Guice 简明教程
Google Guice - Scopes
Guice 会在其默认行为作为其值时,每次都返回一个新实例。它可以通过范围进行配置。以下是 Guice 支持的范围:
-
@Singleton - 应用程序生命周期的单实例。@Singleton 对象需要是线程安全的。
-
@SessionScoped - Web 应用程序特定会话的单实例。@SessionScoped 对象需要是线程安全的。
-
@RequestScoped - Web 应用程序特定请求的单实例。@RequestScoped 对象不需要是线程安全的。
Way to apply scopes. Following are the ways to apply scopes.
Example
让我们在类级别中查看实际作用域。
Result With @Singleton Annotation
创建名为 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;
}
}
编译并运行文件,可能会看到具有相同数字的以下输出。
0.3055839187063575
0.3055839187063575
Result Without @Singleton Annotation
创建名为 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;
}
}