(005) Spring Boot reads the configuration file

　　springboot default configuration file is application.properties or application.yml. Reads the configuration file There are two ways

　　1, the injection Environment object, the object acquired by Environment

　　2, use the Value Notes

　　The default value is a string type obtained, when using the Value annotation, automatic type conversions, use Environment object, designated class, as follows:

　　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>

    <groupId>com.edu.spring</groupId>
    <artifactId>springboot</artifactId>
    <version>1.0.0</version>
    <packaging>jar</packaging>

    <name>springboot</name>
    <!-- FIXME change it to the project's website -->
    <url>http://www.example.com</url>
    
    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-dependencies</artifactId>
                <version>2.1.6.RELEASE</version>
                <scope>import</scope>
                <type>pom</type>
            </dependency>
        </dependencies>
    </dependencyManagement>
    
    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <maven.compiler.source>1.8</maven.compiler.source>
        <maven.compiler.target>1.8</maven.compiler.target>
    </properties>

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

</project>

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　　UserConfig.java

package com.edu.spring.springboot;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.core.env.Environment;
import org.springframework.stereotype.Component;

@Component
public class UserConfig {

    @Autowired
    private Environment environment;
    
    @Value("${local.port}")
    private String port;
    
    @Value("${local.port}")
    private Integer port2;
    
    public void show(){
        System.out.println("local.ip= "+environment.getProperty("local.ip"));
        System.out.println("local.port= "+environment.getProperty("local.port",Integer.class));
        System.out.println("local.port= "+port);
        System.out.println("local.port= "+port2);
    }
}

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　　App.java

package com.edu.spring.springboot;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.ConfigurableApplicationContext;

@SpringBootApplication
public class App 
{
    public static void main( String[] args )
    {
        
        ConfigurableApplicationContext context=SpringApplication.run(App.class, args);
        System.out.println(context.getEnvironment().getProperty("local.ip"));
        context.getBean(UserConfig.class).show();
        context.close();
    }
}

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