Java 实现图片转base64

一. 自己实现byte数组拷贝

public class Base64Util {

    // base64图片 存储的byte数组
    private byte[] baseByte= new byte[0];
    
    public static void main(String[] args) {
        Base64Util base64Util = new Base64Util();
        base64Util.base64Encoding();
    }

    private   void base64Encoding(){
        try {
            // 从本地resource目录下获取图片
            ClassPathResource classPathResource = new ClassPathResource("/images/e88b27550495d06a041a7854fcd07b8c.jpg");
            // base64图片前缀
            String pre = "data:image/jpg;base64,";
            // 读取图片
            FileInputStream fileInputStream = new FileInputStream(classPathResource.getFile());
            // 读取字节长度
            int len = 0;
            // baseByte数组的容量
            int capacity = 0;
            byte [] bytes = new byte[1024];
            while ((len = fileInputStream.read(bytes)) != -1){
                // 对原数组进行拷贝扩容
                baseByte= Arrays.copyOf(baseByte, len + capacity);
                // 将新数据拷贝到新扩容的数组
                System.arraycopy(bytes, 0, baseByte, capacity, len);
                // 数据容量增加
                capacity += len;
            }
            // 获取base64编码器
            Base64.Encoder encoder = Base64.getEncoder();
            // 将字节数组转换base64
            String encodeToString = encoder.encodeToString(baseByte);
            System.out.println("======>>>>>>：" + pre + encodeToString);
            fileInputStream.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

二. 使用ByteArrayOutputStream

public class Base64Util {
    
    public static void main(String[] args) {
        Base64Util base64Util = new Base64Util();
        base64Util.base64Encoding();
    }

    private   void base64Encoding(){
        try {
            // 从本地resource目录下获取图片
            ClassPathResource classPathResource = new ClassPathResource("/images/e88b27550495d06a041a7854fcd07b8c.jpg");
            // base64图片前缀
            String pre = "data:image/jpg;base64,";
            // 读取图片
            FileInputStream fileInputStream = new FileInputStream(classPathResource.getFile());
            // 读取字节长度
            int len = 0;
            byte [] bytes = new byte[1024];
            while ((len = fileInputStream.read(bytes)) != -1){
                // 存储读取的字节数组
                data.write(bytes, 0, len);
            }
            // 获取字节数组
            byte[] baseByte = data.toByteArray();
            // 获取base64编码器
            Base64.Encoder encoder = Base64.getEncoder();
            // 将字节数组转换base64
            String encodeToString = encoder.encodeToString(baseByte);
            System.out.println("======>>>>>>：" + pre + encodeToString);
            fileInputStream.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}