在实际项目中,有些场景我们需要将图片文件转换为base64来进行操作,特此记录一下如何转换
方式一:通过JDK自带的Base64
String imageUrl = "要转换的内容或者是图片url";
Base64.getEncoder().encodeToString(imageUrl.getBytes(StandardCharsets.UTF_8))
方式二:直接将如下代码封装到一个工具类即可
public class Base64Util {
private static final char last2byte = (char) Integer.parseInt("00000011", 2);
private static final char last4byte = (char) Integer.parseInt("00001111", 2);
private static final char last6byte = (char) Integer.parseInt("00111111", 2);
private static final char lead6byte = (char) Integer.parseInt("11111100", 2);
private static final char lead4byte = (char) Integer.parseInt("11110000", 2);
private static final char lead2byte = (char) Integer.parseInt("11000000", 2);
private static final char[] encodeTable = new char[]{'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '+', '/'};
public Base64Util() {
}
/**
* 把图片转为base64串
* @param from
* @return
*/
public static String encode(byte[] from) {
StringBuilder to = new StringBuilder((int) ((double) from.length * 1.34D) + 3);
int num = 0;
char currentByte = 0;
int i;
for (i = 0; i < from.length; ++i) {
for (num %= 8; num < 8; num += 6) {
switch (num) {
case 0:
currentByte = (char) (from[i] & lead6byte);
currentByte = (char) (currentByte >>> 2);
case 1:
case 3:
case 5:
default:
break;
case 2:
currentByte = (char) (from[i] & last6byte);
break;
case 4:
currentByte = (char) (from[i] & last4byte);
currentByte = (char) (currentByte << 2);
if (i + 1 < from.length) {
currentByte = (char) (currentByte | (from[i + 1] & lead2byte) >>> 6);
}
break;
case 6:
currentByte = (char) (from[i] & last2byte);
currentByte = (char) (currentByte << 4);
if (i + 1 < from.length) {
currentByte = (char) (currentByte | (from[i + 1] & lead4byte) >>> 4);
}
}
to.append(encodeTable[currentByte]);
}
}
if (to.length() % 4 != 0) {
for (i = 4 - to.length() % 4; i > 0; --i) {
to.append("=");
}
}
return to.toString();
}
}
参考:https://amore.blog.csdn.net/article/details/110135801?spm=1001.2014.3001.5502