BAEL-2051 Spring Autowiring of Generic Types (#4921)

spring-core/src/main/java/com/baeldung/dependencyinjectiontypes/annotation/CarQualifier.java

@@ -0,0 +1,15 @@
+package com.baeldung.dependencyinjectiontypes.annotation;
+
+import org.springframework.beans.factory.annotation.Qualifier;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+@Target({ElementType.FIELD, ElementType.METHOD,
+        ElementType.TYPE, ElementType.PARAMETER})
+@Retention(RetentionPolicy.RUNTIME)
+@Qualifier
+public @interface CarQualifier {
+}

spring-core/src/main/java/com/baeldung/dependencyinjectiontypes/app/CustomConfiguration.java

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+package com.baeldung.dependencyinjectiontypes.app;
+
+import com.baeldung.dependencyinjectiontypes.annotation.CarQualifier;
+import com.baeldung.dependencyinjectiontypes.model.Car;
+import com.baeldung.dependencyinjectiontypes.model.CarHandler;
+import com.baeldung.dependencyinjectiontypes.model.Motorcycle;
+import com.baeldung.dependencyinjectiontypes.model.Vehicle;
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+import org.springframework.context.ConfigurableApplicationContext;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.ComponentScan;
+
+@SpringBootApplication
+@ComponentScan("com.baeldung.dependencyinjectiontypes.model")
+public class CustomConfiguration {
+	@Bean
+	@CarQualifier
+	public Car getMercedes() {
+		return new Car("E280", "Mercedes", "Diesel");
+	}
+
+	public static void main(String[] args) throws NoSuchFieldException {
+		ConfigurableApplicationContext context = SpringApplication.run(CustomConfiguration.class, args);
+		CarHandler carHandler = context.getBean(CarHandler.class);
+		carHandler.getVehicles().forEach(System.out::println);
+	}
+
+	@Bean
+	@CarQualifier
+	public Car getBmw() {
+		return new Car("M5", "BMW", "Petrol");
+	}
+
+	@Bean
+	public Motorcycle getSuzuki() {
+		return new Motorcycle("Yamaguchi", "Suzuki", true);
+	}
+}

spring-core/src/main/java/com/baeldung/dependencyinjectiontypes/model/Car.java

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+package com.baeldung.dependencyinjectiontypes.model;
+
+public class Car extends Vehicle {
+    private String engineType;
+
+    public Car(String name, String manufacturer, String engineType) {
+        super(name, manufacturer);
+        this.engineType = engineType;
+    }
+
+    public String getEngineType() {
+        return engineType;
+    }
+
+    public void setEngineType(String engineType) {
+        this.engineType = engineType;
+    }
+
+    @Override
+    public String toString() {
+        return "Car{" +
+                "engineType='" + engineType + '\'' +
+                '}';
+    }
+}

spring-core/src/main/java/com/baeldung/dependencyinjectiontypes/model/CarHandler.java

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+package com.baeldung.dependencyinjectiontypes.model;
+
+import com.baeldung.dependencyinjectiontypes.annotation.CarQualifier;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.core.ResolvableType;
+import org.springframework.stereotype.Component;
+
+import java.util.List;
+
+@Component
+public class CarHandler {
+
+    @Autowired
+    @CarQualifier
+    private List<Vehicle> vehicles;
+
+    public List<Vehicle> getVehicles() throws NoSuchFieldException {
+        ResolvableType vehiclesType = ResolvableType.forField(getClass().getDeclaredField("vehicles"));
+        System.out.println(vehiclesType);
+        ResolvableType type = vehiclesType.getGeneric();
+        System.out.println(type);
+        Class<?> aClass = type.resolve();
+        System.out.println(aClass);
+        return this.vehicles;
+    }
+}

spring-core/src/main/java/com/baeldung/dependencyinjectiontypes/model/Motorcycle.java

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+package com.baeldung.dependencyinjectiontypes.model;
+
+public class Motorcycle extends Vehicle {
+    private boolean twoWheeler;
+
+    public Motorcycle(String name, String manufacturer, boolean twoWheeler) {
+        super(name, manufacturer);
+        this.twoWheeler = true;
+    }
+
+    public boolean isTwoWheeler() {
+        return twoWheeler;
+    }
+
+    public void setTwoWheeler(boolean twoWheeler) {
+        this.twoWheeler = twoWheeler;
+    }
+
+    @Override
+    public String toString() {
+        return "Motorcycle{" +
+                "twoWheeler=" + twoWheeler +
+                '}';
+    }
+}

spring-core/src/main/java/com/baeldung/dependencyinjectiontypes/model/Vehicle.java

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+package com.baeldung.dependencyinjectiontypes.model;
+
+public abstract class Vehicle {
+    private String name;
+    private String manufacturer;
+
+
+    public Vehicle(String name, String manufacturer) {
+        this.name = name;
+        this.manufacturer = manufacturer;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+    public String getManufacturer() {
+        return manufacturer;
+    }
+
+    public void setManufacturer(String manufacturer) {
+        this.manufacturer = manufacturer;
+    }
+}