读取properties文件 并解析占位符(借用hibernate代码)

  把hibernate中读取properties文件的代码抽取出来了，直接贴代码：
  java:
 

  
package redolvePlaceHolder;

import java.io.IOException;
import java.io.InputStream;
import java.util.Iterator;
import java.util.Map;
import java.util.Properties;
import java.util.Map.Entry;

/**
 * 此类借用了hibernate读取properties文件的代码，
 * 可以解析占位符比如$
 * @author afei
 *
 */
public class TestMain {

	
	private static final String PLACEHOLDER_START = "${";

	private static Properties pro;
	
	public static void main(String[] args) {
		try {
			pro=buildProperty("afei.properties");
			resolvePlaceHolders(pro);
			printProperties(pro);
		} catch (IOException e) {
			e.printStackTrace();
		}
	}
	
	public static void printProperties(Properties p){
		Iterator it=p.entrySet().iterator();
		while(it.hasNext()){
			Entry ent=(Entry)it.next();
			System.out.println(ent.getKey()+" : "+ent.getValue());
		}
	}
	
	
	
	/**
	 * 解析占位符
	 * @param properties
	 */
	public static void resolvePlaceHolders(Properties properties) {
		Iterator itr = properties.entrySet().iterator();
		while ( itr.hasNext() ) {
			final Map.Entry entry = ( Map.Entry ) itr.next();
			final Object value = entry.getValue();
			if ( value != null && String.class.isInstance( value ) ) {
				final String resolved = resolvePlaceHolder( ( String ) value );
				if ( !value.equals( resolved ) ) {
					if ( resolved == null ) {
						itr.remove();
					}
					else {
						entry.setValue( resolved );
					}
				}
			}
		}
	}
	
	/**
	 * 解析占位符具体操作
	 * @param property
	 * @return
	 */
	public static String resolvePlaceHolder(String property) {
		if ( property.indexOf( PLACEHOLDER_START ) < 0 ) {
			return property;
		}
		StringBuffer buff = new StringBuffer();
		char[] chars = property.toCharArray();
		for ( int pos = 0; pos < chars.length; pos++ ) {
			if ( chars[pos] == '$' ) {
				// peek ahead
				if ( chars[pos+1] == '{' ) {
					// we have a placeholder, spin forward till we find the end
					String systemPropertyName = "";
					int x = pos + 2;
					for (  ; x < chars.length && chars[x] != '}'; x++ ) {
						systemPropertyName += chars[x];
						// if we reach the end of the string w/o finding the
						// matching end, that is an exception
						if ( x == chars.length - 1 ) {
							throw new IllegalArgumentException( "unmatched placeholder start [" + property + "]" );
						}
					}
					String systemProperty = extractFromSystem( systemPropertyName );
					buff.append( systemProperty == null ? "" : systemProperty );
					pos = x + 1;
					// make sure spinning forward did not put us past the end of the buffer...
					if ( pos >= chars.length ) {
						break;
					}
				}
			}
			buff.append( chars[pos] );
		}
		String rtn = buff.toString();
		return isEmpty( rtn ) ? null : rtn;
	}
	
	
	
	/**
	 * 构造properties文件
	 * @param path
	 * @throws IOException 
	 */
	public static Properties buildProperty(String path) throws IOException{
		InputStream is=getResourceAsStream("afei.properties");
		pro=new Properties();
		pro.load(is);
		return pro;
	}
	
	
	/**
	 * 构造properties文件的流
	 * @param resource
	 * @return
	 */
	public static InputStream getResourceAsStream(String resource) {
		String stripped = resource.startsWith("/") ?
				resource.substring(1) : resource;

		InputStream stream = null;
		ClassLoader classLoader = Thread.currentThread().getContextClassLoader();
		if (classLoader!=null) {
			stream = classLoader.getResourceAsStream( stripped );
		}
		if ( stream == null ) {
			stream = TestMain.class.getResourceAsStream( resource );
		}
		if ( stream == null ) {
			stream = TestMain.class.getClassLoader().getResourceAsStream( stripped );
		}
		if ( stream == null ) {
			throw new RuntimeException( resource + " not found" );
		}
		return stream;
	}
	
	
	/**
	 * 获得系统属性 当然 你可以选择从别的地方获取值
	 * @param systemPropertyName
	 * @return
	 */
	private static String extractFromSystem(String systemPropertyName) {
		try {
			return System.getProperty( systemPropertyName );
		}
		catch( Throwable t ) {
			return null;
		}
	}
	
	/**
	 * 判断字符串的空(null或者.length=0)
	 * @param string
	 * @return
	 */
	public static boolean isEmpty(String string) {
		return string == null || string.length() == 0;
	}

}


  

afei.properties文件：

javaeye.url=www.iteye.com
javaeye.homepage=duyunfei.iteye.com
javaeye.username=${user.name}
javaeye.password=123456

home=${user.home}
os=${os.name}
userdir=${user.dir}
javaversion=${java.version} 
javahome=${java.home}

fileseparator=${file.separator}
pathseparator=${path.separator}
lineseparator=${line.separator}


 

评论

2 楼 AngelAndAngel 2012-08-31  

landy8530 写道

你好，请问一下“把hibernate中读取properties文件的代码抽取出来了，直接贴代码： ”这个hibernate的源码，是在哪个jar包中，源码有吗？类路径是什么？谢谢！

不好意思，这个太久了，你搜一下吧。功能就这么一段代码，copy就可用。

1 楼 landy8530 2012-08-31  

你好，请问一下“把hibernate中读取properties文件的代码抽取出来了，直接贴代码： ”这个hibernate的源码，是在哪个jar包中，源码有吗？类路径是什么？谢谢！