springboot使用注解方式加载配置文件

作者: John_Phil | 来源:发表于2019-07-29 21:59 被阅读0次

我们在以往将配置信息从 xml或者properties文件通过类加载器classloader 加载properties文件，将有用的信息读出，再放到对应的位置进行使用
而在spring3.x中提供了使用注解的方式进行配置读取

@Configuration：声明当前类作为配置类使用

@Bean：声明在方法上，将方法的返回值加入Bean容器

@value：属性值注入

@PropertySource：指定外部待加载文件

快速搭建springboot项目以下为pom.xml

<?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 http://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>2.1.6.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.neusoft</groupId>
    <artifactId>springtest1</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>springtest1</name>
    <description>Demo project for Spring Boot</description>

    <properties>
        <java.version>1.8</java.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>

        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid</artifactId>
            <version>1.1.11</version>
        </dependency>
        <!-- https://mvnrepository.com/artifact/org.springframework/spring-webmvc -->
       <!-- <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-webmvc</artifactId>
            <version>5.1.5.RELEASE</version>
        </dependency>-->
        <!-- https://mvnrepository.com/artifact/org.springframework/spring-context -->
      <!--  <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context</artifactId>
            <version>5.1.6.RELEASE</version>
        </dependency>-->



    </dependencies>

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

</project>

aaa.properties配置文件放到resources中

image.png

aaa.a1=aa1123
aaa.a2=aa2123
aaa.a3=aa3123
aaa.a4=aa4123

再创建一个实体类

路径

package com.neusoft.pojo;
public class ConfigPojo {
    public String a1=null;
    public  String a2=null;
    public  String a3=null;
    public  String a4=null;
}

我们先创建一个Configtest类

package com.neusoft.config;

import com.neusoft.pojo.ConfigPojo;
import lombok.Data;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.PropertySource;

@Configuration
@PropertySource("classpath:testaa.properties")
public class Configtest {

    @Value("${aaa.a1}")
    String a1;
    @Value("${aaa.a1}")
    String a2;
    @Value("${aaa.a3}")
    String a3;
    @Value("${aaa.a4}")
    String a4;

    @Bean
    public ConfigPojo getAaa(){
        ConfigPojo cp=new ConfigPojo();
        cp.a1=a1;
        cp.a2=a2;
        cp.a3=a3;
        cp.a4=a4;

        return cp;
    }
}

最后再创建一个control 方便请求与访问

package com.neusoft.control;

import com.neusoft.pojo.ConfigPojo;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;
import javax.annotation.Resource;

@RestController
public class HelloControl {
    @Autowired
    private ConfigPojo configPojo;
    @GetMapping("getconfig")
    public String test1(){
        return configPojo.a1+configPojo.a2+configPojo.a3+configPojo.a4;
    }
}

请求与响应信息

第二种方式可以使用lombok插件
使用方式 https://www.jianshu.com/p/542bf23a9421

将配置放到 application.properties

image.png

新建类 configlombok
使用 @ConfigurationProperties(prefix = "aaa") 并指定前缀名称

package com.neusoft.config;

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

@ConfigurationProperties(prefix = "aaa")
@Data
public class Configlombok {
    public String a1;
    public String a2;
    public String a3;
    public String a4;

修改Configtest
@EnableConfigurationProperties(Configlombok.class) 允许配置生效

package com.neusoft.config;

import com.neusoft.pojo.ConfigPojo;
import lombok.Data;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.boot.context.properties.EnableConfigurationProperties;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.PropertySource;

@Configuration
@EnableConfigurationProperties(Configlombok.class)
public class Configtest {

    public ConfigPojo getAaa(Configlombok configlombok){
        ConfigPojo cp=new ConfigPojo();
        cp.a1=configlombok.getA1();
        cp.a2=configlombok.getA2();
        cp.a3=configlombok.getA3();
        cp.a4=configlombok.getA4();
        return cp;
    }
}

实体类增加 toString（）方法

package com.neusoft.pojo;

public class ConfigPojo {

    public String a1=null;
    public String a2=null;
    public String a3=null;
    public String a4=null;

    @Override
    public String toString() {
        return a1+a2+a3+a4;
    }
}

修改control

package com.neusoft.control;

import com.neusoft.config.Configlombok;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;
import javax.annotation.Resource;
@RestController
public class HelloControl {
    @Autowired
    private Configlombok configlombok;
    @GetMapping("getconfig")
    public String test1(){
        return configlombok.toString();
    }
}

再次访问

image.png

升级方法二进一步简化

在Configlombok中添加生成tostring注解
并将@ConfigurationProperties(prefix = "aaa")注释掉

package com.neusoft.config;

import lombok.Data;
import lombok.ToString;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.stereotype.Component;
//@ConfigurationProperties(prefix = "aaa")
@ToString(includeFieldNames=true)
@Data
public class Configlombok {
    public String a1;
    public String a2;
    public String a3;
    public String a4;
}

再将 Configtest 中的//@EnableConfigurationProperties({Configlombok.class}) 注释掉
以及getAaa方法注释掉。
并添加新的getAaa方法与注解
@ConfigurationProperties(prefix = "aaa") 会根据返回的对象到配置文件中aaa前缀下的名字与值并去找与对象Configlombok中set 方法对应方法进行赋值（自动将配置文件中的内容注入到Configlombok对象属性中）

package com.neusoft.config;

import com.neusoft.pojo.ConfigPojo;
import lombok.Data;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.boot.context.properties.EnableConfigurationProperties;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.PropertySource;

@Configuration
//@PropertySource("classpath:testaa.properties")
//@EnableConfigurationProperties({Configlombok.class})
public class Configtest {

//    @Value("${aaa.a1}")
//    String a1;
//    @Value("${aaa.a1}")
//    String a2;
//    @Value("${aaa.a3}")
//    String a3;
//    @Value("${aaa.a4}")
//    String a4;


//    public ConfigPojo getAaa(Configlombok configlombok){
//        ConfigPojo cp=new ConfigPojo();
//        cp.a1=configlombok.getA1();
//        cp.a2=configlombok.getA2();
//        cp.a3=configlombok.getA3();
//        cp.a4=configlombok.getA4();
//        return cp;
//    }
    @Bean
    @ConfigurationProperties(prefix = "aaa")
    public Configlombok getAaa(){
        return new Configlombok();
    }
    

}

package com.neusoft.control;

import com.neusoft.config.Configlombok;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;
import javax.annotation.Resource;
@RestController
public class HelloControl {
//    @Autowired
//    private ConfigPojo configPojo;
    @Autowired
    private Configlombok configlombok;
    @GetMapping("getconfig")
    public String test1(){
        return configlombok.toString();
    }
}

访问输出结果
4.配置文件为 application.yaml或者application.yml
当appliation.yml与application.properties并存时优先选择application.properties 如果properties 里没有再选择yml
如果再加入外置配置文件
优先顺序 application.properties>appliation.yml>外置配置

image.png

appliction.properties

aaa.a1=aa1123
aaa.a2=aa2123
aaa.a3=aa3123
#aaa.a4=aa4123

application.yml

aaa:
  a1: bb1123
  a2: bb2123
  a3: bb3123
  a4: bb4123

结果

加入外置配置文件

testaa.properties

aaa.a1=cc1123
aaa.a2=cc2123
aaa.a3=cc3123
aaa.a4=cc4123

appliction.properties

aaa.a1=aa1123
aaa.a2=aa2123
#aaa.a3=aa3123
#aaa.a4=aa4123

application.yml

aaa:
  a1: bb1123
  a2: bb2123
  a3: bb3123
 # a4: bb4123

Configtest 加入@PropertySource("classpath:testaa.properties")

package com.neusoft.config;

import com.neusoft.pojo.ConfigPojo;
import lombok.Data;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.boot.context.properties.EnableConfigurationProperties;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.PropertySource;

@Configuration
@PropertySource("classpath:testaa.properties")
//@EnableConfigurationProperties({Configlombok.class})
public class Configtest {

//    @Value("${aaa.a1}")
//    String a1;
//    @Value("${aaa.a1}")
//    String a2;
//    @Value("${aaa.a3}")
//    String a3;
//    @Value("${aaa.a4}")
//    String a4;


//    public ConfigPojo getAaa(Configlombok configlombok){
//        ConfigPojo cp=new ConfigPojo();
//        cp.a1=configlombok.getA1();
//        cp.a2=configlombok.getA2();
//        cp.a3=configlombok.getA3();
//        cp.a4=configlombok.getA4();
//        return cp;
//    }
    @Bean
    @ConfigurationProperties(prefix = "aaa")
    public Configlombok getAaa(){
        return new Configlombok();
    }


}

image.png

springboot使用注解方式加载配置文件

@Configuration：声明当前类作为配置类使用

@Bean：声明在方法上，将方法的返回值加入Bean容器

@value：属性值注入

@PropertySource：指定外部待加载文件

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