javafx学习之数据库操作

上次我们学习的javafx连接数据库的简单操作,这次我们来做一个稍为复杂的操作数据库示例.IDE是:netbeans 6 beat 2,数据库用javaDB(jdb6自带有javaDB数据库,netbeans 6也带有,本例使用IDE自带的javaDB),由于水平问题中文只注解了部份代码,请见谅.(如出错,请把

上次我们学习的javafx连接数据库的简单操作,这次我们来做一个稍为复杂的操作数据库示例.IDE是:netbeans 6 beat 2,数据库用javaDB(jdb6自带有javaDB数据库,netbeans 6也带有,本例使用IDE自带的javaDB),由于水平问题中文只注解了部份代码,请见谅.(如出错,请把中文注解删除)

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;

//-------------------------连接数据库-----------------------------------
operation Database.connect() {
// Load driver class using context class loader
// 加载驱动
var thread = Thread.currentThread();
var classLoader = thread.getContextClassLoader();
var driverClass = classLoader.loadClass(this.driverName);

// Instantiate and register JDBC driver
//实例并注册驱动
this.driver = (Driver) driverClass.instantiate(); // JavaFX Class
DriverManager.registerDriver(driver);

// Connect to database
//连接数据库
this.conn = DriverManager.getConnection(this.jdbcUrl, this.user, this.password);
}// Database.connect

//--------------------关闭资源---------------------------
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
//检查表是否存在，注意这里并没有主动去删除
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;

//---------------------------数据插入---------------------------
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
//往数据库插入一条记录
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
//从数据库得到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){
//以对话框的形式弹出异常
MessageDialog {
messageType: ERROR//消息内型
title : "TODO - Add userName"//标题
message : "SQL: {e.getMessage()}"//消息体
visible : true//可见
}// MessageDialog
} finally {
this.conn.setAutoCommit(true);//自动提交
}
}// if(this.usedb)
}// trigger on insert userName

//---------------------------数据删除------------------------------------
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();
//从数据库删除一条记录
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'//数据库驱动类
jdbcUrl : 'jdbc:derby://localhost:1527/sample'//数据库连接url
user : 'app'//用户名
password : 'app'};//密码

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

//-------------------------------创建表----------------------------
try {
// Connect to database

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

// Create table
//创建表,并插入两条记录
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;
//从数据库读取记录，并插入到model.userNames（其实就是显示在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();//面板关闭，关闭数据库相关资源
}

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

//增加按钮，点击增加一条记录
Button {
text : 'Add'
enabled: bind model.newuserName.length() > 0
action : operation() {
insert userName{userName: model.newuserName} into model.userNames;
model.newuserName = '';
}
}, // Button
//删除按钮，点击删除一条记录
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();
}