Java 生成可直接下载的二维码（spring boot）

最近做的一个项目中，需要提供给web端一个接口：downloadQr。用到了Google的Zxing框架。项目使用的是springboot框架。

一、API文档

二、下面直接上代码

import com.google.zxing.WriterException;
import org.springframework.web.bind.annotation.GetMapping;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

@GetMapping("downloadQr")
public void downloadQr(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse,
String data) throws IOException, WriterException {
globalBiz.downloadQr(httpServletRequest, httpServletResponse, data);
}

import com.google.zxing.WriterException;
import org.springframework.web.bind.annotation.GetMapping;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

void downloadQr(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, String data) throws WriterException, IOException;

import com.google.common.collect.Lists;
import com.google.zxing.BarcodeFormat;
import com.google.zxing.MultiFormatWriter;
import com.google.zxing.WriterException;
import com.google.zxing.client.j2se.MatrixToImageWriter;
import com.google.zxing.common.BitMatrix;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.OutputStream;

其中关键常量：
CharsetConstant.UTF_8 = "UTF_8";
Constant.QR_WIDTH = 300;
QR_FILE_TYPE = "png";

@Override
public void downloadQr(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, String data) throws WriterException, IOException {
String dataHandle = new String(data.getBytes(CharsetConstant.UTF_8), CharsetConstant.UTF_8);
BitMatrix bitMatrix = new MultiFormatWriter().encode(dataHandle, BarcodeFormat.QR_CODE, Constant.QR_WIDTH, Constant.QR_HEIGHT);

httpServletResponse.reset();//清空输出流

OutputStream os = httpServletResponse.getOutputStream();//取得输出流
MatrixToImageWriter.writeToStream(bitMatrix, QR_FILE_TYPE, os);//写入文件刷新

os.flush();
os.close();//关闭输出流
}