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Small utilities and convenience wrappers.
/*
* Copyright 2017-2021 Brambolt.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.brambolt.nio.file;
import java.io.File;
import java.io.IOException;
import java.nio.charset.Charset;
import java.nio.charset.StandardCharsets;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.nio.file.StandardCopyOption;
import java.nio.file.StandardOpenOption;
/**
* Small utility functions, porcelain and mnemonics for file-handling.
*
* These functions are easy to remember and use, and useful for simple use
* cases. If speed, robustness in boundary cases, precise error handling or
* other detailed requirements are more important than ease of use, then it is
* best to use the underlying APIs directly.
*/
public class Files {
/**
* Returns the file type extension for the parameter file.
*
* If the file parameter is null, the return value is null.
*
* If the file name does not contain a dot, the returned extension is
* the empty string.
*
* The extension is returned without the dot: csv
*
* @param file The file to get the extension for
* @return The extension, like "csv" or "txt"
*/
public static String getExtension(File file) {
if (null == file)
return null;
String fileName = file.getName();
int offset = fileName.lastIndexOf(".");
if (-1 == offset)
return ""; // No extension
return fileName.substring(offset + 1);
}
/**
* Reads an entire file into a string.
*
* With Java 11+, use java.nio.file.Files.readString.
*
* @param path The path to read from
* @param encoding The encoding to read with
* @return The content at the parameter path as a string in the encoding
* @throws IOException If unable to read the string content
*/
public static String readString(String path, Charset encoding) throws IOException {
return readString(Paths.get(path), encoding);
}
/**
* Reads an entire file into a string.
*
* With Java 11+, use java.nio.file.Files.readString.
*
* @param path The path to read from
* @param encoding The encoding to read with
* @return The content at the parameter path as a string in the encoding
* @throws IOException If unable to read the string content
*/
public static String readString(Path path, Charset encoding) throws IOException {
return new String(java.nio.file.Files.readAllBytes(path), encoding);
}
/**
* Reads an entire file into a string.
*
* With Java 11+, use java.nio.file.Files.readString.
*
* @param file The file to read from
* @param encoding The encoding to read with
* @return The content at the parameter path as a string in the encoding
* @throws IOException If unable to read the string content
*/
public static String readString(File file, Charset encoding) throws IOException {
return readString(file.toPath(), encoding);
}
/**
* Creates a copy of the content at the parameter path, in the temporary
* files directory (normally /tmp, C:\Temp or a
* user-specific location under the home directory).
*
* @param path The path to the content to copy
* @return The path to the newly created copy
* @throws IOException If unable to copy the content
*/
public static Path createTempCopy(Path path) throws IOException {
return createTempCopy(path, false);
}
/**
* Creates a copy of the content at the parameter path, in the temporary
* files directory (normally /tmp, C:\Temp or a
* user-specific location under the home directory).
*
* If the deleteOnExit parameter is true then
* the copy will be removed when the JVM exits.
*
* @param path The path to the content to copy
* @param deleteOnExit The copy will be deleted at JVM exit iff true
* @return The path to the newly created copy
* @throws IOException If unable to copy the content
*/
public static Path createTempCopy(Path path, boolean deleteOnExit) throws IOException {
FileNames.Split fileName = FileNames.Split.apply(path);
Path tmpPath = java.nio.file.Files.createTempFile(fileName.prefix, fileName.suffix);
java.nio.file.Files.copy(path, tmpPath, StandardCopyOption.REPLACE_EXISTING);
if (deleteOnExit)
tmpPath.toFile().deleteOnExit();
return tmpPath;
}
/**
* Writes the parameter content to the parameter file (and erases whatever
* content the file held before, or creates the file if necessary).
*
* The default character set will be used.
*
* @param file The file to write to
* @param content The content to write
* @throws IOException If unable to write to the file
*/
public static void writeString(File file, String content) throws IOException {
writeString(file, content, Charset.defaultCharset());
}
/**
* Writes the parameter content to the parameter file (and erases whatever
* content the file held before, or creates the file if necessary).
*
* @param file The file to write to.
* @param content The content to write.
* @param encoding The character set to use.
* @throws IOException If unable to write to the file.
*/
public static void writeString(File file, String content, Charset encoding) throws IOException {
java.nio.file.Files.write(file.toPath(), content.getBytes(encoding));
}
/**
* Writes the parameter content to the parameter file (and erases whatever
* content the file held before, or creates the file if necessary).
*
* @param file The file to write to.
* @param content The content to write.
* @param openOption The options for opening the destination file.
* @throws IOException If unable to write to the file.
*/
@SuppressWarnings("unused")
public static void writeString(File file, String content, StandardOpenOption openOption) throws IOException {
writeString(file, content, Charset.defaultCharset(), openOption);
}
/**
* Writes the parameter content to the parameter file (and erases whatever
* content the file held before, or creates the file if necessary).
*
* @param file The file to write to.
* @param content The content to write.
* @param encoding The character set to use.
* @param openOption The options for opening the destination file.
* @throws IOException If unable to write to the file.
*/
public static void writeString(File file, String content, Charset encoding, StandardOpenOption openOption) throws IOException {
java.nio.file.Files.write(file.toPath(), content.getBytes(encoding), openOption);
}
}