在spring-boot中使用@ConfigurationProperties

@ConfigurationProperties註解的做用是能夠根據一個前綴將配置文件的屬性映射成一個POJO實體類，只要屬性名一致就能自動注入進去，使用起來很是方便，這一點容易與@Configuration註解混淆，@Configuration也能夠註解一個配置類，不同的是它須要爲每一個屬性再次聲明綁定的字段，稍微複雜，因此推薦使用@ConfigurationProperties註解。

下面看一個簡單的例子，我有一個配置文件,下面包含了多種數據結構的屬性，以下：

#Simple properties
mail.host=mailer@mail.com
mail.port=9000
mail.from=mailer@mail.com

#List properties
mail.recipients[0]=admin@mail.com
mail.recipients[1]=owner@mail.com

#Map Properties
mail.additionalHeaders.redelivery=true
mail.additionalHeaders.secure=true

#Object properties
mail.credentials.username=john
mail.credentials.password=password
mail.credentials.authMethod=SHA1


#List<Object>

mail.cs[0].username=cs1
mail.cs[0].password=cs1pwd
mail.cs[0].authMethod=SHA1


mail.cs[1].username=cs2
mail.cs[1].password=cs2pwd
mail.cs[1].authMethod=SHA2


#Map<String,Object>

mail.mp.k1.username=k1
mail.mp.k1.password=pwdk1
mail.mp.k1.authMethod=SHA3


mail.mp.k2.username=k2
mail.mp.k2.password=pwdk2
mail.mp.k2.authMethod=SHA3

如今咱們就能夠經過@ConfigurationProperties註解將其映射成一個配置類，這樣使用起來就很是方便了：

@Configuration
@PropertySource("classpath:mail.properties")
@ConfigurationProperties(prefix = "mail")
public class ConfigProperties {


    public static class Credentials{

        private String authMethod;
        private String username;
        private String password;

        public String getAuthMethod() {
            return authMethod;
        }

        public void setAuthMethod(String authMethod) {
            this.authMethod = authMethod;
        }

        public String getUsername() {
            return username;
        }

        public void setUsername(String username) {
            this.username = username;
        }

        public String getPassword() {
            return password;
        }

        public void setPassword(String password) {
            this.password = password;
        }

        @Override
        public String toString() {
            return "Credentials{" +
                    "authMethod='" + authMethod + '\'' +
                    ", username='" + username + '\'' +
                    ", password='" + password + '\'' +
                    '}';
        }
    }


    private String host;
    private int port;
    private  String from;
    private  Credentials credentials;
    private List<String> recipients;//接受者
    private Map<String,String> additionalHeaders;
    private Map<String,Credentials> mp;
    private List<Credentials>  cs;
	
	//getter setter 省略
	
	}

這個類裏面的每一個屬性和配置裏面的屬性對應，注意字段名必須是同樣的才能賦值： 爲了驗證是否成功，咱們建一個controller類,經過http：//localhost:8777/test 來驗證一下，看是否成功：

==============簡單屬性訪問================
mailer@mail.com
mailer@mail.com
9000
==============List[String]訪問================
[admin@mail.com, owner@mail.com]

==============Map[String,String]訪問================
{secure=true, redelivery=true}

==============Object訪問================
Credentials{authMethod='SHA1', username='john', password='password'}

==============List[Object]訪問================
Credentials{authMethod='SHA1', username='cs1', password='cs1pwd'}
Credentials{authMethod='SHA2', username='cs2', password='cs2pwd'}

==============Map[String,Object]訪問================
k2 Credentials{authMethod='SHA3', username='k2', password='pwdk2'}
k1 Credentials{authMethod='SHA3', username='k1', password='pwdk1'}
（注意不支持Set屬性）

能夠看到，已經成功注入，使用起來很是簡潔，不在像spring裏面還得經過一大堆xml來注入各類數據結構到Bean裏面，使得代碼精簡了很多。

工程已經分享到github上了，感興趣的朋友能夠star：https://github.com/qindongliang/spring-boot-properties