JAVA Derby 查询数据库中表格是否存在

package com.han;

import java.sql.Connection;
import java.sql.DatabaseMetaData;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.HashSet;

public class JavaDBUse1 {
	private static Connection con;
	private static Statement s;  
	
	static void createTable(Statement s) throws SQLException{
		s.execute("create table table1(" +
				"id char(6)," +
				"name varchar(40)," +
				"score int)");
		s.execute("insert into table1 values('016954', 'San ZHANG', 86)");
		s.execute("insert into table1 values('016934', 'Wu WANG', 45)");
		s.execute("insert into table1 values('016908', 'Si LI', 97)");
	}
	
	public static void main(String[] args){
		Derby derby=new Derby();
		derby.loadDriver(); 
		try {		
			con=derby.getConnection("use1", "han", "");
			con.setAutoCommit(false);
			s=con.createStatement();
			DatabaseMetaData meta = con.getMetaData();
			ResultSet res = meta.getTables(null, null, null, new String[]{"TABLE"});
			HashSet<String> set=new HashSet<String>();
			while (res.next()) {
				set.add(res.getString("TABLE_NAME"));
			}
			System.out.println(set);
			if(set.contains("table1".toUpperCase())){
				System.out.println("The table already exists, you can then explore it");
				ResultSet rs=s.executeQuery("select * from table1 order by score");
				System.out.println();
				while(rs.next()){
					StringBuilder sb=new StringBuilder(rs.getString("id"));
					sb.append("\t");
					sb.append(rs.getString("name"));
					sb.append("\t");
					sb.append(rs.getInt("score"));
					System.out.println(sb.toString());
				}
				System.out.println();
				rs.close();
				s.close();
				con.commit();
				con.close();
			}else{
				//create a table
			}		
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} 	
		derby.shutdownDatabase("use1");			
		derby.shutdownAll();
	}	
}

package com.han;

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

/**
 * The Embedded mode is limited by that we can't run simultaneously 
 * two programs (two JVM instances) using a same database (databaseName is the same).
 * <p>
 * But we can instead use the NetworkServer mode to avoid this case, 
 * it is to say the "Client/Server" mode.
 * In this mode, you have to first start the NetworkServer by this command :
 * <pre>
 * java org.apache.derby.drda.NetworkServerControl start [-h hostIP -p portNumber]
 * </pre>
 * @author HAN
 *
 */
public class Derby {
	private Connection con=null;
	private String port=null;
	private String ip=null;

	/**
	 * The port will be set to default: 1527
	 */
	public void setPortToDefault(){
		port="1527";		
	}

	public void setPort(String port){
		this.port=port;
	}

	public void setServer(String ip){
		this.ip=ip;
	}

	/**
	 * This express loading driver is not necessary for Java 6 and later, JDBC 4.0 and later.
	 * Because it can be added automatically by <code>DriverManager</code> when connecting to a database.
	 */
	public void loadDriver(){
		//load the driver
		if(port==null){
			try {
				Class.forName("org.apache.derby.jdbc.EmbeddedDriver");
				System.out.println("The embedded driver is successfully loaded");
			} catch (ClassNotFoundException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
		}else{
			try{
				Class.forName("org.apache.derby.jdbc.ClientDriver");
				System.out.println("The client driver is successfully loaded");
			}catch(ClassNotFoundException e){
				e.printStackTrace();
			}
		}
	}

	/**
	 * create and connect a database
	 * @param databaseName
	 * @param user
	 * @param password
	 * @return a connection to the URL 
	 * @throws SQLException 
	 */
	public Connection createDatabaseAndGetConnection(String databaseName, String user, String password) throws SQLException{
		//create and connect the database
		Properties props=new Properties();
		props.put("user",user);	
		props.put("password",password);
		if(port==null){
			con=DriverManager.getConnection("jdbc:derby:"+databaseName+";create=true", props);
			System.out.println("Connection is successfully established, it use an Embedded database");
		}else if(ip==null){
			con=DriverManager.getConnection("jdbc:derby://localhost:"+port+"/"+databaseName+";create=true", props);
			System.out.println("Connection is sucessfully established, it use an network database but stored in the local host via the port: "+port);
		}else{
			con=DriverManager.getConnection("jdbc:derby://"+ip+":"+port+"/"+databaseName+";create=true", props);
			System.out.println("Connection is sucessfully established, it use an network database whose host ip is: "+ip+"and via the port: "+port);
		}
		return con;
	}

	/**
	 * Shut down a specified database. But it doesn't matter that later we could also connect to another database.
	 * @param databaseName
	 */
	public void shutdownDatabase(String databaseName){
		if(port==null){	
			try {
				DriverManager.getConnection("jdbc:derby:"+databaseName+";shutdown=true");				
			} catch (SQLException e) {
				// TODO Auto-generated catch block
				System.out.println("Database: "+databaseName+" shut down normally");
			}
		}else if(ip==null){
			try {
				DriverManager.getConnection("jdbc:derby://localhost:"+port+"/"+databaseName+";shutdown=true");				
			} catch (SQLException e) {
				// TODO Auto-generated catch block
				System.out.println("Database: "+databaseName+" shut down normally");
			}
		}else{
			try {
				DriverManager.getConnection("jdbc:derby://"+ip+":"+port+"/"+databaseName+";shutdown=true");	
			} catch (SQLException e) {
				// TODO Auto-generated catch block
				System.out.println("Database: "+databaseName+" shut down normally");
			}
		}
	}

	/**
	 * shut down all opened databases and close the Derby driver.
	 * The effect is that after the execution of this method, we will not permitted to use Derby again in the rest of our program.
	 * Or else, an exception of "can't find a suitable driver for [a database URL]" will be thrown.
	 */
	public void shutdownAll(){
		try {
			DriverManager.getConnection("jdbc:derby:;shutdown=true");	
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			System.out.println("All databases shut down normally and Derby driver closed");
		}
	}

	/**
	 * Just connect to a database desired by providing the appropriate parameters.
	 * @param databaseName
	 * @param user
	 * @param password
	 * @return
	 * @throws SQLException 
	 */
	public Connection getConnection(String databaseName, String user, String password) throws SQLException{
		if(port==null){
			con=DriverManager.getConnection("jdbc:derby:"+databaseName,user,password);
			System.out.println("Connection is sucessfully established, it use an Embedded database");
		}else if(ip==null){
			con=DriverManager.getConnection("jdbc:derby://localhost:"+port+"/"+databaseName,user,password);
			System.out.println("Connection is sucessfully established, it use an network database but stored in the local host via the port: "+port);
		}else{
			con=DriverManager.getConnection("jdbc:derby://"+ip+":"+port+"/"+databaseName,user,password);
			System.out.println("Connection is sucessfully established, it use an network database whose host ip is: "+ip+"and via the port: "+port);
		}
		return con;
	}
}