Spring-Boot框架的条件注解对Bean的方法和类对象的控制------Spring-Boot框架

package com.example.boot3;

import com.example.boot3.bean.Cat;
import com.example.boot3.bean.Dog;
import com.example.boot3.bean.User;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.annotation.ComponentScan;

@ComponentScan("com.example")//改变包扫描路径
@SpringBootApplication(scanBasePackages = "com.example.boot3")//手动指定扫描包位置
public class Boot3Application
{
    public static void main(String[] args) {
        var ioc = SpringApplication.run(Boot3Application.class, args);
//        for (String name : ioc.getBeanDefinitionNames()) {
//            System.out.println(name);
//        }
//        Object user = ioc.getBean("user");
//        Object user1 = ioc.getBean("user");
//        System.out.println(user == user1);
//        System.out.println(ioc.getBean("fastsqlException"));
        for (String s : ioc.getBeanNamesForType(Cat.class)) {
            System.out.println(s);
        }
        for (String s : ioc.getBeanNamesForType(Dog.class)) {
            System.out.println(s);
        }
        for (String s : ioc.getBeanNamesForType(User.class)) {
            System.out.println(s);
        }
    }
}

package com.example.boot3;

import com.example.boot3.bean.Cat;
import com.example.boot3.bean.Dog;
import com.example.boot3.bean.User;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.annotation.ComponentScan;

@ComponentScan("com.example")//改变包扫描路径
@SpringBootApplication(scanBasePackages = "com.example.boot3")//手动指定扫描包位置
public class Boot3Application
{
    public static void main(String[] args) {
        var ioc = SpringApplication.run(Boot3Application.class, args);
//        for (String name : ioc.getBeanDefinitionNames()) {
//            System.out.println(name);
//        }
//        Object user = ioc.getBean("user");
//        Object user1 = ioc.getBean("user");
//        System.out.println(user == user1);
//        System.out.println(ioc.getBean("fastsqlException"));
        for (String s : ioc.getBeanNamesForType(Cat.class)) {
            System.out.println(s);
        }
        for (String s : ioc.getBeanNamesForType(Dog.class)) {
            System.out.println(s);
        }
        for (String s : ioc.getBeanNamesForType(User.class)) {
            System.out.println(s);
        }
    }
}

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>3.2.1</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.example</groupId>
    <artifactId>boot3</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>boot3</name>
    <description>boot3</description>
    <properties>
        <java.version>17</java.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-thymeleaf</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid</artifactId>
            <version>1.2.16</version>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

</project>

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>3.2.1</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.example</groupId>
    <artifactId>boot3</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>boot3</name>
    <description>boot3</description>
    <properties>
        <java.version>17</java.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-thymeleaf</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid</artifactId>
            <version>1.2.16</version>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

</project>

package com.example.boot3.Config;

import com.alibaba.druid.FastsqlException;
import com.example.boot3.bean.User;
import org.springframework.boot.SpringBootConfiguration;
import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingClass;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Import;
import org.springframework.context.annotation.Scope;

@SpringBootConfiguration//这是一个SpringBoot配置类
//@Configuration//这是一个配置类
@ConditionalOnMissingClass(value = "com.alibaba.druid.FastsqlException")//放在类级别就会使整个类具有条件注解的效果
//如果没有整个不生效
@Import(FastsqlException.class)//导入任意类作为组件,但是组件的名字默认是全类名!!!!!
public class AppConfig
{
//    组件默认是单实例的
    @Scope("prototype")
    @Bean//替代Bean标签
    public User user(){//默认的Bean名字就是方法名字
        var user = new User();
        user.setName("Jack");
        user.setId(1L);
        return user;
    }
//    导入第三方Bean
    @Bean
    public FastsqlException fastsqlException(){
        return new FastsqlException();
    }
}

package com.example.boot3.Config;

import com.alibaba.druid.FastsqlException;
import com.example.boot3.bean.User;
import org.springframework.boot.SpringBootConfiguration;
import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingClass;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Import;
import org.springframework.context.annotation.Scope;

@SpringBootConfiguration//这是一个SpringBoot配置类
//@Configuration//这是一个配置类
@ConditionalOnMissingClass(value = "com.alibaba.druid.FastsqlException")//放在类级别就会使整个类具有条件注解的效果
//如果没有整个不生效
@Import(FastsqlException.class)//导入任意类作为组件,但是组件的名字默认是全类名!!!!!
public class AppConfig
{
//    组件默认是单实例的
    @Scope("prototype")
    @Bean//替代Bean标签
    public User user(){//默认的Bean名字就是方法名字
        var user = new User();
        user.setName("Jack");
        user.setId(1L);
        return user;
    }
//    导入第三方Bean
    @Bean
    public FastsqlException fastsqlException(){
        return new FastsqlException();
    }
}

package com.example.boot3.Config;

import com.example.boot3.bean.Cat;
import com.example.boot3.bean.Dog;
import com.example.boot3.bean.User;
import org.springframework.boot.SpringBootConfiguration;
import org.springframework.boot.autoconfigure.condition.ConditionalOnBean;
import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingClass;
import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
import org.springframework.context.annotation.Bean;

@SpringBootConfiguration
public class AppConfig2 {
    @Bean
    @ConditionalOnClass(name="com.alibaba.druid.FastsqlException")
    public Cat cat01(){
        return new Cat();
    }
    @Bean
    @ConditionalOnMissingClass(value="com.alibaba.druid.FastsqlException")
    public Dog dog01(){
        return new Dog();
    }
    @Bean
    @ConditionalOnBean(name = "dog01")
    public User zhangsan(){
        return new User();
    }
    @Bean
    @ConditionalOnMissingBean(name = "dog01")
    public User lisi(){
        return new User();
    }
}

package com.example.boot3.Config;

import com.example.boot3.bean.Cat;
import com.example.boot3.bean.Dog;
import com.example.boot3.bean.User;
import org.springframework.boot.SpringBootConfiguration;
import org.springframework.boot.autoconfigure.condition.ConditionalOnBean;
import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingClass;
import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
import org.springframework.context.annotation.Bean;

@SpringBootConfiguration
public class AppConfig2 {
    @Bean
    @ConditionalOnClass(name="com.alibaba.druid.FastsqlException")
    public Cat cat01(){
        return new Cat();
    }
    @Bean
    @ConditionalOnMissingClass(value="com.alibaba.druid.FastsqlException")
    public Dog dog01(){
        return new Dog();
    }
    @Bean
    @ConditionalOnBean(name = "dog01")
    public User zhangsan(){
        return new User();
    }
    @Bean
    @ConditionalOnMissingBean(name = "dog01")
    public User lisi(){
        return new User();
    }
}

package com.example.boot3.bean;

public class Cat
{
    private Long id;
    private String name;

    public Cat() {
    }

    public Cat(Long id, String name) {
        this.id = id;
        this.name = name;
    }

    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    @Override
    public String toString() {
        return "Cat{" +
                "id=" + id +
                ", name='" + name + '\'' +
                '}';
    }
}

package com.example.boot3.bean;

public class Cat
{
    private Long id;
    private String name;

    public Cat() {
    }

    public Cat(Long id, String name) {
        this.id = id;
        this.name = name;
    }

    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    @Override
    public String toString() {
        return "Cat{" +
                "id=" + id +
                ", name='" + name + '\'' +
                '}';
    }
}

package com.example.boot3.bean;

public class Dog {
    private Long id;
    private String name;

    public Dog() {
    }

    public Dog(Long id, String name) {
        this.id = id;
        this.name = name;
    }

    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    @Override
    public String toString() {
        return "Dog{" +
                "id=" + id +
                ", name='" + name + '\'' +
                '}';
    }
}

package com.example.boot3.bean;

public class Dog {
    private Long id;
    private String name;

    public Dog() {
    }

    public Dog(Long id, String name) {
        this.id = id;
        this.name = name;
    }

    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    @Override
    public String toString() {
        return "Dog{" +
                "id=" + id +
                ", name='" + name + '\'' +
                '}';
    }
}

package com.example.boot3.bean;

public class User
{
    private Long id;
    private String name;

    public User() {
    }

    public User(Long id, String name) {
        this.id = id;
        this.name = name;
    }

    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    @Override
    public String toString() {
        return "User{" +
                "id=" + id +
                ", name='" + name + '\'' +
                '}';
    }
}

package com.example.boot3.bean;

public class User
{
    private Long id;
    private String name;

    public User() {
    }

    public User(Long id, String name) {
        this.id = id;
        this.name = name;
    }

    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    @Override
    public String toString() {
        return "User{" +
                "id=" + id +
                ", name='" + name + '\'' +
                '}';
    }
}