java新特征

package com.rainhowchan;

import com.rainhowchan.inter.ConvertorInterface;
import com.rainhowchan.po.Artist;
import com.rainhowchan.po.Car;
import com.rainhowchan.po.StudentScore;
import org.junit.Test;

import javax.script.ScriptEngine;
import javax.script.ScriptEngineManager;
import javax.script.ScriptException;
import java.io.*;
import java.nio.ByteBuffer;
import java.nio.channels.FileChannel;
import java.nio.charset.StandardCharsets;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.text.ParsePosition;
import java.text.SimpleDateFormat;
import java.time.Duration;
import java.time.LocalDateTime;
import java.time.Month;
import java.util.*;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.FutureTask;
import java.util.concurrent.ThreadLocalRandom;
import java.util.function.Function;
import java.util.function.Supplier;
import java.util.stream.Collectors;
import java.util.stream.Stream;

import static java.util.stream.Collectors.mapping;
import static java.util.stream.Collectors.toList;

public class TestJava8 {
    @Test
    public void testTime() {
        LocalDateTime from = LocalDateTime.of(2014, Month.APRIL, 16, 23, 24);
        LocalDateTime to = LocalDateTime.of(2015, Month.DECEMBER, 23, 14, 26);
        Duration duration = Duration.between(from, to);
        System.out.println(duration.toDays());

    }

    @Test
    public void testJavaScript() throws ScriptException {
        ScriptEngineManager manager = new ScriptEngineManager();
        ScriptEngine engine = manager.getEngineByName("javascript");
        System.out.println("Result:" + engine.eval("function f() { return 1; }; f() + 1;"));
    }

    @Test
    public void testBase64() {
        final String text = "Base64 finally in Java 8!";
        byte[] encoded = Base64.getEncoder().encode(text.getBytes(StandardCharsets.UTF_8));
        String decoded = new String(Base64.getDecoder().decode(encoded), StandardCharsets.UTF_8);
        System.out.println(decoded);
    }

    public @Test
    void testLambda() {
        List
 
   names = Arrays.asList("peter", "anna", "mike", "xenia");
        names.sort(String::compareTo);
    }

    @Test
    public void testParall() {
        long[] arrayOfLong = new long[20000];

        Arrays.parallelSetAll(arrayOfLong,
                index -> ThreadLocalRandom.current().nextInt(1000000));
        Arrays.stream(arrayOfLong).limit(10).forEach(
                i -> System.out.print(i + " "));
        System.out.println();

        Arrays.parallelSort(arrayOfLong);
        Arrays.stream(arrayOfLong).limit(10).forEach(
                i -> System.out.print(i + " "));
        System.out.println();
    }

    @Test
    public void testOptional() {
        Optional
  
    fullName = Optional.ofNullable(null); System.out.println(fullName.isPresent()); System.out.println(fullName.orElse("sfdsf")); } @Test public void testFunc() { Car car = Car.create(Car::new); List
   
     cars = Arrays.asList(car); cars.forEach(Car::repair); System.out.println(car); } @Test public void testStream() { List
    
      strings = Arrays.asList("abc", "", "bc", "efg", "abcd", "", "jkl"); String collect = strings.stream() .filter(str -> !strings.isEmpty()) .map(String::toUpperCase) .sorted() .collect(Collectors.joining(",")); System.out.println(collect); } @Test public void testSummaryStatistics() { List
     
       numbers = Arrays.asList(3, 2, 2, 3, 7, 3, 5); IntSummaryStatistics stats = numbers.stream().mapToInt(x -> x).summaryStatistics(); System.out.println("列表中最大的数 : " + stats.getMax()); System.out.println("列表中最小的数 : " + stats.getMin()); System.out.println("所有数之和 : " + stats.getSum()); System.out.println("平均数 : " + stats.getAverage()); } public @Test void testReduce() { Integer result = Stream.of(1, 2, 3).reduce(0, Integer::sum); } public @Test void testArtist() { List
      
        artists = new ArrayList<>(); artists.add(new Artist("zhanghanyi", "china")); artists.add(new Artist("ww", "chinese")); List
       
         collect = artists.stream() .flatMap(artist -> Arrays.stream(new String[]{artist.getName(), artist.getNationlity()})) .collect(toList()); System.out.println(collect); } public @Test void testChars() { List
        
          list = new ArrayList<>(); list.add("asdfDFddfDSFdsddfs"); list.add("aEEEEEEfDFddfDSFdsddfs"); list.add("asdfDDssdsdfDSFdsdsfasfasdfasfdfs"); // list.stream() // .max(Comparator.comparingLong(this::countStringLowercaseLetters)) // .ifPresent(System.out::println); list.stream().max(Comparator.comparingLong(str -> str.chars().filter(Character::isLowerCase).count())).ifPresent(System.out::println); } // private long countStringLowercaseLetters(String string) { // return string.chars().filter(Character::isLowerCase).count(); // } public @Test void testMapping() { List
         
           studentList = Arrays.asList( new StudentScore(1, "小明", "语文", 85), new StudentScore(2, "小明", "数学", 90), new StudentScore(3, "小明", "英语", 80), new StudentScore(4, "小红", "语文", 80), new StudentScore(5, "小红", "数学", 80), new StudentScore(6, "小红", "英语", 80)); // Map
          
           > collect = studentList.stream() .collect(Collectors.groupingBy(StudentScore::getName, mapping(StudentScore::getSubject, toList()))); // studentList.stream().map(StudentScore::getName).distinct().collect(toList()).forEach(System.out::println); // IntSummaryStatistics statistics = studentList.stream().mapToInt(StudentScore::getScore).summaryStatistics(); // studentList.stream().flatMap(student -> Stream.of(student.getName(), student.getSubject())).collect(toList()).forEach(System.out::println); } @Test public void convertTest() { List
           
             collected = new ArrayList<>(); collected.add("alpha"); collected.add("beta"); collected.add("cool"); collected.add("delta"); List
            
              collect = collected.stream().map(String::toUpperCase).collect(toList()); System.out.println(collected);//此处打印出来的是大写还是小写，为什么？ System.out.println(collect);//此处打印出来的是大写还是小写，为什么？ } public @Test void testInt() { Optional
             
               collect = Stream.of(1, 23, 34, 231, 34).max(Comparator.comparingInt(o -> o)); System.out.println(collect.get()); } public @Test void testII() { Map
              
                collect = Stream.of(1, 23, 34, 231, 34).collect(Collectors.partitioningBy(i -> i % 2 == 0, Collectors.counting())); System.out.println(collect); } public @Test void testIII() { } public @Test void testFunctionInterface() { Date date = outFunc("2017-12-13 12:41:10", (ConvertorInterface
               
                ) s -> { SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss", Locale.CHINA); return dateFormat.parse(s, new ParsePosition(1)); }); System.out.println(date); ConvertorInterface
                
                  convertorInterface = Double::parseDouble; System.out.println(convertorInterface.convertor("12")); ConvertorInterface
                 
                   stringBooleanConvertorInterface = "asdf"::startsWith; System.out.println(stringBooleanConvertorInterface.convertor("af")); Function
                  
                    toInteger = Integer::valueOf; toInteger.andThen(String::valueOf); Supplier
                   
                     supplier = Car::new; } public 
                    
                      D outFunc(String strDate, ConvertorInterface
                     
                       convertorInterface) { return convertorInterface.convertor((T) strDate); } public @Test void testProperties() throws IOException { Properties properties = new Properties(); properties.setProperty("haha", "asdfl"); FileWriter fw = new FileWriter("e:\\properites.txt"); properties.store(fw, "张涵弈"); } public @Test void testBuffer() throws IOException { ByteBuffer buff = ByteBuffer.allocate(1024); // System.out.println(buff.position()); // buff.putInt(10); // buff.putInt(14); // buff.putInt(13); // System.out.println(buff.position()); // buff.flip(); // System.out.println("切换写模式后，position———limit，" + buff.position() + "———" + buff.limit()); // buff.clear(); // System.out.println("切换读模式后，position———limit，" + buff.position() + "———" + buff.limit()); File f1 = new File("e:\\properites.txt"); FileChannel channel = new RandomAccessFile(f1, "rw").getChannel(); int read = channel.read(buff); System.out.println(buff); } public @Test void testThread() throws ExecutionException, InterruptedException { FutureTask