SpringBoot中生成二维码的案例分享_Java

引言

在spring boot项目中整合zxing库来生成二维码是一个常见的需求。

zxing，全称"zebra crossing"，是一个功能强大的开源java库，专门用于二维码的生成与解析。它不仅能够生成qr码，还能解析包括qr码在内的多种二维码格式。zxing提供了多语言api，使得开发者能够轻松地将二维码功能集成到各种应用中。它支持android、ios、java等多个平台，并且除了qr码，还能解析其他一维码和二维码，如ean、upc、datamatrix等。

1. 添加zxing库的依赖

<dependency>
    <groupid>com.google.zxing</groupid>
    <artifactid>core</artifactid>
    <version>3.5.2</version>
</dependency>
<dependency>
    <groupid>com.google.zxing</groupid>
    <artifactid>javase</artifactid>
    <version>3.5.2</version>
</dependency>

2. 生成二维码

创建一个springboot服务类qrcodeservice，用于生成二维码图片：

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;
import org.springframework.stereotype.service;

import java.io.ioexception;
import java.nio.file.filesystems;
import java.nio.file.path;
import java.util.hashmap;
import java.util.map;

@service
public class qrcodeservice {

    public void generateqrcodeimage(string text, int width, int height, string filepath)
            throws ioexception {
        map<encodehinttype, object> hints = new hashmap<>();
        hints.put(encodehinttype.character_set, "utf-8");
        hints.put(encodehinttype.error_correction, errorcorrectionlevel.m);
        hints.put(encodehinttype.margin, 2);

        bitmatrix bitmatrix = new multiformatwriter().encode(text, barcodeformat.qr_code, width, height, hints);

        path path = filesystems.getdefault().getpath(filepath);
        matrixtoimagewriter.writetopath(bitmatrix, "png", path);
    }
}

3. 调用二维码服务

3.1 将二维码图拍你保存

最后在springboot的controller中调用这个服务：

import org.springframework.beans.factory.annotation.autowired;
import org.springframework.web.bind.annotation.getmapping;
import org.springframework.web.bind.annotation.requestparam;
import org.springframework.web.bind.annotation.restcontroller;

import java.io.ioexception;

@restcontroller
public class qrcodecontroller {

    @autowired
    private qrcodeservice qrcodeservice;

    @getmapping("/generateqrcode")
    public string generateqrcode(@requestparam string text, @requestparam int width, @requestparam int height) {
        try {
            qrcodeservice.generateqrcodeimage(text, width, height, "myqrcode.png");
            return "qr code generated successfully!";
        } catch (ioexception e) {
            return "qr code generation failed: " + e.getmessage();
        }
    }
}

当访问/generateqrcode端点并传递text、width和height参数时，它将生成一个名为myqrcode.png的二维码图片并保存到项目根目录下。

http://localhost:8080/generateqrcode?text=hello,world!&width=350&height=350

3.2 直接返回二维码图片

修改qrcodecontroller来返回二维码图片：

import org.springframework.beans.factory.annotation.autowired;
import org.springframework.core.io.bytearrayresource;
import org.springframework.core.io.resource;
import org.springframework.http.httpheaders;
import org.springframework.http.mediatype;
import org.springframework.http.responseentity;
import org.springframework.web.bind.annotation.getmapping;
import org.springframework.web.bind.annotation.requestparam;
import org.springframework.web.bind.annotation.restcontroller;

import java.awt.image.bufferedimage;
import java.io.bytearrayoutputstream;
import java.io.ioexception;
import javax.imageio.imageio;

import com.google.zxing.barcodeformat;
import com.google.zxing.encodehinttype;
import com.google.zxing.multiformatwriter;
import com.google.zxing.common.bitmatrix;
import com.google.zxing.qrcode.decoder.errorcorrectionlevel;

@restcontroller
public class qrcodecontroller {

    @getmapping("/generateqrcode")
    public responseentity<resource> generateqrcode(@requestparam string text, @requestparam integer width, @requestparam integer  height) throws ioexception {
        bitmatrix bitmatrix = new multiformatwriter().encode(text, barcodeformat.qr_code, width, height, gethints());

        bufferedimage qrcodeimage = matrixtoimagewriter.tobufferedimage(bitmatrix);
        bytearrayoutputstream bytearrayoutputstream = new bytearrayoutputstream();
        imageio.write(qrcodeimage, "png", bytearrayoutputstream);

        byte[] qrcodebytes = bytearrayoutputstream.tobytearray();

        httpheaders headers = new httpheaders();
        headers.add(httpheaders.content_type, mediatype.image_png_value);

        return responseentity.ok()
                .headers(headers)
                .contentlength(qrcodebytes.length)
                .body(new bytearrayresource(qrcodebytes));
    }

    private map<encodehinttype, object> gethints() {
        map<encodehinttype, object> hints = new hashmap<>();
        hints.put(encodehinttype.character_set, "utf-8");
        hints.put(encodehinttype.error_correction, errorcorrectionlevel.m);
        hints.put(encodehinttype.margin, 2);
        return hints;
    }
}

generateqrcode先生成二维码的bitmatrix，然后转换为bufferedimage，以便获取二维码图片的字节流。

3.2 注册bufferedimage消息转换器返回图片

3.2中返回图片也可以通过注册一个springboot的消息转换器来实现:

@bean
 public httpmessageconverter<bufferedimage> createimagehttpmessageconverter() {
  return new bufferedimagehttpmessageconverter();
 }

返回图片

package com.example.demo.controller;

import java.awt.image.bufferedimage;

import org.springframework.http.httpstatus;
import org.springframework.http.mediatype;
import org.springframework.http.responseentity;
import org.springframework.web.bind.annotation.getmapping;
import org.springframework.web.bind.annotation.pathvariable;
import org.springframework.web.bind.annotation.requestmapping;
import org.springframework.web.bind.annotation.requestmapping;
import org.springframework.web.bind.annotation.requestmapping;
import org.springframework.web.bind.annotation.restcontroller;

import com.google.zxing.barcodeformat;
import com.google.zxing.client.j2se.matrixtoimagewriter;
import com.google.zxing.common.bitmatrix;
import com.google.zxing.qrcode.qrcodewriter;

@restcontroller
@requestmapping("/qr")
public class qrcodecontroller {

 @getmapping(value = "/{barcode}", produces = mediatype.image_png_value)
 public responseentity<bufferedimage> barbecueean13barcode(@pathvariable("barcode") string barcode)
   throws exception {

  qrcodewriter barcodewriter = new qrcodewriter();
     bitmatrix bitmatrix = 
       barcodewriter.encode(barcode, barcodeformat.qr_code, 200, 200);

  return new responseentity<>(matrixtoimagewriter.tobufferedimage(bitmatrix),httpstatus.ok);
 }

}

现在，当访问/qr端点时，将直接收到一个二维码图片作为响应。