Java如何把图片转成Base64字符串？

Base64可以将任何二进制文件以可打印字符的方式表示，也就是说，任何二进制文件都可以通过Base64编码技术转成字符串。在Java中，可以使用Base64类实现。

Python中的实现：

1、图片（二进制文件）转字符串

import java.io.FileInputStream;
import java.io.IOException;
import java.util.Base64;

public class ImageBase64Utils {

    public static void main(String[] args) throws IOException {
        FileInputStream inputStream = null;
        try {
            Base64.Encoder encoder = Base64.getEncoder();

            inputStream = new FileInputStream("e://aa.jpg");

            int available = inputStream.available();
            byte[] bytes = new byte[available];
            inputStream.read(bytes);

            String base64Str = encoder.encodeToString(bytes);
            System.out.println(base64Str);

        } catch (Exception e) {
            e.printStackTrace();
        }finally {
            inputStream.close();
        }

    }
}

2、字符串转成图片（二进制文件）

import java.io.FileOutputStream;
import java.io.IOException;
import java.util.Base64;

public class StrBase64Utils {

    public static void main(String[] args) throws IOException {

        FileOutputStream outputStream = null;
        try {
            Base64.Decoder decoder = Base64.getDecoder();

            byte[] bytes = decoder.decode("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");

            outputStream = new FileOutputStream("e://temp.jpg");

            outputStream.write(bytes);

        } catch (Exception e) {
            e.printStackTrace();
        }finally {
            outputStream.close();
        }

    }
}