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="https://maven.apache.org/POM/4.0.0" xmlns:xsi="https://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="https://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="https://maven.apache.org/POM/4.0.0" xmlns:xsi="https://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="https://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 + '\'' +
'}';
}
}
package com.example.boot3;
import com.example.boo
阅读背景：
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
来源：互联网
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