springBoot学习（二）配置环境动态切换和部分注解的运用

springBoot配置环境动态切换

建立第一个配置文件（springBoot默认读取的文件）application.properties

test.name=default
test.defaultAge=12

建立第二个配置文件（开发环境）application-dev.properties

test.name=dev
test.devAge=13

建立第三个配置文件（用户验收测试环境）application-uat.properties

test.name=uat
test.uatAge=14

1.添加启动参数(--spring.profiles.active=),测试结果读取application.properties的值
2.添加启动参数(--spring.profiles.active=dev),测试结果读取application-dev.properties的值
3.添加启动参数(--spring.profiles.active=uat),测试结果读取application-uat.properties的值
4.添加启动参数(--spring.profiles.active=uat,dev),测试结果读取application-dev.properties的值
5.添加启动参数(--spring.profiles.active=dev,uat),测试结果读取application-uat.properties的值
6.添加启动参数(--spring.profiles.active=dev)，可以读到application.properties的(test.defaultAge)值，读不到uat的(test.uatAge)值。
7.添加启动参数(--spring.profiles.active=uat)，可以读到application.properties的(test.defaultAge)值，读不到dev的(test.devAge)值。
8.添加启动参数(--spring.profiles.active=),可以读到application.properties的值，读取不到其他配置文件的值

重点

添加启动参数--spring.profiles.active=“环境代表参数”（此值为文件名“-”与“.”中间的值，此处即为dev或者uat）
可以添加多个参数，通过英文逗号（,）分割
如果添加多个参数，有重复key，值会被覆盖，（配置文件加载顺序详见官方文档：24. Externalized Configuration）
也可以直接在application.properties配置文件中添加spring.profiles.active=“环境代表参数” 来替代启动时候添加的参数

springBoot自动配置bean（@Conditional注解使用）

首先看一个正常配置的bean与打印

建立一个接口

package com.yxj.spring;/*** @ProjectName: springBootDemo* @Package: com.yxj.spring* @Description:* @Author:     阿杰* @CreateDate: 2019/1/22 22:08* @UpdateUser: 暂无* @UpdateDate: 2019/1/22 22:08* @UpdateRemark: The modified content* @Version: 1.0*/
public interface MakeApp {
}

建立两个实现-第一个

package com.yxj.spring;/*** @ProjectName: springBootDemo* @Package: com.yxj.spring* @Description:* @Author: 阿杰* @CreateDate: 2019/1/22 22:13* @UpdateUser: 暂无* @UpdateDate: 2019/1/22 22:13* @UpdateRemark: The modified content* @Version: 1.0*/
public class Wechat implements MakeApp {
}

建立两个实现-第二个

package com.yxj.spring;/*** @ProjectName: springBootDemo* @Package: com.yxj.spring* @Description:* @Author: 阿杰* @CreateDate: 2019/1/22 22:14* @UpdateUser: 暂无* @UpdateDate: 2019/1/22 22:14* @UpdateRemark: The modified content* @Version: 1.0*/
public class PipiXia implements MakeApp {
}

通过@SpringBootConfiguration与@Bean加载bean

package com.yxj.spring;import org.springframework.boot.SpringBootConfiguration;
import org.springframework.context.annotation.Bean;/*** @ProjectName: springBootDemo* @Package: com.yxj.spring* @Description:  @SpringBootConfiguration继承自@Configuration，* 二者功能也一致，标注当前类是配置类，* 并会将当前类内声明的一个或多个以@Bean注解标记的方法的实例纳入到spring容器中，* 并且实例名就是方法名。* @Author: 阿杰* @CreateDate: 2019/1/22 22:14* @UpdateUser: 暂无* @UpdateDate: 2019/1/22 22:14* @UpdateRemark: The modified content* @Version: 1.0*/
@SpringBootConfiguration
public class LoadMyBean {@Beanpublic MakeApp createWechat(){return new Wechat();}@Beanpublic MakeApp createPipiXia(){return new PipiXia();}
}

springBoot启动类测试

package com.yxj.spring;import org.springframework.beans.factory.annotation.Value;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.context.ConfigurableApplicationContext;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Condition;
import org.springframework.context.annotation.PropertySource;
import org.springframework.context.annotation.PropertySources;import java.util.List;/*** @ProjectName: springBootDemo* @Package: com.yxj.spring* @Description:* @Author: 杨小杰* @CreateDate: 2019/1/18 20:18* @UpdateUser: 暂无* @UpdateDate: 2019/1/18 20:18* @UpdateRemark: The modified content* @Version: 1.0*/
@SpringBootApplication
public class SpringBootTestRun {/*** getBeansOfType(MakeApp.class)会装配bean类型是MakeApp的所有实例* @param args*/public static void main(String[] args) {ConfigurableApplicationContext run = SpringApplication.run(SpringBootTestRun.class, args);System.out.println("------------------分割线------------------");System.out.println(run.getBeansOfType(MakeApp.class));}
}

测试结果

------------------分割线------------------
{createWechat=com.yxj.spring.Wechat@5cad8b7d, createPipiXia=com.yxj.spring.PipiXia@7b02e036}

可以看到结果把通过@Bean加载的两个MakeApp实现类对象全部打印出来了

了解Condition接口，实现自定义bean的加载

源代码

/** Copyright 2002-2017 the original author or authors.** Licensed under the Apache License, Version 2.0 (the "License");* you may not use this file except in compliance with the License.* You may obtain a copy of the License at**      http://www.apache.org/licenses/LICENSE-2.0** Unless required by applicable law or agreed to in writing, software* distributed under the License is distributed on an "AS IS" BASIS,* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.* See the License for the specific language governing permissions and* limitations under the License.*/package org.springframework.context.annotation;import org.springframework.beans.factory.config.BeanFactoryPostProcessor;
import org.springframework.core.type.AnnotatedTypeMetadata;/*** A single {@code condition} that must be {@linkplain #matches matched} in order* for a component to be registered.** <p>Conditions are checked immediately before the bean-definition is due to be* registered and are free to veto registration based on any criteria that can* be determined at that point.** <p>Conditions must follow the same restrictions as {@link BeanFactoryPostProcessor}* and take care to never interact with bean instances. For more fine-grained control* of conditions that interact with {@code @Configuration} beans consider the* {@link ConfigurationCondition} interface.** @author Phillip Webb* @since 4.0* @see ConfigurationCondition* @see Conditional* @see ConditionContext*/
@FunctionalInterface
public interface Condition {/*** Determine if the condition matches.* @param context the condition context* @param metadata metadata of the {@link org.springframework.core.type.AnnotationMetadata class}* or {@link org.springframework.core.type.MethodMetadata method} being checked* @return {@code true} if the condition matches and the component can be registered,* or {@code false} to veto the annotated component's registration*/boolean matches(ConditionContext context, AnnotatedTypeMetadata metadata);}

上诉代码描述了matches返回值如果是ture就会再加bean，反之则反

实现自定义Condition

新建Wechat自定义Condition,默认返回false（不装配bean）

package com.yxj.spring;import org.springframework.context.annotation.Condition;
import org.springframework.context.annotation.ConditionContext;
import org.springframework.core.type.AnnotatedTypeMetadata;
import org.springframework.util.StringUtils;/*** @ProjectName: springBootDemo* @Package: com.yxj.spring* @Description:* @Author: 阿杰* @CreateDate: 2019/1/22 22:35* @UpdateUser: 暂无* @UpdateDate: 2019/1/22 22:35* @UpdateRemark: The modified content* @Version: 1.0*/
public class WechatCondition implements Condition {@Overridepublic boolean matches(ConditionContext context, AnnotatedTypeMetadata metadata) {return false;}
}

新建PipiXia自定义Condition,默认返回true（装配bean）

package com.yxj.spring;import org.springframework.context.annotation.Condition;
import org.springframework.context.annotation.ConditionContext;
import org.springframework.core.type.AnnotatedTypeMetadata;
import org.springframework.util.StringUtils;/*** @ProjectName: springBootDemo* @Package: com.yxj.spring* @Description:* @Author: 阿杰* @CreateDate: 2019/1/22 22:35* @UpdateUser: 暂无* @UpdateDate: 2019/1/22 22:35* @UpdateRemark: The modified content* @Version: 1.0*/
public class PipiXiaCondition implements Condition {/***当name不为空的时候，判断如果name中包含appName的时候返回true* @param context* @param metadata* @return*/@Overridepublic boolean matches(ConditionContext context, AnnotatedTypeMetadata metadata) {return true;}
}

在@Bean所在的类中添加自定义条件，配合@Conditional注解来实现

package com.yxj.spring;import org.springframework.boot.SpringBootConfiguration;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Conditional;/*** @ProjectName: springBootDemo* @Package: com.yxj.spring* @Description:  @SpringBootConfiguration继承自@Configuration，* 二者功能也一致，标注当前类是配置类，* 并会将当前类内声明的一个或多个以@Bean注解标记的方法的实例纳入到spring容器中，* 并且实例名就是方法名。* @Author: 阿杰* @CreateDate: 2019/1/22 22:14* @UpdateUser: 暂无* @UpdateDate: 2019/1/22 22:14* @UpdateRemark: The modified content* @Version: 1.0*/
@SpringBootConfiguration
public class LoadMyBean {@Bean@Conditional(WechatCondition.class)public MakeApp createWechat(){return new Wechat();}@Bean@Conditional(PipiXiaCondition.class)public MakeApp createPipiXia(){return new PipiXia();}
}

再次测试，测试结果

------------------分割线------------------
{createPipiXia=com.yxj.spring.PipiXia@420bc288}

可以看到只打印了一个pipixia实例bean，微信没有装配进来

SpringBoot中自带的Condition实现

可以看到这个是继承了@Conditional注解，传了自定义的class对象，变成了一个新的注解
常用@Conditional注解使用，可以查看大佬博客https://blog.csdn.net/u012437781/article/details/78626617

@Import注解

用处

@Import其实就是引入一个或多个配置，可以导入普通类，也可以导入配置类（上述的LoadMyBean为配置类，主要通过@Bean生成bean给spring管理）
@Import用来导入一个或多个类（会被spring容器管理），或者配置类（配置类里的@Bean标记的类也会被spring容器管理）

测试

还是以上的例子，去掉配置类(LoadMyBean)中的@SpringBootConfiguration注解

package com.yxj.spring;import org.springframework.boot.SpringBootConfiguration;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Conditional;/*** @ProjectName: springBootDemo* @Package: com.yxj.spring* @Description:  @SpringBootConfiguration继承自@Configuration，* 二者功能也一致，标注当前类是配置类，* 并会将当前类内声明的一个或多个以@Bean注解标记的方法的实例纳入到spring容器中，* 并且实例名就是方法名。* @Author: 阿杰* @CreateDate: 2019/1/22 22:14* @UpdateUser: 暂无* @UpdateDate: 2019/1/22 22:14* @UpdateRemark: The modified content* @Version: 1.0*/
public class LoadMyBean {@Bean@Conditional(WechatCondition.class)public MakeApp createWechat(){return new Wechat();}@Bean@Conditional(PipiXiaCondition.class)public MakeApp createPipiXia(){return new PipiXia();}
}

修改springboot启动类，添加@Import注解

package com.yxj.spring;import org.springframework.beans.factory.annotation.Value;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.autoconfigure.condition.ConditionalOnBean;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.context.ConfigurableApplicationContext;
import org.springframework.context.annotation.*;import java.util.List;/*** @ProjectName: springBootDemo* @Package: com.yxj.spring* @Description:* @Author: 杨小杰* @CreateDate: 2019/1/18 20:18* @UpdateUser: 暂无* @UpdateDate: 2019/1/18 20:18* @UpdateRemark: The modified content* @Version: 1.0*/
@SpringBootApplication
@Import(LoadMyBean.class)
public class SpringBootTestRun {/*** getBeansOfType(MakeApp.class)会装配bean类型是MakeApp的所有实例* @param args*/public static void main(String[] args) {ConfigurableApplicationContext run = SpringApplication.run(SpringBootTestRun.class, args);System.out.println("------------------分割线------------------");System.out.println(run.getBeansOfType(MakeApp.class));}
}

测试结果

------------------分割线------------------
{createPipiXia=com.yxj.spring.PipiXia@6548bb7d}

测试结果表明了，虽然配置类没有加入@SpringBootConfiguration,@Component，@Service,@Controller等交给spring管理的注解，但是通过启动类添加@Import引入方式，仍然可以在spring进行依赖注入，交由spring管理

声明

本人是与springBoot教学视频同步学习，此文章是看视频与查阅各位大佬博客文章总结出来的重点内容。
如果觉得文章描绘的不够清楚，欢迎留言，也可以关注公众号，在公众号内发送关键字“springboot”或者“springBoot”领取springBoot教程。
排版不易，希望大家能够点点关注，共同学习，有问题请指出，谢谢大家。
ps:我也希望本人能够精准表达springBoot的一些重点内容，减少大家观看视频的大额时间。