使用不同的连接参数将单线程写入不同的数据库 [英] Single thread writing to different database with different connection parameters

问题描述

我正在一个项目中，在一个具有不同模式的不同数据库中有三个表.因此，这意味着对于这三个要使用JDBC-

I am working on a project in which I have three tables in a different database with different schemas. So that means I have three different connection parameters for those three tables to connect using JDBC-

我们假设-

对于表1-

Username:- A
Password:- B
URL:       C

Columns-
ID1         String
Account1    String

对于表2-

Username:- P
Password:- Q
URL:-      R

Columns-
ID2         String
Account2    String

对于表3-

Username:- T
Password:- U
URL:-      V

Columns-
ID3         String
Account3    String

我应该使用JDBC将所有三个表或其中任何一个插入.

And I am supposed to insert in all the three tables or any one of them using JDBC.

下面是我拥有的三个用例-

Below are the three use cases I have-

1. 在命令提示符下，如果假设我仅传递Table1，则假设通过建立连接仅在Table1列中插入 表格1.
2. 如果我从命令提示符传递Table1，Table2，那么我想通过以下方式在Table1和Table2列中插入 连接到Table1和Table2.
3. 如果我要传递Table1，Table2和Table3，那么我想使用各自的连接输入所有三个表 参数

1. From the command prompt if suppose I am passing Table1 only, then I am suppose to insert only in Table1 columns by making connection to Table1.
2. And if I am passing Table1, Table2 from the command prompt then I am suppose to insert in both Table1 and Table2 columns by making connection to Table1 and Table2.
3. And if I am passing Table1, Table2 and Table3 then I am suppose to enter in all the three tables using there respective connection parameter

我无法理解如何以一种更简洁的方式为上述特定场景编写代码，因此如果我提出了四个表，它也可以在不久的将来进行扩展.我可以有一个常量文件，该文件可以存储需要为这三个表中的任何一个执行的SQL，以及一些其他常量.

I am not able to understand how to write code for the above particular scenario in such a cleaner way so that it can be extended in near future as well if I come up with four tables. I can have a one constant file which can store the SQL that needs to be executed for any of the three tables and some other constant thing as well.

public static void main(String[] args) {


}


 class Task implements Runnable {

    private Connection dbConnection = null;
    private PreparedStatement preparedStatement = null;

    public Task() {

    }

    @Override
    public void run() {

    dbConnection = getDbConnection();

    //prepare the statement and execute it

    }
  }


    private Connection getDBConnection() {

    Connection dbConnection = null;

          Class.forName(Constants.DRIVER_NAME);
      dbConnection = DriverManager.getConnection( , , );

      return dbConnection;
    }

任何人都可以对此提出一些想法吗?我应该如何继续前进?

Can anyone provide some thoughts on this how should I proceed forward?

注意:-

每个表中的列将有很大的不同.像在某些表中一样，列可以是10，而在另一些表中，列可以是20.

Column in each table will differ a lot. Like in some tables, column can be 10 and in some other table, column can be 20.

推荐答案

使用以下内容创建databases.properties文件:

Create databases.properties file with content like this:

# Table 1
table1.url: jdbc:mysql://localhost:3306/garden
table1.user: gardener
table1.password: shavel
table1.table: fruits
table1.column.id: fruitID
table1.column.color: fruitColor
table1.column.weight: fruitWeight
# ... More fruit columns here ...

# Table 2
table2.url: jdbc:mysql://otherhost:3306/forest
table2.user: forester
table2.password: axe
table2.table: trees
table2.column.id: treeID
table2.column.height: treeHeight
# ... More tree columns here ...

# ... More tables here ...

然后执行以下操作:

public static void main (String [] args)
{
    Properties databasesProperties = new Properties ();
    databasesProperties.load ("databases.properties");

    for (String arg: args)
    {
        String url = databasesProperties.get (arg + ".url");
        String user = databasesProperties.get (arg + ".user");
        String password= databasesProperties.get (arg + ".password");
        String table = databasesProperties.get (arg + ".table");

        String columnPrefix = arg + ".column."
        Map <String, String> columns = new HashMap <String, String> ();
        for (String key: databasesProperties.stringPropertyNames ())
        {
            if (key.startsWith (columnPrefix))
                columns.put (
                    key.substring (columnPrefix.length ()), 
                    databasesProperties.get (key));
        }

        doInsert (url, user, password, table, columns);
    }
}

以后，您总是可以将更多表添加到databases.properties文件中.

Later you can always add more tables into your databases.properties file.

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