格式:
	public @interface AnnotationName {
		屬性列表;
	}
	
Annotation注解是可以編譯得到對(duì)應(yīng)的.class字節(jié)碼文件，驗(yàn)證了注解是可以參與編譯過程的

通過反編譯工具可以得到一下內(nèi)容
【Annotation本質(zhì)】
public interface MyAnnotation1 extends java.lang.annotation.Annotation {
}

MyAnnotation1
	本質(zhì)是一個(gè)interface，同時(shí)java.lang.annotation.Annotation 子接口

package cn.ocean888.a_annotation.MyAnnotation;

/**
 * 自定義注解?。?！
 * public interface MyAnnotation1 extends java.lang.annotation.Annotation {
 * }
 *
 * @author Anonymous
 * @date 2020/3/10 11:01
 */
public @interface MyAnnotation1 {
    // 屬性 ==> 方法形式
}

className = cn.ocean888.a_annotation.Person
id = 1
name = "ocean"

package cn.ocean888.a_annotation;

public class Person {
    Integer id;
    String name;

    public Person() {
    }

    public Person(Integer id, String name) {
        this.id = id;
        this.name = name;
    }

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    @Override
    public String toString() {
        return "Person{" +
                "id=" + id +
                ", name='" + name + '\'' +
                '}';
    }
}

package cn.ocean888.a_annotation;

import java.io.FileInputStream;
import java.io.IOException;
import java.lang.reflect.Field;
import java.lang.reflect.InvocationTargetException;
import java.util.Properties;

public class Demo1 {
    public static void main(String[] args) throws ClassNotFoundException, NoSuchMethodException, InvocationTargetException, InstantiationException, IllegalAccessException, IOException, NoSuchFieldException {
        Properties properties = new Properties();
        properties.load(new FileInputStream("./src/1.properties"));

        String className = properties.getProperty("className");
        String id = properties.getProperty("id");
        String name = properties.getProperty("name");
        System.out.println(className);

        /*
        使用反射的方法
         */
        Class<?> aClass = Class.forName(className);
        Person person = (Person) aClass.getConstructor().newInstance();
        System.out.println(person);

        Field declaredField = aClass.getDeclaredField("id");
        declaredField.setAccessible(true);
        declaredField.set(person, Integer.parseInt(id));

        Field declaredField2 = aClass.getDeclaredField("name");
        declaredField2.setAccessible(true);
        declaredField2.set(person, name);

        System.out.println(person);
    }
}

package cn.ocean888.a_annotation;

import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

// 聲明當(dāng)前注解有且只能用于類名之上
@Target(ElementType.TYPE)
// 當(dāng)前注解參與代碼運(yùn)行
@Retention(RetentionPolicy.RUNTIME)
@interface MyAnnotaion1 {
    // 屬性
    String className();
    int id();
    String name();
}

package cn.ocean888.a_annotation;

import java.lang.annotation.Annotation;

@MyAnnotaion1(className = "cn.ocean888.a_annotation.Person",
    id = 2,
    name = "ocean")
public class ReflectAnnotation {
    public static void main(String[] args) {
        // 加載ReflectAnnotation
        Class<ReflectAnnotation> cls = ReflectAnnotation.class;

        // 因?yàn)樽⒔庠兕惷?通過Class獲取對(duì)應(yīng)的Annotation
        MyAnnotaion1 annotation = cls.getAnnotation(MyAnnotaion1.class);

        String s = annotation.className();
        int id = annotation.id();
        String name = annotation.name();

        System.out.println(s);
        System.out.println(id);
        System.out.println(name);
    }
}

package cn.ocean888.a_annotation_checkMethod;

import java.util.ArrayList;

/**
 * 需要測試的方法
 */
public class Tools {
    @Check
    public void test1() {
        String str = null;
        System.out.println(str.toString());
    }

    @Check
    public void test2() {
        int[] arr = null;
        System.out.println(arr[5]);
    }

    @Check
    public void test3() {
        int[] arr = {1,2,3,4,5};
        System.out.println(arr[3]);
    }

    @Check
    public void test4() {
        ArrayList<Integer> integers = new ArrayList<>();
        System.out.println(integers.get(20).toString());
    }

    @Check
    public void test5() {
        throw new NullPointerException("NullPointException");
    }
}

package cn.ocean888.a_annotation_checkMethod;

public class Utils {
    @Check
    public void test() {
        throw new IndexOutOfBoundsException("下標(biāo)越界");
    }
}

package cn.ocean888.a_annotation_checkMethod;

import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
/**
 * 該注解沒有任何屬性，只是作為是否需要測試的標(biāo)記
 */
@Target(ElementType.METHOD)
@Retention(RetentionPolicy.RUNTIME)
public @interface Check {
}

package cn.ocean888.a_annotation_checkMethod;

import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

/**
 * 自定義注解
 */
@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.TYPE)
public @interface ClassAnnotation {
    String className();
}

package cn.ocean888.a_annotation_checkMethod;

import java.io.BufferedWriter;
import java.io.FileWriter;
import java.io.IOException;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;

/**
 * 測試Tools類內(nèi)的方法，如果方法帶有Check注解，執(zhí)行測試并記錄異常
 */
@ClassAnnotation(className = "cn.ocean888.a_annotation_checkMethod.Tools")
public class TestProject {
    public static void main(String[] args) throws ClassNotFoundException, NoSuchMethodException, InvocationTargetException, InstantiationException, IllegalAccessException, IOException {

        // 從注解中獲取對(duì)應(yīng)的屬性
        Class<TestProject> testProjectClass = TestProject.class;
        // 獲取所有指定的注解
        ClassAnnotation annotation = testProjectClass.getAnnotation(ClassAnnotation.class);
        String s = annotation.className();
        // s = cn.ocean888.a_annotation_checkMethod.Utils

        Class<?> aClass = Class.forName(s);

        Object tools = aClass.getConstructor().newInstance();
        // 獲取所有Tools類內(nèi)的方法，不包括父類方法
        Method[] declaredMethods = aClass.getDeclaredMethods();

        // 記錄錯(cuò)誤出現(xiàn)次數(shù)
        int count = 0;
        long l = System.currentTimeMillis();
        BufferedWriter bufferedWriter = new BufferedWriter(new FileWriter("./src/log.txt"));

        // 遍歷方法數(shù)組
        for (Method declaredMethod : declaredMethods) {
            declaredMethod.setAccessible(true);

            // 判斷當(dāng)前方法是否帶有注解@Check標(biāo)記
            if (declaredMethod.isAnnotationPresent(Check.class)) {
                try {
                    declaredMethod.invoke(tools);
                } catch (Exception e) {
                    count += 1;

                    // 1.哪一個(gè)方法出現(xiàn)異常
                    bufferedWriter.write("方法:" + declaredMethod.getName());
                    bufferedWriter.newLine();
                    // 2.發(fā)生異常原因,獲取對(duì)應(yīng)的類型
                    bufferedWriter.write("異常類型:" + e.getCause().getClass().getSimpleName());
                    bufferedWriter.newLine();
                    // 3.異常信息
                    bufferedWriter.write("異常信息:" + e.getCause().getMessage());

                    bufferedWriter.newLine();

                }
            }
        }

        long l1 = System.currentTimeMillis();
        bufferedWriter.write("出現(xiàn)錯(cuò)誤的次數(shù)" + count);
        bufferedWriter.newLine();
        bufferedWriter.write("總耗時(shí)" + (l1 - l));

        bufferedWriter.close();
    }
}

public class XXXService {

@Autowired
private XXXXRepository xxxxRepository;

// ...
}

def foo():
print("Hello")

def logit(fn):
def inner():
print("before execute")
fn()
printf("after execute")
return inner

foo = logit(foo)
foo()

@logit
def foo():
print("Hello")

foo()