From fe20abeeec0735df15139dff8a657b04dd546e52 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?=E6=9D=8E=E6=88=90?= Date: Mon, 23 Dec 2024 17:33:18 +0800 Subject: [PATCH 1/7] =?UTF-8?q?20241223:=E5=9B=9E=E8=B0=83=E5=AD=A6?= =?UTF-8?q?=E4=B9=A0-1?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- pom.xml | 6 +++ .../javaStudy/basic/callBack/CallBack.java | 50 +++++++++++++++++++ .../basic/callBack/demo/BottomService.java | 21 ++++++++ .../javaStudy/basic/callBack/demo/Test.java | 25 ++++++++++ .../basic/callBack/demo/UpperService.java | 9 ++++ .../basic/callBack/demo/UpperServiceImpl.java | 29 +++++++++++ 6 files changed, 140 insertions(+) create mode 100644 src/main/java/javaStudy/basic/callBack/CallBack.java create mode 100644 src/main/java/javaStudy/basic/callBack/demo/BottomService.java create mode 100644 src/main/java/javaStudy/basic/callBack/demo/Test.java create mode 100644 src/main/java/javaStudy/basic/callBack/demo/UpperService.java create mode 100644 src/main/java/javaStudy/basic/callBack/demo/UpperServiceImpl.java diff --git a/pom.xml b/pom.xml index a91c75e..1161c15 100644 --- a/pom.xml +++ b/pom.xml @@ -69,6 +69,12 @@ + + junit + junit + 4.13.2 + compile + diff --git a/src/main/java/javaStudy/basic/callBack/CallBack.java b/src/main/java/javaStudy/basic/callBack/CallBack.java new file mode 100644 index 0000000..81ac77e --- /dev/null +++ b/src/main/java/javaStudy/basic/callBack/CallBack.java @@ -0,0 +1,50 @@ +package javaStudy.basic.callBack; + +import org.junit.Test; + +import java.util.Random; +import java.util.concurrent.*; + +public class CallBack { + //这里简单地使用future和callable实现了线程执行完后 + public static void main(String[] args) throws ExecutionException, InterruptedException { + // 创建一个可缓存的线程池，用于执行异步任务 + ExecutorService executor = Executors.newCachedThreadPool(); + Future future = executor.submit(new Callable() { + @Override + public String call() throws Exception { + System.out.println("call"); + TimeUnit.SECONDS.sleep(1); + return "str"; + } + }); + //手动阻塞调用get通过call方法获得返回值。 + System.out.println(future.get()); + //需要手动关闭，不然线程池的线程会继续执行。 + executor.shutdown(); + + //使用futuretask同时作为线程执行单元和数据请求单元。 + FutureTask futureTask = new FutureTask(new Callable() { + @Override + public Integer call() throws Exception { + System.out.println("dasds"); + return new Random().nextInt(); + } + }); + new Thread(futureTask).start(); + //阻塞获取返回值 + System.out.println(futureTask.get()); + } + + @Test + public void test() { + Callable callable = new Callable() { + @Override + public Object call() throws Exception { + return null; + } + }; + FutureTask futureTask = new FutureTask(callable); + + } +} diff --git a/src/main/java/javaStudy/basic/callBack/demo/BottomService.java b/src/main/java/javaStudy/basic/callBack/demo/BottomService.java new file mode 100644 index 0000000..03c3a0e --- /dev/null +++ b/src/main/java/javaStudy/basic/callBack/demo/BottomService.java @@ -0,0 +1,21 @@ +package javaStudy.basic.callBack.demo; + +public class BottomService { + + public String bottom(String param) { + + try { // 模拟底层处理耗时，上层服务需要等待 + + Thread.sleep(3000); + + } catch (InterruptedException e) { + + e.printStackTrace(); + + } + + return param +" BottomService.bottom() execute -->"; + + } + +} diff --git a/src/main/java/javaStudy/basic/callBack/demo/Test.java b/src/main/java/javaStudy/basic/callBack/demo/Test.java new file mode 100644 index 0000000..48f3ec2 --- /dev/null +++ b/src/main/java/javaStudy/basic/callBack/demo/Test.java @@ -0,0 +1,25 @@ +package javaStudy.basic.callBack.demo; + +import java.util.Date; + +public class Test { + + public static void main(String[] args) { + + BottomService bottomService = new BottomService(); + + UpperService upperService = new UpperServiceImpl(bottomService); + + System.out.println("=============== callBottomService start ==================:" + new Date()); + + String result = upperService.callBottomService("callBottomService start --> "); + + //upperTaskAfterCallBottomService执行必须等待callBottomService()调用BottomService.bottom()方法返回后才能够执行 + + upperService.upperTaskAfterCallBottomService(result); + + System.out.println("=============== callBottomService end ====================:" + new Date()); + + } + +} diff --git a/src/main/java/javaStudy/basic/callBack/demo/UpperService.java b/src/main/java/javaStudy/basic/callBack/demo/UpperService.java new file mode 100644 index 0000000..647a3d8 --- /dev/null +++ b/src/main/java/javaStudy/basic/callBack/demo/UpperService.java @@ -0,0 +1,9 @@ +package javaStudy.basic.callBack.demo; + +public interface UpperService { + + public void upperTaskAfterCallBottomService(String upperParam); + + public String callBottomService(final String param); + +} \ No newline at end of file diff --git a/src/main/java/javaStudy/basic/callBack/demo/UpperServiceImpl.java b/src/main/java/javaStudy/basic/callBack/demo/UpperServiceImpl.java new file mode 100644 index 0000000..c9932d6 --- /dev/null +++ b/src/main/java/javaStudy/basic/callBack/demo/UpperServiceImpl.java @@ -0,0 +1,29 @@ +package javaStudy.basic.callBack.demo; + +public class UpperServiceImpl implements UpperService { + + private BottomService bottomService; + + @Override + + public void upperTaskAfterCallBottomService(String upperParam) { + + System.out.println(upperParam + " upperTaskAfterCallBottomService() execute."); + + } + + public UpperServiceImpl(BottomService bottomService) { + + this.bottomService = bottomService; + + } + + @Override + + public String callBottomService(final String param) { + + return bottomService.bottom(param + " callBottomService.bottom() execute --> "); + + } + +} \ No newline at end of file From bdc7c6c3a6907f9f4519bf59135296bd3c89f96c Mon Sep 17 00:00:00 2001 From: licheng <873061361@qq.com> Date: Mon, 23 Dec 2024 22:26:10 +0800 Subject: [PATCH 2/7] =?UTF-8?q?20241223:java=E5=9F=BA=E7=A1=80-=E5=8F=8D?= =?UTF-8?q?=E5=B0=84?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- pom.xml | 5 ++ .../basic/callBack/pratice/CallBack.java | 5 ++ .../basic/callBack/pratice/Student.java | 5 ++ .../basic/callBack/pratice/Teacher.java | 32 ++++++++++++ .../basic/callBack/pratice/Test.java | 16 ++++++ .../javaStudy/basic/callBack/pratice/Tom.java | 16 ++++++ .../javaStudy/basic/reflect/BasicClass.java | 50 +++++++++++++++++++ .../java/javaStudy/basic/reflect/People.java | 23 +++++++++ 8 files changed, 152 insertions(+) create mode 100644 src/main/java/javaStudy/basic/callBack/pratice/CallBack.java create mode 100644 src/main/java/javaStudy/basic/callBack/pratice/Student.java create mode 100644 src/main/java/javaStudy/basic/callBack/pratice/Teacher.java create mode 100644 src/main/java/javaStudy/basic/callBack/pratice/Test.java create mode 100644 src/main/java/javaStudy/basic/callBack/pratice/Tom.java create mode 100644 src/main/java/javaStudy/basic/reflect/BasicClass.java create mode 100644 src/main/java/javaStudy/basic/reflect/People.java diff --git a/pom.xml b/pom.xml index 1161c15..6be9297 100644 --- a/pom.xml +++ b/pom.xml @@ -75,6 +75,11 @@ 4.13.2 compile + + org.projectlombok + lombok + provided + diff --git a/src/main/java/javaStudy/basic/callBack/pratice/CallBack.java b/src/main/java/javaStudy/basic/callBack/pratice/CallBack.java new file mode 100644 index 0000000..016dfc6 --- /dev/null +++ b/src/main/java/javaStudy/basic/callBack/pratice/CallBack.java @@ -0,0 +1,5 @@ +package javaStudy.basic.callBack.pratice; + +public interface CallBack { + void tellAnswer(int res); +} diff --git a/src/main/java/javaStudy/basic/callBack/pratice/Student.java b/src/main/java/javaStudy/basic/callBack/pratice/Student.java new file mode 100644 index 0000000..94791eb --- /dev/null +++ b/src/main/java/javaStudy/basic/callBack/pratice/Student.java @@ -0,0 +1,5 @@ +package javaStudy.basic.callBack.pratice; + +public interface Student { + void resolveProblem (Teacher teacher); +} diff --git a/src/main/java/javaStudy/basic/callBack/pratice/Teacher.java b/src/main/java/javaStudy/basic/callBack/pratice/Teacher.java new file mode 100644 index 0000000..ff102b7 --- /dev/null +++ b/src/main/java/javaStudy/basic/callBack/pratice/Teacher.java @@ -0,0 +1,32 @@ +package javaStudy.basic.callBack.pratice; + +public class Teacher implements CallBack{ + private Student student; + + Teacher(Student student) { + this.student = student; + } + + void askProblem (Student student, Teacher teacher) { + //main方法是主线程运行，为了实现异步回调，这里开启一个线程来操作 + new Thread(new Runnable() { + @Override + public void run() { + student.resolveProblem(teacher); + } + }).start(); + //老师让学生做题以后，等待学生回答的这段时间，可以做别的事，比如玩手机.\ + //而不需要同步等待，这就是回调的好处。 + //当然你可以说开启一个线程让学生做题就行了，但是这样无法让学生通知老师。 + //需要另外的机制去实现通知过程。 + // 当然，多线程中的future和callable也可以实现数据获取的功能。 + for (int i = 1;i < 4;i ++) { + System.out.println("等学生回答问题的时候老师玩了 " + i + "秒的手机"); + } + } + + @Override + public void tellAnswer(int res) { + System.out.println("the answer is " + res); + } +} \ No newline at end of file diff --git a/src/main/java/javaStudy/basic/callBack/pratice/Test.java b/src/main/java/javaStudy/basic/callBack/pratice/Test.java new file mode 100644 index 0000000..b021814 --- /dev/null +++ b/src/main/java/javaStudy/basic/callBack/pratice/Test.java @@ -0,0 +1,16 @@ +package javaStudy.basic.callBack.pratice; + +public class Test { + public static void main(String[] args) { + //测试 + Student tom = new Tom(); + Teacher lee = new Teacher(tom); + lee.askProblem(tom, lee); + //结果 + // 等学生回答问题的时候老师玩了 1秒的手机 + // 等学生回答问题的时候老师玩了 2秒的手机 + // 等学生回答问题的时候老师玩了 3秒的手机 + // work out + // the answer is 111 + } +} diff --git a/src/main/java/javaStudy/basic/callBack/pratice/Tom.java b/src/main/java/javaStudy/basic/callBack/pratice/Tom.java new file mode 100644 index 0000000..d9a264c --- /dev/null +++ b/src/main/java/javaStudy/basic/callBack/pratice/Tom.java @@ -0,0 +1,16 @@ +package javaStudy.basic.callBack.pratice; + +public class Tom implements Student { + + @Override + public void resolveProblem(Teacher teacher) { + try { + //学生思考了3秒后得到了答案，通过老师提供的回调方法告诉老师。 + Thread.sleep(3000); + System.out.println("work out"); + teacher.tellAnswer(111); + } catch (InterruptedException e) { + e.printStackTrace(); + } + } +} diff --git a/src/main/java/javaStudy/basic/reflect/BasicClass.java b/src/main/java/javaStudy/basic/reflect/BasicClass.java new file mode 100644 index 0000000..a618483 --- /dev/null +++ b/src/main/java/javaStudy/basic/reflect/BasicClass.java @@ -0,0 +1,50 @@ +package javaStudy.basic.reflect; + +import java.lang.reflect.Constructor; +import java.lang.reflect.InvocationTargetException; +import java.lang.reflect.Method; + +/** + * @author: li + * @description: 反射的基本运用 + * @date: 2024/12/23 21:56 + */ +public class BasicClass { + public static void main(String[] args) throws Exception { + // 获取Class对象的三种方法 + //1.通过Class.forName(全类名) + Class classA = Class.forName("javaStudy.basic.reflect.People"); + //2.直接获取某一个对象的class + Class classB = People.class; + Class classInt = Integer.TYPE; + //3.调用某个对象的getClass()方法 + People people = new People(); + Class classC = people.getClass(); + + + // 判断是否为某个类的实例 a instanceof b 判断a是否为b的实例 + People tom = new People(); + if (tom instanceof People) { + System.out.println("tom是一个People对象"); + } else { + System.out.println("tom不是一个People对象"); + } + + // 通过反射创建实例 + // 1.使用Class对象的newInstance()方法来创建Class对象对应类的实例 (已过时) + + // 2.使用Class对象获取构造器,再调用构造器对象的newInstance()方法创建实例 + Constructor constructor = classB.getConstructor(); + Object o = constructor.newInstance(); + System.out.println(o); + // 输出:People(name=null, age=0) + + // 获取方法 + // 1.getDeclaredMethods() 获取方法返回类或接口声明的所有方法,包含公共、保护、默认访问和私有方法,但不包含继承的方法 + Method[] declaredMethods = classA.getDeclaredMethods(); + // 2.getMethods() 返回某个类的所有公用(public)方法，包括其继承类的公用方法 + Method[] methods = classA.getMethods(); + // 3.getMethod(String name) 返回一个指定的方法 第一个参数为方法名称 + Method method = classA.getMethod("setName", String.class); + } +} diff --git a/src/main/java/javaStudy/basic/reflect/People.java b/src/main/java/javaStudy/basic/reflect/People.java new file mode 100644 index 0000000..8f126a3 --- /dev/null +++ b/src/main/java/javaStudy/basic/reflect/People.java @@ -0,0 +1,23 @@ +package javaStudy.basic.reflect; + +import lombok.Data; + +/** + * @author: licheng + * @Description: + * @create: 2018-10-24 14:06 + **/ +@Data +public class People { + + private String name; + + private int age; + + public People() { + } + + private static void eat() { + System.out.println("eat"); + } +} From 77feaa50494cfc802a10f84150576a83c66aab09 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?=E6=9D=8E=E6=88=90?= Date: Tue, 24 Dec 2024 09:46:38 +0800 Subject: [PATCH 3/7] =?UTF-8?q?20241224:=E5=8F=8D=E5=B0=84=E5=AD=A6?= =?UTF-8?q?=E4=B9=A0(ac)?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- .../javaStudy/basic/reflect/BasicClass.java | 38 +++++++++++++++++-- 1 file changed, 34 insertions(+), 4 deletions(-) diff --git a/src/main/java/javaStudy/basic/reflect/BasicClass.java b/src/main/java/javaStudy/basic/reflect/BasicClass.java index a618483..05b995c 100644 --- a/src/main/java/javaStudy/basic/reflect/BasicClass.java +++ b/src/main/java/javaStudy/basic/reflect/BasicClass.java @@ -1,8 +1,6 @@ package javaStudy.basic.reflect; -import java.lang.reflect.Constructor; -import java.lang.reflect.InvocationTargetException; -import java.lang.reflect.Method; +import java.lang.reflect.*; /** * @author: li @@ -45,6 +43,38 @@ public static void main(String[] args) throws Exception { // 2.getMethods() 返回某个类的所有公用(public)方法，包括其继承类的公用方法 Method[] methods = classA.getMethods(); // 3.getMethod(String name) 返回一个指定的方法 第一个参数为方法名称 - Method method = classA.getMethod("setName", String.class); + Method method1 = classA.getMethod("setName", String.class); + + /* + * getMethods和getDeclaredMethods的区别 + * getDeclaredMethods是获取该类所有的方法及接口声明的方法 + * getMethods是获取该类及继承类的所有公共方法 + */ + + // 获取构造器 + // 获取所有构造器 getConstructors + Constructor[] constructors = classA.getConstructors(); + + // 获取类的成员变量 + // getFiled:访问公有的成员变量 + // getDeclaredField:所有已声明的成员变量(但得不到父类的成员变量) + Field[] fields = classA.getDeclaredFields(); + for (Field field : fields) { + // 设置访问权限 private属性即使不使用下面这个语句也可以访问 + field.setAccessible(true); + String fieldString = ""; + // 获取字段修饰符 + fieldString += Modifier.toString(field.getModifiers()) + " "; //private + // 获取字段类型 + fieldString += field.getType().getSimpleName() + " "; + // 获取字段名 + fieldString += field.getName(); + fieldString += ";"; + System.out.println(fieldString); + } + + //调用方法,获取方法之后,使用invoke()调用该方法 + + } } From 4797d4d60f7c912ec437d5d6e2557a188df54a92 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?=E6=9D=8E=E6=88=90?= Date: Tue, 24 Dec 2024 17:35:31 +0800 Subject: [PATCH 4/7] =?UTF-8?q?20241224:=E5=AE=B9=E5=99=A8=E5=AD=A6?= =?UTF-8?q?=E4=B9=A0?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- .../collectors/ArrayList,Vector,Stack.txt | 84 +++++++++++++++++++ src/main/java/javaStudy/collectors/note.txt | 18 ++++ 2 files changed, 102 insertions(+) create mode 100644 src/main/java/javaStudy/collectors/ArrayList,Vector,Stack.txt create mode 100644 src/main/java/javaStudy/collectors/note.txt diff --git a/src/main/java/javaStudy/collectors/ArrayList,Vector,Stack.txt b/src/main/java/javaStudy/collectors/ArrayList,Vector,Stack.txt new file mode 100644 index 0000000..86c5c50 --- /dev/null +++ b/src/main/java/javaStudy/collectors/ArrayList,Vector,Stack.txt @@ -0,0 +1,84 @@ +1.ArrayList + (1)概述 + I:实现List接口的动态数组(大小可变),默认初始容量为10,随着ArrayList中元素的增加,容量也会不断自动增长。 + II:每次添加新的元素时,ArrayList会检查是否需要扩容,所以在知道场景数据的时候,构造时指定一个初始容量会减少资源消耗。 + III:ArrayList实现不是同步的,若多个线程同时访问一个ArrayList实例,要保持同步,在创建ArrayList时可以通过 + List list = Collections.synchronizedList(new ArrayList(...));来保持同步 + + (2)ArrayList的继承关系 + public class ArrayList extends AbstractList + implements List, RandomAccess, Cloneable, java.io.Serializable + ArrayList继承AbstractList抽象父类，实现了List接口（规定了List的操作规范）、RandomAccess（可随机访问）、Cloneable（可拷贝）、Serializable（可序列化）。 + + (3)底层数据结构 + 底层是一个object数组,由transient修饰 transient Object[] elementData; + ArrayList底层数组不会参与序列化,而是使用另外的序列化方式. + 使用writeObject方式序列化:只复制数组中有值的位置,其他未赋值的位置不进行序列化,可以节省空间 + // private void writeObject(java.io.ObjectOutputStream s) + // throws java.io.IOException{ + // // Write out element count, and any hidden stuff + // int expectedModCount = modCount; + // s.defaultWriteObject(); + // + // // Write out size as capacity for behavioural compatibility with clone() + // s.writeInt(size); + // + // // Write out all elements in the proper order. + // for (int i=0; i= size) { + throw new IndexOutOfBoundsException(outOfBoundsMsg(index)); + } + } + + V:modCount:在一个迭代器初始的时候会赋予它调用这个迭代器对象的modCount,一旦发现该对象的modCount和迭代器中存储的modCount不一样就抛出异常 + 这被叫做Fail-Fast机制,ArrayList不是线程安全的,所以使用modCount来判断: + 判断 modCount 跟 expectedModCount 是否相等，如果不相等就表示已经有其他线程修改了 ArrayList,不相等就抛出异常 + 建议:遍历非安全的数据结构的时候,最好使用迭代器. + + + VI:初始容量和扩容方式 + ArrayList初始容量为10 + 扩容方法:每次扩容处理是1.5倍,因为一次性扩容太大浪费更多内存,扩容太小,需要多次对数组重新分配内存,所以1.5是比较好的扩容倍数; + + VII:线程安全 + ArrayList是线程不安全的,在迭代器中,如果多线程操作导致modCount改变,会执行fastFail,抛出异常 + final void checkForComodification() { + if (modCount != expectedModCount) { + throw new ConcurrentModificationException(); + } + } + +2.Vector + (1)概述:Vector可以实现可增长的对象数组,可以使用整数索引进行访问的组件.但是Vector大小是可以增加或者减少的 \ No newline at end of file diff --git a/src/main/java/javaStudy/collectors/note.txt b/src/main/java/javaStudy/collectors/note.txt new file mode 100644 index 0000000..040db68 --- /dev/null +++ b/src/main/java/javaStudy/collectors/note.txt @@ -0,0 +1,18 @@ +1.对于已知得场景,要指定集合的初始容量。(可以减少资源的消耗) + +2.asList的缺陷(入参为泛型类型): + (1)asList的参数为泛型的变长参数,若入参类型不为泛型,则会出错 + 例如:int[] ins = {1,2,3,4,5}; + System.out.println(Arrays.asList(ins).size()) -> 1 + 原因:因为ins类型为int,无法泛型化,不能作为asList的参数, + 但是int类型的数组可以泛型化,可以就相当于入参为一个数组,即结果为1 + + (2)asList返回的列表只是披着list的外衣,但是没有list的基本特性(变长),所以在使用asList之后 + 不要试图去改变asList返回的列表,否则会出现问题 + +3.subList(用于对List进行分割)的缺陷: + subList()分割的其实是原表的一个视图,但是子列表的操作都会反应在原列表上。 + +4.保持compareTo和equals同步 + 对于compareTo和equals两个方法我们可以总结为：compareTo是判断元素在排序中的位置是否相等， + equals是判断元素是否相等，既然一个决定排序位置，一个决定相等，所以我们非常有必要确保当排序位置相同时，其equals也应该相等。 \ No newline at end of file From 7e71ac9827658ef723ccbecaad668d103524f573 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?=E6=9D=8E=E6=88=90?= Date: Mon, 30 Dec 2024 17:23:30 +0800 Subject: [PATCH 5/7] =?UTF-8?q?20241230:=E9=9B=86=E5=90=88=E5=AD=A6?= =?UTF-8?q?=E4=B9=A0?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- src/main/java/Test.java | 7 ++- .../javaStudy/basic/reflect/BasicClass.java | 3 +- .../collectors/ArrayList,Vector,Stack.txt | 53 ++++++++++++++++++- .../javaStudy/collectors/Queue&LinkedList.txt | 10 ++++ 4 files changed, 68 insertions(+), 5 deletions(-) create mode 100644 src/main/java/javaStudy/collectors/Queue&LinkedList.txt diff --git a/src/main/java/Test.java b/src/main/java/Test.java index 269694c..4e049dc 100644 --- a/src/main/java/Test.java +++ b/src/main/java/Test.java @@ -1,6 +1,11 @@ import org.springframework.beans.factory.annotation.Lookup; +import org.springframework.core.io.InputStreamSource; +import org.springframework.core.io.Resource; import org.springframework.stereotype.Service; +import java.io.InputStream; +import java.util.LinkedList; + /** * @author hpl * @date 2023/4/15 14:40 @@ -10,9 +15,7 @@ public class Test { - public static void main(String[] args) { - } diff --git a/src/main/java/javaStudy/basic/reflect/BasicClass.java b/src/main/java/javaStudy/basic/reflect/BasicClass.java index 05b995c..3370d99 100644 --- a/src/main/java/javaStudy/basic/reflect/BasicClass.java +++ b/src/main/java/javaStudy/basic/reflect/BasicClass.java @@ -1,6 +1,7 @@ package javaStudy.basic.reflect; import java.lang.reflect.*; +import java.util.Vector; /** * @author: li @@ -19,7 +20,6 @@ public static void main(String[] args) throws Exception { People people = new People(); Class classC = people.getClass(); - // 判断是否为某个类的实例 a instanceof b 判断a是否为b的实例 People tom = new People(); if (tom instanceof People) { @@ -75,6 +75,5 @@ public static void main(String[] args) throws Exception { //调用方法,获取方法之后,使用invoke()调用该方法 - } } diff --git a/src/main/java/javaStudy/collectors/ArrayList,Vector,Stack.txt b/src/main/java/javaStudy/collectors/ArrayList,Vector,Stack.txt index 86c5c50..1ea2b21 100644 --- a/src/main/java/javaStudy/collectors/ArrayList,Vector,Stack.txt +++ b/src/main/java/javaStudy/collectors/ArrayList,Vector,Stack.txt @@ -81,4 +81,55 @@ } 2.Vector - (1)概述:Vector可以实现可增长的对象数组,可以使用整数索引进行访问的组件.但是Vector大小是可以增加或者减少的 \ No newline at end of file + (1)概述:Vector可以实现可增长的对象数组,可以使用整数索引进行访问的组件.但是Vector大小是可以增加或者减少的,便于后续的添加或删除操作 + public class Vector + extends AbstractList + implements List, RandomAccess, Cloneable, java.io.Serializable + 实现List<>,继承AbstractList类:可以将其看做队列,支持相关的添加、删除、修改、遍历等功能 + 实现RandomAccess接口:提供了随机访问功能,能够直接访问元素 + 实现了Cloneable接口:支持clone()方法,可以被克隆 + vector底层数组不加transient,序列化的时候会全部复制 + + (2)增删改查: + I:查:vector.elementAt(int index) + II:改:vector.setElementAt(E obj,int index) + III:删:removeElementAt(int index) + IV:增:insertElementAt(E obj, int index) + addElement(E obj) + + (3)初始容量和扩容: + I:扩容方式和ArrayList一样,通过扩容增量来决定扩容的大小(初始容量和扩容大小:capacityIncrement) + + (4)线程安全: + vector大部分方法都使用了synchronized修饰符,属于线程安全的集合类 + +3.Stack + (1)概述:最常用的结构,继承了Vector类,是一个后进先出(LIFO)的对象堆栈 + + (2)通过5个操作扩展Vector + I:empty():测试堆栈是否为空 + II:peek():查看堆栈顶部的对象,不移除,仅查看 + III:pop():移除堆栈顶部的对象,并作为返回值返回 + IV:push(E item):将项压入堆栈顶部 + V:search(Object o):返回对象在堆栈中的位置,以1为基数 + + + +4.三个集合类的区别 + (1)ArrayList的优缺点: + - 优点:I:底层以数组实现,可以随机访问,实现了RandomAccess接口,get效率高 + II:ArrayList在顺序添加一个元素的时候非常方便 + - 缺点:I:删除元素的时候，涉及到元素的复制,如果需要复制的元素很多,消耗性能 + II:插入元素的时候(非顺序),涉及到元素的复制,如果要复制很多元素,消耗性能 + - 总结:ArrayList适合顺序添加,随机访问的场景 + + (2)ArrayList和Vector的区别 + - Vector:线程安全;ArrayList:线程非安全 + - Vector:可以指定增长因子,扩容的时候会根据增长因子来扩容 + + + + + + + diff --git a/src/main/java/javaStudy/collectors/Queue&LinkedList.txt b/src/main/java/javaStudy/collectors/Queue&LinkedList.txt new file mode 100644 index 0000000..c09d6e2 --- /dev/null +++ b/src/main/java/javaStudy/collectors/Queue&LinkedList.txt @@ -0,0 +1,10 @@ +1.LinkedList + (1)概述:LinkedList与ArrayList一样实现List接口,只是ArrayList是List接口的大小可变数组的实现, + LinkedList是List接口链表的实现。基于链表实现的方式使得LinkedList在插入和删除时更优于ArrayList，而随机访问则比ArrayList逊色些。 + 除了实现 List 接口外，LinkedList 类还为在列表的开头及结尾 get、remove 和 insert 元素提供了统一的命名方法。这些操作允许将链接列表用作堆栈、队列或双端队列。 + (2)源码分析: + I:定义 + public class LinkedList + extends AbstractSequentialList + implements List, Deque, Cloneable, java.io.Serializable + AbstractSequentialList:提供List接口的骨干实现,最大限度减少 \ No newline at end of file From 7dfe8dd2a0d32ea0dd58a26ab11b4cda31c9acd8 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?=E6=9D=8E=E6=88=90?= Date: Thu, 2 Jan 2025 10:26:37 +0800 Subject: [PATCH 6/7] =?UTF-8?q?20250102:=E6=97=B6=E9=97=B4=E7=A8=8B?= =?UTF-8?q?=E5=BA=8F?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- src/main/java/Test.java | 12 ----- src/main/java/WorkTimeCalculator.java | 70 +++++++++++++++++++++++++++ 2 files changed, 70 insertions(+), 12 deletions(-) create mode 100644 src/main/java/WorkTimeCalculator.java diff --git a/src/main/java/Test.java b/src/main/java/Test.java index 4e049dc..adf0310 100644 --- a/src/main/java/Test.java +++ b/src/main/java/Test.java @@ -1,20 +1,8 @@ -import org.springframework.beans.factory.annotation.Lookup; -import org.springframework.core.io.InputStreamSource; -import org.springframework.core.io.Resource; import org.springframework.stereotype.Service; -import java.io.InputStream; -import java.util.LinkedList; - -/** - * @author hpl - * @date 2023/4/15 14:40 - */ @Service public class Test { - - public static void main(String[] args) { } diff --git a/src/main/java/WorkTimeCalculator.java b/src/main/java/WorkTimeCalculator.java new file mode 100644 index 0000000..c790790 --- /dev/null +++ b/src/main/java/WorkTimeCalculator.java @@ -0,0 +1,70 @@ +import java.time.LocalDate; +import java.time.LocalDateTime; +import java.time.LocalTime; +import java.time.format.DateTimeFormatter; +import java.util.ArrayList; +import java.util.List; +import java.util.Scanner; + +public class WorkTimeCalculator { + public static void main(String[] args) { + Scanner sc = new Scanner(System.in); + + System.out.println("请输入开始工作的年份"); + int startYear = sc.nextInt(); + System.out.println("请输入开始工作的月份"); + int startMonth = sc.nextInt(); + System.out.println("请输入开始工作的日"); + int startDay = sc.nextInt(); + System.out.println("请输入开始工作当天的起始时间（24小时制，如0830表示8点30分）"); + int startTimeInput = sc.nextInt(); + int startTimeHour = startTimeInput / 100; + int startTimeMinute = startTimeInput % 100; + LocalTime startTime = LocalTime.of(startTimeHour, startTimeMinute); + + System.out.println("请输入每次工作的时长（分钟）"); + int workTime = sc.nextInt(); + System.out.println("请输入工作的休息间隔（分钟）"); + int intervalTime = sc.nextInt(); + + System.out.println("请输入所选择的年份和月份和日期"); + int selectYear = sc.nextInt(); + int selectMonth = sc.nextInt(); + int selectDay = sc.nextInt(); + sc.close(); + + LocalDate startDate = LocalDate.of(startYear, startMonth, startDay); + LocalDateTime startDateTime = LocalDateTime.of(startDate, startTime); + LocalDate selectDate = LocalDate.of(selectYear, selectMonth, selectDay); + LocalDateTime selectDateTime = LocalDateTime.of(selectDate, LocalTime.MIDNIGHT); + + List workPeriods = calculateWorkPeriods(startDateTime, workTime, intervalTime, selectDateTime); + + for (String period : workPeriods) { + System.out.println(period); + } + } + + public static List calculateWorkPeriods(LocalDateTime startDateTime, int workTimeMinutes, int intervalTimeMinutes, LocalDateTime selectDateTime) { + List periods = new ArrayList<>(); + LocalDateTime currentTime = startDateTime; + DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm"); + + while (!currentTime.isAfter(selectDateTime.withHour(23).withMinute(59).withSecond(59).withNano(999999999))) { + LocalDateTime endTime = currentTime.plusMinutes(workTimeMinutes); + if (endTime.isAfter(selectDateTime.withHour(23).withMinute(59).withSecond(59).withNano(999999999))) { + // 工作时间跨天，只计算到当天的23:59:59 + endTime = selectDateTime.withHour(23).withMinute(59).withSecond(59).withNano(999999999); + } + + String period = currentTime.format(formatter) + " 到 " + endTime.format(formatter); + if (!endTime.isBefore(selectDateTime)) { + periods.add(period); + } + + currentTime = endTime.plusMinutes(intervalTimeMinutes); + } + + return periods; + } +} \ No newline at end of file From e1a5c893fdc1d0cdb0c06ba43aff2f5d0ba5b196 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?=E6=9D=8E=E6=88=90?= Date: Fri, 3 Jan 2025 17:27:24 +0800 Subject: [PATCH 7/7] =?UTF-8?q?20250103:=E6=97=B6=E9=97=B4=E7=A8=8B?= =?UTF-8?q?=E5=BA=8F(=E6=94=B9)?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- src/main/java/Test.java | 13 ++++----- src/main/java/WorkTimeCalculator.java | 42 ++++++++++++++++----------- 2 files changed, 31 insertions(+), 24 deletions(-) diff --git a/src/main/java/Test.java b/src/main/java/Test.java index adf0310..fe0ac04 100644 --- a/src/main/java/Test.java +++ b/src/main/java/Test.java @@ -1,13 +1,12 @@ import org.springframework.stereotype.Service; +import javax.script.*; +import java.io.FileReader; +import java.util.LinkedList; +import java.util.Scanner; + @Service public class Test { - - public static void main(String[] args) { - } - - - public void test(){ - + public static void main(String[] args) throws Exception { } } diff --git a/src/main/java/WorkTimeCalculator.java b/src/main/java/WorkTimeCalculator.java index c790790..09cec9c 100644 --- a/src/main/java/WorkTimeCalculator.java +++ b/src/main/java/WorkTimeCalculator.java @@ -10,25 +10,33 @@ public class WorkTimeCalculator { public static void main(String[] args) { Scanner sc = new Scanner(System.in); - System.out.println("请输入开始工作的年份"); - int startYear = sc.nextInt(); - System.out.println("请输入开始工作的月份"); - int startMonth = sc.nextInt(); - System.out.println("请输入开始工作的日"); - int startDay = sc.nextInt(); - System.out.println("请输入开始工作当天的起始时间（24小时制，如0830表示8点30分）"); - int startTimeInput = sc.nextInt(); - int startTimeHour = startTimeInput / 100; - int startTimeMinute = startTimeInput % 100; - LocalTime startTime = LocalTime.of(startTimeHour, startTimeMinute); +// System.out.println("请输入开始工作的年份"); +// int startYear = sc.nextInt(); +// System.out.println("请输入开始工作的月份"); +// int startMonth = sc.nextInt(); +// System.out.println("请输入开始工作的日"); +// int startDay = sc.nextInt(); +// System.out.println("请输入开始工作当天的起始时间（24小时制，如0830表示8点30分）"); +// int startTimeInput = sc.nextInt(); +// int startTimeHour = startTimeInput / 100; +// int startTimeMinute = startTimeInput % 100; +// LocalTime startTime = LocalTime.of(startTimeHour, startTimeMinute); - System.out.println("请输入每次工作的时长（分钟）"); - int workTime = sc.nextInt(); - System.out.println("请输入工作的休息间隔（分钟）"); - int intervalTime = sc.nextInt(); +// System.out.println("请输入每次工作的时长（分钟）"); +// int workTime = sc.nextInt(); +// System.out.println("请输入工作的休息间隔（分钟）"); +// int intervalTime = sc.nextInt(); - System.out.println("请输入所选择的年份和月份和日期"); - int selectYear = sc.nextInt(); + + int startYear = 2025; + int startMonth = 1; + int startDay = 1; + LocalTime startTime = LocalTime.of(4, 0); + int workTime = 120; + int intervalTime = 480; + + System.out.println("请输入月份和日期"); + int selectYear = 2025; int selectMonth = sc.nextInt(); int selectDay = sc.nextInt(); sc.close();