2020-01-11_Spring5AnnotationUtil

Spring5AnnotationUtils
1 注解概述
AnnotationUtils是一个专门用于处理复杂注解问题的类。其主要由公共和静态方法组成，它允许在类，方法或字段上检查注解。另外，AnnotationUtils不仅仅来做简单的类分析。它也通过查找在超类和接口上的注解来做更多的事情。基于反射的API，AnnotationUtils使用java.lang.reflect的 3个元素来处理注解:
Annotation:表示注解。
AnnotatedElement:表示被注解元素。
Method:提供某些类或接口中的方法的信息。
1.1 MyAnnotationUtils
package com.tech.ability.util;

import java.lang.annotation.Annotation;
import java.lang.reflect.Field;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;
import java.util.Map;

/**

• @author kikop
• @version 1.0
• @project Name: TechnicalAbilityToolBox
• @file Name: MyAnnotationUtils
• @desc 功能描述 springmvc自身也提供该工具类
• @date 2020/1/11
• @time 10:50
• @by IDE: IntelliJ IDEA
  */
  public class MyAnnotationUtils {

/**
 * 类注解判断
 *
 * @param clazz
 * @param annotationClass
 * @return
 */
public static boolean hasAnnotation(Class<?> clazz, Class<? extends Annotation> annotationClass) {
    return clazz.isAnnotationPresent(annotationClass);
}

/**
 * 方法注解判断
 *
 * @param method
 * @param annotationClass
 * @return
 */
public static boolean hasAnnotation(Method method, Class<? extends Annotation> annotationClass) {
    return method.isAnnotationPresent(annotationClass);
}

/**
 * 获取类注解
 *
 * @param clazz
 * @param annotationClass
 * @param <T>
 * @return
 */
public static <T extends Annotation> T getAnnotation(Class<?> clazz, Class<T> annotationClass) {
    return clazz.getDeclaredAnnotation(annotationClass);
}

/**
 * 获取方法注解
 *
 * @param method
 * @param annotationClass
 * @param <T>
 * @return
 */
public static <T extends Annotation> T getAnnotation(Method method, Class<T> annotationClass) {
    return method.getDeclaredAnnotation(annotationClass);
}

/**
 * 获取字段注解
 *
 * @param field
 * @param annotationClass
 * @param <T>
 * @return
 */
public static <T extends Annotation> T getAnnotation(Field field, Class<T> annotationClass) {
    return field.getDeclaredAnnotation(annotationClass);
}


/**
 * 修改注解属性
 *
 * @param annotation
 * @param attrName
 * @param attrValue
 */
@SuppressWarnings("unchecked") // 告诉编译器忽略警告。不用在编译完成后出现警告。
public static void modifyAnnotationProperties(Annotation annotation, String attrName, Object attrValue) {
    InvocationHandler invocationHandler = Proxy.getInvocationHandler(annotation);
    Field declaredField = null;
    try {
        declaredField = invocationHandler.getClass().getDeclaredField("memberValues");
        if (declaredField != null) {
            declaredField.setAccessible(true);
            Map<String, Object> memberKeyValues = (Map<String, Object>) declaredField.get(invocationHandler);
            memberKeyValues.put(attrName, attrValue);
        }
    } catch (Exception ex) {
        ex.printStackTrace();
    }
}

}

1.2 Spring5注解工具类
1.3 辅助类
1.3.1 MyFieldAnnotation
package com.tech.ability.myannotation;

import java.lang.annotation.*;

/**

• @author kikop
• @version 1.0
• @project Name: TechnicalAbilityToolBox
• @file Name: MyFieldAnnotation
• @desc 功能描述 内注解
• @date 2020/1/11
• @time 18:32
• @by IDE: IntelliJ IDEA
  */
  @Target({ElementType.FIELD})
  @Retention(RetentionPolicy.RUNTIME)
  @Documented
  public @interface MyFieldAnnotation {
  String color() default "green";
  String author() default "kikop";
  String version() default "v1";
  }
  1.3.2 MyMethodAnnotation
  package com.tech.ability.myannotation;

import java.lang.annotation.*;

/**

• @author kikop

• @version 1.0

• @project Name: TechnicalAbilityToolBox

• @file Name: MyMethodAnnotation

• @desc 功能描述 方法注解定义

• @date 2020/1/11

• @time 18:38

• @by IDE: IntelliJ IDEA
  */
  @Target({ElementType.METHOD})
  @Retention(RetentionPolicy.RUNTIME)
  @Documented
  public @interface MyMethodAnnotation {

  String className() default "classNameOld";
  String value() default "valueOld";

}
1.3.3 MyClassAnnotation
package com.tech.ability.myannotation;

import java.lang.annotation.*;

/*

• @Retention(RetentionPolicy.SOURCE): 意思是让MyAnnotation注解只在java源文件中存在，编译成.class文件后注解就不存在了
• @Retention(RetentionPolicy.CLASS): 意思是让MyAnnotation注解在java源文件(.java文件)中存在，编译成.class文件后注解也还存在,被MyAnnotation注解类标识的类被类加载器加载到内存中后MyAnnotation注解就不存在了
• @Retention(RetentionPolicy.RUNTIME):意思是让MyAnnotation这个注解的生命周期一直程序运行时都存在
  */

/**

• @author kikop

• @version 1.0

• @project Name: TechnicalAbilityToolBox

• @file Name: MyClassAnnotation

• @desc 功能描述 类注解

• @date 2020/1/11

• @time 18:38

• @by IDE: IntelliJ IDEA
  */
  @Target({ElementType.TYPE})
  @Retention(RetentionPolicy.RUNTIME)
  @Documented
  public @interface MyClassAnnotation {

  String className() default "Empty class name";

  /**

  • 出生地
  • @return
    */
    String bornPlace() default "NJ";

  String[] hobbies() default {"Football", "Tennis", "PingPang"};

  String hobbiesSplit() default "Football,Tennis,PingPang";

  /**

  • 缺省值
  • 如果一个注解中有一个名称为value的属性，且你只想设置value属性(即其他属性都采用默认值或者你只有一个value属性)
  • 那么可以省略掉“value=”部分
  • @return
    /
    String value();
    /*
  • 国籍
  • @return
    */
    MyCountryEnum bornCountry() default MyCountryEnum.CHINA;
    }
    1.3.4 MyCountryEnum
    package com.tech.ability.annotation;

/**

• Created by kikop on 2018/12/16.
  */

/**

• @author kikop
• @version 1.0
• @project Name: TechnicalAbilityToolBox
• @file Name: MyCountryEnum
• @desc 功能描述 枚举定义
• @date 2020/1/11
• @time 18:38
• @by IDE: IntelliJ IDEA
  */

public enum MyCountryEnum {
/**
* 中国
/
CHINA(1),
/*
* 美国
*/
AMERICAN(2);

public int getValue() {
    return value;
}

public void setValue(int value) {
    this.value = value;
}

private int value;

/**
 * 构造函数
 * @param value
 */
MyCountryEnum(int value) {
    this.value = value;
}



public static void main(String[] args) {

    for(MyCountryEnum enumCountry : MyCountryEnum.values()){
        System.out.println(enumCountry.getValue());
    }
    MyCountryEnum china= MyCountryEnum.CHINA;
    System.out.println(china.getClass().toString());
}

}
1.3.5 MyRequest
package com.tech.ability.myannotation;

/**

• @author kikop
• @version 1.0
• @project Name: TechnicalAbilityToolBox
• @file Name: MyRequest
• @desc 功能描述
• @date 2020/2/11
• @time 21:09
• @by IDE: IntelliJ IDEA
  */
  public class MyRequest {
  }
  1.3.6 MyUserInfo
  package com.tech.ability.myannotation;

/**

• @author kikop

• @version 1.0

• @project Name: TechnicalAbilityToolBox

• @file Name: MyUserInfo

• @desc 功能描述

• @date 2020/1/11

• @time 19:22

• @by IDE: IntelliJ IDEA
  */
  @MyClassAnnotation(
  className = "MyClsAnnotation",
  bornCountry = MyCountryEnum.AMERICAN,
  hobbies = {"c", "d", "a", "b", "xyz"},
  hobbiesSplit = "11,22", value = "yes"
  )
  public class MyUserInfo {
  private String strName;
  private Integer age;

  public Integer getAge() {
  return age;
  }

  public void setAge(Integer age) {
  this.age = age;
  }

  public String getStrName() {
  return strName;
  }

  public void setStrName(String strName) {
  this.strName = strName;
  }

  public MyUserInfo(String strName, int age) {
  this.age = age;
  this.strName = strName;
  }

  /**

  • 字段注解
    */
    @MyFieldAnnotation(color = "black")
    public String strColor;

/**
 * 方法注解
 * @param myRequest
 * @return
 */
@MyMethodAnnotation(className = "classNameNew", value = "valueNew")
public String testMethod(MyRequest myRequest) {
    return getStrName();
}

}

1.4 测试
1.4.1 MyAnnotationUtils
package com.tech.ability.myannotation;

import com.tech.ability.util.MyAnnotationUtils;

import java.lang.reflect.Field;
import java.util.Arrays;
import java.util.List;

import static java.util.stream.Collectors.toList;

/**

• @author kikop
• @version 1.0
• @project Name:
• @file Name: CustomAnnotationTest
• @desc 功能描述 自定义注解
• @date 2020/1/11
• @time 18:49
• @by IDE: IntelliJ IDEA
  */
  public class CustomAnnotationTest {

/**
 * @param
 * @return void
 * @description 获取类注解
 * @author kikop
 * @date 2020/1/11
 * @time 19:04
 */
public static void getClassAnnotationTest() throws Exception {

    boolean hasAnnotation = MyAnnotationUtils.hasAnnotation(MyUserInfo.class, MyClassAnnotation.class);
    if (hasAnnotation) {

        //1.读取类注解
        MyClassAnnotation myClassAnnotation = MyAnnotationUtils.getAnnotation(MyUserInfo.class, MyClassAnnotation.class);
        System.out.println(myClassAnnotation.value());
        System.out.println(myClassAnnotation.bornCountry());
        System.out.println(myClassAnnotation.bornPlace());

        //1.1.打印数组值
        String[] hobbiesArray = myClassAnnotation.hobbies();
        for (String str : hobbiesArray) {
            System.out.println(str);
        }

        //1.2.将数组转为list
        List<String> hobbiesLst = Arrays.asList(hobbiesArray);

        List<String> hobbiesLstResult =
                hobbiesLst.stream().filter(par -> !par.equals("a")).sorted().limit(3).collect(toList());
        hobbiesLstResult.forEach(par -> System.out.println(par));

        //2.读取字段注解并修改
        //1.获取类中某个方法定义Method
        Field colorField = MyUserInfo.class.getField("strColor");

        MyFieldAnnotation myFieldAnnotation = MyAnnotationUtils.getAnnotation(colorField, MyFieldAnnotation.class);
        MyAnnotationUtils.modifyAnnotationProperties(myFieldAnnotation, "color", "yellow");
        System.out.println(myFieldAnnotation.color());
    }

}


public static void main(String[] args) throws Exception{
    getClassAnnotationTest();
}

}
1.4.2 SpingAnnotationTest
package com.tech.ability.myannotation;

import org.springframework.core.annotation.AnnotationUtils;

import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.util.Arrays;
import java.util.List;

import static java.util.stream.Collectors.toList;

/**

• @author kikop

• @version 1.0

• @project Name:

• @file Name: SpingAnnotationTest

• @desc 功能描述 Spring注解

• @date 2020/1/11

• @time 18:49

• @by IDE: IntelliJ IDEA
  */
  public class SpingAnnotationTest {

  /**

  • @param

  • @return void

  • @description 获取cls注解

  • @author kikop

  • @date 2020/1/11

  • @time 19:04
    */
    public static void getClassAnnotationTest() {

    //1.读取
    MyClassAnnotation myPersonAnnotation = AnnotationUtils.findAnnotation(MyUserInfo.class, MyClassAnnotation.class);
    if (myPersonAnnotation != null) {

     System.out.println(myPersonAnnotation.value());
     System.out.println(myPersonAnnotation.bornCountry());
     System.out.println(myPersonAnnotation.bornPlace());
    
     //1.1.打印数组值
     String[] hobbiesArray = myPersonAnnotation.hobbies();
     for (String str : hobbiesArray) {
         System.out.println(str);
     }
    
     //1.2.将数组转为list
     List<String> hobbiesLst = Arrays.asList(hobbiesArray);
    
     List<String> hobbiesLstResult =
             hobbiesLst.stream().filter(par -> !par.equals("a")).sorted().limit(3).collect(toList());
     hobbiesLstResult.forEach(par -> System.out.println(par));
    

    }
    }

  /**

  • @param

  • @return void

  • @description 获取方法注解

  • @author kikop

  • @date 2020/1/11

  • @time 20:12
    */
    private static void getMethodAnnotationTest() throws NoSuchMethodException {

    //1.获取类中某个方法定义Method
    Method testMethod = MyUserInfo.class.getMethod("testMethod", new Class[]{MyRequest.class});

    //2.获取方法上的注解
    MyMethodAnnotation myMethodAnnotation = AnnotationUtils.findAnnotation(testMethod, MyMethodAnnotation.class);

    //3.获取注解某个属性默认值
    System.out.println(AnnotationUtils.getDefaultValue(myMethodAnnotation, "className"));

    //4.获取注解某个属性实际值
    System.out.println(AnnotationUtils.getValue(myMethodAnnotation, "className"));
    }

/**
 * @param
 * @return void
 * @description 获取字段注解
 * @author kikop
 * @date 2020/1/11
 * @time 20:12
 */
private static void getFieldAnnotationTest() throws Exception {

    //1.获取类中某个方法定义Method
    Field colorField = MyUserInfo.class.getField("strColor");

    //2.获取方法上的注解
    MyFieldAnnotation myColorAnnotation = AnnotationUtils.findAnnotation(colorField, MyFieldAnnotation.class);

    //3.获取注解某个属性默认值
    System.out.println(AnnotationUtils.getDefaultValue(myColorAnnotation, "color"));

    //4.获取注解某个属性实际值
    System.out.println(AnnotationUtils.getValue(myColorAnnotation, "color"));
}

public static void main(String[] args) throws Exception {
    //getClassAnnotationTest();
    //getMethodAnnotationTest();
    getFieldAnnotationTest();
}

}