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！