java - DriverManager.getConnection() 上的编译错误 "Cannot find symbol"

Question

    import java.io.FileInputStream;
import java.io.IOException;
import java.sql.Connection;
import java.sql.DriverManager;
import java.util.Properties;
import java.util.logging.Level;
import java.util.logging.Logger;

public class Jdbc {

    public static void main(String args[]) {



        FileInputStream in = null;
        Connection con = null;
        try {

            Properties props = new Properties();
            in = new FileInputStream("/external/configuration/dir/db.properties");
            props.load(in);
            in.close();
            String driver = props.getProperty("jdbc.driver");
            if (driver != null) {
                Class.forName(driver);
            }
            String host = props.getProperty("jdbc.host");
            String port = props.getProperty("jdbc.port");
            String database = props.getProperty("jdbc.database");
            String username = props.getProperty("jdbc.username");
            String password = props.getProperty("jdbc.password");
            con = DriverManager.getConnection(host,port,database,username, password);
        } catch (Exception ex) {
            Logger.getLogger(Jdbc.class.getName()).log(Level.SEVERE, null, ex);
        } finally {
            if (in != null) {
                try {
                    in.close();
                } catch (IOException ex) {
                    Logger.getLogger(Jdbc.class.getName()).log(Level.SEVERE, null, ex);
                }
            }
            if (con != null) {
                try {
                    con.close();
                } catch (Exception ex) {
                    Logger.getLogger(Jdbc.class.getName()).log(Level.SEVERE, null, ex);
                }
            }

        }
    }
}

错误是:

1 个错误

C:\Users\Desktop>javac Jdbc.java
Jdbc.java:32: cannot find symbol
symbol  : method getConnection(java.lang.String,java.lang.String,java.lang.Strin
g,java.lang.String,java.lang.String)
location: class java.sql.DriverManager
            con = DriverManager.getConnection(host,port,database,username, passw
ord);

Answer 1

这是你程序的编译版本。
试着找出区别。主要是导入，异常处理

import java.io.FileInputStream;
import java.io.IOException;
import java.sql.Connection;
import java.sql.DriverManager;
import java.util.Properties;
import java.util.logging.Level;
import java.util.logging.Logger;

public class Jdbc {

    public static void main(String args[]) {



        FileInputStream in = null;
        Connection con = null;
        try {

            Properties props = new Properties();
            in = new FileInputStream("/external/configuration/dir/db.properties");
            props.load(in);
            in.close();
            String driver = props.getProperty("jdbc.driver");
            if (driver != null) {
                Class.forName(driver);
            }
            String url = props.getProperty("jdbc.url");
            String username = props.getProperty("jdbc.username");
            String password = props.getProperty("jdbc.password");
            con = DriverManager.getConnection(url, username, password);
        } catch (Exception ex) {
            Logger.getLogger(Jdbc.class.getName()).log(Level.SEVERE, null, ex);
        } finally {
            if (in != null) {
                try {
                    in.close();
                } catch (IOException ex) {
                    Logger.getLogger(Jdbc.class.getName()).log(Level.SEVERE, null, ex);
                }
            }
            if (con != null) {
                try {
                    con.close();
                } catch (Exception ex) {
                    Logger.getLogger(Jdbc.class.getName()).log(Level.SEVERE, null, ex);
                }
            }

        }
    }
}