Micronaut 生命周期方法

2023-02-27 16:46 更新

何时构造 Bean

要在构造 bean 时调用方法，请使用 jakarta.annotation.PostConstruct 注释：

Java Groovy Kotlin

import jakarta.annotation.PostConstruct; // (1)
import jakarta.inject.Singleton;

@Singleton
public class V8Engine implements Engine {

    private int cylinders = 8;
    private boolean initialized = false; // (2)

    @Override
    public String start() {
        if (!initialized) {
            throw new IllegalStateException("Engine not initialized!");
        }

        return "Starting V8";
    }

    @Override
    public int getCylinders() {
        return cylinders;
    }

    public boolean isInitialized() {
        return initialized;
    }

    @PostConstruct // (3)
    public void initialize() {
        initialized = true;
    }
}

import jakarta.annotation.PostConstruct // (1)
import jakarta.inject.Singleton

@Singleton
class V8Engine implements Engine {

    int cylinders = 8
    boolean initialized = false // (2)

    @Override
    String start() {
        if (!initialized) {
            throw new IllegalStateException("Engine not initialized!")
        }

        return "Starting V8"
    }

    @PostConstruct // (3)
    void initialize() {
        initialized = true
    }
}

import jakarta.annotation.PostConstruct
import jakarta.inject.Singleton

@Singleton
class V8Engine : Engine {

    override val cylinders = 8

    var initialized = false
        private set // (2)

    override fun start(): String {
        check(initialized) { "Engine not initialized!" }

        return "Starting V8"
    }

    @PostConstruct // (3)
    fun initialize() {
        initialized = true
    }
}

导入 PostConstruct 注解
定义了一个需要初始化的字段
一个方法用 @PostConstruct 注释，一旦对象被构造并完全注入就会被调用。

当 Bean 被销毁时

要在 bean 被销毁时调用方法，请使用 jakarta.annotation.PreDestroy 注释：

Java Groovy Kotlin

import jakarta.annotation.PreDestroy; // (1)
import jakarta.inject.Singleton;
import java.util.concurrent.atomic.AtomicBoolean;

@Singleton
public class PreDestroyBean implements AutoCloseable {

    AtomicBoolean stopped = new AtomicBoolean(false);

    @PreDestroy // (2)
    @Override
    public void close() throws Exception {
        stopped.compareAndSet(false, true);
    }
}

import jakarta.annotation.PreDestroy // (1)
import jakarta.inject.Singleton
import java.util.concurrent.atomic.AtomicBoolean

@Singleton
class PreDestroyBean implements AutoCloseable {

    AtomicBoolean stopped = new AtomicBoolean(false)

    @PreDestroy // (2)
    @Override
    void close() throws Exception {
        stopped.compareAndSet(false, true)
    }
}

import jakarta.annotation.PreDestroy // (1)
import jakarta.inject.Singleton
import java.util.concurrent.atomic.AtomicBoolean

@Singleton
class PreDestroyBean : AutoCloseable {

    internal var stopped = AtomicBoolean(false)

    @PreDestroy // (2)
    @Throws(Exception::class)
    override fun close() {
        stopped.compareAndSet(false, true)
    }
}

导入 PreDestroy 注解
一个方法用@PreDestroy 注释并且将在上下文关闭时被调用。

对于工厂 beans，Bean 注释中的 preDestroy 值告诉 Micronaut 要调用哪个方法。

Java Groovy Kotlin

import io.micronaut.context.annotation.Bean;
import io.micronaut.context.annotation.Factory;

import jakarta.inject.Singleton;

@Factory
public class ConnectionFactory {

    @Bean(preDestroy = "stop") // (1)
    @Singleton
    public Connection connection() {
        return new Connection();
    }
}

import io.micronaut.context.annotation.Bean
import io.micronaut.context.annotation.Factory

import jakarta.inject.Singleton

@Factory
class ConnectionFactory {

    @Bean(preDestroy = "stop") // (1)
    @Singleton
    Connection connection() {
        new Connection()
    }
}

import io.micronaut.context.annotation.Bean
import io.micronaut.context.annotation.Factory

import jakarta.inject.Singleton

@Factory
class ConnectionFactory {

    @Bean(preDestroy = "stop") // (1)
    @Singleton
    fun connection(): Connection {
        return Connection()
    }
}

Java Groovy Kotlin

import java.util.concurrent.atomic.AtomicBoolean;

public class Connection {

    AtomicBoolean stopped = new AtomicBoolean(false);

    public void stop() { // (2)
        stopped.compareAndSet(false, true);
    }

}

import java.util.concurrent.atomic.AtomicBoolean

class Connection {

    AtomicBoolean stopped = new AtomicBoolean(false)

    void stop() { // (2)
        stopped.compareAndSet(false, true)
    }

}

import java.util.concurrent.atomic.AtomicBoolean

class Connection {

    internal var stopped = AtomicBoolean(false)

    fun stop() { // (2)
        stopped.compareAndSet(false, true)
    }

}

preDestroy 值在注解上设置
注解值与方法名匹配

简单地实现 Closeable 或 AutoCloseable 接口不足以使 bean 随上下文一起关闭。必须使用上述方法之一。

依赖 Bean

从属 bean 是用于构建 bean 的 bean。如果依赖 bean 的范围是 @Prototype 或未知，它将与您的实例一起被销毁。

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