited from class Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details

FileUtils

public FileUtils()

Method Details

writeFile

public static void writeFile(String fileName,
 String content)

Writes a string to a file using UTF-8 encoding.

Parameters:

fileName - the target file name

content - the content to write

loadFile

public static String loadFile(String fileName)

Loads the contents of a file located relative to the calling class.

loadFile

public static String loadFile(Class<?> referencePoint,
 String fileName)

Loads a classpath resource relative to a given reference class.

loadFile

public static String loadFile(String fileName,
 Charset charset)

Loads a file with a specified charset, using the calling class as reference point.

loadFile

public static String loadFile(Class<?> referencePoint,
 String fileName,
 Charset charset)

Loads a file from a classpath location using a reference class and charset.

Throws:

NullPointerException - if the resource cannot be found

getFile

public static URI getFile(Class<?> referencePoint,
 String fileName)

Gets a file from a classpath location using a reference class.

Throws:

NullPointerException - if the resource cannot be found

loadFile

public static String loadFile(URI uri)

Loads file contents from a URI.

loadFile

public static String loadFile(URI uri,
 Charset charset)

Loads file contents from a URI using a specific charset.

loadFile

public static String loadFile(File file)

Loads file contents from a File.

loadFile

public static String loadFile(File file,
 Charset charset)

Loads file contents from a File using a specific charset.

loadFile

public static String loadFile(URL url,
 Charset charset)

Loads file contents from a URL using a specific charset.

Throws:

IllegalArgumentException - if the URL does not represent a file

tryLoadFile

public static Optional<String> tryLoadFile(String fileName)

Attempts to load file content relative to the caller class, returns empty if not found.

tryLoadFile

public static Optional<String> tryLoadFile(Class<?> referencePoint,
 String fileName)

Attempts to load file content relative to a reference class.

tryLoadFile

public static Optional<String> tryLoadFile(String fileName,
 Charset charset)

Attempts to load file content with specified charset.

tryLoadFile

public static Optional<String> tryLoadFile(Class<?> referencePoint,
 String fileName,
 Charset charset)

Attempts to load file content with specified reference class and charset.

tryLoadFile

public static Optional<String> tryLoadFile(File file)

Attempts to load file content from a File.

tryLoadFile

public static Optional<String> tryLoadFile(File file,
 Charset charset)

Attempts to load file content from a File with specified charset.

safeResolve

public static URI safeResolve(URI base,
 String relativePath)

Safely resolves a relative path against a base URI, including JAR URLs.

getResourceBaseUri

public static URI getResourceBaseUri(@NonNull
 @NonNull String resourcePath)

Retrieves the base URI of a given resource path. The resource is resolved relative to the caller's class loader. If the resource path does not exist or cannot be resolved to a valid URI, an exception is thrown.

getResourceBaseUri

public static URI getResourceBaseUri(@NonNull
 @NonNull String resourcePath,
 ClassLoader classLoader)

Retrieves the base URI of a given resource path. The resource is resolved relative to classLoader. If the resource path does not exist or cannot be resolved to a valid URI, an exception is thrown.

loadProperties

public static Properties loadProperties(String fileName)

Loads properties from the classpath, merging from all available matching resources.

If the same key appears in multiple modules, a warning is logged.

Parameters:

fileName - resource path to a properties file

Returns:

merged properties across all modules