java 读取文件的路径

1. 通用定位到用户目录下：

　　  String userDir = System.getProperty("user.dir");

2. web项目定位到WEB-INF/class 目录下：

String userDir = ClassLoader.getSystemClassLoader().getResource("").getPath();

3. 在JSP 中获取路径

　　a. 得到包含工程名的当前页面全路径：request.getRequestURI() ;

　　b. 得到工程名：request.getContextPath() ;

　　c.  得到当前页面所在目录下全名称：request.getServletPath() ;

　　d. 得到页面所在服务器的全路径：application.getRealPath("页面.jsp") ;

4. 在Servlet中取得路径

　　a. 得到工程目录：request.getSession().getServletContext().getRealPath("");

　　b. 得到地址栏地址：request.getRequestURL() ;

　　d. 得到相对地址：request.getRequestURI() ;

5. 附两个读取文件的方式

　　a.  需要打包 成jar，读取指定文件　　　

 package net.sf.jtmt.tokenizers;

 import java.io.BufferedReader;
 import java.io.IOException;
 import java.io.InputStreamReader;
 import java.net.URL;

 public class FileReader {
     public static String read(String fileName) {
         StringBuffer sb = new StringBuffer();
         URL url = null;
         BufferedReader br = null;
         try {
             url = FileReader.class.getResource(fileName);
             br = new BufferedReader(new InputStreamReader(url.openStream(),
                     "UTF-8"));
             String str;

             while ((str = br.readLine()) != null) {
                 sb.append(str+"\n");
             }
         } catch (Exception ex) {
             ex.printStackTrace();
         } finally {
             try {
                 if (br != null)
                     br.close();
             } catch (IOException e) {
                 // TODO Auto-generated catch block
                 e.printStackTrace();
             }

         }
         return sb.toString();
     }
 }

FileReader

 package wisers.samza.report.util;

 import java.io.File;
 import java.io.IOException;
 import org.apache.commons.io.FileUtils;

 public class FileReaderTest {

     public static void main(String[] args) {
         String fileStr = "";
         try {
             fileStr = FileUtils.readFileToString(new File(
                     "src/main/resources/stopwords.txt"), "UTF-8");
         } catch (IOException e) {
             e.printStackTrace();
         }
         System.out.println(fileStr);
     }
 }

　b. 读取properties ，支持去读多个properties(指定默认)

 package wisers.samza.report.util;

 import java.io.BufferedInputStream;
 import java.io.File;
 import java.io.FileInputStream;
 import java.io.IOException;
 import java.io.InputStream;
 import java.util.HashMap;
 import java.util.Map;
 import java.util.Properties;

 /**
  * Created by zf on 2016/8/12 0012.
  */
 public class ProConfigUtil {

     private static final String filePath = "config/config.properties";
     private static Map<String, Properties> propertiesMap = new HashMap<>();

     private ProConfigUtil() {

     }

     public static ProConfigUtil getInstance() {
         return getInstance(filePath);
     }

     private static ProConfigUtil getInstance(String filePath) {
         Properties prop = propertiesMap.get(filePath);
         if (prop == null) {
             prop = new Properties();
             try {
                 String userDir = System.getProperty("user.dir");
                 // WEB-INF/class
                 //String userDir = ClassLoader.getSystemClassLoader().getResource("").getPath();
                 String basePath = userDir + "/src/main/";
                 File file = new File(basePath + filePath);
                 InputStream inputStream = new FileInputStream(file);
                 InputStream in = new BufferedInputStream(inputStream);
                 prop.load(in);
             } catch (IOException e) {
                 e.printStackTrace();
             }
             propertiesMap.put(filePath, prop);
         }
         return classHolder.proConfigUtil;
     }

     public static String readValue(String filePath, String key) {
         return getInstance(filePath).propertiesMap.get(filePath).getProperty(key);
     }

     public String readValue(String key) {
         return propertiesMap.get(filePath).getProperty(key);
     }

     private static class classHolder {

         private static ProConfigUtil proConfigUtil = new ProConfigUtil();
     }

 }