springBoot教程：2.读取配置文件

场景：

在以往的开发中，需要读取properties文件或者yml文件。然后将里面的属性一个个set到实体中。
在spring boot则可以“节省”这些步骤。

spring boot会自动读取classpath下的application.properties(当只有这个文件的时候)。
虽然同名文件不同目录下的读取顺序会有先后顺序，或者会被properties.yml等文件覆盖，这里均不考虑。毕竟在实际开发中会统一约定配置文件。

案例代码

pom.xml

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

application.properties

com.eblly=eblly

eblly.name=eblly
eblly.sex=man

Chapter0202Application.java

package com.eblly;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.context.properties.EnableConfigurationProperties;

@SpringBootApplication
@EnableConfigurationProperties({ConfigBean.class})
public class Chapter0202Application {

    public static void main(String[] args) {
        SpringApplication.run(Chapter0202Application.class, args);
    }
}

@EnableConfigurationProperties开启自动配置。

ConfigBean.java

package com.eblly;

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

/**
 * @author eblly
 * @since 2017/11/18
 */
@ConfigurationProperties(prefix = "eblly")
public class ConfigBean {

    private String name;

    private String sex;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getSex() {
        return sex;
    }

    public void setSex(String sex) {
        this.sex = sex;
    }
}

@ConfigurationProperties 配置属性，会将properties中的eblly.name和eblly.sex注入到当前实体的变量中。

测试controller
IndexController.java

package com.eblly;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

/**
 * @author eblly
 * @since 2017/11/18
 */
@RestController
public class IndexController {

    @Value("${com.eblly}")
    private String name;

    @Autowired
    private ConfigBean configBean;

    @RequestMapping("/")
    public ConfigBean hello() {
        System.out.println("===>" + name);

        return configBean;
    }
}

启动并访问http://localhost:8080/

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