JDBC连接使用不同的文件

Question

首先抱歉标题的名称,但我不知道怎么放另一个,因为英语不是我的母语.

我有以下方法连接到数据库:

import java.sql.DriverManager;
import java.sql.Connection;
import java.sql.SQLException;

public class PgConnect {
    public  void connect() {
        Connection connection = null;
        try {
            connection = DriverManager.getConnection("jdbc:postgresql://pgserver:5432/db", "test","test123");
        } catch (SQLException e) {
            System.out.println("Connection Failed! Check output console");
            e.printStackTrace();
            return;
        }
        if (connection != null) {
            System.out.println("Connection working");
        } else {
            System.out.println("Failed to make connection!");
        }
    }
}

我需要做的是包括PgConnect下面代码中的方法.基本上我需要这个,因为我有很多类型的SQL对数据库的调用,并且这种方式的更改很容易维护,因为凭证/主机只能在一个文件上.

我相信改变应该是我发表评论的地方

// i want to change this, for using the method on the first file. 

如果我错了,请纠正我.

import java.sql.DriverManager;
import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

public class ReturnResults {

    public static void main(String[] args) {
        Connection connection = null;
        try {
                // i want to change this, for using the method on the first file.
            connection = DriverManager.getConnection("jdbc:postgresql://pgserver:5432/db", "test","test123");

        } catch (SQLException e) {
            System.out.println("Connection Failed! Check output console");
            e.printStackTrace();
            return;
        }
        if (connection != null) {

            String result = null;
            String selectString = "select * from mwp.servers where env='TEST' order by server";
            //result ="iServer\tLabel\n";

            try {

                Statement stmt = connection.createStatement();
                ResultSet rs = stmt.executeQuery(selectString);

                while (rs.next()) {

                    String iEnv     = rs.getString("env");
                    String iServer  = rs.getString("iserver");
                    String iLabel   = rs.getString("label");
                    String iTitle   = rs.getString("title");
                    String iLogin   = rs.getString("login");

                    result=iEnv+"\t"+ iServer+"\t"+iLabel+"\t"+iTitle+"\t"+iLogin;

                    System.out.println(result);
                }
                stmt.close();
                connection.close();

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

        } else {
            System.out.println("Failed to make connection!");
        }
    }
}

我知道如何在Perl上执行此操作,但我没有任何Java实践.

Answer 1

隐藏凭据的一种方法是创建connect一个返回 的静态函数Connection，如下所示：

public class PgConnect {
    public static Connection connect() throws SQLException {
    try {
        Connection res = DriverManager.getConnection("jdbc:postgresql://pgserver:5432/db", "test","test123");
        if (res != null) {
            System.out.println("Connection working");
        } else {
            System.out.println("Failed to make connection!");
        }
        return res;
    } catch (SQLException e) {
        System.out.println("Connection Failed! Check output console");
        e.printStackTrace();
        throw e;
    }
}

}

然后你可以像这样使用它：

try {
    connection = PgConnect.connect();
} catch (SQLException e) {
    System.out.println("Connection Failed! Check output console");
    e.printStackTrace();
    return;
}