Java 加载配置文件的方式

一 使用原生方式读取配置文件

1 文件系统加载

InputStream in = new FileInputStream("config.properties");		
Properties p = new Properties();
p.load(in);

2 类加载方式

A 与类同级目录

InputStream in = Main.class.getResourceAsStream("config.properties");

B 在类的下一级目录

InputStream in = 
Main.class.getResourceAsStream("resource/config.properties");

C 指定加载资源配置文件的classes相对路径

InputStream in = 
Main.class.getResourceAsStream("/test/resource/config.properties");

注意事项：如上以/开头的是指从根目录开始加载。

D 使用类加载器的方式

InputStream in = Main.class.getClassLoader().
getResourceAsStream("test/resource/config.properties");

E 资源配置文件在classes下

InputStream in = 
Main.class.getClassLoader().getResourceAsStream("config.properties");

二 使用apache提供的功能组件
参照网上相关资料
1 读取properties文件的方式
示例代码

import java.util.List;
import org.apache.commons.configuration.Configuration;
import org.apache.commons.configuration.ConfigurationException;
import org.apache.commons.configuration.PropertiesConfiguration;

public class PropertiesConfigurationDemo {

    public static void main(String[] args) throws ConfigurationException {

        Configuration config = new PropertiesConfiguration(PropertiesConfigurationDemo.class.getResource("system-config.properties"));
        String ip = config.getString("ip");       
        String[] colors = config.getStringArray("colors.pie"); 
        for (int i = 0; i < colors.length; i++) {
            System.out.println(colors[i]);
        }
             
        List<?> colorList = config.getList("colors.pie");
        for (int i = 0; i < colorList.size(); i++) {
            System.out.println(colorList.get(i));
        }
     }
}

配置文件代码：

ip=10.10.1.1
colors.pie = #FF0000, #00FF00, #0000FF

2 读取XML文件的方式

import java.util.List;
import org.apache.commons.configuration.Configuration;
import org.apache.commons.configuration.ConfigurationException;
import org.apache.commons.configuration.XMLConfiguration;

public class XMLConfigurationDemo {

    public static void main(String[] args) throws ConfigurationException {

        Configuration config = new XMLConfiguration(XMLConfigurationDemo.class
                .getResource("system-config.xml"));
        String ip = config.getString("ip");
        String account = config.getString("account");
        String password = config.getString("password");
        List<?> roles = config.getList("roles.role");
        System.out.println("IP: " + ip);
        System.out.println("Account: " + account);
        System.out.println("Password: " + password);        
        for (int i = 0; i < roles.size(); i++) {
            System.out.println("Role: " + roles.get(i));
        }       
    }
}

Xml文件代码：

<config>
    <ip>10.10.1.1</ip>
    <account>jini</account>
    <password>jakarta99</password>
    <roles>
        <role>admin</role>
        <role>manager</role>
        <role>user</role>
    </roles>
</config>

示例2

import org.apache.commons.configuration.Configuration;
import org.apache.commons.configuration.ConfigurationException;
import org.apache.commons.configuration.XMLConfiguration;
public class XmlConfigurationExample {
	public static void main(String[] args) throws Exception,
			ConfigurationException {
		String resource = "main/global.xml";
		Configuration config = new XMLConfiguration(resource);
		// 只有new一个XMLConfiguration的实例就可以了.
		List<?> startCriteria = config.getList("start-criteria.criteria");		
		for (int i = 0; i < startCriteria.size(); i++) {
			System.out.println("Role: " + startCriteria.get(i));
		}
		int horsepower = config.getInt("horsepower");
		System.out.println(horsepower);
	}
}

global.xml文件代码

<?xml version="1.0" encoding="ISO-8859-1" ?>
<engine-config>
	<start-criteria>
		<criteria>
			Temperature Above -10 Celsius 
        </criteria>
		<criteria>
			Fuel tank is not empty 
       </criteria>
	</start-criteria>
	<volume>4 Liters</volume>
	<horsepower>42</horsepower>
</engine-config>

示例3：混合读取二种文件

import java.util.List;
import org.apache.commons.configuration.CompositeConfiguration;
import org.apache.commons.configuration.ConfigurationException;
import org.apache.commons.configuration.PropertiesConfiguration;
import org.apache.commons.configuration.XMLConfiguration;

public class Test {
	
	public static void main(String[] args) throws ConfigurationException {
		CompositeConfiguration config = new CompositeConfiguration();
		config.addConfiguration(new PropertiesConfiguration(
		"main/global.properties"));
		config.addConfiguration(new XMLConfiguration("main/global.xml"));
		
		List<?> startCriteria = config.getList("start-criteria.criteria");
		int horsepower = config.getInt("horsepower");
		for (int i = 0; i < startCriteria.size(); i++) {
			System.out.println("Role: " + startCriteria.get(i));
		}
		System.out.println(horsepower);
		System.out.println("Speed: " + config.getFloat("speed"));
		System.out.println("Names: " + config.getString("name"));
	}
}

Xml如上所示，global.properties文件如下：
speed=50
name=Default User

示例4

import java.net.URL;
import java.util.List;
import org.apache.commons.configuration.Configuration;
import org.apache.commons.configuration.ConfigurationFactory;
public class PropertiesXmlConfigurationExample {
	
	public static void main(String[] args) throws Exception {			
		ConfigurationFactory factory = new ConfigurationFactory();
		URL configURL = PropertiesXmlConfigurationExample.class.getResource("additional-xml-configuration.xml");
		factory.setConfigurationURL(configURL);
		Configuration config = factory.getConfiguration();
		List<?> startCriteria = config.getList("start-criteria.criteria");
		for (int i = 0; i < startCriteria.size(); i++) {
			System.out.println("Role: " + startCriteria.get(i));
		}
		int horsepower = config.getInt("horsepower");
		System.out.println("Horsepower: " + horsepower);
		
		System.out.println("Speed: " + config.getFloat("speed"));
		System.out.println("Names: " + config.getString("name"));
		
	}
}

additional-xml-configuration.xml文件内容：

<?xml version="1.0" encoding="ISO-8859-1" ?> 
<configuration> 
<properties fileName="global.properties"/> 
<xml fileName="global.xml"/>
</configuration>

相关API说明：
# PropertiesConfiguration 从一个 property 文件中加载配置 .
# XMLConfiguration 从 XML 文件中加载配置信息 .
# XMLPropertyListConfiguration 也可以读取 XML 被 Mac OSX 使用变量 .
# JNDIConfiguration 利用 jndi 树的一个键值，可以返回一个值，这个值来作为配置信息
# BaseConfiguration 访问内存中的一个配置对象 .
# HierarchicalConfiguration 一个在内存中的配置对象，这个对象可以处理复杂的数据结构 .
# SystemConfiguration 一个利用系统属性的配置信息
# ConfigurationConverter 把 java.util.Properties 或者 org.apache.collections.commons.ExtendedProperties 转化为一个 Configuration 对象

参考资料：
common-configuration读取xml,properties文件
http://javamy.iteye.com/blog/252619
使用apache common configuration读取配置文件或修改配置文件
http://www.suneca.com/article.asp?id=9