使用Java的内省和注解将JavaBean转换成Map

柔情只为你懂 2022-09-24 15:16 190阅读 0赞

**注解：Anno.java**

package com.an;
    import java.lang.annotation.ElementType;
    import java.lang.annotation.Retention;
    import java.lang.annotation.RetentionPolicy;
    import java.lang.annotation.Target;
    
    @Target(ElementType.FIELD)
    @Retention(RetentionPolicy.RUNTIME)
    public @interface Anno {
    public String name() default "";
    }

**实体：Cat.java**

package com.an;
    public class Cat {
    @Anno(name="CATNAME")
    private String name;
    @Anno(name="CATAGE")
    private int age;
    public Cat() {}
    public Cat(String name, int age) {
    this.name = name;
    this.age = age;
    }
    public String getName() {
    return name;
    }
    public void setName(String name) {
    this.name = name;
    }
    public int getAge() {
    return age;
    }
    public void setAge(int age) {
    this.age = age;
    }
    @Override
    public String toString() {
    return "Cat [name=" + name + ", age=" + age + "]";
    } 
    }

**转换器类：AnimalUtils.java**

package com.an;
    
    import java.beans.PropertyDescriptor;
    import java.lang.reflect.Field;
    import java.lang.reflect.Method;
    import java.util.HashMap;
    import java.util.Map;
    
    public class AnimalUtils {
    public static Map<String, Object> beanToMap(Object object){
    Map<String, Object> map=new HashMap<String, Object>();
    Class clazz = object.getClass();
    Field[] fields = clazz.getDeclaredFields();
    for (Field field : fields) {
    if (field.isAnnotationPresent(Anno.class)) {
    System.out.println("Anno存在");
    Anno anno = field.getAnnotation(Anno.class);
    String name = anno.name();
    try {
    PropertyDescriptor pd=new PropertyDescriptor(field.getName(), clazz);
    Method method = pd.getReadMethod();
    Object value = method.invoke(object);
    map.put(name, value);
    }  catch (Exception e) {
    e.printStackTrace();
    }
    }
    
    }
    return map;
    }
    }

**测试类：AnimalTest.java**

package com.an;
    
    import java.lang.reflect.Field;
    public class AnimalTest {
    public static void main(String[] args) {
    Cat cat=new Cat("Tom", 12);
    System.out.println(AnimalUtils.beanToMap(cat));
    }
    }