Struts2自定义初始化及Properties文件操作

利用Struts框架开发java web项目，需要进行自己的初始化工作。这个过程常常需要操作配置文件Properties，而且要求在系统初始化的阶段完成。

首先，需要建立properties文件：conf.properties，文件保存于src目录下。然后需要对该文件进行操作：

 /*******************

 * read and write properties file
 * @author 60874
 *
 */
public class RWProp {

    private String propfile;

    protected String readProperty(String key) throws Exception {
        InputStream iStream = null;
        FileInputStream fis = null;
        try {
            Properties prop = new Properties();
            fis = new FileInputStream(propfile);
            iStream = new BufferedInputStream(fis);
            prop.load(iStream);
            return prop.getProperty(key);
        } catch (Exception e) {
            // TODO: handle exception
            throw e;
        } finally {
            if (fis != null) {
                fis.close();
            }
            if (iStream != null) {
                iStream.close();
            }
        }
    }

    @SuppressWarnings("unchecked")
    protected Map<String, String> readProperty() throws Exception{
        InputStream iStream = null;
        FileInputStream fis = null;
        try {
            Properties prop = new Properties();
            fis = new FileInputStream(propfile);
            iStream = new BufferedInputStream(fis);
            prop.load(iStream);
            Enumeration<String> en = (Enumeration<String>) prop.propertyNames();
            Map<String, String> propMap = new HashMap<String, String>();
            while (en.hasMoreElements()) {
                String key = (String) en.nextElement();
                String value = prop.getProperty(key);
                propMap.put(key, value);
            }
            return propMap;
        } catch (Exception e) {
            // TODO: handle exception
            throw e;
        }finally {
            if (fis != null) {
                fis.close();
            }
            if (iStream != null) {
                iStream.close();
            }
        }
    }

    protected Boolean writeProperties(String key, String value) throws Exception {
        if (key == null || key.trim().length() == 0) {
            throw new Exception("parameter: key can not be null!");
        }
        FileInputStream fis = null;
        OutputStream oStream = null;
        try {
            fis = new FileInputStream(propfile);
            Properties prop = new Properties();
            prop.load(fis);
            oStream = new FileOutputStream(propfile);
            prop.setProperty(key, value);
            prop.store(oStream, "Update " + key + " value");
            return true;
        } catch (Exception e) {
            // TODO: handle exception
            throw e;
        } finally {
            if (fis != null) {
                fis.close();
            }
            if (oStream != null) {
                oStream.close();
            }
        }
    }

    protected int writeProperties(Map<String, String> propMap) throws Exception {
        if (propMap == null || propMap.size() == 0) {
            throw new Exception("parameter: propMap can not be null!");
        }
        FileInputStream fis = null;
        OutputStream oStream = null;
        try {
            fis = new FileInputStream(propfile);
            Properties prop = new Properties();
            prop.load(fis);
            oStream = new FileOutputStream(propfile);
            int count = 0;
            Iterator<Entry<String, String>> iterator = propMap.entrySet()
.iterator();
            while (iterator.hasNext()) {
                Entry<String, String> entry = iterator.next();
                if (entry.getKey() != null && entry.getKey().length() > 0) {
                    prop.setProperty(entry.getKey(), entry.getValue());
                    prop.store(oStream, null);
                    count ++;
                }
            }
            return count;
        } catch (Exception e) {
            // TODO: handle exception
            throw e;
        } finally {
            if (fis != null) {
                fis.close();
            }
            if (oStream != null) {
                oStream.close();
            }
        }
    }

    protected String getPropfile() {
        return propfile;
    }

    protected void setPropfile(String propfile) {
        this.propfile = propfile;
    }

}

 该类可以读取、写入properties文件。这里的方法声明为protected，就是不希望外部的程序直接操作这些方法（尤其是修改配置文件的方法）。因为有些属性我们不希望外部应用程序直接修改。

于是，在此基础上，再封装一层，命名为Property。该类中对配置文件的各个项进行操作并对外提供接口。对于不希望外部修改的属性，其set方法置为private或protected。并在该类中创建init()方法和reload(), save()方法。

public static void init() {….}

public static void reload() {….}

public static void save() {….}

public static void save(String key, String value) {….} 

 ======================================

以上是操作配置文件的封装。OK, 现在我们需要在系统启动的时候自动加载配置文件的信息。编写一个类，实现ServletContextListener接口。

 public class InitSys implements ServletContextListener {

    private static Logger logger = Logger.getLogger(InitSys.class);

    public void contextDestroyed(ServletContextEvent sce) {
        // TODO Auto-generated method stub

    }

    public void contextInitialized(ServletContextEvent sce) {
        // TODO Auto-generated method stub
        logger.info("trying to initialize CMail >>>>>>");
        String propertyfile = sce.getServletContext().getRealPath(
                "/WEB-INF/classes/" + SParam.PROPERTY_FILE);
        Property.setPropfile(propertyfile);
        Property.init();
        logger.info("**********************");
        logger.info("CMAIL SYSTEM VERSION " + Property.getVersion());
        logger.info("Domain at: " + Property.getDomain());
        logger.info("**********************");
        logger.info("<<<<<< initialize CMail");
    }

}

 然后在web.xml配置文件中配置该类，使得系统初始化时自动加载它。

 <listener>

    <listener-class>com.csc.mail.jsh.config.inisys.InitSys</listener-class>
</listener>

 DONE！