Java 设计模式最佳实践：1~5（3）

jshell> class PS2Device {};
| created class PS2Device
jshell> class USBDevice {};
| created class USBDevice
jshell> Optional.of(new PS2Device()).stream().map(x -> new USBDevice()).findFirst().get()
$39 ==> USBDevice@15bb6bea

jshell> Consumer<String> toASCII = x -> System.out.println("Print ASCII: " + x);
toASCII ==> $Lambda$159/1690859824@400cff1a
jshell> Function<String, String> toHex = x -> x.chars().boxed().map(y -> "0x" + Integer.toHexString(y)).collect(Collectors.joining(" "));
toHex ==> $Lambda$158/1860250540@55040f2f
jshell> Consumer<String> decorateToHex = x -> System.out.println("Print HEX: " + toHex.apply(x))
decorateToHex ==> $Lambda$160/1381965390@75f9eccc
jshell> toASCII.andThen(decorateToHex).accept("text")
Print ASCII: text
Print HEX: 0x74 0x65 0x78 0x74

jshell> String text = "Text";
text ==> "Text"
jshell> Stream.<Function<String, String>>of(String::toLowerCase, x -> LocalDateTime.now().toString() + " " + x).map(f -> f.apply(text)).collect(Collectors.toList())
$55 ==> [text, 2017-08-10T08:41:28.243310800 Text]

jshell> List<Consumer<String>> tasks = List.of(System.out::println, x -> System.out.println(LocalDateTime.now().toString() + " " + x))
tasks ==> [$Lambda$192/728258269@6107227e, $Lambda$193/1572098393@7c417213]
jshell> tasks.forEach(x -> x.accept(text))
Text
2017-08-10T08:47:31.673812300 Text

jshell> Map<String, IntBinaryOperator> operands = Map.of("+", (x, y) -> x + y, "-", (x, y) -> x - y)
operands ==> {-=$Lambda$208/1259652483@65466a6a, +=$Lambda$207/1552978964@4ddced80}
jshell> Arrays.asList("4 5 + 6 -".split(" ")).stream().reduce("0 ",(acc, x) -> {
...> if (operands.containsKey(x)) {
...> String[] split = acc.split(" ");
...> System.out.println(acc);
...> acc = split[0] + " " + operands.get(x).applyAsInt(Integer.valueOf(split[1]), Integer.valueOf(split[2])) + " ";
...> } else { acc = acc + x + " ";}
...> return acc; }).split(" ")[1]
0 4 5
0 9 6
$76 ==> "3"

jshell> List.of(1, 4).forEach(System.out::println)
jshell> for(Integer i: List.of(1, 4)) System.out.println(i);

JButton button = new Jbutton("Click Here");
button.addActionListener(new ActionListener() 
{ 
  public void actionPerformed(ActionEvent e) 
  {
    System.out.println("Handled by the old listener");
  }
});

button.addActionListener(e -> System.out.println("Handled by lambda"));

jshell> Function<Double, Double> tenPercentDiscount = x -> x * 0.9;
tenPercentDiscount ==> $Lambda$217/1990160809@4c9f8c13
jshell> List.<Double>of(5.4, 6.27, 3.29).stream().map(tenPercentDiscount).collect(Collectors.toList())
$98 ==> [4.86, 5.643, 2.9610000000000003]

jshell> class TemplateMethod {
...> private Runnable call1 = () -> {};
...> private Runnable call2 = () -> System.out.println("Call2");
...> private Runnable call3 = () -> {};
...> public void setCall1(Runnable call1) { this.call1 = call1;}
...> public void setCall2(Runnable call2) { this.call2 = call2; }
...> public void setCall3(Runnable call3) { this.call3 = call3; }
...> public void run() {
...> call1.run();
...> call2.run();
...> call3.run();
...> }
...> }
| created class TemplateMethod
jshell> TemplateMethod t = new TemplateMethod();
t ==> TemplateMethod@70e8f8e
jshell> t.setCall1(() -> System.out.println("Call1"));
jshell> t.setCall3(() -> System.out.println("Call3"));
jshell> t.run();
Call1
Call2
Call3

jshell> import java.time.*
jshell> import java.time.format.*
jshell> DateTimeFormatter dtf = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss.SSS")
dtf ==> Value(YearOfEra,4,19,EXCEEDS_PAD)'-'Value(MonthOf ... Fraction(NanoOfSecond,3,3)
jshell> try (Stream<Path> files = Files.find(Paths.get("d:/"), 1, (path, attr) -> String.valueOf(path).endsWith(".log"))) {
...> files.parallel().
...> flatMap(x -> { try { return Files.lines(x); } catch (IOException e) {} return null;}).
...> filter(x -> x.contains("2485ec27856c56f4")).
...> map(x -> x.substring(0, 23) + " " + x.split(":")[3]).
...> sorted((x, y) -> LocalDateTime.parse(x.substring(0, 23), dtf).compareTo(LocalDateTime.parse(y.substring(0, 23), dtf))).
...> collect(Collectors.toList()).stream().sequential().
...> reduce((acc, x) -> {
...> if (acc.length() > 0) {
...> Long duration = Long.valueOf(Duration.between(LocalDateTime.parse(acc.substring(0, 23), dtf), LocalDateTime.parse(x.substring(0, 23), dtf)).t oMillis());
...> acc += "n After " + duration.toString() + "ms " + x.substring(24);
...> } else {
...> acc = x;
...> }
...> return acc;}).ifPresent(System.out::println);
...> }
2016-02-26 11:15:47.561 Hello from service1\. Calling service2
After 149ms Hello from service2\. Calling service3 and then service4
After 334ms Hello from service3
After 363ms Got response from service3 [Hello from service3]
After 573ms Hello from service4
After 595ms Got response from service4 [Hello from service4]
After 621ms Got response from service2 [Hello from service2, response from service3 [Hello from service3] and from service4 [Hello from service4]]

jshell> class Connection {
...> public void commit() {};
public void rollback() {};
public void close() {};
public void setAutoCommit(boolean autoCommit) {};
...> public static void runWithinTransaction(Consumer<Connection> c) {
...> Connection t = null;
...> try { t = new Connection(); t.setAutoCommit(false);
...> c.accept(t);
...> t.commit();
...> } catch(Exception e) { t.rollback(); } finally { t.close(); } } }
| created class Connection
jshell> Connection.runWithinTransaction(x -> System.out.println("Execute statement..."));
Execute statement...