java获取包下面的自定义注解

太过爱你忘了你带给我的痛 2022-07-16 04:27 385阅读 0赞

自定义了Controller和RequestMapping两个注解，先去扫描加了@Controller注解的类，接着扫描这些类下面加了@RequestMapping注解的方法，然后通过java的反射invoke方法去调用加了RequestMapping注解的方法。

（1）该工程的目录结构如下

完整的工程代码下载链接如下：[https://github.com/HelloKittyNII/JavaCustomAnnotation][https_github.com_HelloKittyNII_JavaCustomAnnotation]

> ![20161005172034516][]

（2）annotation包下面自定义了两个注解。

Controller.java

package com.huawi.annotation;
    
    import java.lang.annotation.ElementType;
    import java.lang.annotation.Retention;
    import java.lang.annotation.RetentionPolicy;
    import java.lang.annotation.Target;
    
    /**
     * Created by wzj on 2016/10/1.
     */
    @Target(ElementType.TYPE)
    @Retention(RetentionPolicy.RUNTIME)
    public @interface Controller
    {
        String value() default "";
    }

package com.huawi.annotation;
    
    import java.lang.annotation.ElementType;
    import java.lang.annotation.Retention;
    import java.lang.annotation.RetentionPolicy;
    import java.lang.annotation.Target;
    
    /**
     * Created by wzj on 2016/10/1.
     */
    @Target({ElementType.METHOD, ElementType.TYPE})
    @Retention(RetentionPolicy.RUNTIME)
    public @interface RequestMapping
    {
        String value() default "";
    }

（3）bean包下面定义了一个存放RequestMapping注解方法的对象

ExecutorBean.java

package com.huawi.bean;
    
    import java.lang.reflect.Method;
    import java.util.Objects;
    
    /**
     * Created by wzj on 2016/10/1.
     */
    public class ExecutorBean
    {
        private Object object;
    
        private Method method;
    
        public Object getObject()
        {
            return object;
        }
    
        public void setObject(Object object)
        {
            this.object = object;
        }
    
        public Method getMethod()
        {
            return method;
        }
    
        public void setMethod(Method method)
        {
            this.method = method;
        }
    }

（4）controller包下面定义了几个类，其中有两个类使用了自定义的Controller注解

CatController.java

package com.huawi.controller;
    
    import com.huawi.annotation.Controller;
    import com.huawi.annotation.RequestMapping;
    
    /**
     * Created by wzj on 2016/10/1.
     */
    @Controller
    public class CatController
    {
        @RequestMapping(value = "/test1")
        public void test1()
        {
            System.out.println("CatController->test1()");
        }
    
        @RequestMapping(value = "/test2")
        public void test2()
        {
            System.out.println("CatController->test2()");
        }
    }

DogController.java

package com.huawi.controller;
    
    import com.huawi.annotation.Controller;
    import com.huawi.annotation.RequestMapping;
    
    /**
     * Created by wzj on 2016/10/1.
     */
    @Controller
    public class DogController
    {
        @RequestMapping(value = "/test3")
        public void test3()
        {
            System.out.println("DogController->test3()");
        }
    
        @RequestMapping(value = "/test4")
        public void test4()
        {
            System.out.println("DogController->test4()");
        }
    }
    Rabbit.java

package com.huawi.controller;
    
    import com.huawi.annotation.RequestMapping;
    
    /**
     * Created by wzj on 2016/10/5.
     */
    public class Rabbit
    {
        @RequestMapping
        public void test1()
        {
            System.out.println("Rabbit->test1()");
        }
    }
    
    (5)util包下面定义了一个工具类，来对包进行扫描获取自定义注解的类和方法

AnnoManageUtil.java

package com.huawi.util;
    
    import com.huawi.annotation.RequestMapping;
    import com.huawi.bean.ExecutorBean;
    
    import java.io.File;
    import java.io.FileFilter;
    import java.io.IOException;
    import java.io.UnsupportedEncodingException;
    import java.lang.annotation.Annotation;
    //import java.lang.reflect.Method;
    import java.lang.reflect.Method;
    import java.net.URL;
    import java.net.URLDecoder;
    import java.nio.file.DirectoryStream;
    import java.nio.file.Files;
    import java.nio.file.Path;
    import java.nio.file.Paths;
    import java.util.ArrayList;
    import java.util.Enumeration;
    import java.util.List;
    import java.util.Map;
    
    /**
     * Created by wzj on 2016/10/1.
     */
    public final class AnnoManageUtil
    {
        /**
         * 获取当前包路径下指定的Controller注解类型的文件
         * @param packageName 包名
         * @param annotation 注解类型
         * @return 文件
         */
        public static  List<Class<?>> getPackageController(String packageName, Class<? extends Annotation> annotation)
        {
            List<Class<?>> classList = new ArrayList<Class<?>>();
    
            String packageDirName = packageName.replace('.', '/');
    
            Enumeration<URL> dirs = null;
    
            //获取当前目录下面的所有的子目录的url
            try
            {
                dirs = Thread.currentThread().getContextClassLoader().getResources(packageDirName);
            }
            catch (IOException e)
            {
                e.printStackTrace();
            }
    
            while (dirs.hasMoreElements())
            {
                URL url = dirs.nextElement();
    
                //得到但钱url的类型
                String protocol = url.getProtocol();
    
                //如果当前类型是文件类型
                if ("file".equals(protocol))
                {
                    //获取包的物理路径
                    String filePath = null;
                    try
                    {
                        filePath = URLDecoder.decode(url.getFile(), "UTF-8");
                    }
                    catch (UnsupportedEncodingException e)
                    {
                        e.printStackTrace();
                    }
    
                    filePath = filePath.substring(1);
                    getFilePathClasses(packageName,filePath,classList,annotation);
                }
            }
    
    
                return classList;
        }
    
        /**
         * 从指定的包下面找到文件名
         * @param packageName
         * @param filePath
         * @param classList
         * @param annotation 注解类型
         */
        private static void getFilePathClasses(String packageName,String filePath,List<Class<?>> classList,
                                               Class<? extends Annotation> annotation)
        {
            Path dir = Paths.get(filePath);
    
            DirectoryStream<Path> stream = null;
            try
            {
                //获得当前目录下的文件的stream流
                stream = Files.newDirectoryStream(dir);
            }
            catch (IOException e)
            {
                e.printStackTrace();
            }
    
            for(Path path : stream)
            {
                String fileName = String.valueOf(path.getFileName());
    
                String className = fileName.substring(0, fileName.length() - 6);
    
                Class<?> classes = null;
                try
                {
                    classes = Thread.currentThread().getContextClassLoader().loadClass(packageName + "." + className);
                }
                catch (ClassNotFoundException e)
                {
                    e.printStackTrace();
                }
    
                //判断该注解类型是不是所需要的类型
                if (null != classes && null != classes.getAnnotation(annotation))
                {
                    //把这个文件加入classlist中
                    classList.add(classes);
                }
            }
        }
    
        /**
         * 获取classList下面的RequestMapping方法保存在mapp中
         * @param classList 保存加了Controller的类
         * @param mapp  存放url和ExecutorBean的对应关系
         */
        public static void getRequestMappingMethod(List<Class<?>> classList, Map<String,ExecutorBean> mapp)
        {
            for (Class classes : classList)
            {
                //得到该类下面的所有方法
                Method[] methods = classes.getDeclaredMethods();
    
                for (Method method : methods)
                {
                    //得到该类下面的RequestMapping注解
                    RequestMapping requestMapping = method.getAnnotation(RequestMapping.class);
                    if (null != requestMapping)
                    {
                        ExecutorBean executorBean = new ExecutorBean();
                        try
                        {
                            executorBean.setObject(classes.newInstance());
                        }
                        catch (InstantiationException e)
                        {
                            e.printStackTrace();
                        }
                        catch (IllegalAccessException e)
                        {
                            e.printStackTrace();
                        }
    
                        executorBean.setMethod(method);
    
                        mapp.put(requestMapping.value(),executorBean);
    
                    }
                }
            }
        }
    
    
    
    
    }
    
    (6)test包下面是一个测试的类

main.java

package com.huawi.test;
    
    import com.huawi.annotation.Controller;
    import com.huawi.bean.ExecutorBean;
    import com.huawi.util.AnnoManageUtil;
    
    import java.io.IOException;
    import java.lang.reflect.InvocationTargetException;
    import java.util.HashMap;
    import java.util.List;
    import java.util.Map;
    
    public class Main {
    
        public static void main(String[] args)
        {
            List<Class<?>> classesList = null;
            classesList = AnnoManageUtil.getPackageController("com.huawi.controller",Controller.class);
    
            Map<String,ExecutorBean> mmap = new HashMap<String,ExecutorBean>();
    
            AnnoManageUtil.getRequestMappingMethod(classesList,mmap);
    
            ExecutorBean bean = mmap.get("/test1");
            try {
                bean.getMethod().invoke(bean.getObject());
            } catch (IllegalAccessException e) {
                e.printStackTrace();
            } catch (InvocationTargetException e) {
                e.printStackTrace();
            }
    
        }
    }

[https_github.com_HelloKittyNII_JavaCustomAnnotation]: https://github.com/HelloKittyNII/JavaCustomAnnotation
[20161005172034516]: /images/20220716/aae6dcd94e9c420e8128523e65563736.png