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2016-07-03

Java 读取 Properties 和 Yaml Properties

Java 可以使用 PropertiesConfiguration 来读取 properties 属性文件，Spring 4.3 后还支持了 Yaml 格式的属性文件

  • PropertiesConfiguration: 读取时可以自动进行类型转换，可以给定默认值

  • Yaml 格式的属性文件: 可以使用树形结构，方便分组，支持中文，比 .properties 属性文件更灵活，但是以普通的 java.util.Properties 来读取:

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    # 1. 配置分组
    jdbc:
        driverClassName:        com.mysql.jdbc.Driver    a     # 2. 前后空格会被自动去掉，注释不会被读取
        url: jdbc:mysql://localhost:3306/test?useUnicode=true&characterEncoding=UTF-8
        username: root
        password: 密码 # 3. 支持中文
    urls:
        - http://127.0.0.1 # 4. 定义数组
        - http://localhost

Gradle 依赖

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compile 'org.springframework:spring-context:4.3.0.RELEASE'
compile 'org.yaml:snakeyaml:1.17'
compile 'commons-configuration:commons-configuration:1.10'

testCompile 'org.springframework:spring-test:4.3.0.RELEASE'
testCompile 'junit:junit:4.12'

属性文件

config.properties

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username=Dr. Alice
age=22

# 存储试卷文件的目录
papersDirectory=/Users/Biao/Documents/套卷/papers

config.yml

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#mysql
mysql:
    jdbc:
        url: jdbc:mysql://localhost:3306
        dirverClass: com.mysql.jdbc.Driver
        username: root
        password: root
username: Dr. Alice

Spring Bean 配置文件

spring-beans-config.xml

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<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
       http://www.springframework.org/schema/beans/spring-beans.xsd">
    <bean id="yamlProperties" class="org.springframework.beans.factory.config.YamlPropertiesFactoryBean">
        <property name="resources">
            <list>
                <value>classpath:config.yml</value>
            </list>
        </property>
    </bean>

    <bean id="propertiesConfig" class="org.apache.commons.configuration.PropertiesConfiguration" init-method="load">
        <property name="encoding" value="UTF-8"/>
        <property name="URL" value="classpath:/config.properties"/>
    </bean>
</beans>

propertiesConfig 的 encoding 设置为 UTF-8，则 properties 文件里就可以用中文了

测试案例

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import org.apache.commons.configuration.PropertiesConfiguration;
import org.junit.runner.RunWith;
import org.junit.Test;
import org.springframework.test.context.ContextConfiguration;
import org.springframework.test.context.junit4.SpringRunner;

import javax.annotation.Resource;
import java.util.Properties;

@RunWith(SpringRunner.class)
@ContextConfiguration({"classpath:spring-beans-config.xml"})
public class TestYamlPropertiesAndPropertiesConfig {
    @Resource(name = "yamlProperties")
    private Properties yamlProperties;

    @Resource(name = "propertiesConfig")
    private PropertiesConfiguration propertiesConfig;

    @Test
    public void testYamlProperties() {
        System.out.println(yamlProperties.getProperty("mysql.jdbc.url"));
        System.out.println(yamlProperties.getProperty("username"));
    }

    @Test
    public void testPropertiesConfig() {
        System.out.println(propertiesConfig.getString("username"));
        System.out.println(propertiesConfig.getInteger("age", 0));
    }
}

输出:

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Dr. Alice
22
jdbc:mysql://localhost:3306
Dr. Alice