@ConfigurationProperties注解的作用是可以根据一个前缀将配置文件的属性映射成一个POJO实体类,只要属性名一致就能自动注入进去,使用起来非常方便,这一点容易与@Configuration注解混淆,@Configuration也可以注解一个配置类,不一样的是它需要为每个属性再次声明绑定的字段,稍微复杂,所以推荐使用@ConfigurationProperties注解。
下面看一个简单的例子,我有一个配置文件,下面包含了多种数据结构的属性,如下:
#Simple properties [email protected] mail.port=9000 [email protected] #List properties mail.recipients[0][email protected] mail.recipients[1][email protected] #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
现在我们就可以通过@ConfigurationProperties注解将其映射成一个配置类,这样使用起来就非常方便了:
@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 }
这个类里面的每个属性和配置里面的属性对应,注意字段名必须是一样的才能赋值:
为了验证是否成功,我们建一个controller类,通过http://localhost:8777/test
来验证一下,看是否成功:
==============简单属性访问================ [email protected] [email protected] 9000 ==============List[String]访问================ [[email protected], [email protected]] ==============Map[String,String]访问================ {secure=true, redelivery=true} ==============Object访问================ Credentials{authMethod='SHA1', username='john', password='password'} ==============List[Object]访问================ Credentials{authMethod='SHA1', username='cs1', password='cs1pwd'} Credentials{authMethod='SHA2', username='cs2', password='cs2pwd'} ==============Map[String,Object]访问================ k2 Credentials{authMethod='SHA3', username='k2', password='pwdk2'} k1 Credentials{authMethod='SHA3', username='k1', password='pwdk1'} (注意不支持Set属性)
可以看到,已经成功注入,使用起来非常简洁,不在像spring里面还得通过一大堆xml来注入各种数据结构到Bean里面,使得代码精简了不少。
工程已经分享到github上了,感兴趣的朋友可以star: https://github.com/qindongliang/spring-boot-properties