每当Guice提供一个值作为其默认行为时,它都会返回一个新实例.它可以通过范围进行配置.以下是Guice支持和减去的范围;
@Singleton : 应用程序生命周期的单个实例. @Singleton对象需要线程安全.
@SessionScoped : Web应用程序的特定会话的单个实例. @SessionScoped对象需要是线程安全的.
@RequestScoped : Web应用程序的特定请求的单个实例. @RequestScoped对象不需要是线程安全的.
以下是应用范围的方法.
@Singleton class SpellCheckerImpl implements SpellChecker { public SpellCheckerImpl(){} @Override public void checkSpelling() { System.out.println("Inside checkSpelling." ); } }
bind(SpellChecker.class).to(SpellCheckerImpl.class).in(Singleton.class);
@Provides @Singleton public SpellChecker provideSpellChecker() { String dbUrl = "jdbc:mysql://localhost:5326/emp"; String user = "user"; int timeout = 100; SpellChecker SpellChecker = new SpellCheckerImpl(dbUrl, user, timeout); return SpellChecker; }
让我们在课堂上看到范围内的范围.
创建一个名为GuiceTester的java类.
GuiceTester.java
import com.google.inject.AbstractModule; import com.google.inject.Guice; import com.google.inject.Inject; import com.google.inject.Injector; import com.google.inject.Singleton; public class GuiceTester { public static void main(String[] args) { Injector injector = Guice.createInjector(new TextEditorModule()); SpellChecker spellChecker = new SpellCheckerImpl(); injector.injectMembers(spellChecker); TextEditor editor = injector.getInstance(TextEditor.class); System.out.println(editor.getSpellCheckerId()); TextEditor editor1 = injector.getInstance(TextEditor.class); System.out.println(editor1.getSpellCheckerId()); } } class TextEditor { private SpellChecker spellChecker; @Inject public void setSpellChecker(SpellChecker spellChecker) { this.spellChecker = spellChecker; } public TextEditor() { } public void makeSpellCheck() { spellChecker.checkSpelling(); } public double getSpellCheckerId() { return spellChecker.getId(); } } //Binding Module class TextEditorModule extends AbstractModule { @Override protected void configure() { bind(SpellChecker.class).to(SpellCheckerImpl.class); } } interface SpellChecker { public double getId(); public void checkSpelling(); } @Singleton class SpellCheckerImpl implements SpellChecker { double id; public SpellCheckerImpl() { id = Math.random(); } @Override public void checkSpelling() { System.out.println("Inside checkSpelling." ); } @Override public double getId() { return id; } }
编译并运行该文件,您可能会看到以下输出具有相同的数字.
0.3055839187063575 0.3055839187063575
创建一个名为GuiceTester的java类.
GuiceTester.java
import com.google.inject.AbstractModule; import com.google.inject.Guice; import com.google.inject.Inject; import com.google.inject.Injector; public class GuiceTester { public static void main(String[] args) { Injector injector = Guice.createInjector(new TextEditorModule()); SpellChecker spellChecker = new SpellCheckerImpl(); injector.injectMembers(spellChecker); TextEditor editor = injector.getInstance(TextEditor.class); System.out.println(editor.getSpellCheckerId()); TextEditor editor1 = injector.getInstance(TextEditor.class); System.out.println(editor1.getSpellCheckerId()); } } class TextEditor { private SpellChecker spellChecker; @Inject public void setSpellChecker(SpellChecker spellChecker) { this.spellChecker = spellChecker; } public TextEditor() { } public void makeSpellCheck() { spellChecker.checkSpelling(); } public double getSpellCheckerId() { return spellChecker.getId(); } } //Binding Module class TextEditorModule extends AbstractModule { @Override protected void configure() { bind(SpellChecker.class).to(SpellCheckerImpl.class); } } interface SpellChecker { public double getId(); public void checkSpelling(); } class SpellCheckerImpl implements SpellChecker { double id; public SpellCheckerImpl() { id = Math.random(); } @Override public void checkSpelling() { System.out.println("Inside checkSpelling." ); } @Override public double getId() { return id; } }
编译并运行该文件,您可能会看到以下不同数字的输出.
0.556007079571739 0.22095011760351602