之前有粉丝后台跟我说，作为一个初学者，真的是不清楚该如何去进行学习，直接上ssm框架也看不明白，那我作为这么一个宠粉的人，怎么可能让粉丝有这样的顾虑啊，今天真的是基础到极点了，分享我这边的相应的一些代码实例，因为在代码的备注中已经写的很清楚了，所以基本不会再通过文字进行讲解

文章首发公众号：Java架构师联盟，每日更新技术好文，后面也会开源我的代码仓库，毕竟现在还比较单薄

注释+源码+结果，这边应该展示的很清楚，也比较好理解，不过，一定要自己去实践一下，不实践再简单的技术理解起来也不容易

我敢说这是全网最详细的基础讲解，附源码实例，没人学不明白

而向多线程什么的学习实例，我这边之前的文章也整理过，大家可以去查看，每一个都带着相应的源码展示

好了，话不多说，看正题

Java基础之：OOP——抽象类

<pre spellcheck="false" class="md-fences md-end-block ty-contain-cm modeLoaded" lang="" cid="n9" mdtype="fences" style="box-sizing: border-box; overflow: visible; font-family: var(--monospace); font-size: 0.9em; display: block; break-inside: avoid; text-align: left; white-space: normal; background-image: inherit; background-position: inherit; background-size: inherit; background-repeat: inherit; background-attachment: inherit; background-origin: inherit; background-clip: inherit; background-color: rgb(248, 248, 248); position: relative !important; border: 1px solid rgb(231, 234, 237); border-radius: 3px; padding: 8px 4px 6px; margin-bottom: 15px; margin-top: 15px; width: inherit; color: rgb(51, 51, 51); font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;">package com.biws.testabstract;
​
/**

• @author ：biws
• @date ：Created in 2020/12/22 21:14
• @description：抽象类测试
  */
  public class Abstract_Test {
  ​
  public static void main(String[] args) {
  ​
  Cat cat = new Cat("小花猫");
  cat.eat();
  }
  ​
  }
  ​
  ​
  abstract class Animal { //抽象类
  private String name;
  ​
  public Animal(String name) {
  super();
  this.name = name;
  }
  ​
  public String getName() {
  return name;
  }
  ​
  public void setName(String name) {
  this.name = name;
  }
  ​
  //eat , 抽象方法
  public abstract void eat();
  }
  ​
  //解读
  //1. 当一个类继承了抽象类,就要把抽象类的所有抽象方法实现
  //2. 所谓方法实现，指的是 把方法体写出, 方法体是空，也可以.
  class Cat extends Animal {
  public Cat(String name) {
  super(name);
  // TODO Auto-generated constructor stub
  }
  ​
  public void eat() {
  System.out.println(getName() + " 爱吃 <・)))><<");
  }
  }</pre>

然后呢，我们看一下多态的实现

<pre spellcheck="false" class="md-fences md-end-block ty-contain-cm modeLoaded" lang="" cid="n11" mdtype="fences" style="box-sizing: border-box; overflow: visible; font-family: var(--monospace); font-size: 0.9em; display: block; break-inside: avoid; text-align: left; white-space: normal; background-image: inherit; background-position: inherit; background-size: inherit; background-repeat: inherit; background-attachment: inherit; background-origin: inherit; background-clip: inherit; background-color: rgb(248, 248, 248); position: relative !important; border: 1px solid rgb(231, 234, 237); border-radius: 3px; padding: 8px 4px 6px; margin-bottom: 15px; margin-top: 15px; width: inherit; color: rgb(51, 51, 51); font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;">package com.biws.testabstract;
​
/**

• @author ：biws
• @date ：Created in 2020/12/22 21:17
• @description：多态在抽象类中的实现
  */
  public class AbstractPolArray {
  ​
  public static void main(String[] args) {
  //抽象类不可以实例化，但可以使用多态数组
  Animal1[] animal1 = new Animal1[2];
  ​
  animal1[0] = new Dog1("小黑狗");
  animal1[1] = new Cat1("小花猫");
  ​
  //多态数组的使用
  for (int i = 0; i < animal1.length; i++) {
  show(animal1[i]);
  }
  }
  ​
  //这里不用担心会传入一个Animal类型的实例，因为Animal不能实例化
  //编译器不会通过，所以只会传入Animal的子类实例
  public static void show(Animal1 a) {
  a.eat(); //多态的使用
  ​
  if(a instanceof Dog1) {
  ((Dog1)a).watch();
  }else if(a instanceof Cat1) {
  ((Cat1)a).catchMouse();
  }
  }
  }
  ​
  abstract class Animal1{
  private String name;
  ​
  public Animal1(String name) {
  super();
  this.name = name;
  }
  ​
  public String getName() {
  return name;
  }
  ​
  public void setName(String name) {
  this.name = name;
  }
  ​
  //动物都有eat的动作，但我们并不知道每一个动物具体怎么样eat
  //所以这里通过抽象提供了eat方法，需要子类来实现
  public abstract void eat();
  }
  ​
  class Dog1 extends Animal1{
  public Dog1(String name) {
  super(name);
  }
  ​
  @Override
  public void eat() {
  System.out.println(getName() + "啃骨头......");
  }
  ​
  public void watch() {
  System.out.println(getName() + "守家.....");
  }
  }
  ​
  class Cat1 extends Animal1{
  public Cat1(String name) {
  super(name);
  }
  ​
  @Override
  public void eat() {
  System.out.println(getName() + "吃鱼......");
  }
  ​
  public void catchMouse(){
  System.out.println(getName() + "抓老鼠.....");
  }
  }</pre>

最后举个小例子总结一下

<pre spellcheck="false" class="md-fences md-end-block ty-contain-cm modeLoaded" lang="" cid="n13" mdtype="fences" style="box-sizing: border-box; overflow: visible; font-family: var(--monospace); font-size: 0.9em; display: block; break-inside: avoid; text-align: left; white-space: normal; background-image: inherit; background-position: inherit; background-size: inherit; background-repeat: inherit; background-attachment: inherit; background-origin: inherit; background-clip: inherit; background-color: rgb(248, 248, 248); position: relative !important; border: 1px solid rgb(231, 234, 237); border-radius: 3px; padding: 8px 4px 6px; margin-bottom: 15px; margin-top: 15px; width: inherit; color: rgb(51, 51, 51); font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;">package com.biws.testabstract;
​
/**

• @author ：biws
• @date ：Created in 2020/12/22 21:24
• @description：模板设计模式
  */
  public class Abstract_Template {
  public static void main(String[] args) {
  Template sub = new Sub();
  sub.caleTimes(); //实际是调用了Template中的caleTimes方法
  ​
  Template subStringB = new SubStringB();
  subStringB.caleTimes();
  ​
  //这里可以看到 StringBuffer在拼接字符串时，远远优于String拼接的效率
  }
  }
  ​
  abstract class Template{ //抽象类
  public abstract void code(); //抽象方法
  public void caleTimes(){ // 统计耗时多久是确定
  //统计当前时间距离 1970-1-1 0:0:0 的时间差，单位ms
  long start = System.currentTimeMillis();
  code(); //这里的code在调用时，就是指向子类中已经重写实现了的code
  long end = System.currentTimeMillis();
  System.out.println("耗时："+(end-start));
  }
  }
  ​
  class Sub extends Template{
  ​
  @Override
  public void code() {
  String x = "";
  for(int i = 0;i < 10000 ; i++) { //拼接1W个hello 看处理时间
  x += "hello" + i;
  }
  }
  }
  ​
  class SubStringB extends Template{
  @Override
  public void code() {
  StringBuffer stringBuffer = new StringBuffer();
  for(int i = 0;i < 10000 ; i++) { //拼接1W个hello 看处理时间
  stringBuffer.append("hello" + i);
  }
  }
  }</pre>

Java基础之：StringBuffer与StringBuilder

简单直白点，直接一套代码走起

<pre spellcheck="false" class="md-fences md-end-block ty-contain-cm modeLoaded" lang="" cid="n16" mdtype="fences" style="box-sizing: border-box; overflow: visible; font-family: var(--monospace); font-size: 0.9em; display: block; break-inside: avoid; text-align: left; white-space: normal; background-image: inherit; background-position: inherit; background-size: inherit; background-repeat: inherit; background-attachment: inherit; background-origin: inherit; background-clip: inherit; background-color: rgb(248, 248, 248); position: relative !important; border: 1px solid rgb(231, 234, 237); border-radius: 3px; padding: 8px 4px 6px; margin-bottom: 15px; margin-top: 15px; width: inherit; color: rgb(51, 51, 51); font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;">package com.biws.string;
​
/**

• @author ：biws
• @date ：Created in 2020/12/22 21:27
• @description：String_StringBuffer_StringBuilder对比
  */
  public class String_StringBuffer_StringBuilder {
  public static void main(String[] args) {
  // TODO Auto-generated method stub
  ​
  String text = ""; //字符串
  long startTime = 0L;
  long endTime = 0L;
  StringBuffer buffer = new StringBuffer("");//StringBuffer
  StringBuilder builder = new StringBuilder("");//StringBuilder
  ​
  startTime = System.currentTimeMillis();
  for (int i = 0; i < 80000; i++) {
  buffer.append(String.valueOf(i));
  }
  endTime = System.currentTimeMillis();
  System.out.println("StringBuffer的执行时间：" + (endTime - startTime));
  ​
  ​
  ​
  startTime = System.currentTimeMillis();
  for (int i = 0; i < 80000; i++) {
  builder.append(String.valueOf(i));
  }
  endTime = System.currentTimeMillis();
  System.out.println("StringBuilder的执行时间：" + (endTime - startTime));
  ​
  ​
  ​
  startTime = System.currentTimeMillis();
  for (int i = 0; i < 80000; i++) {
  text = text + i;
  }
  endTime = System.currentTimeMillis();
  System.out.println("String的执行时间：" + (endTime - startTime));
  ​
  }
  }</pre>

查看一下执行结果

我敢说这是全网最详细的基础讲解，附源码实例，没人学不明白

Java基础之：Math & Arrays

Math

简单粗暴，直接进行代码展示

<pre spellcheck="false" class="md-fences md-end-block ty-contain-cm modeLoaded" lang="" cid="n23" mdtype="fences" style="box-sizing: border-box; overflow: visible; font-family: var(--monospace); font-size: 0.9em; display: block; break-inside: avoid; text-align: left; white-space: normal; background-image: inherit; background-position: inherit; background-size: inherit; background-repeat: inherit; background-attachment: inherit; background-origin: inherit; background-clip: inherit; background-color: rgb(248, 248, 248); position: relative !important; border: 1px solid rgb(231, 234, 237); border-radius: 3px; padding: 8px 4px 6px; margin-bottom: 15px; margin-top: 15px; width: inherit; color: rgb(51, 51, 51); font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;">package com.biws.testmath;
​
/**

• @author ：biws
• @date ：Created in 2020/12/22 21:42
• @description：测试math类
  /
  public class ClassTest {
  public static void main(String[] args) {
  //1.abs 绝对值
  int abs = Math.abs(9);
  System.out.println(abs);
  //2.pow 求幂
  double pow = Math.pow(-3.5, 4);
  System.out.println(pow);
  //3.ceil 向上取整,返回>=该参数的最小整数;
  double ceil = Math.ceil(-3.0001);
  System.out.println(ceil);
  //4.floor 向下取整，返回<=该参数的最大整数
  double floor = Math.floor(-4.999);
  System.out.println(floor);
  //5.round 四舍五入 Math.floor(该参数+0.5)
  long round = Math.round(-5.001);
  System.out.println(round);
  //6.sqrt 求开方
  double sqrt = Math.sqrt(-9.0);
  System.out.println(sqrt);
  //7.random 返回随机数【0——1)
  //[a-b]:int num = (int)(Math.random()（b-a+1）+a)
  double random = Math.random();
  System.out.println(random);
  ​
  //小技巧：获取一个 a-b 之间的一个随机整数
  int a = (int)(Math.random()(15-7+1)+7);
  System.out.println(a);
  /
• 理解：
• 1.Math.random() 是 [0，1)的随机数
• 2.(Math.random()*(15-7+1) 就是[0，9)
• 3.Math.random()*(15-7+1)+7 就是[7，16)
• 4.(int)取整就是 [7,15] ，即[a,b]之间的随机整数
  */
  }
  }</pre>

执行结果

我敢说这是全网最详细的基础讲解，附源码实例，没人学不明白

Arrays

正常的执行

<pre spellcheck="false" class="md-fences md-end-block ty-contain-cm modeLoaded" lang="" cid="n29" mdtype="fences" style="box-sizing: border-box; overflow: visible; font-family: var(--monospace); font-size: 0.9em; display: block; break-inside: avoid; text-align: left; white-space: normal; background-image: inherit; background-position: inherit; background-size: inherit; background-repeat: inherit; background-attachment: inherit; background-origin: inherit; background-clip: inherit; background-color: rgb(248, 248, 248); position: relative !important; border: 1px solid rgb(231, 234, 237); border-radius: 3px; padding: 8px 4px 6px; margin-bottom: 15px; margin-top: 15px; width: inherit; color: rgb(51, 51, 51); font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;">package com.biws.testarray;
​
import java.util.Arrays;
import java.util.Comparator;
​
/**

• @author ：biws
• @date ：Created in 2020/12/22 21:44
• @description：Array中常用排序方法
  */
  public class TestArray1 {
  public static void main(String[] args) {
  Integer[] arr = { 25, 35, 11, 32, 98, 22 };
  // Arrays.sort(arr); //默认小到大排序
  System.out.println(Arrays.toString(arr));
  ​
  // 使用匿名内部类重写compare方法，实现从大到小排序
  Arrays.sort(arr, new Comparator<Integer>() {
  ​
  @Override
  public int compare(Integer o1, Integer o2) {
  if (o1 > o2) {
  return -1;
  } else if (o1 < o2) {
  return 1;
  } else {
  return 0;
  }
  }
  });
  System.out.println(Arrays.toString(arr));
  }
  }</pre>

结果查看

我敢说这是全网最详细的基础讲解，附源码实例，没人学不明白

重写之后的执行结果

<pre spellcheck="false" class="md-fences md-end-block ty-contain-cm modeLoaded" lang="" cid="n34" mdtype="fences" style="box-sizing: border-box; overflow: visible; font-family: var(--monospace); font-size: 0.9em; display: block; break-inside: avoid; text-align: left; white-space: normal; background-image: inherit; background-position: inherit; background-size: inherit; background-repeat: inherit; background-attachment: inherit; background-origin: inherit; background-clip: inherit; background-color: rgb(248, 248, 248); position: relative !important; border: 1px solid rgb(231, 234, 237); border-radius: 3px; padding: 8px 4px 6px; margin-bottom: 15px; margin-top: 15px; width: inherit; color: rgb(51, 51, 51); font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;">package com.biws.testarray;
​
import java.util.Arrays;
import java.util.Comparator;
​
/**

• @author ：biws
• @date ：Created in 2020/12/22 21:46
• @description：重写array中的排序方法
  */
  public class overwriteArraySort {
  @SuppressWarnings("unchecked")
  public static void sort(Integer[] arr, Comparator c) {
  Integer temp = 0;// 自动装箱
  for (int i = 0; i < arr.length; i++) {
  for (int j = 0; j < arr.length - 1 - i; j++) {
  if (c.compare(arr[j] , arr[j + 1]) > 0) {
  temp = arr[j];
  arr[j] = arr[j + 1];
  arr[j + 1] = temp;
  }
  }
  }
  }
  ​
  public static void main(String[] args) {
  Integer[] arr = { 35, 25, 11, 32, 98, 22 };
  // MyArrays.sort(arr);//不添加 Comparator接口对象为参数，就是简单的冒泡排序方法
  System.out.println(Arrays.toString(arr));
  //添加匿名内部类对象为参数，就可以改变排序方式。用此方法可以很灵活的使用排序。
  overwriteArraySort.sort(arr, new Comparator<Integer>() {
  ​
  @Override
  public int compare(Integer o1, Integer o2) {
  //通过返回值的正负来控制，升序还是降序
  //只有当返回值为1时，才会发生交换。例如这里，o1 < o2时返回1 ，进行交换
  //也就是需要前面的数，比后面的数大，即降序
  if (o1 < o2) {
  return -1;
  } else if (o1 > o2) {
  return 1;
  } else {
  return 0;
  }
  }
  });
  System.out.println(Arrays.toString(arr));
  }
  ​
  }</pre>

结果

我敢说这是全网最详细的基础讲解，附源码实例，没人学不明白

Java基础之：大数

<pre spellcheck="false" class="md-fences md-end-block ty-contain-cm modeLoaded" lang="" cid="n39" mdtype="fences" style="box-sizing: border-box; overflow: visible; font-family: var(--monospace); font-size: 0.9em; display: block; break-inside: avoid; text-align: left; white-space: normal; background-image: inherit; background-position: inherit; background-size: inherit; background-repeat: inherit; background-attachment: inherit; background-origin: inherit; background-clip: inherit; background-color: rgb(248, 248, 248); position: relative !important; border: 1px solid rgb(231, 234, 237); border-radius: 3px; padding: 8px 4px 6px; margin-bottom: 15px; margin-top: 15px; width: inherit; color: rgb(51, 51, 51); font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;">package com.biws.bignum;
​
import java.math.BigDecimal;
import java.math.BigInteger;
​
/**

• @author ：biws
• @date ：Created in 2020/12/22 22:03
• @description：
  */
  public class test {
  public static void main(String[] args) {
  BigInteger i1 = new BigInteger("1234567890");
  BigInteger i2 = new BigInteger("200");
  // 2.调用常见的运算方法
  // System.out.println(b1+b2); 不能使用 这样的 + 方法运行
  // 并且，add 这些方法只能是大数于大数相加，BigInteger.add(BigInteger);
  System.out.println(i1.add(i2));// 加
  System.out.println(i1.subtract(i2));// 减
  System.out.println(i1.multiply(i2));// 乘
  System.out.println(i1.divide(i2));// 除
  ​
  BigDecimal b1 = new BigDecimal("1234567890.567");
  BigDecimal b2 = new BigDecimal("123");
  // 2.调用常见的运算方法
  // System.out.println(b1+b2); 不能使用 + 号运算..
  // 并且，add 这些方法只能是大数于大数相加，BigDecimal.add(BigDecimal);
  System.out.println(b1.add(b2));// 加
  System.out.println(b1.subtract(b2));// 减
  System.out.println(b1.multiply(b2));// 乘
  //后面这个 BigDecimal.ROUND_CEILING 需要指定，是精度
  //没有这个参数，则会提示:错误
  System.out.println(b1.divide(b2, BigDecimal.ROUND_CEILING));// 除
  }
  }</pre>

查看一下结果

我敢说这是全网最详细的基础讲解，附源码实例，没人学不明白

Java基础之：日期类

日期类中所包含的方法有点多，所以在这里我用junit方法进行测试，那是真的香 啊，节省了大量的代码编写时间

<pre spellcheck="false" class="md-fences md-end-block ty-contain-cm modeLoaded" lang="" cid="n45" mdtype="fences" style="box-sizing: border-box; overflow: visible; font-family: var(--monospace); font-size: 0.9em; display: block; break-inside: avoid; text-align: left; white-space: normal; background-image: inherit; background-position: inherit; background-size: inherit; background-repeat: inherit; background-attachment: inherit; background-origin: inherit; background-clip: inherit; background-color: rgb(248, 248, 248); position: relative !important; border: 1px solid rgb(231, 234, 237); border-radius: 3px; padding: 8px 4px 6px; margin-bottom: 15px; margin-top: 15px; width: inherit; color: rgb(51, 51, 51); font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;">package com.biws.TestDate;
​
import org.junit.jupiter.api.Test;
​
import java.time.;
import java.time.format.DateTimeFormatter;
import java.time.temporal.ChronoUnit;
import java.util.Date;
​
/*

• @author ：biws
• @date ：Created in 2020/12/22 22:06
• @description：测试全部date类方法
  */
  public class allDateFunction {
  public static void main(String[] args) {
  // TODO Auto-generated method stub
  new allDateFunction().hi();
  new allDateFunction().hello();
  }
  ​
  // JUnit 测试单元
  // 1. 配置快捷键 alt + J
  // 2. 如果要运行某个 测试单元，就选中方法名或光标定位在方法名，在运行 Junit
  // 3. 如果不选，就运行，就把所有的测试单元都运行
  // 4.@Test,代表此方法是测试单元，可以单独运行测试
  ​
  ​
  @Test
  public void hi() {
  System.out.println("hi ");
  }
  ​
  @Test
  public void hello() {
  System.out.println("hello");
  }
  ​
  @Test
  public void testLocalDate() {
  // 获取当前日期（只包含日期，不包含时间）
  LocalDate date = LocalDate.now();
  System.out.println(date);
  ​
  // 获取日期的指定部分
  System.out.println("year:" + date.getYear());
  System.out.println("month:" + date.getMonth());
  System.out.println("day:" + date.getDayOfMonth());
  System.out.println("week:" + date.getDayOfWeek());
  ​
  // 根据指定的日期参数，创建LocalDate对象
  LocalDate of = LocalDate.of(2010, 3, 2);
  System.out.println(of);
  ​
  }
  ​
  // 测试LocalTime类
  @Test
  public void testLocalTime() {
  // 获取当前时间（只包含时间，不包含日期）
  LocalTime time = LocalTime.now();
  System.out.println(time);
  ​
  // 获取时间的指定部分
  System.out.println("hour:" + time.getHour());
  System.out.println("minute:" + time.getMinute());
  ​
  System.out.println("second:" + time.getSecond());
  System.out.println("nano:" + time.getNano());
  ​
  // 根据指定的时间参数，创建LocalTime对象
  LocalTime of = LocalTime.of(10, 20, 55);
  System.out.println(of);
  ​
  }
  ​
  // 测试LocalDateTime类
  ​
  @Test
  public void testLocalDateTime() { // 获取当前时间（包含时间+日期）
  ​
  LocalDateTime time = LocalDateTime.now();
  ​
  // 获取时间的指定部分 System.out.println("year:" + time.getYear());
  System.out.println("month:" + time.getMonthValue());
  System.out.println("day:" + time.getMonth());
  System.out.println("day:" + time.getDayOfMonth());
  System.out.println("hour:" + time.getHour());
  System.out.println("minute:" + time.getMinute());
  ​
  System.out.println("second:" + time.getSecond());
  System.out.println("nano:" + time.getNano());
  ​
  // 根据指定的时间参数，创建LocalTime对象
  LocalDateTime of = LocalDateTime.of(2020, 2, 2, 10, 20, 55);
  System.out.println(of);
  ​
  }
  ​
  @Test
  public void testMonthDay() {
  ​
  LocalDate birth = LocalDate.of(1994, 7, 14); // 生日
  MonthDay birthMonthDay = MonthDay.of(birth.getMonthValue(), birth.getDayOfMonth());
  ​
  LocalDate now = LocalDate.now(); // 当前日期
  MonthDay current = MonthDay.from(now);
  ​
  if (birthMonthDay.equals(current)) {
  System.out.println("今天生日");
  } else {
  System.out.println("今天不生日");
  }
  ​
  }
  ​
  // 判断是否为闰年
  @Test
  public void testIsLeapYear() {
  ​
  LocalDate now = LocalDate.now();
  ​
  System.out.println(now.isLeapYear());
  ​
  }
  // 测试增加日期的某个部分
  ​
  @Test
  public void testPlusDate() {
  ​
  LocalDate now = LocalDate.now(); // 日期
  // 3年前 的日期
  LocalDate plusYears = now.plusDays(-1);
  System.out.println(plusYears);
  ​
  }
  ​
  // 使用plus方法测试增加时间的某个部分
  // 时间范围判断
  @Test
  public void testPlusTime() {
  ​
  LocalTime now = LocalTime.now();// 时间
  ​
  LocalTime plusHours = now.plusSeconds(-500);
  ​
  System.out.println(plusHours);
  ​
  }
  ​
  // 使用minus方法测试查看一年前和一年后的日期
  ​
  @Test
  public void testMinusTime() {
  LocalDate now = LocalDate.now();
  ​
  LocalDate minus = now.minus(1, ChronoUnit.YEARS);
  ​
  // LocalDate minus2 = now.minusYears(1);
  System.out.println(minus);
  ​
  }
  ​
  // 测试时间戳类：Instant ，相当于以前的Date类
  @Test
  public void testInstant() {
  Instant now = Instant.now();
  System.out.println(now);
  ​
  // 与Date类的转换
  Date date = Date.from(now);
  System.out.println(date);
  ​
  Instant instant = date.toInstant();
  ​
  System.out.println(instant);
  }
  ​
  // 格式转换
  @Test
  public void testDateTimeFormatter() {
  DateTimeFormatter pattern = DateTimeFormatter.ofPattern("MM-dd yyyy HH:mm:ss");
  ​
  // 将字符串转换成日期
  LocalDateTime parse = LocalDateTime.parse("03-03 2017 08:40:50", pattern);
  System.out.println(parse);
  ​
  // 将日期转换成字符串
  //LocalDateTime parse = LocalDateTime.now();
  ​
  String format = pattern.format(parse);
  System.out.println(format);
  }
  }</pre>