Создание серверных приложений

// Код файла JDBCBean.java:
package myjspjdbc1;
import java.io.*;
import java.util.*;
import java.sql.*;
public class JDBCBean {
    String classname ; // JDBC-драйвер
    String url ;
    String username ;
    String password ;
    String query ;  // SQL-оператор.
    int rows, cols; // Число строк и столбцов результирующего набора
    Vector result;
    public void setClassname(String classname) {
				this.classname = classname;    }
    public String getClassname() {	return classname;    }
    public void setUrl(String url) {
	this.url = url;
    }
    public String getUrl(){	return url;    }
    public void setUsername(String username) {
				this.username = username;    }
    public String getUsername() {	return username;    }
    public void setPassword(String password) {
				this.password = password;    }
    public String getPassword() {	return password;    }
    public void setQuery(String query) { this.query = query;  }
    public String getQuery() { return query;  }

    protected void go()  // Подключение к БД и выполнение запроса
	throws ClassNotFoundException, SQLException
    {
	// Загрузка JDBC-драйвера
	Class.forName(classname);
	// Создание соединения с базой данных
	Connection con = DriverManager.getConnection(url, 
                               username,
	                             password);
	// Создание и выполнение запроса
	Statement stmt = con.createStatement();
	ResultSet rs = stmt.executeQuery(query);
	ResultSetMetaData rsmd = rs.getMetaData();
	cols = rsmd.getColumnCount();
	rows = 0;
	result = new Vector();
	String s[] = new String[cols];
	for (int i=1; i<=cols; i++) {
	    s[i-1] = rsmd.getColumnLabel(i) ;
	}
	result.addElement(s);
	rows ++;
	// Извлечение данных
	while (rs.next()) {
	    s = new String[cols];
	    for (int i=1; i<=cols; i++) {
	        s[i-1] = helper(rs, rsmd.getColumnType(i), i);
	    }
	    result.addElement(s);
	    rows ++;
	}
    }
    public static void main (String[] args)
    {
	JDBCBean jdbcBean = new JDBCBean();
	String classname = "com.imaginary.sql.msql.MsqlDriver";
	//String url = "jdbc:msql://gaby.eng:4333/demo";
	String url = "jdbc:msql://ridgetop.eng:1114/test";
	String username = "lfu";
	String password = "password";
	//String query = "select * from details";
	String query = "select * from table1";
	jdbcBean.setClassname(classname);
	jdbcBean.setUrl(url);
	jdbcBean.setUsername(username);
	jdbcBean.setPassword(password);
	jdbcBean.setQuery(query);
	try {
	    jdbcBean.go();
	    System.out.println("Seems okay");
	} catch (Exception ex) {
	    ex.printStackTrace();
	}
    }
    public int getColumnCount() {	return cols;    }
    public int getRowCount() {	return rows;    }
    public String getColumnLabels(int col) {
	String[] s = (String[])result.firstElement();
	return s[col];
    }
    public String getCell(int col, int row) {
	String[] s = (String[])result.elementAt(row);
	return s[col];
    }
    protected String helper (ResultSet rs, int dataType, int col)
	throws SQLException
    { 	String retVal = null;   Integer intObj;
	// Запрос данных в зависимости от их типа
	switch(dataType) {
	case Types.DATE:
	    java.sql.Date date = rs.getDate(col);
	    retVal = date.toString();
	    break;
	case Types.TIME:
	    java.sql.Time time = rs.getTime(col);
	    retVal = time.toString();
	    break;
	case Types.TIMESTAMP:
	    java.sql.Timestamp timestamp = rs.getTimestamp(col);
	    retVal = timestamp.toString();
	    break;
	case Types.CHAR:
	case Types.VARCHAR:
	case Types.LONGVARCHAR:
	    retVal = rs.getString(col);
	    break;
	case Types.NUMERIC:
	case Types.DECIMAL:
	    java.math.BigDecimal numeric = rs.getBigDecimal(col, 10);
	    retVal = numeric.toString();
	    break;
	case Types.BIT:
	    boolean bit = rs.getBoolean(col);
	    Boolean boolObj = new Boolean(bit);
	    retVal = boolObj.toString();
	    break;
	case Types.TINYINT:
	    byte tinyint = rs.getByte(col);
	    intObj = new Integer(tinyint);
	    retVal = intObj.toString();
	    break;
	case Types.SMALLINT:
	    short smallint = rs.getShort(col);
	    intObj = new Integer(smallint);
	    retVal = intObj.toString();
	    break;
	case Types.INTEGER:
	    int integer = rs.getInt(col);
	    intObj = new Integer(integer);
	    retVal = intObj.toString();
	    break;
	case Types.BIGINT:
	    long bigint = rs.getLong(col);
	    Long longObj = new Long(bigint);
	    retVal = longObj.toString();
	    break;
	case Types.REAL:
	    float real = rs.getFloat(col);
	    Float floatObj = new Float(real);
	    retVal = floatObj.toString();
	  break;
	case Types.FLOAT:
	case Types.DOUBLE:
	  double longreal = rs.getDouble(col);
	  Double doubleObj = new Double(longreal);
	  retVal = doubleObj.toString();
	  break;
	case Types.BINARY:
	case Types.VARBINARY:
	case Types.LONGVARBINARY:
	  byte[] binary = rs.getBytes(col);
	  retVal = new String(binary);
	  break;
	}
	return retVal;
    }
}
// Код файла HttpJDBCBean.java:
package myjspjdbc1;
import java.io.*;
import java.util.*;
import javax.servlet.http.*;
import java.sql.*;
public class HttpJDBCBean extends JDBCBean {
    public void processRequest(HttpServletRequest request,
	       HttpServletResponse response)
	throws IOException
    {
	// Получение значений параметров, если они заданы
	String _p ;
	if ((_p = request.getParameter("classname")) != null) {
	    classname = _p;
	}
	if ((_p = request.getParameter("url")) != null) {
	    url = _p;
	}
	if ((_p = request.getParameter("username")) != null) {
	    username = _p;
	}
	if ((_p = request.getParameter("password")) != null) {
	    password = _p;
	}
	if ((_p = request.getParameter("query")) != null) {
	    query = _p;
	}
	// Если параметры не заданы, то отображать только форму
	boolean form_only = false;
	if (classname == "" || classname == null) form_only = true;
	if (url == "" || url == null) form_only = true;
	if (username == null) form_only = true;
	if (password == null) form_only = true;
	if (query == null) form_only = true;
	if (form_only) {
	    return;
	}
	try {
	    this.go();  // Вызов метода, выполняющего запрос
	} catch (ClassNotFoundException ex) {
	    PrintWriter writer = response.getWriter();    // Поток вывода
	    writer.println("class " + classname + " not found.");
	} catch (SQLException ex) {
	    PrintWriter writer = response.getWriter();
	    writer.println("Message: " + ex.getMessage());
	    writer.println("Error code: " + ex.getErrorCode());
	    ex.printStackTrace(writer);
	} catch (Exception ex) {
	    PrintWriter writer = response.getWriter();
	    ex.printStackTrace(writer);
	}
    }  }