使用反射和注解模拟BeanUtils工具

Java Bean与Map互转

最新推荐文章于 2023-12-15 15:16:52 发布

流苏丶丶

最新推荐文章于 2023-12-15 15:16:52 发布

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分类专栏： Java基础文章标签：反射和注解

本文链接：https://blog.youkuaiyun.com/weixin_43916926/article/details/90084682

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本文介绍了一种在Java中实现Bean与Map互相转换的方法，通过自定义BeanUtils工具类和Column注解，实现了属性映射，适用于数据传输对象与实体类之间的灵活转换。

模拟工具类BeanUtils将Map和Bean互相转换的功能

public class BeanUtils {
	
	private BeanUtils() {}
	
	public static <T> T MapToBean(Map<String,Object> map,Class<T> clazz) throws Exception{
		T t = clazz.newInstance();
		Field[] fields = clazz.getDeclaredFields();
			for (Field field : fields) {
				Column annotation = field.getAnnotation(Column.class);
				if(annotation != null) {
					String key = annotation.value();
					Object object = map.get(key);
					if(object != null) {
						String setMethodName = "set" + field.getName().substring(0, 1).toUpperCase() + field.getName().substring(1);
						Method setMethod = clazz.getMethod(setMethodName, object.getClass());
						setMethod.invoke(t, object);
					}
				}
			}
		return t;
	}
	
	public static Map<String,Object> beanToMap(Object object) throws Exception {
		HashMap<String,Object> map = new HashMap<>();
		Class<?> clazz = object.getClass();
		Field[] fields = clazz.getDeclaredFields();
		for (Field field : fields) {
			Column annotation = field.getAnnotation(Column.class);
			if(annotation != null) {
				String key = annotation.value();
				String methodName = field.getName();
				Method method = clazz.getMethod("get" + methodName.substring(0, 1).toUpperCase() + methodName.substring(1));
				Object value = method.invoke(object);
				map.put(key, value);
			}
		}
		return map;
	}
	
}

自定义注解

@Target(ElementType.FIELD)
@Retention(RetentionPolicy.RUNTIME)
public @interface Column {
	String value();
}

bean

public class Student {
	@Column("sname")
	private String name;
	@Column("age")
	private Integer age;
	public Student() {
		super();
	}
	public Student(String name, Integer age) {
		super();
		this.name = name;
		this.age = age;
	}
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	public Integer getAge() {
		return age;
	}
	public void setAge(Integer age) {
		this.age = age;
	}
	@Override
	public String toString() {
		return "Student [name=" + name + ", age=" + age + "]";
	}
}

测试类

public class Test01 {

	public static void main(String[] args) throws Exception {
		HashMap<String,Object> map = new HashMap<String,Object>();
		map.put("sname", "zhangsan");
		map.put("age", 18);
		Student s = BeanUtils.MapToBean(map, Student.class);
		System.out.println(s);
		
		Map<String, Object> map2 = BeanUtils.beanToMap(s);
		for (Entry<String, Object> keyValue : map2.entrySet()) {
			System.out.println(keyValue.getKey() + "=" + keyValue.getValue());
			
		}
	}
	
}