上次我們學習的javafx連線資料庫的簡單操作,這次我們來做一個稍為複雜的操作資料庫示例.IDE是:netbeans 6 beat 2,資料庫用javaDB(jdb6自帶有javaDB資料庫,netbeans 6也帶有,本例使用IDE自帶的javaDB),由於水平問題中文只註解了部份程式碼,請見諒.(如出錯,請把中文註解刪除)

import javafx.ui.*;
import java.lang.Thread;
import java.lang.Exception;
import java.sql.*;
import org.apache.derby.jdbc.*;

// Connect to database

public class Database {
    public attribute driverName: String;
    public attribute jdbcUrl   : String;
    public attribute user      : String;
    public attribute password  : String;

    public attribute driver    : Driver;
    public attribute conn      : Connection;

    public operation connect();
    public operation shutdown();

    public operation tableExists(table: String);
}// Database

attribute Database.conn = null;

//-------------------------連線資料庫-----------------------------------
operation Database.connect() {
    // Load driver class using context class loader
    // 載入驅動
    var thread      = Thread.currentThread();
    var classLoader = thread.getContextClassLoader();
    var driverClass = classLoader.loadClass(this.driverName);

    // Instantiate and register JDBC driver
    //例項並註冊驅動
    this.driver = (Driver) driverClass.instantiate();  // JavaFX Class
    DriverManager.registerDriver(driver);

    // Connect to database
    //連線資料庫
    this.conn = DriverManager.getConnection(this.jdbcUrl, this.user, this.password);
}// Database.connect

//--------------------關閉資源---------------------------
operation Database.shutdown() {
    var stmt: Statement = null;

    if(null <> this.conn) {
        try {
            stmt = this.conn.createStatement();
            stmt.close();
        } catch(e:SQLException) {           
            e.printStackTrace();
        } finally {
            if(null <> stmt) {stmt.close();}
            this.conn.close();
        }
    }// if(null <> stmt)
}// operation.Database.shutdown

operation Database.tableExists(table: String)
{
    // Check if table exists
   //檢查表是否存在，注意這裡並沒有主動去刪除
    var tableExists = false;
    var dbmd        = this.conn.getMetaData();
    var rs          = dbmd.getTables(null, null, '%', ['TABLE']);
  
    while(rs.next()) {
        if(table == rs.getString(3)) {
            tableExists = true;
            break;
        }
    }// while(rs.next())
   
   
    return tableExists;
}// tableExists

// Single userName in the Todo list

class userName {
    attribute id  : Number;
    attribute userName: String;
}// userName

// Todo list

class TODO {
    attribute userNames       : userName*;
    attribute selecteduserName: Number;
    attribute newuserName     : String;

    attribute conn        : Connection;
    attribute usedb       : Boolean;
}// TODO

TODO.conn  = null;
TODO.usedb = true;

//---------------------------資料插入---------------------------
trigger on insert userName into TODO.userNames {  
    // TODO: Remove userName from ListBox if an error occurs

    if(this.usedb) {
        try {
            var stmt: Statement = this.conn.createStatement();

            this.conn.setAutoCommit(false);

            // Insert new userName in database
            //往資料庫插入一條記錄
            var rows = stmt.executeUpdate("INSERT INTO Uuser (userName) VALUES('{userName.userName}')");
            println("INSERT rows: {rows} for {userName.userName}");

            // Get userName of the userName from database
            //從資料庫得到userName
            var rs = stmt.executeQuery('SELECT userName FROM Uuser');
            if(rs.next()) {
                userName.userName = rs.getString(1);
                this.conn.commit();
            }// if(rs.next())
        } catch(e:SQLException){
            //以對話方塊的形式彈出異常
            MessageDialog {
                messageType: ERROR//訊息內型
                title      : "TODO - Add userName"//標題
                message    : "SQL: {e.getMessage()}"//訊息體
                visible    : true//可見
            }// MessageDialog      
        } finally {
            this.conn.setAutoCommit(true);//自動提交
        }
    }// if(this.usedb)       
}// trigger on insert userName

//---------------------------資料刪除------------------------------------
trigger on delete userName from TODO.userNames {
    // TODO: Insert userName again in ListBox if an error occurs

    if(this.usedb) {
        try {
            var stmt: Statement = this.conn.createStatement();
           //從資料庫刪除一條記錄
            var rows = stmt.executeUpdate("DELETE FROM Uuser WHERE userName = '{userName.userName}'");
            println("DELETE rows: {rows} for {userName.userName}");
        } catch(e:SQLException) {
            MessageDialog {
                messageType: ERROR
                title      : "TODO - Delete userName"
                message    : "SQL: {e.getMessage()}"
                visible    : true
            }// MessageDialog 
        }
    }// if(this.usedb)
}// trigger on delete

// Database vars

var db  : Database  = null;
var stmt: Statement = null;
var rs  : ResultSet = null;

var rows: Number;

db = Database{driverName: 'org.apache.derby.jdbc.ClientDriver'//資料庫驅動類
              jdbcUrl   : 'jdbc:derby://localhost:1527/sample'//資料庫連線url
              user      : 'app'//使用者名稱
              password  : 'app'};//密碼
                 

var model = TODO {
    conn: bind lazy db.conn
};

//-------------------------------建立表----------------------------
try {
    // Connect to database

    db.connect();
    stmt = db.conn.createStatement();

    // Create table
    //建立表,並插入兩條記錄
    if(not db.tableExists('Uuser'))
    {
        rows = stmt.executeUpdate("CREATE TABLE Uuser(id   INT  , userName VARCHAR(50))");
        println("CREATE TABLE rows: {rows}");                                           

        rows = stmt.executeUpdate("INSERT INTO Uuser VALUES(1, 'do')");
        println("INSERT rows: {rows}");

        rows = stmt.executeUpdate("INSERT INTO Uuser VALUES(2, 'did')");
        println("INSERT rows: {rows}");

       
    }// if(not db.tableExists('Uuser'))

    // Get userNames from database and add userNames to model.userNames (ListBox)
   
    model.usedb = false;
    //從資料庫讀取記錄，並插入到model.userNames（其實就是顯示在listBox)
    var rs = stmt.executeQuery("SELECT * FROM Uuser ORDER BY id ASC");
   
    while(rs.next()) {
        println("id: {rs.getInt('id')} userName: {rs.getString('userName')}");
        insert userName{id: rs.getInt('id') userName: rs.getString('userName')} into model.userNames;
    }
   
    model.usedb = true;

//--------------------------面板-----------------------------
    Frame {
        title  : "TODO list with JFXTrigger Example"
        onClose: function() {
            return db.shutdown();//面板關閉，關閉資料庫相關資源
        }

        content: BorderPanel {
            center: ListBox {
                selection: bind model.selecteduserName
                cells    : bind foreach (userName in model.userNames)
                    ListCell {
                       text: userName.userName
                    }
            }// ListBox

            bottom: FlowPanel {
                content: [
                    TextField {
                        columns: 30
                        value  : bind model.newuserName
                    }, // TextField

                   //增加按鈕，點選增加一條記錄
                    Button {
                        text   : 'Add'
                        enabled: bind model.newuserName.length() > 0
                        action : operation() {
                            insert userName{userName: model.newuserName} into model.userNames;
                            model.newuserName = '';
                        }
                    }, // Button
                   //刪除按鈕，點選刪除一條記錄
                    Button {
                       text   : 'Delete'
                       enabled: bind sizeof model.userNames > 0
                       action : operation() {
                           delete model.userNames[model.selecteduserName];
                       }// Button
                    }
                ]// content
            }// FlowPanel
        }// BorderPanel
       
        visible: true
    }// Frame
          
} catch(e:SQLException) {
    e.printStackTrace();
}