12.使用AspectJ

• AspectJ是一个面向切面的框架,它扩展了Java语言

12.1启用@AspectJ

可以通过XML或Java配置来启用@AspectJ支持,配置@AspectJ

1.9.2
 
            org.aspectj
            aspectjweaver
            ${aspectj.version}
        

12.2声明Aspect

在启用@AspectJ支持下,在应用上下文中定义的任意带有一个@AspectJ注解的切面的bean都将被Spring自动识别并用于配置Spring AOP。

 
    
    
@Aspect
public class Fighter {
    @Pointcut("execution(* com.spring.aop.Tiger.walk())")
    public void foundTiger(){

    }
    @Before(value = "foundTiger()")
    public void foundBefore(){
        System.out.println("Fighter wait for tiger...");
    }
    @AfterReturning("foundTiger()")
        public void foundAfter(){
            System.out.println("Fighter fight with tiger");
        }
}

注意:切点方法必须为空

12.3定义主应用

public class Application {
    public static void main(String[] args) {
        @SuppressWarnings("resource")
        ApplicationContext context=new ClassPathXmlApplicationContext("Spring.xml");
        Tiger tiger=context.getBean(Tiger.class);
        tiger.walk();
    }
}

运行结果为:

image.png

12.4使用hutool进行一个图片练习

• 创建一个ImageCopy类,来实现图片的拷贝

public class ImageCopy {
    private static final Logger logger= LoggerFactory.getLogger(ImageCopy.class);
    public void copyImage() throws IOException{
        logger.info("开始将图片从D盘复制到E盘...");
        File srcFile=new File("D:/110.jpg");
        File destFile=new File("E:/110.jpg");
        InputStream in=new FileInputStream(srcFile);
        OutputStream out=new FileOutputStream(destFile);
        byte[] bytes=new byte[(int) srcFile.length()];
        int len;
        while((len=in.read(bytes))!=-1){
            out.write(bytes,0,len);
        }
        in.close();
        out.close();
    }
}

• 新建一个ImageHandler类
  创建一个前置方法为图片添加水印
  再添加一个后置方法把图片变成黑白色

@Aspect
public class ImageHandler {
    private static final Logger logger= LoggerFactory.getLogger(ImageHandler.class);
    @Pointcut("execution(* com.spring.aop.ImageCopy.copyImage())")
    public void handleImage(){}
    @Before(value = "handleImage()")
    public void pressTextOnImage() throws IOException {
        logger.info("开始给图片添加水印");
        File srcFile=new File("D:/100.jpg");
        BufferedImage srcImg= ImageIO.read(new FileInputStream(srcFile));
        int height=srcImg.getHeight();
        int width=srcImg.getWidth();
        File destFile=new File("D:/110.jpg");
        Color color =new Color(211,71,38);
        int size=15;
        Font font=new Font("微软雅黑",Font.BOLD,size);
        String text="微信";
        ImageUtil.pressText(srcFile,destFile,text,color,font,width/2-text.length()*size,height/2-size,0.8f);
    }
    @AfterReturning("handleImage()")
    public void grayImage(){
        logger.info("开始讲图片转成黑白色");
        File srcFile=new File("E:/110.jpg");
        File destFile=new File("E:/112.jpg");
        ImageUtil.gray(srcFile,destFile);
    }
}

• 定义主应用程序ImageCopyApp

public class ImageCopyApp {
    public static void main(String[] args) {
        ApplicationContext context=new ClassPathXmlApplicationContext("com/spring/aop/Spring-aop.xml");
        ImageCopy imageCopy=context.getBean(ImageCopy.class);
        try {
            imageCopy.copyImage();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

二维码练习

• 建一个QrcodeTest类

public class QrCodetest {
    public static void main(String[] args) {
        QrConfig config=new QrConfig(300,300);
        config.setMargin(3);
        config.setImg("d:/timg.jpg");
        Color foreColor=new Color(238,110,115);
        int foreColorRGB=foreColor.getRGB();
        config.setForeColor(foreColorRGB);
        config.setBackColor(Color.white.getRGB());
        QrCodeUtil.generate("https://www.jianshu.com/u/a32873d23481",config,FileUtil.file("D:/qrcode.jpg"));
    }
}

更多hutool工具请访问：hutool官网
依赖添加

       4.5.1
 
            cn.hutool
            hutool-all
            ${hutool.version}