//文件：PropertyManager.java
//这个类其实没什么用了，可以去掉，但需要去掉前面几个类中对这个类的引用。
package com.qingtuo.db.pool;
import java.util.*;
http://www.gaodaima.com/41653.html一个连接池的例子（来自JIVE）（6）
import java.io.*;
/**
* Manages properties for the entire Jive system. Properties are merely
* pieces of information that need to be saved in between server restarts.
* <p>
* At the moment, properties are stored in a Java Properties file. In a version
* of Jive coming soon, the properties file format will move to xml. XML
* properties will allow hierarchical property structures which may mean the
* API of this class will have to change.
* <p>
* Jive properties are only meant to be set and retrevied by core Jive classes.
* Therefore, skin writers should probably ignore this class.
* <p>
* This class is implemented as a singleton since many classloaders seem to
* take issue with doing classpath resource loading from a static context.
*/
public class PropertyManager {
private static PropertyManager manager = null;
private static Object managerLock = new Object();
private static String propsName = "/pcc_2000.properties";
/**
* Returns a Jive property
*
* @param name the name of the property to return.
* @returns the property value specified by name.
*/
public static String getProperty(String name) {
if (manager == null) {
synchronized(managerLock) {
if (manager == null) {
String sysname=System.getProperty("os.name").toUpperCase();
if(sysname.indexOf("WIN")!=-1){
propsName=propsName2000;
}
else{
propsName=propsNamelinux;
}
manager = new PropertyManager(propsName);
}
}
}
return manager.getProp(name);
}
/**
* Sets a Jive property.
*
* @param name the name of the property being set.
* @param value the value of the property being set.
*/
public static void setProperty(String name, String value) {
if (manager == null) {
synchronized(managerLock) {
if (manager == null) {
manager = new PropertyManager(propsName);
}
}
}
manager.setProp(name, value);
}
/**
* Returns true if the properties are readable. This method is mainly
* valuable at setup time to ensure that the properties file is setup
* correctly.
*/
public static boolean propertyFileIsReadable() {
if (manager == null) {
synchronized(managerLock) {
if (manager == null) {
manager = new PropertyManager(propsName);
}
}
}
return manager.propFileIsReadable();
}
/**
* Returns true if the properties are writable. This method is mainly
* valuable at setup time to ensure that the properties file is setup
* correctly.
*/
public static boolean propertyFileIsWritable() {
if (manager == null) {
synchronized(managerLock) {
if (manager == null) {
manager = new PropertyManager(propsName);
}
}
}
return manager.propFileIsWritable();
}
/**
* Returns true if the jive.properties file exists where the path property
* purports that it does.
*/
public static boolean propertyFileExists() {
if (manager == null) {
synchronized(managerLock) {
if (manager == null) {
manager = new PropertyManager(propsName);
}
}
}
return manager.propFileExists();
}
private Properties properties = null;
private Object propertiesLock = new Object();
private String resourceURI;
/**
* Singleton access only.
*/
private PropertyManager(String resourceURI) {
this.resourceURI = resourceURI;
}
/**
* Gets a Jive property. Jive properties are stored in jive.properties.
* The properties file should be accesible from the classpath. Additionally,
* it should have a path field that gives the full path to where the
* file is located. Getting properties is a fast operation.
*/
public String getProp(String name) {
//If properties aren’t loaded yet. We also need to make this thread
//safe, so synchronize…
if (properties == null) {
synchronized(propertiesLock) {
//Need an additional check
if (properties == null) {
loadProps();
}
}
}
return properties.getProperty(name);
}
/**
* Sets a Jive property. Because the properties must be saved to disk
* every time a property is set, property setting is relatively slow.
*/
public void setProp(String name, String value) {
//Only one thread should be writing to the file system at once.
synchronized (propertiesLock) {
//Create the properties object if necessary.
if (properties == null) {
loadProps();
}
properties.setProperty(name, value);
//Now, save the properties to disk. In order for this to work, the user
//needs to have set the path field in the properties file. Trim
//the String to make sure there are no extra spaces.
String path = properties.getProperty("path").trim();
OutputStream out = null;
try {
out = new FileOutputStream(path);
properties.store(out, "jive.properties — " + (new java.util.Date()));
}
catch (Exception ioe) {
System.err.println("There was an error writing jive.properties to " + path + ". " +
"Ensure that the path exists and that the Jive process has permission " +
"to write to it — " + ioe);
ioe.printStackTrace();
}
finally {
try {
out.close();
} catch (Exception e) { }
}
}
}
/**
* Loads Jive properties from the disk.
*/
private void loadProps() {
properties = new Properties();
InputStream in = null;
try {
in = getClass().getResourceAsStream(resourceURI);
properties.load(in);
}
catch (IOException ioe) {
System.err.println("Error reading Pcc properties" + ioe);
ioe.printStackTrace();
}
finally {
try {
in.close();
} catch (Exception e) { }
}
}
/**
* Returns true if the properties are readable. This method is mainly
* valuable at setup time to ensure that the properties file is setup
* correctly.
*/
public boolean propFileIsReadable() {
try {
InputStream in = getClass().getResourceAsStream(resourceURI);
return true;
}
catch (Exception e) {
return false;
}
}
/**
* Returns true if the jive.properties file exists where the path property
* purports that it does.
*/
public boolean propFileExists() {
String path = getProp("path");
File file = new File(path);
if (file.isFile()) {
return true;
}
else {
return false;
}
}
/**
* Returns true if the properties are writable. This method is mainly
* valuable at setup time to ensure that the properties file is setup
* correctly.
*/
public boolean propFileIsWritable() {
String path = getProp("path");
File file = new File(path);
if (file.isFile()) {
//See if we can write to the file
if (file.canWrite()) {
return true;
}
else {
return false;
}
}
else {
return false;
}
}
private static String propsName2000 = "/pcc_2000.properties";
private static String propsNameLinux = "/pcc_linux.properties";
}
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