我得到了什么异常并帮助我？ [复制]

Question

package jdbc.examples;

import java.io.FileInputStream;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;
import java.util.Properties;

public class PropertiesDemo {
    private static Connection conn;
    private static Statement st;
    private static ResultSet rs;

    public static void main(String[] args) throws Exception{
        Properties p = new Properties();
        FileInputStream fis = new FileInputStream("db.properties");
        p.load(fis);
        String driver = (String)p.getProperty("driver");
        String url = (String)p.getProperty("url");
        String user = (String)p.getProperty("user");
        String pwd = (String)p.getProperty("pwd");

            Class.forName(driver);
            conn = DriverManager.getConnection(url, user, pwd);
            st = conn.createStatement();
            rs = st.executeQuery("select ename, sal, deptno from emp");

        while(rs.next()) {
            System.out.println(rs.getString(1)+"  "+rs.getDouble(2)+"  "+rs.getInt(3));
        }

        rs.close();
        st.close();
        conn.close();
    }

}

输出：

Exception in thread "main" java.io.FileNotFoundException: db.properties (The system cannot find the file specified)     
at java.base/java.io.FileInputStream.open0(Native Method)   
at java.base/java.io.FileInputStream.open(Unknown Source)   
at java.base/java.io.FileInputStream.<init>(Unknown Source)     
at j

Answer 1

就像@Carlos 和@PM77-1 提到的那样，答案是直截了当的“找不到文件”，简而言之，

FileInputStream fis = new FileInputStream("db.properties");

上面一行在java代码的同一文件夹中搜索文件db.properties，但没有找到。

解决方案：您可能必须移动属性文件，或者您必须提及绝对/相对路径

FileInputStream fis = new FileInputStream("c:\myFile\db.properties");

Answer 2

您尝试打开的文件不存在。下面的行是您的问题的原因。该文件很可能在另一个文件夹中或具有不同的名称，所以我会先检查一下。

FileInputStream fis = new FileInputStream("db.properties");