util:properties

示例

<util:properties id="db" location="classpath:db.properties" />

全部属性

功能概述

Loads a Properties instance from the resource location specified by the '

<code>location</code>

' attribute.

属性详解

id

#{A['B']}

A means util:properties id

B means properties key

location

The location of the properties file, as a Spring resource location: a URL, a "classpath:" pseudo URL, or a relative file path. Multiple locations may be specified, separated by commas.

ignore-resource-not-found

Specifies if failure to find the property resource location should be ignored. Default is "false", meaning that if there is no file in the location specified an exception will be raised at runtime.

local-override

Specifies whether local properties override properties from files. Default is "false": properties from files override local defaults. If set to "true", local properties will override defaults from files.

scope

The scope of this collection bean: typically "singleton" (one shared instance, which will be returned by all calls to getBean with the given id), or "prototype" (independent instance resulting from each call to getBean). Default is "singleton". Further scopes, such as "request" or "session", might be supported by extended bean factories (e.g. in a web environment).

value-type

The default Java type for nested values. Must be a fully qualified class name.

源码

org.springframework.beans.factory.config.PropertiesFactoryBean extends PropertiesLoaderSupport

/*
 * Copyright 2002-2013 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.beans.factory.config;

import java.io.IOException;
import java.util.Properties;

import org.springframework.beans.factory.FactoryBean;
import org.springframework.beans.factory.InitializingBean;
import org.springframework.core.io.support.PropertiesLoaderSupport;

/**
 * Allows for making a properties file from a classpath location available
 * as Properties instance in a bean factory. Can be used to populate
 * any bean property of type Properties via a bean reference.
 *
 * <p>Supports loading from a properties file and/or setting local properties
 * on this FactoryBean. The created Properties instance will be merged from
 * loaded and local values. If neither a location nor local properties are set,
 * an exception will be thrown on initialization.
 *
 * <p>Can create a singleton or a new object on each request.
 * Default is a singleton.
 *
 * @author Juergen Hoeller
 * @see #setLocation
 * @see #setProperties
 * @see #setLocalOverride
 * @see java.util.Properties
 */
public class PropertiesFactoryBean extends PropertiesLoaderSupport
        implements FactoryBean<Properties>, InitializingBean {

    private boolean singleton = true;

    private Properties singletonInstance;

    /**
     * Set whether a shared 'singleton' Properties instance should be
     * created, or rather a new Properties instance on each request.
     * <p>Default is "true" (a shared singleton).
     */
    public final void setSingleton(boolean singleton) {
        this.singleton = singleton;
    }

    @Override
    public final boolean isSingleton() {
        return this.singleton;
    }

    @Override
    public final void afterPropertiesSet() throws IOException {
        if (this.singleton) {
            this.singletonInstance = createProperties();
        }
    }

    @Override
    public final Properties getObject() throws IOException {
        if (this.singleton) {
            return this.singletonInstance;
        }
        else {
            return createProperties();
        }
    }

    @Override
    public Class<Properties> getObjectType() {
        return Properties.class;
    }

    /**
     * Template method that subclasses may override to construct the object
     * returned by this factory. The default implementation returns the
     * plain merged Properties instance.
     * <p>Invoked on initialization of this FactoryBean in case of a
     * shared singleton; else, on each {@link #getObject()} call.
     * @return the object returned by this factory
     * @throws IOException if an exception occured during properties loading
     * @see #mergeProperties()
     */
    protected Properties createProperties() throws IOException {
        return mergeProperties();
    }

}

/*
 * Copyright 2002-2014 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.core.io.support;

import java.io.IOException;
import java.util.Properties;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import org.springframework.core.io.Resource;
import org.springframework.util.CollectionUtils;
import org.springframework.util.DefaultPropertiesPersister;
import org.springframework.util.PropertiesPersister;

/**
 * Base class for JavaBean-style components that need to load properties
 * from one or more resources. Supports local properties as well, with
 * configurable overriding.
 *
 * @author Juergen Hoeller
 * @since 1.2.2
 */
public abstract class PropertiesLoaderSupport {

    /** Logger available to subclasses */
    protected final Log logger = LogFactory.getLog(getClass());

    protected Properties[] localProperties;

    protected boolean localOverride = false;

    private Resource[] locations;

    private boolean ignoreResourceNotFound = false;

    private String fileEncoding;

    private PropertiesPersister propertiesPersister = new DefaultPropertiesPersister();

    /**
     * Set local properties, e.g. via the "props" tag in XML bean definitions.
     * These can be considered defaults, to be overridden by properties
     * loaded from files.
     */
    public void setProperties(Properties properties) {
        this.localProperties = new Properties[] {properties};
    }

    /**
     * Set local properties, e.g. via the "props" tag in XML bean definitions,
     * allowing for merging multiple properties sets into one.
     */
    public void setPropertiesArray(Properties... propertiesArray) {
        this.localProperties = propertiesArray;
    }

    /**
     * Set a location of a properties file to be loaded.
     * <p>Can point to a classic properties file or to an XML file
     * that follows JDK 1.5's properties XML format.
     */
    public void setLocation(Resource location) {
        this.locations = new Resource[] {location};
    }

    /**
     * Set locations of properties files to be loaded.
     * <p>Can point to classic properties files or to XML files
     * that follow JDK 1.5's properties XML format.
     * <p>Note: Properties defined in later files will override
     * properties defined earlier files, in case of overlapping keys.
     * Hence, make sure that the most specific files are the last
     * ones in the given list of locations.
     */
    public void setLocations(Resource... locations) {
        this.locations = locations;
    }

    /**
     * Set whether local properties override properties from files.
     * <p>Default is "false": Properties from files override local defaults.
     * Can be switched to "true" to let local properties override defaults
     * from files.
     */
    public void setLocalOverride(boolean localOverride) {
        this.localOverride = localOverride;
    }

    /**
     * Set if failure to find the property resource should be ignored.
     * <p>"true" is appropriate if the properties file is completely optional.
     * Default is "false".
     */
    public void setIgnoreResourceNotFound(boolean ignoreResourceNotFound) {
        this.ignoreResourceNotFound = ignoreResourceNotFound;
    }

    /**
     * Set the encoding to use for parsing properties files.
     * <p>Default is none, using the {@code java.util.Properties}
     * default encoding.
     * <p>Only applies to classic properties files, not to XML files.
     * @see org.springframework.util.PropertiesPersister#load
     */
    public void setFileEncoding(String encoding) {
        this.fileEncoding = encoding;
    }

    /**
     * Set the PropertiesPersister to use for parsing properties files.
     * The default is DefaultPropertiesPersister.
     * @see org.springframework.util.DefaultPropertiesPersister
     */
    public void setPropertiesPersister(PropertiesPersister propertiesPersister) {
        this.propertiesPersister =
                (propertiesPersister != null ? propertiesPersister : new DefaultPropertiesPersister());
    }

    /**
     * Return a merged Properties instance containing both the
     * loaded properties and properties set on this FactoryBean.
     */
    protected Properties mergeProperties() throws IOException {
        Properties result = new Properties();

        if (this.localOverride) {
            // Load properties from file upfront, to let local properties override.
            loadProperties(result);
        }

        if (this.localProperties != null) {
            for (Properties localProp : this.localProperties) {
                CollectionUtils.mergePropertiesIntoMap(localProp, result);
            }
        }

        if (!this.localOverride) {
            // Load properties from file afterwards, to let those properties override.
            loadProperties(result);
        }

        return result;
    }

    /**
     * Load properties into the given instance.
     * @param props the Properties instance to load into
     * @throws IOException in case of I/O errors
     * @see #setLocations
     */
    protected void loadProperties(Properties props) throws IOException {
        if (this.locations != null) {
            for (Resource location : this.locations) {
                if (logger.isInfoEnabled()) {
                    logger.info("Loading properties file from " + location);
                }
                try {
                    PropertiesLoaderUtils.fillProperties(
                            props, new EncodedResource(location, this.fileEncoding), this.propertiesPersister);
                }
                catch (IOException ex) {
                    if (this.ignoreResourceNotFound) {
                        if (logger.isWarnEnabled()) {
                            logger.warn("Could not load properties from " + location + ": " + ex.getMessage());
                        }
                    }
                    else {
                        throw ex;
                    }
                }
            }
        }
    }

}

应用

spring bean 配置文件中

<util:properties id="config" location="classpath:conf/config.properties"></util:properties>

java 常量文件中

package cn.zno.common.constants;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;

@Component
public class ApplicationConstants {

    public static String SWAGGER_PATH;

    @Autowired(required = true)
    public void setSWAGGER_PATH(@Value("#{config['swagger.path']}") String SWAGGER_PATH) {
        ApplicationConstants.SWAGGER_PATH = SWAGGER_PATH;
    }
}

高级用法

util: 命名空间是通过工厂bean 返回 java.util 包下的实例，交给spring 工厂管理

理解了原理就可以实现 java-based 配置

import java.io.IOException;
import java.util.Properties;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.Bean;
import org.springframework.core.io.ClassPathResource;
import org.springframework.stereotype.Component;

/**
 * 说明：WeixinProperties
 * 创建人：zxg
 * 创建时间：2018-05-23
 */
@Component
public class WeixinProperties {

    public static String appsecret;

    public static String appid;

    public static String urlCheckcode;

    @Autowired
    public void setAppsecret(@Value("#{weixin['appsecret']}") String appsecret) {
        WeixinProperties.appsecret = appsecret;
    }

    @Autowired
    public void setAppid(@Value("#{weixin['appid']}") String appid) {
        WeixinProperties.appid = appid;
    }

    @Autowired
    public void setUrlCheckcode(@Value("#{weixin['url.checkcode']}") String urlCheckcode) {
        WeixinProperties.urlCheckcode = urlCheckcode;
    }

    @Bean("weixin")
    public Properties getProperties() {
        Properties properties = new Properties();
        try {
            properties.load(new ClassPathResource("env/weixin.properties").getInputStream());
        } catch (IOException e) {
            throw new RuntimeException("读取属性文件", e);
        }
        return properties;
    }
}

此文件可自动生成

//TODO 类的加载优先级需要调高