但 Spring Boot 提供了另一种方式 ，能够根据类型校验和管理application中的bean。 这里会介绍如何使用@ConfigurationProperties。
继续使用mail做例子。配置放在mail.properties文件中。属性必须命名规范才能绑定成功。举例：
1 protocol and PROTOCOL will be bind to protocol field of a bean
2 smtp-auth , smtp_auth , smtpAuth will be bind to smtpAuth field of a bean
3 smtp.auth will be bind to … hmm to smtp.auth field of a bean!
Spring Boot 使用一些松的规则来绑定属性到@ConfigurationProperties bean 并且支持分层结构（hierarchical structure）。
开始创建一个@ConfigurationProperties bean:
package com.dxz.property; import org.springframework.boot.context.properties.ConfigurationProperties; @ConfigurationProperties(locations = "classpath:mail.properties", ignoreUnknownFields = false, prefix = "mail")
public class MailProperties {
private String host;
private int port;
private String from;
private String username;
private String password;
private Smtp smtp; // ... getters and setters
public String getHost() {
return host;
} public void setHost(String host) {
this.host = host;
} public int getPort() {
return port;
} public void setPort(int port) {
this.port = port;
} public String getFrom() {
return from;
} public void setFrom(String from) {
this.from = from;
} 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;
} public Smtp getSmtp() {
return smtp;
} public void setSmtp(Smtp smtp) {
this.smtp = smtp;
} @Override
public String toString() {
return "MailProperties [host=" + host + ", port=" + port + ", from=" + from + ", username=" + username
+ ", password=" + password + ", smtp=" + smtp + "]";
} public static class Smtp {
private boolean auth;
private boolean starttlsEnable; public boolean isAuth() {
return auth;
} public void setAuth(boolean auth) {
this.auth = auth;
} public boolean isStarttlsEnable() {
return starttlsEnable;
} public void setStarttlsEnable(boolean starttlsEnable) {
this.starttlsEnable = starttlsEnable;
} }
}
如下属性中创建 ( mail.properties )：
mail.host=localhost
mail.port=25
mail.smtp.auth=false
mail.smtp.starttls-enable=false
mail.from=me@localhost
mail.username=duan
mail.password=duan123456
上例中我们用@ConfigurationProperties注解就可以绑定属性了。ignoreUnknownFields = false告诉Spring Boot在有属性不能匹配到声明的域的时候抛出异常。开发的时候很方便! prefix 用来选择哪个属性的prefix名字来绑定。
请注意setters 和 getters 需要在@ConfigurationProperties bean中创建! 与@Value注解相反。
我们需要用属性来配置 application。 有至少两种方式来创建@ConfigurationProperties。即可以搭配@Configuration 注解来提供 @Beans 也可以单独使用并注入 @Configuration bean。
方案1:定义spring的一个实体bean装载配置文件信息，其它要使用配置信息是注入该实体bean
package com.dxz.property3; import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.stereotype.Component; @Component
@ConfigurationProperties(locations = "classpath:mail.properties", ignoreUnknownFields = false, prefix = "mail")
public class MailProperties {
private String host;
private int port;
private String from;
private String username;
private String password;
private Smtp smtp; // ... getters and setters
public String getHost() {
return host;
} public void setHost(String host) {
this.host = host;
} public int getPort() {
return port;
} public void setPort(int port) {
this.port = port;
} public String getFrom() {
return from;
} public void setFrom(String from) {
this.from = from;
} 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;
} public Smtp getSmtp() {
return smtp;
} public void setSmtp(Smtp smtp) {
this.smtp = smtp;
} @Override
public String toString() {
return "MailProperties [host=" + host + ", port=" + port + ", from=" + from + ", username=" + username
+ ", password=" + password + ", smtp=" + smtp + "]";
} public static class Smtp {
private boolean auth;
private boolean starttlsEnable; public boolean isAuth() {
return auth;
} public void setAuth(boolean auth) {
this.auth = auth;
} public boolean isStarttlsEnable() {
return starttlsEnable;
} public void setStarttlsEnable(boolean starttlsEnable) {
this.starttlsEnable = starttlsEnable;
} }
}
启动及测试类：
package com.dxz.property3; import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.builder.SpringApplicationBuilder;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.ResponseBody;
import org.springframework.web.bind.annotation.RestController; @RestController
@SpringBootApplication
//@EnableConfigurationProperties(MailProperties.class)
public class TestProperty3 { @Autowired
private MailProperties mailProperties; @RequestMapping(value = "/hello", method = RequestMethod.GET)
@ResponseBody
public String hello() {
System.out.println("mailProperties" + mailProperties);
return "hello world";
} public static void main(String[] args) {
//SpringApplication.run(TestProperty1.class, args);
new SpringApplicationBuilder(TestProperty3.class).web(true).run(args); }
}
结果：
mailPropertiesMailProperties [host=localhost, port=25, from=me@localhost, username=duan, password=duan123456, smtp=com.dxz.property3.MailProperties$Smtp@37cebacb]
方案2：@Bean+@ConfigurationProperties
我们还可以把@ConfigurationProperties还可以直接定义在@bean的注解上，这是bean实体类就不用@Component和@ConfigurationProperties了
package com.dxz.property4;
public class MailProperties {
private String host;
private int port;
private String from;
private String username;
private String password;
private Smtp smtp;
// ... getters and setters
public String getHost() {
return host;
}
public void setHost(String host) {
this.host = host;
}
public int getPort() {
return port;
}
public void setPort(int port) {
this.port = port;
}
public String getFrom() {
return from;
}
public void setFrom(String from) {
this.from = from;
}
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;
}
public Smtp getSmtp() {
return smtp;
}
public void setSmtp(Smtp smtp) {
this.smtp = smtp;
}
@Override
public String toString() {
return "MailProperties [host=" + host + ", port=" + port + ", from=" + from + ", username=" + username
+ ", password=" + password + ", smtp=" + smtp + "]";
}
public static class Smtp {
private boolean auth;
private boolean starttlsEnable;
public boolean isAuth() {
return auth;
}
public void setAuth(boolean auth) {
this.auth = auth;
}
public boolean isStarttlsEnable() {
return starttlsEnable;
}
public void setStarttlsEnable(boolean starttlsEnable) {
this.starttlsEnable = starttlsEnable;
}
}
}
配置类（启动类）
package com.dxz.property4; import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.builder.SpringApplicationBuilder;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.context.annotation.Bean; @SpringBootApplication
public class TestProperty4 { @Bean
@ConfigurationProperties(locations = "classpath:mail.properties", prefix = "mail")
public MailProperties mailProperties(){
MailProperties mp = new MailProperties();
System.out.println("zheli " + mp);
return mp; } public static void main(String[] args) {
//SpringApplication.run(TestProperty1.class, args);
new SpringApplicationBuilder(TestProperty4.class).web(true).run(args); }
}
测试类：
package com.dxz.property4; import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController; @RestController
@RequestMapping("/task")
public class TaskController { @Autowired
MailProperties mailProperties; @RequestMapping(value = {"/",""})
public String hellTask(){
System.out.println("mailProperties" +mailProperties);
return "hello task !!";
} }
结果：
方案3:@ConfigurationProperties + @EnableConfigurationProperties
我们和上面例子一样注解属性，然后用 Spring的@Autowire来注入 mail configuration bean:
package com.dxz.property; import org.springframework.boot.context.properties.ConfigurationProperties; @ConfigurationProperties(locations = "classpath:mail.properties", ignoreUnknownFields = false, prefix = "mail")
public class MailProperties {
private String host;
private int port;
private String from;
private String username;
private String password;
private Smtp smtp; // ... getters and setters
public String getHost() {
return host;
} public void setHost(String host) {
this.host = host;
} public int getPort() {
return port;
} public void setPort(int port) {
this.port = port;
} public String getFrom() {
return from;
} public void setFrom(String from) {
this.from = from;
} 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;
} public Smtp getSmtp() {
return smtp;
} public void setSmtp(Smtp smtp) {
this.smtp = smtp;
} @Override
public String toString() {
return "MailProperties [host=" + host + ", port=" + port + ", from=" + from + ", username=" + username
+ ", password=" + password + ", smtp=" + smtp + "]";
} public static class Smtp {
private boolean auth;
private boolean starttlsEnable; public boolean isAuth() {
return auth;
} public void setAuth(boolean auth) {
this.auth = auth;
} public boolean isStarttlsEnable() {
return starttlsEnable;
} public void setStarttlsEnable(boolean starttlsEnable) {
this.starttlsEnable = starttlsEnable;
} }
}
启动类及测试类：
package com.dxz.property; import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.builder.SpringApplicationBuilder;
import org.springframework.boot.context.properties.EnableConfigurationProperties;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.ResponseBody;
import org.springframework.web.bind.annotation.RestController; @RestController
@SpringBootApplication
@EnableConfigurationProperties(MailProperties.class)
public class TestProperty1 { @Autowired
private MailProperties mailProperties; @RequestMapping(value = "/hello", method = RequestMethod.GET)
@ResponseBody
public String hello() {
System.out.println("mailProperties" + mailProperties);
return "hello world";
} public static void main(String[] args) {
//SpringApplication.run(TestProperty1.class, args);
new SpringApplicationBuilder(TestProperty1.class).web(true).run(args); }
}
结果：
请注意@EnableConfigurationProperties注解。该注解是用来开启对@ConfigurationProperties注解配置Bean的支持。也就是@EnableConfigurationProperties注解告诉Spring Boot 能支持@ConfigurationProperties。如果不指定会看到如下异常:
Caused by: org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type [com.dxz.property.MailProperties] found for dependency: expected at least 1 bean which qualifies as autowire candidate for this dependency. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}
注意: 还有其他办法 (Spring Boot 总是有其他办法!) 让@ConfigurationProperties beans 被添加 – 用@Configuration或者 @Component注解, 这样就可以在 component scan时候被发现了。
总结：
@ConfigurationProperties很方便使用。 比用@Value注解好吗? 在特定的方案中是的,这只是一个选择问题。
看下Spring Boot的文档有更多的关于typesafe configuration 属性
转自原文：https://www.cnblogs.com/duanxz/p/4520571.html