1. js编码（第一种方式，字符串中即使有中文，在Java后台也能正常解码）

encode64(value) {let typeValue = typeof value;if (typeValue == 'string' || typeValue == 'number') {return window.btoa(window.encodeURIComponent(value).replace(/%([0-9A-F]{2})/g,function toSolidBytes(match, p1) {return String.fromCharCode('0x' + p1);}));} else {return value;}
}

2. js编码（第二种方式，这种方式如果字符串中有中文的话在Java后台解码后会乱码）

encode64(input) {// base64加密开始var keyStr = "ABCDEFGHIJKLMNOP" + "QRSTUVWXYZabcdef" + "ghijklmnopqrstuv"+ "wxyz0123456789+/" + "=";var output = "";var chr1, chr2, chr3 = "";var enc1, enc2, enc3, enc4 = "";var i = 0;do {chr1 = input.charCodeAt(i++);chr2 = input.charCodeAt(i++);chr3 = input.charCodeAt(i++);enc1 = chr1 >> 2;enc2 = ((chr1 & 3) << 4) | (chr2 >> 4);enc3 = ((chr2 & 15) << 2) | (chr3 >> 6);enc4 = chr3 & 63;if (isNaN(chr2)) {enc3 = enc4 = 64;} else if (isNaN(chr3)) {enc4 = 64;}output = output + keyStr.charAt(enc1) + keyStr.charAt(enc2)+ keyStr.charAt(enc3) + keyStr.charAt(enc4);chr1 = chr2 = chr3 = "";enc1 = enc2 = enc3 = enc4 = "";} while (i < input.length);return output;
}

3. Java解码

public static byte[] decode(String str) {
byte[] data = str.getBytes();
int len = data.length;
ByteArrayOutputStream buf = new ByteArrayOutputStream(len);
int i = 0;
int b1, b2, b3, b4;while (i < len) {do {b1 = base64DecodeChars[data[i++]];} while (i < len && b1 == -1);if (b1 == -1) {break;}do {b2 = base64DecodeChars[data[i++]];} while (i < len && b2 == -1);if (b2 == -1) {break;}buf.write((int) ((b1 << 2) | ((b2 & 0x30) >>> 4)));do {b3 = data[i++];if (b3 == 61) {return buf.toByteArray();}b3 = base64DecodeChars[b3];} while (i < len && b3 == -1);if (b3 == -1) {break;}buf.write((int) (((b2 & 0x0f) << 4) | ((b3 & 0x3c) >>> 2)));do {b4 = data[i++];if (b4 == 61) {return buf.toByteArray();}b4 = base64DecodeChars[b4];} while (i < len && b4 == -1);if (b4 == -1) {break;}buf.write((int) (((b3 & 0x03) << 6) | b4));
}System.out.println(buf.toByteArray());
return buf.toByteArray();
}