propertygroups.java

java xml开发指南（初学者推荐）Java Xml 编程指南书籍源码

package MyNa.utils;

import java.util.*;


public class PropertyGroups extends Hashtable {

/*
 represent a file from the classpath, such as 
  C:\JRun\jsm-default\classes\tst.properties
which we load via   
  load("\tst.properties")
as a group of Properties in a hashtable; thus
   alpha_zip=1111
   beta_zip=2222
   gamma_zip=3333
   alpha_zap=uggle
   wurple=wing
   beta_zap=wuggle
   zurple=zing

becomes a PropertyGroups with 
  Enumeration propertyKeys()=[alpha,beta,gamma]
  Enumeration simpleKeys()=[wurple,zurple]
  Properties getProperties("alpha") = {zip=1111,zap=uggle}
  String getProperty("wurple")=wing.
  String getProperty("alpha","bibble")=bibble
  
It is an error to define a key both as a group name and a property:
  alpha=stringval
would be an error; it would conflict with alpha_zip or alpha_zap.
it is not an error to ask for a property whose name is a group name,
but the answer is null.
  
*/

private Properties props=null; 
private String fileName=null; 
Logger lg;
int simpleKeys;
int compoundKeys;

public PropertyGroups(){
  props=new Properties(); 
  lg=new Logger();
  simpleKeys=0;
  compoundKeys=0;
}
   

public PropertyGroups(String name)throws Exception{
  this();
  load(name);
}

public void load(String name)throws Exception{fileName=name; load();}

public void load()throws Exception{
  java.io.InputStream is=getClass().getResourceAsStream(fileName);
  if(null==is) throw
     new Exception("PropertyGroups.load: can't get resource "+fileName);
  props.load(is);
  is.close();
  Enumeration keys=props.keys();
  while(keys.hasMoreElements()){
    String key=(String)keys.nextElement();
    int sloc;
    if(0>(sloc=key.indexOf('_'))){
       simpleKeys++;
       put(key,props.get(key));
       }
    else{
      String key1=key.substring(0,sloc);
      String key2=key.substring(1+sloc);
      Properties subprops=(Properties)get(key1);
      if(null==subprops){
          compoundKeys++;
          put(key1,subprops=new Properties());
          }
      subprops.put(key2,props.get(key));
      }
    }
}

public String getProperty(String key){
  Object ob=get(key);
  if(ob instanceof String)return (String)ob;
  return null;
}
public String getProperty(String key,String dflt){
  if(null==key)return dflt;
  String p=getProperty(key);
  return p==null?dflt:p;
}
public Properties getProperties(String key){
  if(null==key){lg.logIt("getProperties null"); return null;}
  Object ob=get(key);
  if(ob instanceof Properties)return (Properties)ob;
  return null;
}
Enumeration propertyKeys(){return new PropertyKeysEnum();}
Enumeration simpleKeys(){return new SimpleKeysEnum();}

private void keyVal(StringBuffer sB,Object key){
  String k=(String)key;
  sB.append(k); sB.append("=");
  sB.append(get(key).toString());
}
 public synchronized String toString(){
  StringBuffer sB=new StringBuffer();
  Enumeration pk=propertyKeys();
  if(pk.hasMoreElements())keyVal(sB,pk.nextElement());
  while(pk.hasMoreElements()){
    sB.append(", ");
    keyVal(sB,pk.nextElement());
    }
  Enumeration sk=simpleKeys();
  if(sk.hasMoreElements())keyVal(sB,sk.nextElement());
  while(sk.hasMoreElements()){
    sB.append(", ");
    keyVal(sB,sk.nextElement());
    }
  return sB.toString();
}


class PropertyKeysEnum implements Enumeration{
  int howMany; Enumeration baseEnum;
public PropertyKeysEnum(){
  howMany=compoundKeys;
  baseEnum=keys();
}
public boolean hasMoreElements(){return howMany>0;}
public Object nextElement(){
  Object ob;
  while(baseEnum.hasMoreElements()){
    Object k=baseEnum.nextElement();
    Object v=get(k);
    if(v instanceof Properties){
      howMany--;
      return k;
      }
    }
  howMany=0;
  return null;
}

} // end of PropertyKeysEnum inner class     

class SimpleKeysEnum implements Enumeration{
  int howMany; Enumeration baseEnum;
public SimpleKeysEnum(){
  howMany=simpleKeys;
  baseEnum=keys();
}
public boolean hasMoreElements(){return howMany>0;}
public Object nextElement(){
  Object ob;
  while(baseEnum.hasMoreElements()){
    Object k=baseEnum.nextElement();
    Object v=get(k);
    if(v instanceof String){
      howMany--;
      return k;
      }
    }
  howMany=0;
  return null;
}

} // end of SimpleKeysEnum inner class     

}