构造函数绑定(Constructor Bindings)
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2023-12-01
Guice提供了一种使用toConstructor()方法与对象的特定构造函数创建绑定的方法。
@Override
protected void configure() {
try {
bind(SpellChecker.class)
.toConstructor(SpellCheckerImpl.class.getConstructor(String.class));
} catch (NoSuchMethodException | SecurityException e) {
System.out.println("Required constructor missing");
}
}
请参阅下面的完整示例。
完整的示例 (Complete Example)
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.name.Named;
import com.google.inject.name.Names;
public class GuiceTester {
public static void main(String[] args) {
Injector injector = Guice.createInjector(new TextEditorModule());
TextEditor editor = injector.getInstance(TextEditor.class);
editor.makeSpellCheck();
}
}
class TextEditor {
private SpellChecker spellChecker;
@Inject
public TextEditor( SpellChecker spellChecker) {
this.spellChecker = spellChecker;
}
public void makeSpellCheck() {
spellChecker.checkSpelling();
}
}
//Binding Module
class TextEditorModule extends AbstractModule {
@Override
protected void configure() {
try {
bind(SpellChecker.class)
.toConstructor(SpellCheckerImpl.class.getConstructor(String.class));
} catch (NoSuchMethodException | SecurityException e) {
System.out.println("Required constructor missing");
}
bind(String.class)
.annotatedWith(Names.named("JDBC"))
.toInstance("jdbc:mysql://localhost:5326/emp");
}
}
//spell checker interface
interface SpellChecker {
public void checkSpelling();
}
//spell checker implementation
class SpellCheckerImpl implements SpellChecker {
private String dbUrl;
public SpellCheckerImpl(){}
public SpellCheckerImpl(@Named("JDBC") String dbUrl) {
this.dbUrl = dbUrl;
}
@Override
public void checkSpelling() {
System.out.println("Inside checkSpelling." );
System.out.println(dbUrl);
}
}
输出 (Output)
编译并运行该文件,您将看到以下输出。
Inside checkSpelling.
jdbc:mysql://localhost:5326/emp