文件与 byte 数组相互转换

一、获取文件字节流转字节数组输出流再转字节数组

1、file转byte[]

 FileInputStream --> ByteArrayOutputStream --> byte[]

public static byte[] fileToBytes(File file) throws IOException {
    FileInputStream fis = null;
    ByteArrayOutputStream bos = null;
    byte[] resultBytes = null;
    try {
        fis = new FileInputStream(file);
        bos = new ByteArrayOutputStream();
        byte[] bytes = new byte[1024];
        int len;
        while((len = fis.read(bytes))!=-1){
            bos.write(bytes,0,len);
        }
        resultBytes = bos.toByteArray();
    } catch (IOException e) {
        e.printStackTrace();
    } finally {
        bos.close();
        fis.close();
    }
    return  resultBytes;
 }

2、byte数组转File文件

byte [] --> FileOutputStream

 /**
  * byte数组转成file文件
  * @param bytes
  */
public static void  bytesToFile(byte [] bytes,String path) throws IOException {
    //根据路径创建对象，路径不存在会自动创建
    FileOutputStream fos=new FileOutputStream(path);
    //将bytes数组读取到文件中
    fos.write(bytes,0,bytes.length);
    fos.close();
}

二、Files工具类方法

1、file转byte[]

import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Paths;
import java.util.Arrays;

public class FileByte {

    public static void main(String[] args) {

        String path = System.getProperty("user.dir") + "\\src\\test.txt";

        try {
            byte[] encoded = Files.readAllBytes(Paths.get(path));
            System.out.println(Arrays.toString(encoded));
        } catch (IOException e) {

        }
    }
}

2、byte[]转file

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

public class ByteFile {

    public static void main(String[] args) {

        String path = System.getProperty("user.dir") + "\\src\\test.txt";
        String finalPath = System.getProperty("user.dir") + "\\src\\final.txt";

        try {
            byte[] encoded = Files.readAllBytes(Paths.get(path));
            Files.write(Paths.get(finalPath), encoded);
        } catch (IOException e) {

        }
    }
}