//方式一
 //这边值得一提的是在中国的时区偏移是8小时，本次示例转的时间戳是秒级别，得到的值是一个long值；知识追寻者这边是当前时间，故读者得到的结果与知识追寻者得到的结果不一致；读者可以使用站长工具进行测试校验
 // https://unixtime.51240.com/
 @Test
 public void localTimeTest1(){
     // 获得当前时间
     LocalDateTime localDateTime = LocalDateTime.now();
     // 将当前时间转为时间戳
     long second = localDateTime.toEpochSecond(ZoneOffset.ofHours(8));
     // 1580706475
     System.out.println(second);

 }
 
 //方式二
 // 此方法执行的结果与之前一致，也是秒级别
 @Test
 public void localTimeTest2(){
     // 获得当前时间
     LocalDateTime localDateTime = LocalDateTime.now();
     // 将当前时间转为时间戳
     long second = localDateTime.toInstant(ZoneOffset.ofHours(8)).getEpochSecond();
     // 1580707001
     System.out.println(second);

 }

// 方式三
// 此方式转的将是毫秒级别，直接用于站长工具是测试不出来，读者应该将其除1000取商获得正确的秒级时间戳；
 public void localTimeTest3(){
     // 获得当前时间
     LocalDateTime localDateTime = LocalDateTime.now();
     // 将当前时间转为时间戳
     long milliseconds =localDateTime.toInstant(ZoneOffset.ofHours(8)).toEpochMilli();
     // 1580707268
     System.out.println(milliseconds/1000);
 }

// 方式一
// 先获取时间戳为秒级别，然后通过转换为LocalDateTime
public void localTimeTest4(){
    //获得时间戳
    long second = LocalDateTime.now().toInstant(ZoneOffset.of("+8")).getEpochSecond();
    // 将时间戳转为当前时间
    LocalDateTime localDateTime = LocalDateTime.ofEpochSecond(second, 0, ZoneOffset.ofHours(8));
    // 2020-02-03T13:30:44
    System.out.println(localDateTime);
}


//方式二
//本次获取的时间搓将是毫秒级别故要除以1000

public void localTimeTest5(){
    //获得时间戳
    long milliseconds = LocalDateTime.now().toInstant(ZoneOffset.of("+8")).toEpochMilli();
    // 将时间戳转为当前时间
    LocalDateTime localDateTime = LocalDateTime.ofEpochSecond(milliseconds/1000, 0, ZoneOffset.ofHours(8));
    // 2020-02-03T13:35:53
    System.out.println(localDateTime);

}

//方式三
//本方式精确值是毫秒级别，故得到的结果会存在三位小数点；

@Test
public void localTimeTest6(){
    //获得时间戳
    long milliseconds = LocalDateTime.now().toInstant(ZoneOffset.of("+8")).toEpochMilli();
    // 将时间戳转为当前时间
    LocalDateTime localDateTime = Instant.ofEpochMilli(milliseconds).atZone(ZoneOffset.ofHours(8)).toLocalDateTime();
    // 2020-02-03T13:38:35.799
    System.out.println(localDateTime);

}

public void LocalDateTest(){
    // 1当前日期 常用
    LocalDate now = LocalDate.now();
    System.out.println(now);//2019-10-27
    // 2指定年月 日 方式 常用
    LocalDate ofDate = LocalDate.of(2018, 8, 8);
    System.out.println(ofDate);//2018-08-08
    // 3使用Clock方式创建 不常用
    Clock clock = Clock.systemDefaultZone();
    LocalDate date = LocalDate.now(clock);
    System.out.println(date);// 2019-10-27
    // 4 指定年份 和 一年的天数进行创建
    LocalDate localDate = LocalDate.ofYearDay(2018, 256);
    System.out.println(localDate);// 2018-09-13
    
}

List<People> list = new ArrayList<>();

//取前20个
list=list.stream().limit(20).collect(Collectors.toList());


//取属性
List<String> spuCodes = list.stream().map(People::getName).collect(Collectors.toList());
	
//拼接	
List<Integer> numbers = ImmutableList.of(1, 2, 3, 4, 5);
String result = numbers.stream().map(Object::toString).collect(Collectors.joining(","));
String result = numbers.stream().collect(Collectors.joining(", ", "[", "]"));
 

//根据age对list分组     List<X>  ->   map<x.id,List<x>>  
Map<String,List<People>> groupByAge = list.stream().collect(Collectors.groupingBy(People::getAge));

//根据age对list的属性分组    List<X>  ->   map<x.id,List<x.name>>

Map<Long,List<String>> exhibitionPitemMap = list.stream().collect(
Collectors.groupingBy(People::getLong, Collectors.mapping(People::getName, Collectors.toList())));


//根据age进行排序（reserve倒序）
List<People> peopleListSorted = list.stream().sorted(Comparator.comparing(People::getAge)
	.reversed()).collect(Collectors.toList());


//提取age,并排序
List<String> ageList = list.stream().map(People::getAge).distinct().sorted().collect(Collectors.toList());



//提取年龄大于20的people
List<People> olderThan20 = list.stream().filter(e->Integer.parseInt(e.getAge()) > 20)
	.collect(Collectors.toList());

//累加
BigDecimal totalMoney = list.stream().map(People::getMoney).reduce(BigDecimal.ZERO, BigDecimal::add);

list.stream().mapToLong(People::getAge).sum();


Long sum2 = list.stream().reduce(0L, Long::sum); 


//过滤取单个值
People people = list.stream().filter(e->e.getAge().equals("20")).findFirst().orElse(null);



//查找流中最大值和最小值
List<Person> personList = generatePersonList();
        Person olderOne = personList.stream().max(Comparator.comparing(Person::getAge)).orElse(null);
        Person youngerOne = personList.stream().min(Comparator.comparing(Person::getAge)).orElse(null);

//对象去重
ArrayList<Person> collect = personList.stream().collect(Collectors.collectingAndThen(
      Collectors.toCollection(() -> new TreeSet<>(Comparator.comparingInt(Person::getAge))),
                ArrayList::new));
				
	
//转换成String[]
list..stream().toArray(String[]::new)


//拼接字符串
request.getModuleIdList().stream().map(x-> x.toString()).collect(Collectors.joining(","));


// List<x> ->  Map<x.id,x>

//1,key存在重复时,会抛出异常
Map<Long, Person> id2Entity = personList.stream().collect(Collectors.toMap(Person::getId, x-> x));
		
//2,解决key重复异常情况
Map<Long, Person> entityMap= personList.stream().collect(Collectors.toMap(Person::getId, Function.identity(),(x,y) -> y));
	
	

//list 分割
int pageNum = (list.size()+ PAGE_SIZE -1) / PAGE_SIZE;
List<List<Long>> splitList = Stream.iterate(0, n->n+1).limit(pageNum).parallel()
	.map(a-> list.stream().skip(a*PAGE_SIZE).limit(PAGE_SIZE).parallel().collect(Collectors.toList())).collect(Collectors.toList());