动手写web框架(1): 加载配置项

定义框架所需的配置项 smart.properties

在src/main/resources目录下创建名为smart.properties的文件。

jdbc.driver=com.mysql.jdbc.Driver
jdbc.url=jdbc:mysql://localhost:3306/test
jdbc.username=root
jdbc.password=root

# 应用基础包名
app.base_package=com.roger.demo
# 应用jsp路径
app.jsp_path=/WEB-INF/view
# 应用静态资源路径
app.asset_path=/asset/

加载配置项

ConfigHelper

package org.smart4j.framework.helper;

import org.smart4j.framework.util.ConfigConstant;
import org.smart4j.framework.util.PropsUtil;

import java.util.Properties;

/**
 * Created by Roger on 2016/11/24.
 */
public class ConfigHelper {

    private static final Properties CONFIG_PROPS = PropsUtil.loadProps(ConfigConstant.CONFIG_FILE);

    /**
     * 获取JDBC驱动配置
     * @return
     */
    public static String getJdbcDriver(){
        return PropsUtil.getString(CONFIG_PROPS, ConfigConstant.JDBC_DRIVER);
    }

    /**
     * 获取JDBC URL
     * @return
     */
    public static String getJdbcUrl(){
        return PropsUtil.getString(CONFIG_PROPS, ConfigConstant.JDBC_URL);
    }

    /**
     * 获取JDBC 用户名
     * @return
     */
    public static String getJdbcUsername(){
        return PropsUtil.getString(CONFIG_PROPS, ConfigConstant.JDBC_USERNAME);
    }

    /**
     * 获取JDBC 密码
     * @return
     */
    public static String getJdbcPassword(){
        return PropsUtil.getString(CONFIG_PROPS, ConfigConstant.JDBC_PASSWORD);
    }

    /**
     * 获取应用基础包名
     * @return
     */
    public static String getAppBasePackage(){
        return PropsUtil.getString(CONFIG_PROPS, ConfigConstant.APP_BASE_PACKAGE);
    }

    /**
     * 获取应用jsp路径
     * @return
     */
    public static String getAppJspPath(){
        return PropsUtil.getString(CONFIG_PROPS, ConfigConstant.APP_JSP_PATH, "/WEB-INF/view/");
    }

    /**
     * 获取应用静态资源路径
     * @return
     */
    public static String getAppAssetPath(){
        return PropsUtil.getString(CONFIG_PROPS, ConfigConstant.APP_ASSET_PATH, "/asset/");
    }
}

ConfigConstant

package org.smart4j.framework.util;

/**
 * 提供相关配置项常量
 * Created by Roger on 2016/11/23.
 */
public interface ConfigConstant {

    String CONFIG_FILE = "smart.properties";

    String JDBC_DRIVER = "jdbc.driver";
    String JDBC_URL = "jdbc.url";
    String JDBC_USERNAME = "jdbc.username";
    String JDBC_PASSWORD = "jdbc.password";

    String APP_BASE_PACKAGE = "app.base_package";
    String APP_JSP_PATH = "app.jsp_path";
    String APP_ASSET_PATH = "app.asset_path";
}

PropsUtil

package org.smart4j.framework.util;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

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

/**
 * Created by Roger on 2016/11/23.
 */
public final class PropsUtil {

    private static final Logger LOGGER = LoggerFactory.getLogger(PropsUtil.class);

    /**
     * 加载属性文件
     *
     * @param fileName
     * @return
     * @throws FileNotFoundException
     */
    public static Properties loadProps(String fileName) {
        Properties props = null;
        InputStream is = null;
        try {
            is = Thread.currentThread().getContextClassLoader().getResourceAsStream(fileName);
            if (is == null) {
                throw new FileNotFoundException(fileName + " file is not found");
            }
            props = new Properties();

            props.load(is);
        } catch (IOException e) {
            LOGGER.error("load properties '?' file failure", fileName, e);
        } finally {
            if (is != null) {
                try {
                    is.close();
                } catch (IOException e) {
                    LOGGER.error("close input stream failure", e);
                }
            }
        }
        return props;
    }

    /**
     * 获取String类型属性(默认值为空字符串)
     *
     * @param props
     * @param key
     * @return
     */
    public static String getString(Properties props, String key) {
        return getString(props, key, "");
    }

    /**
     * 获取String类型属性(可以设置默认值)
     *
     * @param props
     * @param key
     * @param defaultValue
     * @return
     */
    public static String getString(Properties props, String key, String defaultValue) {
        String value = defaultValue;
        if (props.containsKey(key)) {
            value = props.getProperty(key);
        }
        return value;
    }

    /**
     * 获取int类型属性(默认值为0)
     *
     * @param props
     * @param key
     * @return
     */
    public static int getInt(Properties props, String key) {
        return getInt(props, key, 0);
    }

    /**
     * 获取int类型属性(可以设置默认值)
     *
     * @param props
     * @param key
     * @param defaultValue
     * @return
     */
    public static int getInt(Properties props, String key, int defaultValue) {
        int value = defaultValue;
        if (props.containsKey(key)) {
            value = Integer.parseInt(props.getProperty(key));
        }
        return value;
    }

    /**
     * 获取boolean类型属性(默认值为false)
     *
     * @param props
     * @param key
     * @return
     */
    public static boolean getBoolean(Properties props, String key) {
        return getBoolean(props, key, false);
    }

    /**
     * 获取boolean类型属性(可以设置默认值)
     *
     * @param props
     * @param key
     * @param defaultValue
     * @return
     */
    public static boolean getBoolean(Properties props, String key, boolean defaultValue) {
        boolean value = defaultValue;
        if (props.containsKey(key)) {
            value = Boolean.parseBoolean(props.getProperty(key));
        }
        return value;
    }
}