Spring Boot @ConfigurationProperties實例

Spring Boot [@ConfigurationProperties](https://github.com/ConfigurationProperties "@ConfigurationProperties")是讓開發人員比較容易地將整個文件映射成一個對象。

簡單屬性文件

通常，我們使用[@Value](https://github.com/Value "@Value")註釋來逐個注入.properties值，這對於小而簡單的結構.properties文件很有用。

文件：global.properties

[email protected]
thread-pool=12

@Value 示例
文件：GlobalProperties.java

@Component
@PropertySource("classpath:global.properties")
public class GlobalProperties {

    @Value("${thread-pool}")
    private int threadPool;

    @Value("${email}")
    private String email;

    //getters and setters

}

@ConfigurationProperties實例

文件：GlobalProperties.java

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

@Component
@PropertySource("classpath:global.properties")
@ConfigurationProperties
public class GlobalProperties {

    private int threadPool;
    private String email;

    //getters and setters

}

2.複雜屬性文件

2.1. 查看複雜的結構.properties文件，如何通過[@Value](https://github.com/Value "@Value")註釋映射值。

文件：application.properties

#Logging
logging.level.org.springframework.web=ERROR
logging.level.com.yiibai=DEBUG

#Global
[email protected]
thread-pool=10

#App
app.menus[0].title=Home
app.menus[0].name=Home
app.menus[0].path=/
app.menus[1].title=Login
app.menus[1].name=Login
app.menus[1].path=/login

app.compiler.timeout=5
app.compiler.output-folder=/temp/

app.error=/error/

或YAML中的下面配置， 文件： application.yml

logging:
  level:
    org.springframework.web: ERROR
    com.yiibai: DEBUG
email: [email protected]
thread-pool: 10
app:
  menus:
    - title: Home
      name: Home
      path: /
    - title: Login
      name: Login
      path: /login
  compiler:
    timeout: 5
    output-folder: /temp/
  error: /error/

注意：[@ConfigurationProperties](https://github.com/ConfigurationProperties "@ConfigurationProperties")支持.properties和.yml文件。

下面可使用[@ConfigurationProperties](https://github.com/ConfigurationProperties "@ConfigurationProperties")來配置完成，創建一個[@ConfigurationProperties](https://github.com/ConfigurationProperties "@ConfigurationProperties") bean，如下所示：

文件： AppProperties.java -

package com.yiibai;

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

import java.util.ArrayList;
import java.util.List;

@Component
@ConfigurationProperties("app") // prefix app, find app.* values
public class AppProperties {

    private String error;
    private List<Menu> menus = new ArrayList<>();
    private Compiler compiler = new Compiler();

    public static class Menu {
        private String name;
        private String path;
        private String title;

        //getters and setters

        @Override
        public String toString() {
            return "Menu{" +
                    "name='" + name + '\'' +
                    ", path='" + path + '\'' +
                    ", title='" + title + '\'' +
                    '}';
        }
    }

    public static class Compiler {
        private String timeout;
        private String outputFolder;

        //getters and setters

        @Override
        public String toString() {
            return "Compiler{" +
                    "timeout='" + timeout + '\'' +
                    ", outputFolder='" + outputFolder + '\'' +
                    '}';
        }

    }

    //getters and setters
}

文件：GlobalProperties.java -

package com.yiibai;

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

@Component
@ConfigurationProperties // no prefix, find root level values.
public class GlobalProperties {

    private int threadPool;
    private String email;

    //getters and setters
}
`

演示實例

測試以確保.properties值正確映射到對象。文件：WelcomeController.java -

package com.yiibai;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;

import java.util.Map;

@Controller
public class WelcomeController {

    private static final Logger logger = LoggerFactory.getLogger(WelcomeController.class);

    private AppProperties app;
    private GlobalProperties global;

    @Autowired
    public void setApp(AppProperties app) {
        this.app = app;
    }

    @Autowired
    public void setGlobal(GlobalProperties global) {
        this.global = global;
    }

    @RequestMapping("/")
    public String welcome(Map<String, Object> model) {

        String appProperties = app.toString();
        String globalProperties = global.toString();

        logger.debug("Welcome {}, {}", app, global);

        model.put("message", appProperties + globalProperties);
        return "welcome";
    }

}

文件：SpringBootWebApplication.java -

package com.yiibai;

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

@SpringBootApplication
public class SpringBootWebApplication {

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

}

使用Maven命令mvn spring-boot:run啓動Spring Boot，運行成功後訪問默認/控制器，查看控制檯輸出：

Welcome
    AppProperties{error='/error/',
        menus=[
            Menu{name='Home', path='/', title='Home'},
            Menu{name='Login', path='/login', title='Login'}
        ],
        compiler=Compiler{timeout='5', outputFolder='/temp/'}},

    GlobalProperties{threadPool=10, email='[email protected]'}

@ConfigurationProperties驗證

讓這個[@ConfigurationProperties](https://github.com/ConfigurationProperties "@ConfigurationProperties")支持JSR-303 bean驗證 - javax.validation

文件：GlobalProperties.java -

package com.yiibai;

import org.hibernate.validator.constraints.NotEmpty;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.stereotype.Component;

import javax.validation.constraints.Max;
import javax.validation.constraints.Min;

@Component
@ConfigurationProperties
public class GlobalProperties {

    @Max(5)
    @Min(0)
    private int threadPool;

    @NotEmpty
    private String email;

    //getters and setters
}

嘗試再次使用Maven命令mvn spring-boot:run啓動Spring Boot，並查看控制檯：

本項目名稱爲： spring-boot-properties， 請找到下載Spring Boot代碼下載目錄，並下載。