註解裝配bean

最簡單的例子

@Component("role")
public class Role {
	
	@Value("1")
	private Long id;
	@Value("zhangsan")
	private String roleName;
	@Value("hehe")
	private String note;
	
}

如果Component未顯示給出名稱，則去類名首字母小寫為預設名稱

獲取ioc容器獲取bean入口

未配置，掃碼當前預設包

package priv.dengjl.spring.day1;

import org.springframework.context.annotation.ComponentScan;

@ComponentScan
public class PojoConfig {

}

 

配置掃碼指定包,多個逗號隔開

@ComponentScan(basePackages = {"priv.dengjl.spring.day1.service"})
public class ApplicationConfig {

}

配置掃碼指定類,多個逗號隔開

@ComponentScan(basePackageClasses = {Role.class})
public class ApplicationConfig {

}

註解方式呼叫

		ApplicationContext context = new AnnotationConfigApplicationContext(ApplicationConfig.class);
		Role role = context.getBean(Role.class);
		System.out.prinln(role);
 

自動裝配，Autowired

裝配類屬性成員

public interface RoleService2 {
	void printRole();
}

@Component("roleService2")
public class RoleServiceImpl2 implements RoleService2{

	@Autowired
	private Role role = null;
	
	@Override
	public void printRole() {
		System.out.println(role);
	}

}

測試例子

		ApplicationContext context = new AnnotationConfigApplicationContext(ApplicationConfig.class);
		RoleService2 service = context.getBean(RoleServiceImpl2.class);
		service.printRole();

 

[email protected]

自動裝配失敗

Autowired表示必須裝配成功

@Component("roleService4")
public class RoleServiceImpl4 implements RoleService2{

	@Autowired
	private Map map = null;
	
	@Override
	public void printRole() {
		System.out.println(map);
	}

}

測試例子

		ApplicationContext context = new AnnotationConfigApplicationContext(ApplicationConfig.class);
		RoleService2 service = context.getBean(RoleServiceImpl4.class);
		service.printRole();

Exception in thread "main" org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'roleService4': Unsatisfied dependency expressed through field 'map'; nested exception is org.springframework.beans.factory.NoUniqueBeanDefinitionException: No qualifying bean of type 'java.util.Map<?, ?>' available: expected single matching bean but found 2: systemProperties,systemEnvironment

Autowired(required=false)

將required屬性置為false，表示注入屬性可以為空

@Component("roleService4")
public class RoleServiceImpl4 implements RoleService2{

	@Autowired(required=false)
	private Map map = null;
	
	@Override
	public void printRole() {
		System.out.println(map);
	}

}

測試通過

自動注入Autowired，子類過多歧義性

--RoleService2
	--RoleServiceImpl2
	--RoleServiceImpl4

定義類RoleController

@Component
public class RoleController {
	@Autowired
	private RoleService2 service;
	
	public void printRole() {
		service.printRole();
	}
}

測試檔案

		ApplicationContext context = new AnnotationConfigApplicationContext(ApplicationConfig.class);
		RoleController controller = context.getBean(RoleController.class);
		controller.printRole();

測試結果

Exception in thread "main" org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'roleController': Unsatisfied dependency expressed through field 'service'; nested exception is org.springframework.beans.factory.NoUniqueBeanDefinitionException: No qualifying bean of type 'priv.dengjl.spring.day1.service.RoleService2' available: expected single matching bean but found 2: roleService2,roleService4

@Primary標記為預設首選，元件自身設定

@Component("roleService2")
@Primary
public class RoleServiceImpl2 implements RoleService2{

	@Autowired
	private Role role = null;
	
	@Override
	public void printRole() {
		System.out.println(role);
	}

}

測試通過

@Primary 按名稱選擇，呼叫方自動選擇

@Component
public class RoleController {
	@Autowired
	@Qualifier("roleService2")
	private RoleService2 service;
	
	public void printRole() {
		service.printRole();
	}
}

測試通過

裝配構造方法

@Component
public class RoleController2 {
	private RoleService2 service;

	public RoleController2(@Autowired @Qualifier("roleService2") RoleService2 service) {
		this.service = service;
	}

	public void printRole() {
		service.printRole();
	}
}

測試通過

為第三方jar包擴充套件

由於註解@Component無法註釋到jar等地方包，可以通過bean這種方式轉換，達到擴充套件目的

將第三方程式碼寫在方法中，通過方法生成一個Bean物件

@Component
public class PersonData {

	// 由於註解@Component無法註釋到jar等地方包，可以通過bean這種方式轉換，達到擴充套件目的
	@Bean(name = "cust")
	public Map getMap() {
		Map temp = new HashMap();
		temp.put("name", "張三");
		temp.put("sex", "1");
		return temp;
	}
}

注入bean

@Component
public class Person {

	@Autowired(required = true)
	@Qualifier("cust")
	private Map map;

	@Override
	public String toString() {
		return map.toString();
	}
	
}

測試

		ApplicationContext context = new AnnotationConfigApplicationContext(ApplicationConfig.class);
		Person person = context.getBean(Person.class);
		System.out.println(person);

{sex=1, name=張三}