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

接口名称：/downloadQr
接口描述：生成可直接下载的二维码图片
请求方式：GET
请求参数：String data
响应内容：二维码图片数据流

二、下面直接上代码

• controller层

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);}

• biz层 interface

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;

• biz层 实现

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    }