springboot将配置文件注入到class中

在properties或者yml中定义一些属性和参数,在bean或者config中需要使用这些参数.

• 1. 启动类开启 support for {@link ConfigurationProperties}

package org.springframework.boot.context.properties;

import java.lang.annotation.Documented;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Import;

/**
 * Enable support for {@link ConfigurationProperties} annotated beans.
 * {@link ConfigurationProperties} beans can be registered in the standard way (for
 * example using {@link Bean @Bean} methods) or, for convenience, can be specified
 * directly on this annotation.
 *
 * @author Dave Syer
 */
@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Import(EnableConfigurationPropertiesImportSelector.class)
public @interface EnableConfigurationProperties {

    /**
     * Convenient way to quickly register {@link ConfigurationProperties} annotated beans
     * with Spring. Standard Spring Beans will also be scanned regardless of this value.
     * @return {@link ConfigurationProperties} annotated beans to register
     */
    Class<?>[] value() default {};

}

• 2. 配置类中使用@ConfigurationProperties(prefix = "")注解

package org.springframework.boot.context.properties;

import java.lang.annotation.Documented;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

import org.springframework.core.annotation.AliasFor;

/**
 * Annotation for externalized configuration. Add this to a class definition or a
 * {@code @Bean} method in a {@code @Configuration} class if you want to bind and validate
 * some external Properties (e.g. from a .properties file).
 * <p>
 * Note that contrary to {@code @Value}, SpEL expressions are not evaluated since property
 * values are externalized.
 *
 * @author Dave Syer
 * @see ConfigurationPropertiesBindingPostProcessor
 * @see EnableConfigurationProperties
 */
@Target({ ElementType.TYPE, ElementType.METHOD })
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface ConfigurationProperties {

    /**
     * The name prefix of the properties that are valid to bind to this object. Synonym
     * for {@link #prefix()}. A valid prefix is defined by one or more words separated
     * with dots (e.g. {@code "acme.system.feature"}).
     * @return the name prefix of the properties to bind
     */
    @AliasFor("prefix")
    String value() default "";

    /**
     * The name prefix of the properties that are valid to bind to this object. Synonym
     * for {@link #value()}. A valid prefix is defined by one or more words separated with
     * dots (e.g. {@code "acme.system.feature"}).
     * @return the name prefix of the properties to bind
     */
    @AliasFor("value")
    String prefix() default "";

    /**
     * Flag to indicate that when binding to this object invalid fields should be ignored.
     * Invalid means invalid according to the binder that is used, and usually this means
     * fields of the wrong type (or that cannot be coerced into the correct type).
     * @return the flag value (default false)
     */
    boolean ignoreInvalidFields() default false;

    /**
     * Flag to indicate that when binding to this object unknown fields should be ignored.
     * An unknown field could be a sign of a mistake in the Properties.
     * @return the flag value (default true)
     */
    boolean ignoreUnknownFields() default true;

}

• 3. 在配置类中直接声明属性即可