七、自定义配置

1、自定义条件

a>构造条件

MyCondition

package com.yzh.boot.conditional;
import org.springframework.context.annotation.Condition;
import org.springframework.context.annotation.ConditionContext;
import org.springframework.core.type.AnnotatedTypeMetadata;
public class MyCondition implements Condition{
    
	@Override
	public boolean matches(ConditionContext context, AnnotatedTypeMetadata metadata) {
    
		return context.getResourceLoader().getResource("classpath:test.properties").exists();
	}
}

YourCondition

package com.yzh.boot.conditional;
import org.springframework.context.annotation.Condition;
import org.springframework.context.annotation.ConditionContext;
import org.springframework.core.type.AnnotatedTypeMetadata;
public class YourCondition implements Condition{
    
	@Override
	public boolean matches(ConditionContext context, AnnotatedTypeMetadata metadata) {
    
		return !context.getResourceLoader().getResource("classpath:test.properties").exists();
	}
}

b>创建不同条件下bean的类

MessagePrint

package com.yzh.boot.conditional;
public interface MessagePrint {
    
	public String showMessage();
}

MyMessagePrint

package com.yzh.boot.conditional;
public class MyMessagePrint implements MessagePrint{
    
	@Override
	public String showMessage() {
    
		return "test.properties文件存在。";
	}
}

YourMessagePrint

package com.yzh.boot.conditional;
public class YourMessagePrint implements MessagePrint{
    
	@Override
	public String showMessage() {
    
		return "test.properties文件不存在！";
	}

}

c>创建配置类

package com.yzh.boot.conditional;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Conditional;
import org.springframework.context.annotation.Configuration;
@Configuration //标注这是一个配置文件
public class ConditionConfig {
    
	@Bean
	@Conditional(MyCondition.class)
	public MessagePrint myMessage() {
    
		return new MyMessagePrint();
	}
	@Bean
	@Conditional(YourCondition.class)
	public MessagePrint yourMessage() {
    
		return new YourMessagePrint();
	}
}

d>创建测试类

package com.yzh.boot.conditional;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;
public class TestMain {
    
	private static AnnotationConfigApplicationContext context;
	public static void main(String[] args) {
    
		context = new AnnotationConfigApplicationContext(ConditionConfig.class);
		MessagePrint mp = context.getBean(MessagePrint.class);
		System.out.println(mp.showMessage());
	}
}

2、自定义Starters

a>新建项目

b>修改pom文件

<?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>
    <groupId>com.yzh</groupId>
    <artifactId>mystarters</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>mystarters</name>
    <description>Demo project for Spring Boot</description>

    <properties>
        <java.version>1.8</java.version>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
        <spring-boot.version>2.3.7.RELEASE</spring-boot.version>
    </properties>

    <dependencies>

        <!--springboot自身的自动配置依赖-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-autoconfigure</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-configuration-processor</artifactId>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
            <exclusions>
                <exclusion>
                    <groupId>org.junit.vintage</groupId>
                    <artifactId>junit-vintage-engine</artifactId>
                </exclusion>
            </exclusions>
        </dependency>
    </dependencies>

    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-dependencies</artifactId>
                <version>${
    spring-boot.version}</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>

    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>3.8.1</version>
                <configuration>
                    <source>1.8</source>
                    <target>1.8</target>
                    <encoding>UTF-8</encoding>
                </configuration>
            </plugin>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
                <version>2.3.7.RELEASE</version>
                <configuration>
                    <mainClass>com.yzh.mystarters.MystartersApplication</mainClass>
                </configuration>
                <executions>
                    <execution>
                        <id>repackage</id>
                        <goals>
                            <goal>repackage</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>
        </plugins>
    </build>

</project>

c>创建属性配置类MyProperties

package com.yzh.mystarters;

import org.springframework.boot.context.properties.ConfigurationProperties;

@ConfigurationProperties(prefix = "my")
public class MyProperties {
    
    private String msg="默认值";
    public String getMsg(){
    
      return msg;
    }

    public void setMsg(String msg){
    
        this.msg=msg;
    }
}

d>创建判断依据类MyService

package com.yzh.mystarters;


public class MyService {
    
    private String msg;
    public String sayMsg(String msg){
    
        return "my "+ this.msg;
    }

    public void setMsg(String msg) {
    
        this.msg = msg;
    }

    public String getMsg() {
    
        return msg;
    }
}

e>创建自动配置类MyAutoConfiguration

package com.yzh.mystarters;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.autoconfigure.condition.ConditionalOnBean;
import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty;
import org.springframework.boot.context.properties.EnableConfigurationProperties;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

@Configuration
//开启属性配置类MyProperties提供参数
@EnableConfigurationProperties(MyProperties.class)
//类路径中是否存在对应的类
@ConditionalOnBean(MyService.class)
//应用环境中属性是否存在指定的值
@ConditionalOnProperty(prefix = "my",name = "msg",matchIfMissing = true)
public class MyAutoConfiguration {
    
    @Autowired
    private MyProperties myProperties;
    @Bean
    @ConditionalOnMissingBean(MyService.class)
    public MyService myService(){
    
        MyService myService = new MyService();
        myService.sayMsg(myProperties.getMsg());
        return myService;
    }
}

f>注册配置

#若有多个自动配置，用逗号隔开
org.springframework.boot.autoconfigure.EnableAutoConfiguration=com.yzh.mystarters.MyAutoConfiguration