如何解决Java错误“系统找不到指定的路径”？

Question

我正在运行 Mac OS X 并且代码有效。我的队友正在运行 Windows 7，他得到了错误（即使目录结构和文件存在于他的系统上）。有任何想法吗？我已经花了几个小时在这上面，但无法弄清楚。谢谢。

import java.io.BufferedReader;
import java.io.FileReader;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement; // Not used
import java.sql.ResultSet; // Not used
import java.sql.SQLException;
import java.sql.Statement;
import java.util.ArrayList; // Not used
import java.util.Scanner; // Not used

public class CreateDB {

   public CreateDB() {
   }

   public void createDB() {

      Connection conn = null;

      String url = "jdbc:mysql://localhost:3306/";
      String dbName = ""; // Not used (yet?)
      String driver = "com.mysql.jdbc.Driver";
      String userName = "root"; // Tell user userName is "root". OR/TODO: Change to something more secure?
      String password = ""; // Tell user password is "". Or/TODO: Change to something more secure?
      String line;
      String sqlDump = null;
      String [] sqlDumpArray;

      String fileSeperator = System.getProperty("file.separator");
      System.out.println("fileSeperator is: " + fileSeperator);  // Testing
      String path = System.getProperty("user.dir");
      System.out.println("path is: " + path); // Testing
      String pathToFile = (path + fileSeperator + "src" + fileSeperator + "files" + fileSeperator);
      System.out.println("pathToFile is: " + pathToFile); // Testing.
      String fileName = "create_db_and_tables.sql"; // NOTE: Rename file, if necessary. Make sure it's in right place.
      System.out.println("pathToFile + fileName is: " + pathToFile + fileName); // Testing.

      try {
         Class.forName(driver).newInstance();
         conn = DriverManager.getConnection(url, userName, password);
         System.out.println("Connected to the database.\n"); // Testing

         BufferedReader reader = new BufferedReader(new FileReader(pathToFile + fileName));
         line = reader.readLine();
         while (line != null) {
            sqlDump += line + "\n";
            line = reader.readLine();
         }

         System.out.println(sqlDump); // Testing
         sqlDumpArray = sqlDump.split(";");
         System.out.println("sqlDumpArray size is " + sqlDumpArray.length); // Testing

         for (int i = 0; i < sqlDumpArray.length; i++) {
            System.out.println("\nsqlDumpArray[" + i + "] is: " + sqlDumpArray[i]);  // Testing
         }

         for (int j = 1; j < sqlDumpArray.length -1; j++) {
            try {
               Statement statement = conn.createStatement();
               statement.addBatch(sqlDumpArray[j]);
               statement.executeBatch(); // Could refactor or us another method
            }
            catch (SQLException e) {
               System.err.println("SQLException: " + e.getMessage());

            }
            catch (Exception e) {
               System.err.println("Exception: " + e.getMessage());
            }
         }
      }
      catch (java.lang.ClassNotFoundException e) {
         System.err.println("ClassNotFoundException: " + e.getMessage());

      }
      catch (SQLException e) {
         System.err.println("SQLException: " + e.getMessage());

      }
      catch (Exception e) {
         System.err.println("Exception: " + e.getMessage());
      }
      finally {
         try {
            // conn.commit(); // Not necessary
            conn.close();
            System.out.println("Successfully disconnected from database. Yeah!");
         }
         catch (SQLException e) {
            System.err.println("SQLException in 'finally' block: " + e.getMessage());
         }
      }
   }
   public static void main(String[] args) {
     CreateDB create = new CreateDB();
     create.createDB();
   }
}

Windows 上的用户在尝试执行数据库创建过程时收到错误消息。即使路径和文件看起来正确，也会发生此错误，例如文件中以下System.out.println 语句返回的内容（在下面突出显示）：

String fileSeperator = System.getProperty("file.separator");
System.out.println("fileSeperator is: " + fileSeperator);
String path = System.getProperty("user.dir");
System.out.println("path is: " + path);
String pathToFile = (path + fileSeperator + "src" + fileSeperator + "files" + fileSeperator);
System.out.println("pathToFile is: " + pathToFile);
String fileName = "create_db_and_tables.sql";
System.out.println("pathToFile + fileName is: " + pathToFile + fileName);

这是该语句在 Windows 7 计算机上返回的示例：

Exception: C:\Users\USER\workspace\mrbs2011a\src\files\create_db_and_tables.sql (The system cannot find the path specified)

即使 USER 的文件 create_db_and_tables.sql 位于 src/files 文件夹中，它也会被打印出来。

Answer 1

文件可能被锁定，或者运行 Java 程序的用户权限不允许访问该文件。

如果文件确实在那里，那么文件被锁定（例如，被另一个进程保持打开以供写入）可能是原因。 documentation for FileReader 表示如果“指定的文件不存在，是目录而不是常规文件，或者由于某些其他原因无法打开读取”，它将抛出 FileNotFoundException。