为什么我用中文不行啊，明明写了UTF-8

package com.xiaoqi.zxing;

import java.io.File;

import java.nio.file.Path;

import java.util.HashMap;

import com.google.zxing.BarcodeFormat;

import com.google.zxing.EncodeHintType;

import com.google.zxing.MultiFormatWriter;

import com.google.zxing.client.j2se.MatrixToImageWriter;

import com.google.zxing.common.BitMatrix;

import com.google.zxing.qrcode.decoder.ErrorCorrectionLevel;

public class CreatQRCode {

public static void main(String[] args) {

int width = 300;

int height = 300;

String format = "png";

String content = "爱";

HashMap hints = new HashMap();

hints.put(EncodeHintType.CHARACTER_SET, "utf-8");

hints.put(EncodeHintType.ERROR_CORRECTION, ErrorCorrectionLevel.M);

hints.put(EncodeHintType.MARGIN, "2");

try {

BitMatrix bitMatrix=new MultiFormatWriter().encode(content, BarcodeFormat.QR_CODE, width, height);

Path file = new File("D:/code/img.png").toPath();

MatrixToImageWriter.writeToPath(bitMatrix, format, file);

} catch (Exception e) {

e.printStackTrace();

}

}

}