java read the file using a relative path

Mar 29 posted in Java (RSS), comments.

Advertisements

1.java project environment, the use of java.io read the file using a relative path examples:

* Directory structure:
DecisionTree
| ___src
| ___com.decisiontree.SamplesReader.java
| ___resource
| ___train.txt, test.txt

* SamplesReader.java:

  String filepath="resource/train.txt";// Note the contents of the filepath;  
  File file=new File(filepath);
   ……

* We pay attention to filepath content, java.io default to the current user directory ( "user.dir") under, namely: Project root directory "D: \ DecisionTree", it is therefore at this time relative path (to user.dir Path-based path) to "resource / train.txt". This, JVM can be under the "user.dir" and "resource / train.txt" get the full path (ie, the absolute path) "D: \ DecisionTree \ resource \ train.txt", has never been found train.txt file.

* Note: Relative paths start at non-diagonal "/"; For example:
filepath = "resource / train.txt";
Rather than filepath = "/ resource / train.txt"; / / error!

2, javaEE the environment, the use of Classloader to use relative path to read xml example:

* Reads as follows:
java read xml file using a relative path:
A, xml file location for the general there are three:
1. Placed under WEB-INF;
2.xml files in the / WEB-INF/classes directory or classpath of the jar package;
3. Devoted to analysis of its java similar to a package, not necessarily the classpath;

B, corresponding to the two kinds of use relative paths to read method:

Method 1: (not verified)
Xml file in the WEB-INF directory, and then code:

InputStream is=getServletContext().getResourceAsStream( "/WEB-INF/xmlfile.xml" );

Method 2: The xml file in the / WEB-INF/classes directory or classpath of the jar package, you can use the static ClassLoader

Methods getSystemResourceAsStream (String s) to read;
Code:

String s_xmlpath="com/spf/web/ext/hotspot/hotspotxml/hotspot.xml";
InputStream in=ClassLoader.getSystemResourceAsStream(s_xmlpath);

Method 3: xml in the random path to a package:

String s_xmlpath="com/spf/web/ext/hotspot/hotspotxml/hotspot.xml";
ClassLoader classLoader=HotspotXmlParser.class.getClassLoader();
InputStream in=classLoader.getResourceAsStream(s_xmlpath);

Original Address: http://www.blogjava.net/flysky19/articles/93492.html