Java, Up to Date

JAVA, UP TO DATE
JavaSE7 & JavaEE6

Copyright © 2012 Akira Koyasu. Some rights reserved.

JavaOne Tokyo 2012
April 4-5

2 Copyright © 2012 Akira Koyasu. Some rights reserved.

今使える、Javaの最新技術



JavaSE7
Project Coin

Fork/Join Framework

InvokeDynamic

More New I/O



JavaSE7 JavaEE6
Project Coin Simpliﬁed Packaging

Fork/Join Framework ManagedBean

InvokeDynamic CDI

More New I/O


JavaSE7


JavaSE Roadmap

2011 2012 2013

2011/7/28 2012 later 2013 Summer

JavaSE7 JavaSE7u6 JavaSE8
JRE for MacOSX Jigsaw
2012/4/27 Auto-update Lambda
JavaFX3.0
JavaSE7u4 HotRockit
JDK for MacOSX Nashorn
JavaFX2.1 2012/11
G1GC
JRE default JavaSE6
Last public update


Themes of JavaSE7
(from JSR 336)


Themes of JavaSE7
(from JSR 336)

Compatiblity


Themes of JavaSE7
(from JSR 336)

Compatiblity

Productivity Universality
Performance Integration


JavaSE7

Project Coin
Fork/Join Framework
InvokeDynamic
More New I/O


Project Coin

言語仕様の小さな変更

photo.1


Project Coin

言語仕様の小さな変更 Small Change = Coin

photo.1


Project Coin


Strings in switch

photo.1


Project Coin


Strings in switch
Numeric literal improvements

photo.1


Project Coin


Strings in switch
Multi-catch with more precise rethrow

photo.1


Project Coin


Strings in switch
try-with-resources

photo.1


Project Coin


Strings in switch
try-with-resources
Diamond

photo.1


Project Coin


Strings in switch
try-with-resources
Diamond
Safe varargs
photo.1


Strings in switch


Strings in switch

String flag = "aaa";
switch (flag) {
case "aaa":
System.out.println("aaa");
break;
case "bbb":
System.out.println("bbb");
break;
case "ccc":
System.out.println("ccc");
break;
}


Strings in switch

String flag = "aaa"; コンパイル時に
switch (flag) {
hashCode()などを
case "aaa":
System.out.println("aaa"); 使用した比較に
break;
case "bbb": 書き換えられる
break;
case "ccc":
break;
}


Strings in switch

String flag = "aaa"; コンパイル時に
switch (flag) {
hashCode()などを
case "aaa":
System.out.println("aaa"); 使用した比較に
break;
case "bbb": 書き換えられる
break;
case "ccc":
break;
} nullに注意


Numeric literal
improvements


Numeric literal
improvements
Binary literals
int b = 0b1110; // binary (new!)

int o = 016; // octal
int d = 14; // decimal
int x = 0xE; // hexadecimal


Numeric literal
improvements
Binary literals
int b = 0b1110; // binary (new!)

int o = 016; // octal
int d = 14; // decimal
int x = 0xE; // hexadecimal

Underscores in numeric literals
int m = 1_000_000;


Multi-catch with more
precise rethrow


precise rethrow
try {
“|”で複数の例外を foo(); // throws Exception1, Exception2
} catch (Exception1 | Exception2 e) {
catch
}
e.printStackTrace();


precise rethrow
try {
“|”で複数の例外を foo(); // throws Exception1, Exception2
} catch (Exception1 | Exception2 e) {
catch
}

スーパータイプでcatch
→ 実際のサブタイプでthrows宣言可能
void callBar() throws SubException1, SubException2 {
try {
bar(); // throws SubException1, SubException2
} catch (SuperException e) {
throw e;
}
}


try-with-resources


try-with-resources

tryに続けて宣言したリソースが
自動的にclose()される


try-with-resources

try (Writer writer = new FileWriter(file)) {
writer.write("hello!!");
} catch (IOException e) {
}


try-with-resources

try (Writer writer = new FileWriter(file)) {
writer.write("hello!!");
}

java.lang.AutoCloseable / java.io.Closeable
“;”で複数リソースを宣言可


Diamond


Diamond

型推論により、コンストラクタの
ジェネリクスパラメータを省略可能
Map<String, List<Integer>> map = new HashMap<>();


Diamond

型推論により、コンストラクタの
ジェネリクスパラメータを省略可能
Map<String, List<Integer>> map = new HashMap<>();

省略できないケース
// 匿名クラス
List<String> list = new ArrayList<>(){};

void call() {
doSomething(new ArrayList<>()); // メソッド呼び出し
}


Safe Varargs (1)


Safe Varargs (1)

ジェネリック型の可変長引数をもつメソッド
static void pol(List<String>... strLists) {
// ...
}


Safe Varargs (1)

// ...
}

呼び出し側に警告（今まで通り）
List<String> b = ...
List<String> s = ...
// WARNING: Type safety: A generic array of List<String>
// is created for a varargs parameter
pol(b, s);


Safe Varargs (1)

// ...
}

加えて定義側にも警告が出るように
// WARNING: Type safety: Potential heap pollution
// via varargs parameter strLists
// ...
}


Safe Varargs (2)


Safe Varargs (2)

@SafeVarargs
このメソッドは安全であるという表明
@SafeVarargs
static void notpol(List<String>... strLists) {
// ...
}


Safe Varargs (2)

@SafeVarargs
このメソッドは安全であるという表明
@SafeVarargs
static void notpol(List<String>... strLists) {
// ...
}

呼び出し側の警告も抑制される
List<String> b = ...
List<String> s = ...
notpol(b, s);


JavaSE7

Project Coin
Fork/Join Framework
InvokeDynamic
More New I/O


Fork/Join Framework

photo.2


Fork/Join Framework

並列処理のためのフレームワーク

photo.2


Fork/Join Framework

並列処理のためのフレームワーク

？
photo.2


Concurrency Utilities



java.util.concurrent.ExecutorService
(since: JavaSE5)



(since: JavaSE5)

ExecutorService executor = Executors.newCachedThreadPool();

executor.submit(new Runnable() {
@Override
public void run() {
// ...
}
});

executor.shutdown();



(since: JavaSE5)

ExecutorService executor = Executors.newCachedThreadPool();

executor.submit(new Runnable() {
@Override
public void run() {
// ...
}
});

executor.shutdown();

１つのタスクの粒度が大きい


分割統治法
(Divide and Conquer Algorithm)


分割統治法

（再帰的に）小さなタスクへ分割して並列に処理できるようなタスク

Task


分割統治法


Task

fork()
Task Task


分割統治法


Task

fork()
Task Task

Task Task Task Task

分割統治法


Task
join()
fork()
Task Task

Task Task Task Task

Fork/Join Framework


Fork/Join Framework
ForkJoinPool pool = new ForkJoinPool();
Integer r = pool.invoke(new MyTask());
pool.shutdown();

static class MyTask extends RecursiveTask<Integer> {
private static final long serialVersionUID = 1L;
@Override
protected Integer compute() {
if (size <= SMALL_ENOUGH) {
return computeDirect(); // 直接処理
}
MyTask task1 = divideTask(); // 分割
MyTask task2 = divideTask();
task1.fork();
Integer i2 = task2.compute();
Integer i1 = task1.join();
return combine(i1, i2); // 統合
}
}


ワークスレッドの動き(1)

WorkThread-1
processing push Deque

task task task task
pop

take(steal)
WorkThread-2
processing Deque

task


ワークスレッドの動き(2)

ワークスレッドはタスクを各々のDequeに持つ

fork()したタスクをDequeの先頭にpushする

join()してタスクの結果を取得する。
まだ結果が出ていない場合は、Dequeの先頭から
次のタスクをpopして処理を行う（LIFO）

Dequeにタスクが無くなった場合、
他のワークスレッドのDequeの末尾からタスクを
takeして処理を行う（work-stealing）


Merge Sort

マージソートを
Fork/Join Frameworkで
実装してみましょう


Merge Sort

マージソートを 2 7 6 4 8 1 3 5


Merge Sort

マージソートを 2 7 6 4 8 1 3 5
2 7 6 4 8 1 3 5


Merge Sort

マージソートを 2 7 6 4 8 1 3 5
2 7 6 4 8 1 3 5

2 7 6 4 8 1 3 5


Merge Sort

マージソートを 2 7 6 4 8 1 3 5
2 7 6 4 8 1 3 5

2 7 6 4 8 1 3 5

2 7 4 6 1 8 3 5


Merge Sort

マージソートを 2 7 6 4 8 1 3 5
2 7 6 4 8 1 3 5

2 7 6 4 8 1 3 5

2 7 4 6 1 8 3 5

2 4 6 7 1 3 5 8


Merge Sort

マージソートを 2 7 6 4 8 1 3 5
2 7 6 4 8 1 3 5

2 7 6 4 8 1 3 5

2 7 4 6 1 8 3 5

2 4 6 7 1 3 5 8

1 2 3 4 5 6 7 8


JavaSE7

Project Coin
Fork/Join Framework
InvokeDynamic
More New I/O


InvokeDynamic (indy)

動的型付け言語向けの新たなサポート

invokedynamic
新しいJavaバイトコード命令（メソッド呼び出し）

MethodHandle
新しいメソッド・リンケージ・メカニズム


JavaSE7

Project Coin
Fork/Join Framework
InvokeDynamic
More New I/O


More New I/O

JavaSE1.4で導入されたNIOの積み残し
NIO.2と呼ばれます


More New I/O

JavaSE1.4で導入されたNIOの積み残し
NIO.2と呼ばれます

新しいファイルシステムAPI

非同期I/O

ソケットチャネルの機能追加


新しいファイルシステムAPI

java.nio.ﬁleパッケージ以下

FileSystem
ファイルシステム

Attribute
Files Path
View
ユーティリティファイルメタデータ
ディレクトリ
リンク

Watch
FileVisitor Service
ツリー走査監視


Basic Use

FileSystem fs = FileSystems.getDefault();
Path path = fs.getPath("/path", "to", "file");

try (BufferedWriter bw = Files.newBufferedWriter(path,
StandardCharsets.UTF_8,
StandardOpenOption.CREATE)) {

bw.write("Oh, NIO.2 !!");

}


Files

Files.createFile(path1);
Files.createSymbolicLink(link, path1);
Files.copy(path1, path2,
StandardCopyOption.COPY_ATTRIBUTES);
Files.move(path1, path2,
StandardCopyOption.ATOMIC_MOVE);
byte[] bytes = Files.readAllBytes(path2);

try (DirectoryStream<Path> ds
= Files.newDirectoryStream(dir)) {
for (Path path : ds) {
System.out.println(path);
}
}


AttributeView
Path path = Paths.get("/path", "to", "file");
BasicFileAttributeView view
= Files.getFileAttributeView(path, BasicFileAttributeView.class);
PosixFileAttributeView view2
= Files.getFileAttributeView(path, PosixFileAttributeView.class);
try {
if (view != null) {
BasicFileAttributes attributes = view.readAttributes();
System.out.println(attributes.creationTime());
System.out.println(attributes.lastModifiedTime());
System.out.println(attributes.lastAccessTime());
}
if (view2 != null) {
PosixFileAttributes attributes2 = view2.readAttributes();
System.out.println(attributes2.owner());
System.out.println(attributes2.group());
System.out.println(attributes2.permissions());
}
}


FileVisitor

ディレクトリツリーを深さ優先探索
Files.walkFileTree(dir, new SimpleFileVisitor<Path>(){
@Override
public FileVisitResult preVisitDirectory(Path dir,
BasicFileAttributes attrs) throws IOException {
System.out.println("preVisitDir: " + dir);
return FileVisitResult.CONTINUE;
}
@Override
public FileVisitResult postVisitDirectory(Path dir,
IOException exc) throws IOException {
System.out.println("postVisitDir: " + dir);
}
@Override
public FileVisitResult visitFile(Path file,
System.out.println("visitFile: " + file);
}
});


FileVisitor


Visitor Pattern

@Override
}
@Override
public FileVisitResult postVisitDirectory(Path dir,
}
@Override
}
});


FileVisitor


Visitor Pattern

@Override
コールバック }
@Override
メソッドを実装 public FileVisitResult postVisitDirectory(Path dir,
}
@Override
}
});


FileVisitor


Visitor Pattern

@Override
コールバック }
@Override
メソッドを実装 public FileVisitResult postVisitDirectory(Path dir,
戻り値4種類 return FileVisitResult.CONTINUE;
}
•CONTINUE

@Override
•TERMINATE BasicFileAttributes attrs) throws IOException {
•SKIP_SUBTREE return FileVisitResult.CONTINUE;
•SKIP_SIBLINGS
});
}


WatchService

監視対象イベントの種類を指定して監視

WatchService watcher = fs.newWatchService();
dir.register(watcher,
StandardWatchEventKinds.ENTRY_CREATE,
StandardWatchEventKinds.ENTRY_MODIFY,
StandardWatchEventKinds.ENTRY_DELETE);
boolean valid;
do {
WatchKey key = watcher.take(); // ブロック
for(WatchEvent<?> event : key.pollEvents()) {
if (event.kind() == StandardWatchEventKinds.OVERFLOW) {
System.out.println("overflow!!");
} else {
System.out.println(
event.kind() + " : " + event.context());
}
}
valid = key.reset();
} while (valid);


非同期I/O

java.nio.channelsパッケージに追加

AsynchronousChannel

Future<V> operation(...)
or
void operation(..., CompletionHandler<V, A>)


Puzzle


Puzzle

次のコードは何を表示しますか？


Puzzle

次のコードは何を表示しますか？

List<String>[] stringLists = new List<String>[10];
stringLists[0] = Arrays.asList("first string!");
Object[] array = stringLists;
array[0] = Arrays.asList(0);
System.out.println(stringLists[0].get(0));


Answer

コンパイルエラー
通常、ジェネリック型の配列を生成することはできません。

仮に1行目の記述が許されるとすれば、5行目
でClassCastExceptionが発生することにな
List<String>[] stringLists = new List<String>[10];
り、結果としてジェネリクスの型安全性が損 stringLists[0] = Arrays.asList("first string!");
なわれるためです。 Object[] array = stringLists;
array[0] = Arrays.asList(0);
このように潜在的な危険性を持つジェネリッ
System.out.println(stringLists[0].get(0));
ク型の配列を生成できてしまうのが、ジェネ
リック型の可変長引数を持つメソッドです。


JavaEE6


JavaEE Roadmap

2009 2010 2011 2012 2013

2009/12/10 2013 Q2

JavaEE6 JavaEE7
Extensibility Provisioning
Profile 2011/2/28 Elasticity
Pruning Multi-tenancy
Glassfish Orchestration
Server 3.1
Clustering Glassfish
Glassfish v3
JavaEE6 support
Server 4
JavaEE7 support


Themes of JavaEE6
(from JSR 316)

In the past 8 years, the Java EE platform has grown and matured,
and is now able to cover a wide range of enterprise and web
application development needs. In addition, the Java EE platform
has fostered a vibrant community and marketplace for additional
technologies, frameworks, and applications that work with the
platform. Some of these provide facilities that are missing from
the platform. Others provide alternatives to platform facilities. A
major theme for this release is to embrace and support those
technologies as part of the overall Java EE landscape, while also
continuing to simplify the platform to better target a wider range
of developers. To that end we propose two goals for this release -
extensibility and proﬁles.


Themes of JavaEE6
(from JSR 316)

Simplify
and

Embrace

What’s New in JavaEE6

Servlet 3.0 CDI/DI
JSF 2.0 / EL 2.2 Interceptors 1.1
EJB 3.1 (+Lite) Bean Validation
Managed Beans JAX-RS 2.1


JavaEE6

Simpliﬁed Packaging
ManagedBean
CDI
Sample


Simplified Packaging



javaee5.war
WEB-INF/classes/
MyServlet.class
MyFilter.class
WEB-INF/lib/
someFramework.jar
WEB-INF/
web.xml
index.html
css/style.css
js/jquery.js
js/plugin/jplugin.js



javaee5.war javaee6.war
WEB-INF/classes/ WEB-INF/classes/
MyServlet.class MyServlet.class
MyFilter.class MyFilter.class
WEB-INF/lib/ WEB-INF/lib/
someFramework.jar someFramework.jar
someResource.jar
WEB-INF/
web.xml
index.html index.html
css/style.css css/style.css
js/jquery.js
js/plugin/jplugin.js


javax.servlet.annotation



@WebServlet(name="MyServlet",
urlPatterns="/myServlet")
@WebServlet public class MyServlet extends HttpServlet {
// ...
}



// ...
}

@WebFilter(filterName="MyFilter",
urlPatterns="/*")
@WebFilter public class MyFilter implements Filter {
// ...
}



// ...
}

@WebFilter(filterName="MyFilter",
urlPatterns="/*")
@WebFilter public class MyFilter implements Filter {
// ...
}

@WebListener
public class MyListener
@WebListener implements ServletContextListener {
// ...
}


web-fragment.xml

someFramework.jar com/fw/SomeFWServlet.class
com/fw/SomeFWFilter.class
META-INF/web-fragment.xml


web-fragment.xml

someFramework.jar com/fw/SomeFWServlet.class
com/fw/SomeFWFilter.class
META-INF/web-fragment.xml

web-fragment.xml
<?xml version="1.0" encoding="UTF-8"?>
<web-fragment xmlns="http://java.sun.com/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
http://java.sun.com/xml/ns/javaee/web-fragment_3_0.xsd"
version="3.0">





</web-fragment>

Resource Jar

app.war
WEB-INF/lib/
someResource.jar http://serv.com:8080/app/
META-INF/resources/ js/jquery.js
js/jquery.js js/plugin/jplugin.js
js/plugin/jplugin.js css/jplugin.css
css/jplugin.css images/jplugin.png
images/jplugin.png


JavaEE6

ManagedBean
CDI
Sample


ManagedBean

photo.3


ManagedBean

Plain Java Objects

photo.3


ManagedBean

Plain Java Objects
Lifecycle managed by container

photo.3


ManagedBean

Plain Java Objects
Lifecycle managed by container

@ManagedBean
(javax.annotation)

photo.3


Lifecycle


Lifecycle

Scope
(javax.enterprise.context)


Lifecycle

@ApplicationScoped
@SessionScoped
Scope @ConversationScoped

@RequestScoped


Lifecycle

@ApplicationScoped
@SessionScoped

@RequestScoped

Callbacks
(javax.annotation)


Lifecycle

@ApplicationScoped
@SessionScoped

@RequestScoped

@PostConstruct
Callbacks @PreDestroy
(javax.annotation)


JavaEE6

ManagedBean
CDI
Sample


CDI


CDI

Context and Dependency
Injection


CDI

Context and Dependency
Injection

@Inject
(javax.annotation)


Injection Points


Injection Points

Field @Inject
private MyService myService;
Injection


Injection Points

Field @Inject
Injection

@Inject
Constructor private MyBean(MyService myService) {
// ...
Injection }


Injection Points

Field @Inject
Injection

@Inject
Constructor private MyBean(MyService myService) {
// ...
Injection }

@Inject
Parameter void init(MyService myService) {
// ...
Injection }


javax.enterprise.inject.
Produces

Factory Method
provides Injection Object

public class Factory {
@Produces
public static ComplexObject getInstance() {
return new ComplexObject("prop1", "prop2");
}
}


javax.inject.Qualifier

@Qualifier
@Retention(RetentionPolicy.RUNTIME)
public @interface MyQualifier {
}

SomeInterface
@MyQualifier
public class OneImpl
implements SomeInterface {
// ...
}
OneImpl AnotherImpl

@Inject @MyQualifier
private SomeInterface some;


JavaEE6

ManagedBean
CDI
Sample


index.xhtml


index.xhtml

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE html>
<html xmlns:h="http://java.sun.com/jsf/html">
<head>
<title>Greeting</title>
</head>
<h:body>
#{myBean.greeting}
</h:body>
</html>


MyBean.java


MyBean.java

@Named
public class MyBean {
@Inject

public String getGreeting() {
return myService.getGreeting();
}
}


MyService.java


MyService.java

@ManagedBean
public class MyService {
public String getGreeting() {
return "Hello JavaEE6!!";
}
}


beans.xml


beans.xml

(empty)


faces-config.xml


faces-config.xml

(empty)


Packaging

app.war
`---WEB-INF/
`---classes/
`---MyBean.class
`---MyService.class
`---beans.xml
`---faces-config.xml
`---index.xhtml


Deploy


Deploy
$ asadmin deploy /path/to/app.war


Deploy
appという名前のアプリケーションがデプロイされました。
コマンドdeployは正常に実行されました。


Deploy

$ curl "http://localhost:8080/app/index.jsf"


Deploy

$ curl "http://localhost:8080/app/index.jsf"
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE html>
<html>
<head>
<title>Greeting</title>
</head><body>
Hello JavaEE6!!
</body>
</html>


Conclusion


Conclusion

InvokeDynamic Fork/Join Framework
Servlet 3.0 EJB 3.0 (+Lite)
More New I/O
G1GC CDI/DI Project Coin
Bean Validation
JAX-RS
Managed Bean


Conclusion

InvokeDynamic Fork/Join Framework
Servlet 3.0 EJB 3.0 (+Lite)
More New I/O

Your Java, Update now!!
G1GC CDI/DI Project Coin
Bean Validation
JAX-RS
Managed Bean

Notes

This work is licensed under the Creative Commons
Attribution-NonCommercial 3.0 Unported License. To view
a copy of this license, visit http://creativecommons.org/
licenses/by-nc/3.0/.

photo.1
http://www.flickr.com/photos/brockli/475833924/
from

photo.2
http://www.flickr.com/photos/29487767@N02/2866453076/
from

photo.3
http://www.flickr.com/photos/amanda28192/6216031916/
from


Java, Up to Date

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