A
Allen
In jsp, forName("sun.jdbc.odbc.JdbcOdbcDriver") run successfully. When
used in JavaBean,
forName will fail. While run JavaBean class directly, it works. Why?
The following is the code.
package com;
import java.io.*;
import java.util.*;
import java.sql.*;
public class Publisher {
String driver = "sun.jdbc.odbc.JdbcOdbcDriver";
Connection conn = null;
ResultSet rs = null;
public Publisher() {
}
public boolean open(String url, String user, String passwd) {
try {
Class.forName(driver).newInstance();
conn = DriverManager.getConnection(url, user, passwd);
} catch (ClassNotFoundException e) {
e.printStackTrace();
return false;
} catch (SQLException e) {
e.printStackTrace();
return false;
} catch (Exception e) {
e.printStackTrace();
return false;
}
return true;
}
public ResultSet executeQuery(String sql) {
if (conn == null) {
return null;
}
rs = null;
try {
Statement stmt = conn.createStatement();
rs = stmt.executeQuery(sql);
}
catch (SQLException e) {
e.printStackTrace();
}
return rs;
}
public void close() {
try {
rs.close();
conn.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
public static void main(String[] args) {
Publisher pb = new Publisher();
pb.open("jdbc
dbcublisher", "user", "user");
ResultSet rs = pb.executeQuery("SELECT * FROM Publisher");
String id, name, url;
System.out.println("Publisher_ID Name URL");
try {
while (rs.next()) {
id = rs.getString("Publisher_ID");
name = rs.getString("name");
url = rs.getString("url");
System.out.println(id + " " + name + " " + url);
}
} catch (SQLException e) {
e.printStackTrace();
}
pb.close();
}
}
// !!!!!!!!!!!!!!!!!!!!!!!!! NOTE !!!!!!!!!!!!!!!!!!!!!!!!!!!
http://localhost:8080/publisher.jsp will report error for open(url,
user, passwd) return false;
used in JavaBean,
forName will fail. While run JavaBean class directly, it works. Why?
The following is the code.
package com;
import java.io.*;
import java.util.*;
import java.sql.*;
public class Publisher {
String driver = "sun.jdbc.odbc.JdbcOdbcDriver";
Connection conn = null;
ResultSet rs = null;
public Publisher() {
}
public boolean open(String url, String user, String passwd) {
try {
Class.forName(driver).newInstance();
conn = DriverManager.getConnection(url, user, passwd);
} catch (ClassNotFoundException e) {
e.printStackTrace();
return false;
} catch (SQLException e) {
e.printStackTrace();
return false;
} catch (Exception e) {
e.printStackTrace();
return false;
}
return true;
}
public ResultSet executeQuery(String sql) {
if (conn == null) {
return null;
}
rs = null;
try {
Statement stmt = conn.createStatement();
rs = stmt.executeQuery(sql);
}
catch (SQLException e) {
e.printStackTrace();
}
return rs;
}
public void close() {
try {
rs.close();
conn.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
public static void main(String[] args) {
Publisher pb = new Publisher();
pb.open("jdbc
dbcublisher", "user", "user");ResultSet rs = pb.executeQuery("SELECT * FROM Publisher");
String id, name, url;
System.out.println("Publisher_ID Name URL");
try {
while (rs.next()) {
id = rs.getString("Publisher_ID");
name = rs.getString("name");
url = rs.getString("url");
System.out.println(id + " " + name + " " + url);
}
} catch (SQLException e) {
e.printStackTrace();
}
pb.close();
}
}
// !!!!!!!!!!!!!!!!!!!!!!!!! NOTE !!!!!!!!!!!!!!!!!!!!!!!!!!!
http://localhost:8080/publisher.jsp will report error for open(url,
user, passwd) return false;