[Java] Spring Boot2.0 @ConfigurationProperties使用详解

<parent>
  <groupid>org.springframework.boot</groupid>
  <artifactid>spring-boot-starter-parent</artifactid>
  <version>2.0.4.release</version>
  <relativepath/> <!-- lookup parent from repository -->
 </parent>

• 添加web,因为我们需要使用到jsr-303规范的validator,如果不想使用web依赖,也可以直接依赖hibernate-validator
  
• 添加spring-boot-configuration-processor,可以在编译时生成属性元数据(spring-configuration-metadata.json).
  
• 添加lombok,可以方便使用注释处理器的功能省去pojo定义中get set这些麻烦工作.
  

<dependency>
 <groupid>org.springframework.boot</groupid>
 <artifactid>spring-boot-starter-web</artifactid>
</dependency>
<!--<dependency>-->
 <!--<groupid>org.hibernate.validator</groupid>-->
 <!--<artifactid>hibernate-validator</artifactid>-->
 <!--<version>6.0.11.final</version>-->
 <!--<scope>compile</scope>-->
<!--</dependency>-->
<dependency>
 <groupid>org.projectlombok</groupid>
 <artifactid>lombok</artifactid>
</dependency>
<dependency>
 <groupid>org.springframework.boot</groupid>
 <artifactid>spring-boot-configuration-processor</artifactid>
 <optional>true</optional>
</dependency>

@getter
@setter
public class documentserverproperties {
 
  private string remoteaddress;
  private boolean preferipaddress;
  private int maxconnections=0;
  private int port;
  private authinfo authinfo;
  private list<string> whitelist;
  private map<string,string> converter;
  private list<person> defaultshareusers;
 
  @getter
  @setter
  public static class authinfo {
 
  private string username;
  private string password;
  }
}

@configurationproperties(prefix = "doc")
@component
public class documentserverproperties {
  //代码...
}

@configurationproperties(prefix = "doc")
public class documentserverproperties {
  //代码...
}

@enableconfigurationproperties
@configuration
public class someconfiguration {
  private documentserverproperties documentserverproperties
  
  public someconfiguration(documentserverproperties documentserverproperties) {
  this.documentserverproperties = documentserverproperties;
  }
 
}

@configuration
public class someconfiguration {
  
  @bean
  public documentserverproperties documentserverproperties(){
  return new documentserverproperties();
  }
  
  @configurationproperties("demo.third")
  @bean
  public thirdcomponent thirdcomponent(){
  return new thirdcomponent();
  }
 
}

doc.remote-address=127.0.0.1
doc.port=8080
doc.max-connections=30
doc.prefer-ip-address=true
#doc.whitelist=192.168.0.1,192.168.0.2
# 这种等同于下面的doc.whitelist[0] doc.whitelist[1]
doc.whitelist[0]=192.168.0.1
doc.whitelist[1]=192.168.0.2
doc.default-share-users[0].name=jack
doc.default-share-users[0].age=18
doc.converter.a=xxconverter
doc.converter.b=xxconverter
doc.auth-info.username=user
doc.auth-info.password=password

doc:
 remote-address: 127.0.0.1
 port: 8080
 max-connections: 30
 prefer-ip-address: true
 whitelist: 
  - 192.168.0.1
  - 192.168.0.2
 default-share-users: 
  - name: jack
   age: 18
 converter: 
  a: aconverter
  b: bconverter
 auth-info:
  username: user
  password: password

@configurationproperties(prefix = "doc")
@validated
public class documentserverproperties {
  @notnull // 判断不为空的情况
  private string remoteaddress;
  
  //限制端口只能是80-65536之间
  @min(80)
  @max(65536)
  private int port;
  //其他代码
}

public class userloginvalidator implements validator {
 
  private static final int minimum_password_length = 6;
 
  public boolean supports(class clazz) {
  return userlogin.class.isassignablefrom(clazz);
  }
 
  public void validate(object target, errors errors) {
  validationutils.rejectifemptyorwhitespace(errors, "username", "field.required");
  validationutils.rejectifemptyorwhitespace(errors, "password", "field.required");
  userlogin login = (userlogin) target;
  if (login.getpassword() != null
     && login.getpassword().trim().length() < minimum_password_length) {
   errors.rejectvalue("password", "field.min.length",
    new object[]{integer.valueof(minimum_password_length)},
    "the password must be at least [" + minimum_password_length + "] characters in );
  }
  }
}

@configurationproperties(prefix = "doc")
public class documentserverproperties implements validator{
  @notnull
  private string remoteaddress;
  private boolean preferipaddress;
  //其他属性 
  
  @override
  public boolean supports(class<?> clazz) {
  return true;
  }
 
  @override
  public void validate(object target, errors errors) {
  //判断逻辑其实可以参照上面的代码片段
  }
}

• 只有在需要使用jsr303规范实现的验证器时,才需要对对象配置@validated,刚刚上面两种方式并不需要。
  
• 第一种实现和第二种实现都是实现org.springframework.validation.validator接口,但是前者是针对全局的,后者只针对实现这个接口的配置对象
  

private list<validator> getvalidators(bindable<?> target) {
  list<validator> validators = new arraylist<>(3);
  if (this.configurationpropertiesvalidator != null) {
  validators.add(this.configurationpropertiesvalidator);
  }
  if (this.jsr303present && target.getannotation(validated.class) != null) {
    validators.add(getjsr303validator());
  }
  if (target.getvalue() != null && target.getvalue().get() instanceof validator) {
  validators.add((validator) target.getvalue().get());
  }
  return validators;
}