Description:
getObject() method doesn't return the correct type all the time.
If I insert a double to the blob type column, getObject retrieves
it as String. However if I store it as an ArrayList, getObject retrieves
it as ArrayList which is correct.
I'm using 5.0.45 and connector version is 5.1.6
Please try the following code after replacing the appropriate fields
and see what happens.
The oitput will be
readJavaObject: done de-serializing: java.lang.String
where is should be
readJavaObject: done de-serializing: java.lang.Double
/*
* mysql> CREATE TABLE java_objects (
* id INT AUTO_INCREMENT,
* name varchar(128),
* object_value BLOB,
* primary key (id));
**/
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.util.ArrayList;
import java.util.Date;
import java.util.List;
public class SerializeJavaObjects_MySQL {
static final String WRITE_OBJECT_SQL = "INSERT INTO java_objects(name, object_value) VALUES (?, ?)";
static final String READ_OBJECT_SQL = "SELECT object_value FROM java_objects WHERE id = ?";
public static Connection getConnection() throws Exception {
String driver = "org.gjt.mm.mysql.Driver";
String url = "jdbc:mysql://localhost/testdb?autoDeserialize=true";
String username = "user";
String password = "pass";
Class.forName(driver);
Connection conn = DriverManager.getConnection(url, username, password);
return conn;
}
public static long writeJavaObject(Connection conn, Object object) throws Exception {
String className = object.getClass().getName();
PreparedStatement pstmt = conn.prepareStatement(WRITE_OBJECT_SQL);
// set input parameters
pstmt.setString(1, className);
pstmt.setObject(2, object);
pstmt.executeUpdate();
// get the generated key for the id
ResultSet rs = pstmt.getGeneratedKeys();
int id = -1;
if (rs.next()) {
id = rs.getInt(1);
}
rs.close();
pstmt.close();
System.out.println("writeJavaObject: done serializing: " + className);
return id;
}
public static Object readJavaObject(Connection conn, long id) throws Exception {
PreparedStatement pstmt = conn.prepareStatement(READ_OBJECT_SQL);
pstmt.setLong(1, id);
ResultSet rs = pstmt.executeQuery();
rs.next();
Object object = rs.getObject(1);
String className = object.getClass().getName();
rs.close();
pstmt.close();
System.out.println("readJavaObject: done de-serializing: " + className);
return object;
}
public static void main(String args[])throws Exception {
Connection conn = null;
try {
conn = getConnection();
System.out.println("conn=" + conn);
conn.setAutoCommit(false);
/*
List<Object> list = new ArrayList<Object>();
list.add("This is a short string.");
list.add(new Integer(1234));
list.add(new Date());
long objectID = writeJavaObject(conn, list);
*/
long objectID = writeJavaObject(conn, 2.0);
conn.commit();
System.out.println("Serialized objectID => " + objectID);
Object value = readJavaObject(conn, objectID);
System.out.println("[After De-Serialization] value=" + value);
} catch (Exception e) {
e.printStackTrace();
} finally {
conn.close();
}
}
}
How to repeat:
It can be repeated all the time.
Description: getObject() method doesn't return the correct type all the time. If I insert a double to the blob type column, getObject retrieves it as String. However if I store it as an ArrayList, getObject retrieves it as ArrayList which is correct. I'm using 5.0.45 and connector version is 5.1.6 Please try the following code after replacing the appropriate fields and see what happens. The oitput will be readJavaObject: done de-serializing: java.lang.String where is should be readJavaObject: done de-serializing: java.lang.Double /* * mysql> CREATE TABLE java_objects ( * id INT AUTO_INCREMENT, * name varchar(128), * object_value BLOB, * primary key (id)); **/ import java.sql.Connection; import java.sql.DriverManager; import java.sql.PreparedStatement; import java.sql.ResultSet; import java.util.ArrayList; import java.util.Date; import java.util.List; public class SerializeJavaObjects_MySQL { static final String WRITE_OBJECT_SQL = "INSERT INTO java_objects(name, object_value) VALUES (?, ?)"; static final String READ_OBJECT_SQL = "SELECT object_value FROM java_objects WHERE id = ?"; public static Connection getConnection() throws Exception { String driver = "org.gjt.mm.mysql.Driver"; String url = "jdbc:mysql://localhost/testdb?autoDeserialize=true"; String username = "user"; String password = "pass"; Class.forName(driver); Connection conn = DriverManager.getConnection(url, username, password); return conn; } public static long writeJavaObject(Connection conn, Object object) throws Exception { String className = object.getClass().getName(); PreparedStatement pstmt = conn.prepareStatement(WRITE_OBJECT_SQL); // set input parameters pstmt.setString(1, className); pstmt.setObject(2, object); pstmt.executeUpdate(); // get the generated key for the id ResultSet rs = pstmt.getGeneratedKeys(); int id = -1; if (rs.next()) { id = rs.getInt(1); } rs.close(); pstmt.close(); System.out.println("writeJavaObject: done serializing: " + className); return id; } public static Object readJavaObject(Connection conn, long id) throws Exception { PreparedStatement pstmt = conn.prepareStatement(READ_OBJECT_SQL); pstmt.setLong(1, id); ResultSet rs = pstmt.executeQuery(); rs.next(); Object object = rs.getObject(1); String className = object.getClass().getName(); rs.close(); pstmt.close(); System.out.println("readJavaObject: done de-serializing: " + className); return object; } public static void main(String args[])throws Exception { Connection conn = null; try { conn = getConnection(); System.out.println("conn=" + conn); conn.setAutoCommit(false); /* List<Object> list = new ArrayList<Object>(); list.add("This is a short string."); list.add(new Integer(1234)); list.add(new Date()); long objectID = writeJavaObject(conn, list); */ long objectID = writeJavaObject(conn, 2.0); conn.commit(); System.out.println("Serialized objectID => " + objectID); Object value = readJavaObject(conn, objectID); System.out.println("[After De-Serialization] value=" + value); } catch (Exception e) { e.printStackTrace(); } finally { conn.close(); } } } How to repeat: It can be repeated all the time.