Spring Boot中的 @ConfigurationProperties

看各種框架的spring boot版本,配置信息都寫在yml或properties文件裏了,這裏實際上用了@ConfigurationProperties註解,源代碼的流程很複雜,先看看怎麼使用.

方式1:註解加在類上

@Component
@ConfigurationProperties(prefix = "test")
public class TestConfiguration {
    private String name;
    private Integer age;

     ...........
}

配置文件: 

test.name=liming
test.age=25

測試: 

@RestController
@RequestMapping("/con")
public class Controller {

    @Autowired
    private TestConfiguration testConfiguration;

    @GetMapping("/test1")
    public String get(){
        return testConfiguration.toString();
    }
}

/test1結果:TestConfiguration{name='liming', age=25}

 

方式2:註解加在Bean上

public class TestConfiguration2 {
    private String name;
    private Integer age;
    ......
}

建一個配置類,在配置類裏建個Bean,new個實體類

@Configuration
public class Confi {
 
    @Bean(name="TEST2") // 如果沒有name,默認是類名TestConfiguration2 
    @ConfigurationProperties(prefix = "test")
    public TestConfiguration2 get2(){
        TestConfiguration2 testConfiguration2 = new TestConfiguration2();
        System.out.println(testConfiguration2.toString());
        return testConfiguration2;
    }
}

controller測試: 

注意: spring只會對同一個類管理一個bean,如果有兩個bean對象,spring就會報錯,提示你用@Primary來標註優先級

    // 如果bean的name爲默認,則用@autowired注入
    /*@Autowired
    private TestConfiguration2 testConfiguration2;*/


    @Resource(name="TEST2")
    private TestConfiguration2 testConfiguration2;

    @GetMapping("/test2")
    public String get2(){
        return testConfiguration2.toString();
    }

項目啓動發現,spring 加載bean,bean的打印結果爲:TestConfiguration{name='null', age=null}

說明加載bean比從Properties裏拿值要快,

訪問/test2已經有值了 :TestConfiguration{name='liming', age=25}

 

擴展:與@Qualifier 組合運用

Properties文件裏添加test_前綴

test_.name=Tom
test_.age=27

讓TEST3對象作爲參數傳給TEST4裏.

    @Bean(name = "TEST3")
    @ConfigurationProperties(prefix = "test_")
    public TestConfiguration2 get3(){

        TestConfiguration2 testConfiguration2 = new TestConfiguration2();
        System.out.println(testConfiguration2.toString());
        return testConfiguration2;
    }


    @Bean(name = "TEST4")
    public String test(@Qualifier("TEST3") TestConfiguration2 testConfiguration2){

        return testConfiguration2.toString();
    }

controller測試:

    @Resource(name="TEST4")
    private String TEST4str;
    @GetMapping("/test3")
    public String get3(){
       return TEST4str;
    }

訪問結果:TestConfiguration{name='Tom', age=27}