java数据库访问标准格式(no transaction)

java 代码

    
/**
     * The SQL statement to insert the entity details.
     */
    private
 
static
 
final
 String INSERT_DETAILS = 
"INSERT INTO message (message_id, from_handle, project_id, "
                    + "project_name, timestamp, subject, message) VALUES (?, ?, ?, ?, ?, ?, ?)"
;

   /**
     * Creates a new database connection using the configured database connection factory and connection name.
     *
     * @return a new database connection created using the configured database connection factory and
     *         connection name
     * @throws MessagePersistenceException if an error occurs while creating the connection
     */
    private
 Connection getConnection() {
        logEntry("getConnection()"
);

        Connection conn = null
;

        try
 {
            this
.logExternalCall(
"calling connectionFactory.createConnection({0})"
, connectionName);
            conn = this
.connectionFactory.createConnection(connectionName);
            this
.logExternalCall(
"returned from connectionFactory.createConnection({0})"
, connectionName);
        } catch
 (DBConnectionException ex) {
            this
.throwPersistenceException(ex, 
"error creating connection: "
);
        } finally
 {
            this
.logExit(
"getConnection"
);
        }

        return
 conn;
    }

    /**
     * Closes the connection and logs any exception that occurs.
     *
     * @param conn the connection to close (may be null)
     */
    private
 
void
 closeConnection(Connection conn) {
        this
.logEntry(
"closeConnection({0})"
, conn);

        try
 {
            if
 (conn != 
null
) {
                conn.close();
            }
        } catch
 (SQLException ex) {
            // this exception doesn't really affect the user, so we'll just log it and continue
            this
.logException(ex);
        } finally
 {
            this
.logExit(
"closeConnection"
);
        }
    }


    /**
     * Closes a prepared statement and logs any exception that occurs.
     *
     * @param statement the prepared statement to close (may be null)
     */
    private
 
void
 closeStatement(PreparedStatement statement) {
        this
.logEntry(
"closeStatement({0})"
, statement);

        try
 {
            if
 (statement != 
null
) {
                statement.close();
            }
        } catch
 (SQLException ex) {
            // this exception doesn't really affect the user, so we'll just log it and continue
            this
.logException(ex);
        } finally
 {
            this
.logExit(
"closeStatement"
);
        }
    }

/**
 *  Save an entity with no transaction. Transaction here is handled by the EJB container.
 */
    public
 
void
 saveEntity(Entity entity) {
        this
.checkObject(entity, 
"entity"
);
        this
.logEntry(
"saveMessage({0})"
, entity);

        Connection conn = null
;
        PreparedStatement statement = null
;

        try
 {
            conn = this
.getConnection();

            try
 {
                statement = conn.prepareStatement(INSERT_DETAILS);

                int
 pos = 
1
; 
// work around checkstyle warning about "magic numbers"
                statement.setLong(pos++, entity.getMessageId());
                statement.setString(pos, entity.getText());

                statement.executeUpdate();
            } catch
 (SQLException ex) {
                this
.throwPersistenceException(ex, 
"error saving message: "
);
            }
        } finally
 {
            this
.closeStatement(statement );
            this
.closeConnection(conn);
            this
.logExit(
"saveMessage"
);
        }
    }

/**
 *  Save an entity with transaction.  When errors occur, we need to roll back the transaction.
 */
    public
 
void
 saveEntity(Entity entity) {
        this
.checkObject(entity, 
"entity"
);
        this
.logEntry(
"saveMessage({0})"
, entity);

        Connection conn = null
;
        PreparedStatement statement = null
;

        try
 {
            conn = this
.getConnection();

            try
 {
                statement = conn.prepareStatement(INSERT_DETAILS);

                int
 pos = 
1
; 
// work around checkstyle warning about "magic numbers"
                statement.setLong(pos++, entity.getMessageId());
                statement.setString(pos, entity.getText());

                statement.executeUpdate();
            } catch
 (SQLException ex) {
                this
.throwPersistenceException(ex, 
"error saving message: "
);
            }
        } finally
 {
            this
.closeStatement(statement );
            this
.closeConnection(conn);
            this
.logExit(
"saveMessage"
);
        }
    }
    /**
     * Creates a MessagePersistenceException
 based on the specified exception, logs it, and
     * throws it.
     *
     * @param ex the wrapped exception
     * @param what a description of the operation that failed
     * @throws MessagePersistenceException a MessagePersistenceException
 wrapping the
     *             lower-level exception
     */
    private
 
void
 throwPersistenceException(Throwable ex, String what) {
        // simple helper method, so no logging

        MessagePersistenceException mpe = new
 MessagePersistenceException(what + ex.getMessage(), ex);
        logException(mpe);
        throw
 mpe;
    }