您可以自由地使用任何标准的 Spring Framework 技术来定义您的 Bean 及其注入的依赖项。
我们通常建议使用构造函数注入来连接依赖关系并查找 bean。@ComponentScan
如果按照上面的建议构建代码(将应用程序类放在顶部包中),则可以在没有任何参数的情况下添加代码,也可以使用隐式包含它的注释。
所有应用程序组件(、、、等)都会自动注册为 Spring Beans。@ComponentScan
@SpringBootApplication
@Component
@Service
@Repository
@Controller
下面的示例显示了一个使用构造函数注入来获取所需 Bean 的 Bean:@Service
RiskAssessor
-
Java
-
Kotlin
import org.springframework.stereotype.Service;
@Service
public class MyAccountService implements AccountService {
private final RiskAssessor riskAssessor;
public MyAccountService(RiskAssessor riskAssessor) {
this.riskAssessor = riskAssessor;
}
// ...
}
import org.springframework.stereotype.Service
@Service
class MyAccountService(private val riskAssessor: RiskAssessor) : AccountService
如果一个 bean 有多个构造函数,则需要标记您希望 Spring 使用的构造函数:@Autowired
-
Java
-
Kotlin
import java.io.PrintStream;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
@Service
public class MyAccountService implements AccountService {
private final RiskAssessor riskAssessor;
private final PrintStream out;
@Autowired
public MyAccountService(RiskAssessor riskAssessor) {
this.riskAssessor = riskAssessor;
this.out = System.out;
}
public MyAccountService(RiskAssessor riskAssessor, PrintStream out) {
this.riskAssessor = riskAssessor;
this.out = out;
}
// ...
}
import org.springframework.beans.factory.annotation.Autowired
import org.springframework.stereotype.Service
import java.io.PrintStream
@Service
class MyAccountService : AccountService {
private val riskAssessor: RiskAssessor
private val out: PrintStream
@Autowired
constructor(riskAssessor: RiskAssessor) {
this.riskAssessor = riskAssessor
out = System.out
}
constructor(riskAssessor: RiskAssessor, out: PrintStream) {
this.riskAssessor = riskAssessor
this.out = out
}
// ...
}
请注意,使用构造函数注入如何将字段标记为 ,表明该字段随后无法更改。riskAssessor final |
请注意,使用构造函数注入如何将字段标记为 ,表明该字段随后无法更改。riskAssessor final |