使用java系统属性user.dir读取配置文件

适用于windows和linux服务器读取配置文件

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

import org.apache.log4j.Logger;

public final class PropertyUtil {
private static Logger LOG = Logger.getLogger(PropertyUtil.class);

// 配置文件
private static Properties demoProps = new Properties();
// 单例模式
private static PropertyUtil instance = null;

private PropertyUtil() {
    // user.dir为应用目录
    String filePath = System.getProperty("user.dir") + File.separator
            + "WEB-INF" + File.separator + "classes" + File.separator
            + "resources" + File.separator;
    LOG.info(filePath);
    try {
        File demoFile = new File(filePath + "demo.properties");

        if (httpFile.exists()) {
            demoProps.load(new FileInputStream(filePath
                    + "demo.properties"));
        }

    } catch (IOException e) {
        LOG.info("The Exception occured.", e);
    }
}

public synchronized static PropertyUtil getInstance() {
    if (null == instance) {
        instance = new PropertyUtil();
    }

    return instance;
}

/**
 * 获取参数值
 * 
 * @param key
 *            properites的key值
 * @param defValue
 *            默认值
 * @return
 */
public String getValues(String key, String defValue) {
    String rtValue = null;

    if (null == key) {
        LOG.error("key is null");
    } else {
        rtValue = getPropertiesValue(key);
    }

    if (null == rtValue) {
        LOG.warn("PropertyUtil.getValues return null, key is " + key);
        rtValue = defValue;
    }

    LOG.info("PropertyUtil.getValues: key is " + key + "; Value is "
            + rtValue);

    return rtValue;
}

/**
 * 根据key值获取server.properties的值
 * 
 * @param key
 * @return
 */
private String getPropertiesValue(String key) {
    String rtValue = demoProps.getProperty(key);

    return rtValue;
}

}