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();
    }
}

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();
    }


}