add OptionalBean

CHANGELOG.md

@@ -6,6 +6,7 @@
 # 5.4.7 (2020-10-23)
 
 ### 新特性
+* 【core   】     增加OptionalBean（pr#1182@Github）
 ### Bug修复
 
 -------------------------------------------------------------------------------------------------------------

hutool-core/src/main/java/cn/hutool/core/bean/OptionalBean.java

@@ -1,130 +1,152 @@
 package cn.hutool.core.bean;
 
+import cn.hutool.core.lang.Assert;
+import cn.hutool.core.util.ObjectUtil;
+
 import java.util.Objects;
 import java.util.function.Consumer;
 import java.util.function.Function;
 import java.util.function.Supplier;
 
 /**
- * optional 判空
+ * optional对象判空，参考：https://mp.weixin.qq.com/s/0c8iC0OTtx5LqPkhvkK0tw<br>
- * @param <T>
+ * from：https://github.com/looly/hutool/pull/1182
+ *
+ * @param <T> Bean类型
  * @author totalo
  * @since 5.4.7
- * @see https://mp.weixin.qq.com/s/0c8iC0OTtx5LqPkhvkK0tw
  */
 public final class OptionalBean<T> {
 
-    private static final OptionalBean<?> EMPTY = new OptionalBean<>();
+	private static final OptionalBean<?> EMPTY = new OptionalBean<>();
 
-    private final T value;
+	/**
+	 * 空值常量
+	 *
+	 * @param <T> 对象类型
+	 * @return 空
+	 */
+	public static <T> OptionalBean<T> empty() {
+		@SuppressWarnings("unchecked")
+		OptionalBean<T> none = (OptionalBean<T>) EMPTY;
+		return none;
+	}
 
-    private OptionalBean() {
+	private final T value;
-        this.value = null;
-    }
 
-    /**
+	/**
-     * 空值会抛出空指针
+	 * 构造
-     * @param value
+	 */
-     */
+	private OptionalBean() {
-    private OptionalBean(T value) {
+		this.value = null;
-        this.value = Objects.requireNonNull(value);
+	}
-    }
 
-    /**
+	/**
-     * 包装一个不能为空的 bean
+	 * 空值会抛出空指针
-     * @param value
+	 *
-     * @param <T>
+	 * @param value Bean值
-     * @return
+	 */
-     */
+	private OptionalBean(T value) {
-    public static <T> OptionalBean<T> of(T value) {
+		this.value = Objects.requireNonNull(value);
-        return new OptionalBean<>(value);
+	}
-    }
 
-    /**
+	/**
-     * 包装一个可能为空的 bean
+	 * 包装一个不能为空的 bean
-     * @param value
+	 *
-     * @param <T>
+	 * @param <T>   bean类型
-     * @return
+	 * @param value Bean值
-     */
+	 * @return OptionalBean
-    public static <T> OptionalBean<T> ofNullable(T value) {
+	 */
-        return value == null ? empty() : of(value);
+	public static <T> OptionalBean<T> of(T value) {
-    }
+		return new OptionalBean<>(value);
+	}
 
-    /**
+	/**
-     * 取出具体的值
+	 * 包装一个可能为空的 bean
-     * @return
+	 *
-     */
+	 * @param value Bean值
-    public T get() {
+	 * @param <T>   bean类型
-        return Objects.isNull(value) ? null : value;
+	 * @return OptionalBean
-    }
+	 */
+	public static <T> OptionalBean<T> ofNullable(T value) {
+		return value == null ? empty() : of(value);
+	}
 
-    /**
+	/**
-     * 取出一个可能为空的对象
+	 * 取出具体的值
-     * @param fn
+	 *
-     * @param <R>
+	 * @return bean值
-     * @return
+	 */
-     */
+	public T get() {
-    public <R> OptionalBean<R> getBean(Function<? super T, ? extends R> fn) {
+		return value;
-        return Objects.isNull(value) ? OptionalBean.empty() : OptionalBean.ofNullable(fn.apply(value));
+	}
-    }
 
-    /**
+	/**
-     * 如果目标值为空 获取一个默认值
+	 * 取出一个可能为空的对象
-     * @param other
+	 *
-     * @return
+	 * @param <R> 对象类型
-     */
+	 * @param fn  从已有bean中获取新bean字段的函数
+	 * @return 新的bean
+	 */
+	public <R> OptionalBean<R> getBean(Function<? super T, ? extends R> fn) {
+		return Objects.isNull(value) ? OptionalBean.empty() : OptionalBean.ofNullable(fn.apply(value));
+	}
 
-    public T orElse(T other) {
+	/**
-        return value != null ? value : other;
+	 * 如果目标值为空 获取一个默认值
-    }
+	 *
+	 * @param other 默认值
+	 * @return 空返回默认值，否则返回原值
+	 */
 
-    /**
+	public T orElse(T other) {
-     * 如果目标值为空 通过lambda表达式获取一个值
+		return ObjectUtil.defaultIfNull(this.value, other);
-     * @param other
+	}
-     * @return
-     */
-    public T orElseGet(Supplier<? extends T> other) {
-        return value != null ? value : other.get();
-    }
 
-    /**
+	/**
-     * 如果目标值为空 抛出一个异常
+	 * 如果目标值为空 通过lambda表达式获取一个值
-     * @param exceptionSupplier
+	 *
-     * @param <X>
+	 * @param other 默认值函数
-     * @return
+	 * @return 空返回默认值函数获得的值，否则返回原值
-     * @throws X
+	 */
-     */
+	public T orElseGet(Supplier<? extends T> other) {
-    public <X extends Throwable> T orElseThrow(Supplier<? extends X> exceptionSupplier) throws X {
+		return null != value ? value : other.get();
-        if (value != null) {
+	}
-            return value;
-        } else {
-            throw exceptionSupplier.get();
-        }
-    }
 
-    public boolean isPresent() {
+	/**
-        return value != null;
+	 * 如果目标值为空 抛出一个异常
-    }
+	 *
+	 * @param exceptionSupplier 抛出的异常
+	 * @param <X>               异常类型
+	 * @return 非空值
+	 * @throws X 对象为空时抛出的异常
+	 */
+	public <X extends Throwable> T orElseThrow(Supplier<? extends X> exceptionSupplier) throws X {
+		return Assert.notNull(this.value, exceptionSupplier);
+	}
 
-    public void ifPresent(Consumer<? super T> consumer) {
+	/**
-        if (value != null) {
+	 * 检查值是否为空
-            consumer.accept(value);
+	 *
-        }
+	 * @return 是否为空
-    }
+	 */
+	public boolean isPresent() {
+		return null != this.value;
+	}
 
-    @Override
+	/**
-    public int hashCode() {
+	 * 如果值非空，则使用指定函数处理值
-        return Objects.hashCode(value);
+	 *
-    }
+	 * @param consumer 处理非空对象的函数
+	 */
+	public void ifPresent(Consumer<? super T> consumer) {
+		if (value != null) {
+			consumer.accept(value);
+		}
+	}
 
-    /**
+	@Override
-     * 空值常量
+	public int hashCode() {
-     * @param <T>
+		return Objects.hashCode(value);
-     * @return
+	}
-     */
-    public static <T> OptionalBean<T> empty() {
-        @SuppressWarnings("unchecked")
-        OptionalBean<T> none = (OptionalBean<T>) EMPTY;
-        return none;
-    }
 }

hutool-core/src/test/java/cn/hutool/core/bean/OptionalBeanTest.java

@@ -6,44 +6,45 @@ import org.junit.Test;
 
 public class OptionalBeanTest {
 
-    @Test
+	@Test
-    public void OptionalBeanTest() {
+	public void optionalBeanTest() {
-        User user = new User();
+		User user = new User();
-        user.setName("hello");
+		user.setName("hello");
-        String value1 = OptionalBean.ofNullable(user)
+		String value1 = OptionalBean.ofNullable(user)
-                .getBean(User::getSchool)
+				.getBean(User::getSchool)
-                .getBean(User.School::getAddress).get();
+				.getBean(User.School::getAddress).get();
-        Assert.assertEquals(value1, null);
+        Assert.assertNull(value1);
 
-        boolean present = OptionalBean.ofNullable(user)
+		boolean present = OptionalBean.ofNullable(user)
-                .getBean(User::getSchool)
+				.getBean(User::getSchool)
-                .getBean(User.School::getAddress).isPresent();
+				.getBean(User.School::getAddress).isPresent();
-        Assert.assertFalse(present);
+		Assert.assertFalse(present);
 
-        String value2 = OptionalBean.ofNullable(user)
+		String value2 = OptionalBean.ofNullable(user)
-                .getBean(User::getSchool)
+				.getBean(User::getSchool)
-                .getBean(User.School::getAddress).orElse("没得地址");
+				.getBean(User.School::getAddress).orElse("没得地址");
-        Assert.assertEquals(value2, "没得地址");
+		Assert.assertEquals(value2, "没得地址");
-        try {
+		try {
-            OptionalBean.ofNullable(user)
+			OptionalBean.ofNullable(user)
-                    .getBean(User::getSchool)
+					.getBean(User::getSchool)
-                    .getBean(User.School::getAddress).orElseThrow(() -> new RuntimeException("空指针了"));
+					.getBean(User.School::getAddress).orElseThrow(() -> new RuntimeException("空指针了"));
-        } catch (Exception e) {
+		} catch (Exception e) {
-            Assert.assertEquals(e.getMessage(), "空指针了");
+			Assert.assertEquals(e.getMessage(), "空指针了");
-        }
+		}
-    }
+	}
 
 
-    @Data
+	@Data
-    public class User {
+	public static class User {
-        private String name;
+		private String name;
-        private String gender;
+		private String gender;
-        private School school;
+		private School school;
-        @Data
+
-        public class School {
+		@Data
-            private String name;
+		public static class School {
-            private String address;
+			private String name;
-        }
+			private String address;
-    }
+		}
+	}
 
 }