B4J Tutorial [jRDC2] Raspberry Pi MySQL accessed by B4J UI application using jRDC2

Discussion in 'B4J Tutorials' started by rwblinn, May 27, 2016.

  1. rwblinn

    rwblinn Well-Known Member Licensed User


    wanted to learn more about jRDC2. Let me share testing jRDC2 accessing a MySQL database, running on a Raspberry Pi (RPi), via a B4J UI application.

    Raspberry Pi MySQL Setup
    • MySQL running on RPi with IP
    • RDC folder on the RPi /home/pi/b4j/rdc
    Below the steps of creating a MySQL table called 'notes', inserting some records, select records.
    The MySQL commands have been entered in a MySQL session via Putty Terminal to access the RPi.

    login as: pi
    58:~ $ mysql -uroot -hlocalhost -p 
    mysql> CREATE DATABASE notes;
    mysql> CREATE USER 
    'notesuser'@'localhost' IDENTIFIED BY 'nu';
    mysql> GRANT ALL PRIVILEGES ON notes.* TO 'notesuser'@'localhost';
    58:~ $ mysql -unotesuser -hlocalhost notes -p
    mysql> CREATE TABLE notes (
    mysql> INSERT INTO notes(description,content) VALUES (
    'Note 1', 'The content of note 1.');
    mysql> INSERT INTO notes(description,content) VALUES ('Note 2', 'The content of note 2.');
    mysql> SELECT * FROM  notes;
    id | description | content  | created  |
    1 | Note 1  | The content of note 1. | 2016-05-26 11:32:18 |
    2 | Note 2  | The content of note 2. | 2016-05-26 11:32:29 |
    B4J Class jRDC2
    The reference used.
    Changes to original code:
    Config.properties file: Set the location to File.DirApp instead if File.DirAssets to be flexible in changing the configuration with rebuild the class.

    Read the config.properties file located in the dirapps folder.

    Example extracts output running jRDC2 on the RPi
    is running (version = 2.11)
    Command: query: select3, took: 1623ms, client=
    Command: query: select3, took: 44ms, client=
    B4J UI application RDCClientUI
    * CRUD (Create, Read, Update, Delete) operations from the Remote MySQL database (defined in jRDC2 config.properties)
    * Show the records in a tableview, set initial tableview message (Java API method using JavaObject).
    * Toastmessage dialog when waiting for database operation to complete (Library jRLDialogs8).
    * Toolbar used for the buttons (Java API methods using JavaObject).
    * Set styling for buttons & toolbar (Library CSSUtils).
    * Set styling for tooltips (external CSS file in the dirassets folder)

    Class DBRequestManager
    Changes to original code:
    Modified Image handling by setting conditional defines for B4A and B4J.

    Read the attached source code which is well documented.

    The application is running well.
    Hint: On the RPI 3 turn the WLAN power off (define in /etc/rc.local: iw dev wlan0 set power_save off).


    B4J Bridge

    While developing, the B4J Bridge was running on the RPi. Ensure to copy the config.properties to the tempjars folder.
    Hint: Create the tempjars folder as user pi, which makes it easier to copy the update config.properties file.


    Attached Files:

    Johan Hormaza, KMatle, Erel and 2 others like this.
  2. Johan Hormaza

    Johan Hormaza Active Member Licensed User

    ¡Gran trabajo!
    rwblinn and José J. Aguilar like this.
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