From eb5fbbb11e014fda8ae44c85354a57457b456ec9 Mon Sep 17 00:00:00 2001
From: Looly <loolly@gmail.com>
Date: Sat, 26 Mar 2022 00:15:12 +0800
Subject: [PATCH] add method

---
 .../hutool/core/builder/GenericBuilder.java   |  1 +
 .../cn/hutool/core/lang/func/LambdaUtil.java  | 70 +++++++++----------
 .../hutool/core/lang/func/LambdaUtilTest.java | 33 ++++++---
 3 files changed, 58 insertions(+), 46 deletions(-)

diff --git a/hutool-core/src/main/java/cn/hutool/core/builder/GenericBuilder.java b/hutool-core/src/main/java/cn/hutool/core/builder/GenericBuilder.java
index 5d9f0e1f3..817df55ad 100644
--- a/hutool-core/src/main/java/cn/hutool/core/builder/GenericBuilder.java
+++ b/hutool-core/src/main/java/cn/hutool/core/builder/GenericBuilder.java
@@ -62,6 +62,7 @@ import java.util.function.Supplier;
  * @since 5.7.21
  */
 public class GenericBuilder<T> implements Builder<T> {
+	private static final long serialVersionUID = 1L;
 
 	/**
 	 * 实例化器
diff --git a/hutool-core/src/main/java/cn/hutool/core/lang/func/LambdaUtil.java b/hutool-core/src/main/java/cn/hutool/core/lang/func/LambdaUtil.java
index fec85ba75..25d28aacb 100644
--- a/hutool-core/src/main/java/cn/hutool/core/lang/func/LambdaUtil.java
+++ b/hutool-core/src/main/java/cn/hutool/core/lang/func/LambdaUtil.java
@@ -1,14 +1,15 @@
 package cn.hutool.core.lang.func;
 
-import java.io.Serializable;
-import java.lang.invoke.SerializedLambda;
-
 import cn.hutool.core.bean.BeanUtil;
 import cn.hutool.core.lang.SimpleCache;
 import cn.hutool.core.util.ClassUtil;
 import cn.hutool.core.util.ReflectUtil;
 import cn.hutool.core.util.StrUtil;
 
+import java.io.Serializable;
+import java.lang.invoke.MethodHandleInfo;
+import java.lang.invoke.SerializedLambda;
+
 /**
  * Lambda相关工具类
  *
@@ -25,7 +26,7 @@ public class LambdaUtil {
 	 * <pre>{@code
 	 * @Data
 	 * @EqualsAndHashCode(callSuper = true)
-	 * static class MyTeacher extends Entity<MyTeacher> {
+	 * static class MyTeacher extends Entity&lt;MyTeacher&gt; {
 	 *
 	 * 	public String age;
 	 *
@@ -64,9 +65,10 @@ public class LambdaUtil {
 	 * @return lambda实现类
 	 * @throws IllegalArgumentException 如果是不支持的方法引用，抛出该异常，见{@link LambdaUtil#checkLambdaTypeCanGetClass}
 	 * @since 5.8.0
+	 * @author VampireAchao
 	 */
 	public static <R> Class<R> getRealClass(Func0<?> func) {
-		SerializedLambda lambda = resolve(func);
+		final SerializedLambda lambda = resolve(func);
 		checkLambdaTypeCanGetClass(lambda.getImplMethodKind());
 		return ClassUtil.loadClass(lambda.getImplClass());
 	}
@@ -125,7 +127,7 @@ public class LambdaUtil {
 	 * <pre>{@code
 	 * @Data
 	 * @EqualsAndHashCode(callSuper = true)
-	 * static class MyTeacher extends Entity<MyTeacher> {
+	 * static class MyTeacher extends Entity&lt;MyTeacher&gt; {
 	 *
 	 * 	public String age;
 	 *
@@ -152,27 +154,15 @@ public class LambdaUtil {
 	 * @return lambda实现类
 	 * @throws IllegalArgumentException 如果是不支持的方法引用，抛出该异常，见{@link LambdaUtil#checkLambdaTypeCanGetClass}
 	 * @since 5.8.0
+	 * @author VampireAchao
 	 */
 	public static <P, R> Class<P> getRealClass(Func1<P, R> func) {
-		SerializedLambda lambda = resolve(func);
+		final SerializedLambda lambda = resolve(func);
 		checkLambdaTypeCanGetClass(lambda.getImplMethodKind());
-		String instantiatedMethodType = lambda.getInstantiatedMethodType();
+		final String instantiatedMethodType = lambda.getInstantiatedMethodType();
 		return ClassUtil.loadClass(StrUtil.sub(instantiatedMethodType, 2, StrUtil.indexOf(instantiatedMethodType, ';')));
 	}
 
-	/**
-	 * 检查是否为支持的类型
-	 *
-	 * @param implMethodKind 支持的lambda类型
-	 * @throws IllegalArgumentException 如果是不支持的方法引用，抛出该异常
-	 */
-	private static void checkLambdaTypeCanGetClass(int implMethodKind) {
-		if (implMethodKind != LambdaKindEnum.REF_invokeVirtual.ordinal() &&
-				implMethodKind != LambdaKindEnum.REF_invokeStatic.ordinal()) {
-			throw new IllegalArgumentException("该lambda不是合适的方法引用");
-		}
-	}
-
 	/**
 	 * 获取lambda表达式Getter或Setter函数（方法）对应的字段名称，规则如下：
 	 * <ul>
@@ -211,9 +201,28 @@ public class LambdaUtil {
 		return BeanUtil.getFieldName(getMethodName(func));
 	}
 
+	//region Private methods
+	/**
+	 * 检查是否为支持的类型
+	 *
+	 * @param implMethodKind 支持的lambda类型
+	 * @throws IllegalArgumentException 如果是不支持的方法引用，抛出该异常
+	 */
+	private static void checkLambdaTypeCanGetClass(int implMethodKind) {
+		if (implMethodKind != MethodHandleInfo.REF_invokeVirtual &&
+				implMethodKind != MethodHandleInfo.REF_invokeStatic) {
+			throw new IllegalArgumentException("该lambda不是合适的方法引用");
+		}
+	}
+
 	/**
 	 * 解析lambda表达式,加了缓存。
-	 * 该缓存可能会在任意不定的时间被清除
+	 * 该缓存可能会在任意不定的时间被清除。
+	 *
+	 * <p>
+	 * 通过反射调用实现序列化接口函数对象的writeReplace方法，从而拿到{@link SerializedLambda}<br>
+	 * 该对象中包含了lambda表达式的所有信息。
+	 * </p>
 	 *
 	 * @param func 需要解析的 lambda 对象
 	 * @return 返回解析后的结果
@@ -221,20 +230,5 @@ public class LambdaUtil {
 	private static SerializedLambda _resolve(Serializable func) {
 		return cache.get(func.getClass().getName(), () -> ReflectUtil.invoke(func, "writeReplace"));
 	}
-
-	/**
-	 * Lambda类型枚举
-	 */
-	public enum LambdaKindEnum {
-		REF_NONE,
-		REF_getField,
-		REF_getStatic,
-		REF_putField,
-		REF_putStatic,
-		REF_invokeVirtual,
-		REF_invokeStatic,
-		REF_invokeSpecial,
-		REF_newInvokeSpecial,
-	}
-
+	//endregion
 }
diff --git a/hutool-core/src/test/java/cn/hutool/core/lang/func/LambdaUtilTest.java b/hutool-core/src/test/java/cn/hutool/core/lang/func/LambdaUtilTest.java
index 2facb9336..e13ef6fa8 100644
--- a/hutool-core/src/test/java/cn/hutool/core/lang/func/LambdaUtilTest.java
+++ b/hutool-core/src/test/java/cn/hutool/core/lang/func/LambdaUtilTest.java
@@ -7,6 +7,8 @@ import lombok.AllArgsConstructor;
 import lombok.Data;
 import lombok.EqualsAndHashCode;
 
+import java.lang.invoke.MethodHandleInfo;
+
 public class LambdaUtilTest {
 
 	@Test
@@ -24,19 +26,19 @@ public class LambdaUtilTest {
 	@Test
 	public void resolveTest() {
 		// 引用构造函数
-		Assert.assertEquals(LambdaUtil.LambdaKindEnum.REF_newInvokeSpecial.ordinal(),
+		Assert.assertEquals(MethodHandleInfo.REF_newInvokeSpecial,
 				LambdaUtil.resolve(MyTeacher::new).getImplMethodKind());
 		// 数组构造函数引用
-		Assert.assertEquals(LambdaUtil.LambdaKindEnum.REF_invokeStatic.ordinal(),
+		Assert.assertEquals(MethodHandleInfo.REF_invokeStatic,
 				LambdaUtil.resolve(MyTeacher[]::new).getImplMethodKind());
 		// 引用静态方法
-		Assert.assertEquals(LambdaUtil.LambdaKindEnum.REF_invokeStatic.ordinal(),
+		Assert.assertEquals(MethodHandleInfo.REF_invokeStatic,
 				LambdaUtil.resolve(MyTeacher::takeAge).getImplMethodKind());
 		// 引用特定对象的实例方法
-		Assert.assertEquals(LambdaUtil.LambdaKindEnum.REF_invokeVirtual.ordinal(),
+		Assert.assertEquals(MethodHandleInfo.REF_invokeVirtual,
 				LambdaUtil.resolve(new MyTeacher()::getAge).getImplMethodKind());
 		// 引用特定类型的任意对象的实例方法
-		Assert.assertEquals(LambdaUtil.LambdaKindEnum.REF_invokeVirtual.ordinal(),
+		Assert.assertEquals(MethodHandleInfo.REF_invokeVirtual,
 				LambdaUtil.resolve(MyTeacher::getAge).getImplMethodKind());
 	}
 
@@ -47,8 +49,8 @@ public class LambdaUtilTest {
 		Class<MyTeacher> functionClass = LambdaUtil.getRealClass(MyTeacher::getAge);
 		Assert.assertEquals(MyTeacher.class, functionClass);
 		// 枚举测试，不会导致类型擦除
-		Class<LambdaUtil.LambdaKindEnum> enumFunctionClass = LambdaUtil.getRealClass(LambdaUtil.LambdaKindEnum::ordinal);
-		Assert.assertEquals(LambdaUtil.LambdaKindEnum.class, enumFunctionClass);
+		Class<LambdaKindEnum> enumFunctionClass = LambdaUtil.getRealClass(LambdaKindEnum::ordinal);
+		Assert.assertEquals(LambdaKindEnum.class, enumFunctionClass);
 		// 调用父类方法，能获取到正确的子类类型
 		Class<MyTeacher> superFunctionClass = LambdaUtil.getRealClass(MyTeacher::getId);
 		Assert.assertEquals(MyTeacher.class, superFunctionClass);
@@ -58,7 +60,7 @@ public class LambdaUtilTest {
 		Class<MyTeacher> supplierClass = LambdaUtil.getRealClass(myTeacher::getAge);
 		Assert.assertEquals(MyTeacher.class, supplierClass);
 		// 枚举测试，只能获取到枚举类型
-		Class<Enum<?>> enumSupplierClass = LambdaUtil.getRealClass(LambdaUtil.LambdaKindEnum.REF_NONE::ordinal);
+		Class<Enum<?>> enumSupplierClass = LambdaUtil.getRealClass(LambdaKindEnum.REF_NONE::ordinal);
 		Assert.assertEquals(Enum.class, enumSupplierClass);
 		// 调用父类方法，只能获取到父类类型
 		Class<Entity<?>> superSupplierClass = LambdaUtil.getRealClass(myTeacher::getId);
@@ -116,4 +118,19 @@ public class LambdaUtilTest {
 
 		public String age;
 	}
+
+	/**
+	 * 测试Lambda类型枚举
+	 */
+	enum LambdaKindEnum {
+		REF_NONE,
+		REF_getField,
+		REF_getStatic,
+		REF_putField,
+		REF_putStatic,
+		REF_invokeVirtual,
+		REF_invokeStatic,
+		REF_invokeSpecial,
+		REF_newInvokeSpecial,
+	}
 }