一、概述

在 二维码初体验 com.google.zxing 实现 我们实现了二维码的生成，但是大部分情况下，二维码的相关功能是作为API接口来提供服务的。

我们下面便演示在springboot、Knife4j下封装api接口来实现二维码生成功能。

二、最终效果

三、源码结构

四、完整代码

如何使用下面的备份文件恢复成原始的项目代码，请移步查阅：神奇代码恢复工具
dog.jpg

//goto pom.xml
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
	<modelVersion>4.0.0</modelVersion>
	<groupId>com.fly</groupId>
	<artifactId>qrcode-web</artifactId>
	<version>1.0.0</version>
	<packaging>jar</packaging>

	<parent>
		<groupId>org.springframework.boot</groupId>
		<artifactId>spring-boot-starter-parent</artifactId>
		<version>2.2.4.RELEASE</version>
		<relativePath />
	</parent>

	<properties>
		<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
		<java.version>1.8</java.version>
	</properties>

	<dependencies>
		<!-- Compile -->
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-web</artifactId>
			<exclusions>
				<exclusion>
					<groupId>org.springframework.boot</groupId>
					<artifactId>spring-boot-starter-logging</artifactId>
				</exclusion>
			</exclusions>
		</dependency>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-log4j2</artifactId>
		</dependency>
		<dependency>
			<groupId>com.github.xiaoymin</groupId>
			<artifactId>knife4j-spring-boot-starter</artifactId>
			<version>2.0.8</version>
		</dependency>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-devtools</artifactId>
			<optional>true</optional>
		</dependency>

		<dependency>
			<groupId>com.google.zxing</groupId>
			<artifactId>core</artifactId>
			<version>3.4.0</version>
		</dependency>
		<dependency>
			<groupId>org.apache.commons</groupId>
			<artifactId>commons-lang3</artifactId>
		</dependency>
		<dependency>
			<groupId>org.projectlombok</groupId>
			<artifactId>lombok</artifactId>
		</dependency>

		<!-- 异步日志，需要加入disruptor依赖 -->
		<dependency>
			<groupId>com.lmax</groupId>
			<artifactId>disruptor</artifactId>
			<version>3.4.2</version>
		</dependency>
	</dependencies>
	<build>
		<finalName>${project.artifactId}-${project.version}</finalName>
		<plugins>
			<plugin>
				<groupId>org.springframework.boot</groupId>
				<artifactId>spring-boot-maven-plugin</artifactId>
			</plugin>
			<plugin>
				<groupId>org.apache.maven.plugins</groupId>
				<artifactId>maven-surefire-plugin</artifactId>
				<configuration>
					<useSystemClassLoader>false</useSystemClassLoader>
				</configuration>
			</plugin>
		</plugins>
	</build>
</project>
//goto src\main\java\com\fly\core\config\Knife4jConfig.java
package com.fly.core.config;

import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Import;

import com.github.xiaoymin.knife4j.spring.annotations.EnableKnife4j;

import io.swagger.annotations.ApiOperation;
import springfox.bean.validators.configuration.BeanValidatorPluginsConfiguration;
import springfox.documentation.builders.ApiInfoBuilder;
import springfox.documentation.builders.PathSelectors;
import springfox.documentation.builders.RequestHandlerSelectors;
import springfox.documentation.service.ApiInfo;
import springfox.documentation.spi.DocumentationType;
import springfox.documentation.spring.web.plugins.Docket;
import springfox.documentation.swagger2.annotations.EnableSwagger2WebMvc;

/**
 * knife4j
 *
 * @author jack
 */
@EnableKnife4j
@Configuration
@EnableSwagger2WebMvc
@Import(BeanValidatorPluginsConfiguration.class)
public class Knife4jConfig
{
    @Value("${knife4j.enable: true}")
    private boolean enable;
    
    @Bean
    Docket defaultApi()
    {
        return new Docket(DocumentationType.SWAGGER_2).enable(enable).apiInfo(apiInfo()).groupName("0.1版").select().apis(RequestHandlerSelectors.basePackage("com.fly.qrcode.api"))
            .apis(RequestHandlerSelectors.withMethodAnnotation(ApiOperation.class)) // 同时满足apis多个条件
            .paths(PathSelectors.any())
            .build();
    }
    
    private ApiInfo apiInfo()
    {
        return new ApiInfoBuilder().title("数据接口API").description("接口文档").termsOfServiceUrl("http://00fly.online/").version("1.0.0").build();
    }
}
//goto src\main\java\com\fly\core\utils\SpringContextUtils.java
package com.fly.core.utils;

import java.net.InetAddress;
import java.net.UnknownHostException;

import javax.servlet.ServletContext;

import org.apache.commons.lang3.StringUtils;
import org.springframework.beans.BeansException;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;
import org.springframework.stereotype.Component;
import org.springframework.util.Assert;

import lombok.extern.slf4j.Slf4j;

/**
 * Spring Context 工具类
 * 
 * @author 00fly
 *
 */
@Slf4j
@Component
public class SpringContextUtils implements ApplicationContextAware
{
    private static ApplicationContext applicationContext;
    
    /**
     * web服务器基准URL
     */
    private static String SERVER_BASE_URL = null;
    
    @Override
    public void setApplicationContext(ApplicationContext applicationContext)
        throws BeansException
    {
        log.info("###### execute setApplicationContext ######");
        SpringContextUtils.applicationContext = applicationContext;
    }
    
    public static ApplicationContext getApplicationContext()
    {
        return applicationContext;
    }
    
    public static <T> T getBean(Class<T> clazz)
    {
        Assert.notNull(applicationContext, "applicationContext is null");
        return applicationContext.getBean(clazz);
    }
    
    /**
     * execute @PostConstruct May be SpringContextUtils not inited, throw NullPointerException
     * 
     * @return
     */
    public static String getActiveProfile()
    {
        Assert.notNull(applicationContext, "applicationContext is null");
        String[] profiles = applicationContext.getEnvironment().getActiveProfiles();
        return StringUtils.join(profiles, ",");
    }
    
    /**
     * can use in @PostConstruct
     * 
     * @param context
     * @return
     */
    public static String getActiveProfile(ApplicationContext context)
    {
        Assert.notNull(context, "context is null");
        String[] profiles = context.getEnvironment().getActiveProfiles();
        return StringUtils.join(profiles, ",");
    }
    
    /**
     * get web服务基准地址，一般为 http://${ip}:${port}/${contentPath}
     * 
     * @return
     * @throws UnknownHostException
     * @see [类、类#方法、类#成员]
     */
    public static String getServerBaseURL()
        throws UnknownHostException
    {
        if (SERVER_BASE_URL == null)
        {
            ServletContext servletContext = getBean(ServletContext.class);
            Assert.notNull(servletContext, "servletContext is null");
            String ip = InetAddress.getLocalHost().getHostAddress();
            SERVER_BASE_URL = "http://" + ip + ":" + getProperty("server.port") + servletContext.getContextPath();
        }
        return SERVER_BASE_URL;
    }
    
    /**
     * getProperty
     * 
     * @param key eg：server.port
     * @return
     * @see [类、类#方法、类#成员]
     */
    public static String getProperty(String key)
    {
        return applicationContext.getEnvironment().getProperty(key, "");
    }
}
//goto src\main\java\com\fly\qrcode\api\ApiController.java
package com.fly.qrcode.api;

import java.awt.image.BufferedImage;
import java.net.URL;

import javax.imageio.ImageIO;
import javax.servlet.http.HttpServletResponse;

import org.apache.commons.lang3.StringUtils;
import org.springframework.core.io.ClassPathResource;
import org.springframework.core.io.Resource;
import org.springframework.http.MediaType;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.PostMapping;

import com.fly.qrcode.qr.QRCodeUtil;

import io.swagger.annotations.Api;
import io.swagger.annotations.ApiImplicitParam;
import io.swagger.annotations.ApiOperation;

/**
 * 
 * QR
 * 
 * @author 00fly
 * @version [版本号, 2021年4月14日]
 * @see [相关类/方法]
 * @since [产品/模块版本]
 */
@Controller
@Api(tags = "二维码API接口")
public class ApiController
{
    @ApiOperation("生成二维码")
    @ApiImplicitParam(name = "content", value = "二维码文本", required = true, example = "乡愁是一棵没有年轮的树,永不老去")
    @PostMapping(value = "/create", produces = MediaType.IMAGE_JPEG_VALUE)
    public void index(String content, HttpServletResponse response)
        throws Exception
    {
        if (StringUtils.isNotBlank(content))
        {
            Resource resource = new ClassPathResource("qrCode/dog.jpg");
            URL imgURL = resource.getURL();
            BufferedImage image = QRCodeUtil.createImage(content, imgURL, true);
            
            // 输出图象到页面
            ImageIO.write(image, "JPEG", response.getOutputStream());
        }
    }
}
//goto src\main\java\com\fly\qrcode\qr\BufferedImageLuminanceSource.java
package com.fly.qrcode.qr;

import java.awt.Graphics2D;
import java.awt.geom.AffineTransform;
import java.awt.image.BufferedImage;

import com.google.zxing.LuminanceSource;

public class BufferedImageLuminanceSource extends LuminanceSource
{
    private BufferedImage image;
    
    private int left;
    
    private int top;
    
    public BufferedImageLuminanceSource(BufferedImage image)
    {
        this(image, 0, 0, image.getWidth(), image.getHeight());
    }
    
    public BufferedImageLuminanceSource(BufferedImage image, int left, int top, int width, int height)
    {
        super(width, height);
        
        int sourceWidth = image.getWidth();
        int sourceHeight = image.getHeight();
        if (left + width > sourceWidth || top + height > sourceHeight)
        {
            throw new IllegalArgumentException("Crop rectangle does not fit within image data.");
        }
        
        for (int y = top; y < top + height; y++)
        {
            for (int x = left; x < left + width; x++)
            {
                if ((image.getRGB(x, y) & 0xFF000000) == 0)
                {
                    image.setRGB(x, y, 0xFFFFFFFF);
                }
            }
        }
        
        this.image = new BufferedImage(sourceWidth, sourceHeight, BufferedImage.TYPE_BYTE_GRAY);
        this.image.getGraphics().drawImage(image, 0, 0, null);
        this.left = left;
        this.top = top;
    }
    
    @Override
    public byte[] getRow(int y, byte[] row)
    {
        if (y < 0 || y >= getHeight())
        {
            throw new IllegalArgumentException("Requested row is outside the image: " + y);
        }
        int width = getWidth();
        if (row == null || row.length < width)
        {
            row = new byte[width];
        }
        image.getRaster().getDataElements(left, top + y, width, 1, row);
        return row;
    }
    
    @Override
    public byte[] getMatrix()
    {
        int width = getWidth();
        int height = getHeight();
        int area = width * height;
        byte[] matrix = new byte[area];
        image.getRaster().getDataElements(left, top, width, height, matrix);
        return matrix;
    }
    
    @Override
    public boolean isCropSupported()
    {
        return true;
    }
    
    @Override
    public LuminanceSource crop(int left, int top, int width, int height)
    {
        return new BufferedImageLuminanceSource(image, this.left + left, this.top + top, width, height);
    }
    
    @Override
    public boolean isRotateSupported()
    {
        return true;
    }
    
    @Override
    public LuminanceSource rotateCounterClockwise()
    {
        int sourceWidth = image.getWidth();
        int sourceHeight = image.getHeight();
        AffineTransform transform = new AffineTransform(0.0, -1.0, 1.0, 0.0, 0.0, sourceWidth);
        BufferedImage rotatedImage = new BufferedImage(sourceHeight, sourceWidth, BufferedImage.TYPE_BYTE_GRAY);
        Graphics2D g = rotatedImage.createGraphics();
        g.drawImage(image, transform, null);
        g.dispose();
        int width = getWidth();
        return new BufferedImageLuminanceSource(rotatedImage, top, sourceWidth - (left + width), getHeight(), width);
    }
}
//goto src\main\java\com\fly\qrcode\qr\QRCodeUtil.java
package com.fly.qrcode.qr;

import java.awt.BasicStroke;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Image;
import java.awt.Shape;
import java.awt.geom.RoundRectangle2D;
import java.awt.image.BufferedImage;
import java.io.File;
import java.net.URL;
import java.util.Hashtable;

import javax.imageio.ImageIO;

import com.google.zxing.BarcodeFormat;
import com.google.zxing.BinaryBitmap;
import com.google.zxing.DecodeHintType;
import com.google.zxing.EncodeHintType;
import com.google.zxing.MultiFormatReader;
import com.google.zxing.MultiFormatWriter;
import com.google.zxing.Result;
import com.google.zxing.common.BitMatrix;
import com.google.zxing.common.HybridBinarizer;
import com.google.zxing.qrcode.decoder.ErrorCorrectionLevel;

public class QRCodeUtil
{
    private static final String CHARSET = "utf-8";
    
    /**
     * 二维码尺寸
     */
    private static final int QRCODE_SIZE = 300;
    
    /**
     * LOGO宽度
     */
    private static final int WIDTH = 60;
    
    /**
     * LOGO高度
     */
    private static final int HEIGHT = 60;
    
    /**
     * 给定内容、图标生成二维码图片
     * 
     * @param content 內容
     * @param imgURL 图标
     * @param needCompress 是否压缩尺寸
     * @return
     * @throws Exception
     * @see [类、类#方法、类#成员]
     */
    public static BufferedImage createImage(String content, URL imgURL, boolean needCompress)
        throws Exception
    {
        Hashtable<EncodeHintType, Object> hints = new Hashtable<>();
        hints.put(EncodeHintType.ERROR_CORRECTION, ErrorCorrectionLevel.H);
        hints.put(EncodeHintType.CHARACTER_SET, CHARSET);
        hints.put(EncodeHintType.MARGIN, 1);
        BitMatrix bitMatrix = new MultiFormatWriter().encode(content, BarcodeFormat.QR_CODE, QRCODE_SIZE, QRCODE_SIZE, hints);
        int width = bitMatrix.getWidth();
        int height = bitMatrix.getHeight();
        BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
        for (int x = 0; x < width; x++)
        {
            for (int y = 0; y < height; y++)
            {
                image.setRGB(x, y, bitMatrix.get(x, y) ? 0xFF000000 : 0xFFFFFFFF);
            }
        }
        if (imgURL == null)
        {
            return image;
        }
        // 插入图片
        insertImage(image, imgURL, needCompress);
        return image;
    }
    
    private static void insertImage(BufferedImage source, URL imgURL, boolean needCompress)
        throws Exception
    {
        if (imgURL == null)
        {
            System.err.println("文件不存在！");
            return;
        }
        Image src = ImageIO.read(imgURL);
        int width = src.getWidth(null);
        int height = src.getHeight(null);
        if (needCompress)
        {
            // 压缩LOGO
            width = Math.min(width, WIDTH);
            height = Math.min(height, HEIGHT);
            Image image = src.getScaledInstance(width, height, Image.SCALE_SMOOTH);
            BufferedImage tag = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
            Graphics g = tag.getGraphics();
            g.drawImage(image, 0, 0, null);
            g.dispose();
            src = image;
        }
        // 插入LOGO
        Graphics2D graph = source.createGraphics();
        int x = (QRCODE_SIZE - width) / 2;
        int y = (QRCODE_SIZE - height) / 2;
        graph.drawImage(src, x, y, width, height, null);
        Shape shape = new RoundRectangle2D.Float(x, y, width, width, 6, 6);
        graph.setStroke(new BasicStroke(3f));
        graph.draw(shape);
        graph.dispose();
    }
    
    /**
     * 解析二维码图
     * 
     * @param file
     * @return
     * @throws Exception
     * @see [类、类#方法、类#成员]
     */
    public static String decode(File file)
        throws Exception
    {
        BufferedImage image = ImageIO.read(file);
        if (image == null)
        {
            return null;
        }
        BufferedImageLuminanceSource source = new BufferedImageLuminanceSource(image);
        BinaryBitmap bitmap = new BinaryBitmap(new HybridBinarizer(source));
        Hashtable<DecodeHintType, String> hints = new Hashtable<>();
        hints.put(DecodeHintType.CHARACTER_SET, CHARSET);
        Result result = new MultiFormatReader().decode(bitmap, hints);
        return result.getText();
    }
    
    /**
     * 解析二维码图
     * 
     * @param path
     * @return
     * @throws Exception
     * @see [类、类#方法、类#成员]
     */
    public static String decode(String path)
        throws Exception
    {
        return decode(new File(path));
    }
}
//goto src\main\java\com\fly\QrCodeApplication.java
package com.fly;

import java.io.IOException;

import org.apache.commons.lang3.SystemUtils;
import org.springframework.boot.CommandLineRunner;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

import com.fly.core.utils.SpringContextUtils;

import lombok.extern.slf4j.Slf4j;

@Slf4j
@SpringBootApplication
public class QrCodeApplication implements CommandLineRunner
{
    public static void main(String[] args)
    {
        SpringApplication.run(QrCodeApplication.class, args);
    }
    
    @Override
    public void run(String... args)
        throws IOException
    {
        if (SystemUtils.IS_OS_WINDOWS)
        {
            log.info("★★★★★★★★  now open Browser ★★★★★★★★ ");
            String url = SpringContextUtils.getServerBaseURL();
            Runtime.getRuntime().exec("cmd /c start /min " + url + "/doc.html");
        }
    }
}
//goto src\main\resources\application.yml
server:
  port: 8080
  servlet:
    context-path: /
    session:
      timeout: 1800
spring:
  mvc:
    view:
      prefix: /WEB-INF/views/
      suffix: .jsp
//goto src\main\resources\log4j2.xml
<?xml version="1.0" encoding="UTF-8"?>
<Configuration status="off">
	<!-- 日志文件目录和压缩文件 -->
	<Properties>
		<Property name="fileName">../logs/hello</Property>
		<Property name="fileGz">../logs/hello/7z</Property>
	</Properties>
	<Appenders>
		<!--这个输出控制台的配置 -->
		<Console name="console" target="SYSTEM_OUT">
			<!--控制台只输出level及以上级别的信息（onMatch），其他的直接拒绝（onMismatch） -->
			<ThresholdFilter level="info" onMatch="ACCEPT" onMismatch="NEUTRAL" />
			<!--输出日志的格式 -->
			<PatternLayout pattern="%d{HH:mm:ss.SSS} [%t] %-5level %logger{36} %L %M - %msg%xEx%n" />
		</Console>

		<!--这个会打印出所有的信息，每次大小超过size，则这size大小的日志会自动存入按年份-月份建立的文件夹下面并进行压缩，作为存档 -->
		<RollingRandomAccessFile name="rollingInfoFile" fileName="${fileName}/springboot-info.log" immediateFlush="false"
			filePattern="${fileGz}/$${date:yyyy-MM}/app-%d{MM-dd-yyyy}-%i.springboot-info.gz">
			<PatternLayout pattern="%d{yyyy-MM-dd 'at' HH:mm:ss z} [%t] %-5level %logger{36} %L %M - %msg%xEx%n" />
			<Policies>
				<TimeBasedTriggeringPolicy interval="6" modulate="true" />
				<SizeBasedTriggeringPolicy size="50 MB" />
			</Policies>
			<Filters>
				<!-- 只记录info级别信息 -->
				<ThresholdFilter level="error" onMatch="DENY" onMismatch="NEUTRAL" />
				<ThresholdFilter level="info" onMatch="ACCEPT" onMismatch="DENY" />
			</Filters>
			<!-- 指定每天的最大压缩包个数，默认7个，超过了会覆盖之前的 -->
			<DefaultRolloverStrategy max="50" />
		</RollingRandomAccessFile>


		<RollingRandomAccessFile name="rollingErrorFile" fileName="${fileName}/springboot-error.log" immediateFlush="false"
			filePattern="${fileGz}/$${date:yyyy-MM}/app-%d{MM-dd-yyyy}-%i.springboot-error.gz">
			<PatternLayout pattern="%d{yyyy-MM-dd 'at' HH:mm:ss z} [%t] %-5level %logger{36} %L %M - %msg%xEx%n" />
			<Policies>
				<TimeBasedTriggeringPolicy interval="6" modulate="true" />
				<SizeBasedTriggeringPolicy size="50 MB" />
			</Policies>
			<Filters>
				<!-- 只记录error级别信息 -->
				<ThresholdFilter level="error" onMatch="ACCEPT" onMismatch="DENY" />
			</Filters>
			<!-- 指定每天的最大压缩包个数，默认7个，超过了会覆盖之前的 -->
			<DefaultRolloverStrategy max="50" />
		</RollingRandomAccessFile>

	</Appenders>

	<Loggers>
		<!-- 全局配置，默认所有的Logger都继承此配置 -->
		<AsyncRoot level="INFO" additivity="false">
			<AppenderRef ref="console" />
			<AppenderRef ref="rollingInfoFile" />
			<AppenderRef ref="rollingErrorFile" />
		</AsyncRoot>
	</Loggers>
</Configuration>

---

有任何问题和建议，都可以向我提问讨论,大家一起进步，谢谢!

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