Cómo obtener metadatos de la base de datos

java.sql.DatabaseMetaData La interfaz proporciona métodos para obtener metadatos de su servidor de base de datos conectado. Los siguientes ejemplos le mostrarán cómo hacerlo uno por uno.

instancia java.sql.DatabaseMetaData

El objeto DatabaseMetaData se recupera del objeto Connection de la base de datos.

DatabaseMetaData dbmd = dbConn.getMetaData();

Nombre y versión de la base de datos

String dbProductName = dbmd.getDatabaseProductName();
String dbProductVersion = dbmd.getDatabaseProductVersion();

int dbMajorVersion = dbmd.getDatabaseMajorVersion();
int dbMinorVersion = dbmd.getDatabaseMinorVersion();

Versión del controlador JDBC

int jdbcDriverMajorVersion = dbmd.getDriverMajorVersion();
int jdbcDriverMinorVersion = dbmd.getDriverMinorVersion();

Lista de bases de datos

ResultSet rs = dbmd.getCatalogs();
if(rs!=null)
{
      while(rs.next())
      {
          String catalogName = rs.getString(1);
	  System.out.println("Database catalog : " + catalogName);
      }
}

Lista de tablas

// Get all tables of this database.
ResultSet tblRs = dbmd.getTables(catalogName, "", "", null);				
if(tblRs!=null)
{
	while(tblRs.next())
	{
		// Get table
		String tmpDBName = tblRs.getString(1);
		String tmpTblName = tblRs.getString(3);
		System.out.println("DB : " + tmpDBName + " , table : " + tmpTblName);
         }
}

Lista de columnas de tabla

// Get columns
ResultSet columnRs = dbmd.getColumns(catalogName, "", tmpTblName, "");
						
if(columnRs!=null)
{
	while(columnRs.next())
	{
		// Get column type and name.
		String cType = columnRs.getString(6);
						
	        String cName = columnRs.getString(4);
		
		System.out.println("Column Name : " + cName + " , Column Type : " + cType);
	}
}

Código de ejemplo completo

El siguiente ejemplo utilizará el servidor de base de datos MySQL.

public class DatabaseMetaDataExample {

	public static void main(String[] args) {
		
		try
		{
			/* Below are db connection required data. */
			String ip = "localhost";
			int port = 3306;
			String dbName = "test";
			String userName = "root";
			String password = "";
	
			DatabaseMetaDataExample dbmdExample = new DatabaseMetaDataExample();
			
			// Get database connection.
			Connection dbConn = dbmdExample.getMySqlConnection(ip, port, dbName, userName, password);
			
			// Get database metadata. 
			DatabaseMetaData dbmd = dbConn.getMetaData();
			
			// Get db name.
			String dbProductName = dbmd.getDatabaseProductName();
			System.out.println("DB product name : " + dbProductName);
			
			// Get db product version.
			String dbProductVersion = dbmd.getDatabaseProductVersion();
			System.out.println("DB product version : " + dbProductVersion);
			
			// Get db major & minor version.
			int dbMajorVersion = dbmd.getDatabaseMajorVersion();
			System.out.println("DB major version : " + dbMajorVersion);
			int dbMinorVersion = dbmd.getDatabaseMinorVersion();
			System.out.println("DB minor version : " + dbMinorVersion);
			
			// Get jdbc driver major & minor version.
			int jdbcDriverMajorVersion = dbmd.getDriverMajorVersion();
			System.out.println("JDBC driver major version : " + jdbcDriverMajorVersion);
			int jdbcDriverMinorVersion = dbmd.getDriverMinorVersion();
			System.out.println("JDBC driver minor version : " + jdbcDriverMinorVersion);
			
			// Get all database catalogs.
			ResultSet rs = dbmd.getCatalogs();
			if(rs!=null)
			{
				while(rs.next())
				{
					String catalogName = rs.getString(1);
					System.out.println("Database catalog : " + catalogName);
					
					// Get all tables of this database.
					ResultSet tblRs = dbmd.getTables(catalogName, "", "", null);
					
					if(tblRs!=null)
					{
						while(tblRs.next())
						{
							// Get table
							String tmpDBName = tblRs.getString(1);
							String tmpTblName = tblRs.getString(3);
							System.out.println("DB : " + tmpDBName + " , table : " + tmpTblName);
							
							// Get columns
							ResultSet columnRs = dbmd.getColumns(catalogName, "", tmpTblName, "");
							
							if(columnRs!=null)
							{
								while(columnRs.next())
								{
									// Get column type and name.
									String cType = columnRs.getString(6);
									
									String cName = columnRs.getString(4);
									
									System.out.println("Column Name : " + cName + " , Column Type : " + cType);
								}
							}
							
						}
					}
					
				}
			}
			
			
			dbmdExample.closeDBResource(null, dbConn);
		} catch (SQLException ex) {
			ex.printStackTrace();
		}
	}
	
	/* This method return java.sql.Connection object from MySQL server. */
	public Connection getMySqlConnection(String ip, int port, String dbName, String userName, String password)
	{
		/* Declare and initialize a sql Connection variable. */
		Connection ret = null;
		
		try
		{
		
			/* Register for mysql jdbc driver class. */
			Class.forName("com.mysql.jdbc.Driver");
			
			/* Create mysql connection url. */
			String mysqlConnUrl = "jdbc:mysql://" + ip + ":" + port + "/" + dbName;
			
			/* Get the mysql Connection object. */
			ret = DriverManager.getConnection(mysqlConnUrl, userName , password);
		}catch(Exception ex)
		{
			ex.printStackTrace();
		}finally
		{
			return ret;
		}
	}
	
	/* Close statement and connection after use, this can avoid resource waste. */
	public void closeDBResource(Statement stmt, Connection conn)
	{
		try
		{
			if(stmt!=null)
			{
				stmt.close();
				stmt = null;
			}
			
			if(conn!=null)
			{
				conn.close();
				conn = null;
			}
		}catch(Exception ex)
		{
			ex.printStackTrace();
		}
	}

}

Código fuente:

1. [ID de descarga=”2567″]

Referencia:

1. Metadatos de la base de datos de la interfaz