中英文字符转换解决乱码问题

public class Base64 {
/**
 * Translates the specified byte array into a Base64 string as per
 * Preferences.put(byte[]).
 */
public  static String byteArrayToBase64(byte[] a) {//中文字符编码转换，解决传中文字符乱码
return byteArrayToBase64(a, false);
}
   

/**
 * Translates the specified byte array into an "alternate representation"
 * Base64 string. This non-standard variant uses an alphabet that does not
 * contain the uppercase alphabetic characters, which makes it suitable for
 * use in situations where case-folding occurs.
 */
public static String byteArrayToAltBase64(byte[] a) {
return byteArrayToBase64(a, true);
}

public static String byteArrayToBase64(byte[] a, boolean alternate) {
int aLen = a.length;
int numFullGroups = aLen / 3;
int numBytesInPartialGroup = aLen - 3 * numFullGroups;
int resultLen = 4 * ((aLen + 2) / 3);
StringBuffer result = new StringBuffer(resultLen);
char[] intToAlpha = (alternate ? intToAltBase64 : intToBase64);

// Translate all full groups from byte array elements to Base64
int inCursor = 0;
for (int i = 0; i < numFullGroups; i++) {
int byte0 = a[inCursor++] & 0xff;
int byte1 = a[inCursor++] & 0xff;
int byte2 = a[inCursor++] & 0xff;
result.append(intToAlpha[byte0 >> 2]);
result.append(intToAlpha[(byte0 << 4) & 0x3f | (byte1 >> 4)]);
result.append(intToAlpha[(byte1 << 2) & 0x3f | (byte2 >> 6)]);
result.append(intToAlpha[byte2 & 0x3f]);
}

// Translate partial group if present
if (numBytesInPartialGroup != 0) {
int byte0 = a[inCursor++] & 0xff;
result.append(intToAlpha[byte0 >> 2]);
if (numBytesInPartialGroup == 1) {
result.append(intToAlpha[(byte0 << 4) & 0x3f]);
result.append("==");
} else {
// assert numBytesInPartialGroup == 2;
int byte1 = a[inCursor++] & 0xff;
result.append(intToAlpha[(byte0 << 4) & 0x3f | (byte1 >> 4)]);
result.append(intToAlpha[(byte1 << 2) & 0x3f]);
result.append('=');
}
}
// assert inCursor == a.length;
// assert result.length() == resultLen;
return result.toString();