This article shows a few ways to save a byte[] into a file.
For JDK 1.7 and above, the NIO Files.write is the simplest solution to save byte[] to a file.
// bytes = byte[]
Path path = Paths.get("/path/file");
Files.write(path, bytes);FileOutputStream is the best alternative.
try (FileOutputStream fos = new FileOutputStream("/path/file")) {
fos.write(bytes);
//fos.close // no need, try-with-resources auto close
}If we have Apache Commons IO, try FileUtils.
FileUtils.writeByteArrayToFile(new File("/path/file"), bytes);pom.xml
<dependency>
<groupId>commons-io</groupId>
<artifactId>commons-io</artifactId>
<version>2.7</version>
</dependency>
1. Save byte[] to a file.
The below example reads a file and converts the data into a byte[]. Later, we save the byte[] into another file.
ByteToFile.java
package com.favtuts.io.howto;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import org.apache.commons.io.FileUtils;
public class ByteToFile {
public static void main(String[] args) {
try {
// tested with character data
String filePath = "/home/tvt/workspace/favtuts/file.txt";
// file to bytes[]
// byte[] bytes = Files.readAllBytes(Paths.get(filePath));
// byte[] bytes = readFileToBytesClassic(filePath);
// byte[] bytes = readFileToBytesJava7(filePath);
// byte[] bytes = readFileToBytesJavaNio(filePath);
byte[] bytes = readFileToBytesCommonsIO(filePath);
// save byte[] to a file
writeBytesToFile("/home/tvt/workspace/favtuts/file2.txt", bytes);
writeBytesToFileNio("/home/tvt/workspace/favtuts/file3.txt", bytes);
writeBytesToFileApache("/home/tvt/workspace/favtuts/file4.txt", bytes);
System.out.println("Done");
// tested with binary data
filePath = "/home/tvt/workspace/favtuts/phone.png";
bytes = readFileToBytesJavaNio(filePath);
// save byte[] to a file
writeBytesToFile("/home/tvt/workspace/favtuts/phone2.png", bytes);
writeBytesToFileNio("/home/tvt/workspace/favtuts/phone3.png", bytes);
writeBytesToFileApache("/home/tvt/workspace/favtuts/phone4.png", bytes);
} catch (IOException e) {
e.printStackTrace();
}
}
private static byte[] readFileToBytesJavaNio(String filePath) throws IOException {
byte[] bytes = Files.readAllBytes(Paths.get(filePath));
return bytes;
}
// Apache Commons IO, try FileUtils.
private static byte[] readFileToBytesCommonsIO(String filePath) throws IOException {
//...
File file = new File(filePath);
byte[] bytes = FileUtils.readFileToByteArray(file);
return bytes;
}
// try-with-resources version
private static byte[] readFileToBytesJava7(String filePath) throws IOException {
File file = new File(filePath);
byte[] bytes = new byte[(int) file.length()];
// funny, if can use Java 7, please uses Files.readAllBytes(path)
try(FileInputStream fis = new FileInputStream(file)){
fis.read(bytes);
}
return bytes;
}
// file to byte[], old and classic way, before Java 7
private static byte[] readFileToBytesClassic(String filePath) throws IOException {
File file = new File(filePath);
byte[] bytes = new byte[(int) file.length()];
FileInputStream fis = null;
try {
fis = new FileInputStream(file);
//read file into bytes[]
fis.read(bytes);
} finally {
if (fis != null) {
fis.close();
}
}
return bytes;
}
//JDK 7 - FileOutputStream + try-with-resources
private static void writeBytesToFile(String fileOutput, byte[] bytes)
throws IOException {
try (FileOutputStream fos = new FileOutputStream(fileOutput)) {
fos.write(bytes);
}
}
//JDK 7, NIO, Files.write
private static void writeBytesToFileNio(String fileOutput, byte[] bytes)
throws IOException {
Path path = Paths.get(fileOutput);
Files.write(path, bytes);
}
// Apache Commons IO
private static void writeBytesToFileApache(String fileOutput, byte[] bytes)
throws IOException {
FileUtils.writeByteArrayToFile(new File(fileOutput), bytes);
}
}
Download Source Code
$ git clone https://github.com/favtuts/java-core-tutorials-examples
$ cd java-io/howto