TableModel，导致Java JFrame中的数据库信息重复
我在一个JFrame中设置了这个方法，当用户按下按钮“加载文件”时调用它；但是，当用户再次按下按钮时。他们在第一个表的下面有另一个表，所以所有的信息都会被复制，并扩展到我的“不可调整大小”框架之外 无论用户按下按钮多少次，我如何让它只加载一个表TableModel，导致Java JFrame中的数据库信息重复,java,swing,jdbc,jframe,tablemodel,Java,Swing,Jdbc,Jframe,Tablemodel,我在一个JFrame中设置了这个方法，当用户按下按钮“加载文件”时调用它；但是，当用户再次按下按钮时。他们在第一个表的下面有另一个表，所以所有的信息都会被复制，并扩展到我的“不可调整大小”框架之外 无论用户按下按钮多少次，我如何让它只加载一个表 JButton btnLoad = new JButton("Load File") private void GetAction() { ActionHandler handler = new ActionHandler();
JButton btnLoad = new JButton("Load File")
private void GetAction()
{
ActionHandler handler = new ActionHandler();
btnLoad.addActionListener(handler);
}
private class ActionHandler implements ActionListener
{
public void actionPerformed(ActionEvent evt)
{
String incmd = evt.getActionCommand();
if (incmd.equals("Load File")) // If Load File button is pressed
DatabaseLoad();
else if (incmd.equals("Exit")) // If Exit button is pressed
System.exit(0);
}
}
private void DatabaseLoad()
{
try
{
// The driver allows you to query the database with Java
// forName dynamically loads the class for you
Class.forName("com.mysql.jdbc.Driver");
// DriverManager is used to handle a set of JDBC drivers
// getConnection establishes a connection to the database
// You must also pass the userid and password for the database
String url = "jdbc:mysql://localhost:3306/charity";
conn = DriverManager.getConnection (url,"root","password");
// Statement objects executes a SQL query
// createStatement returns a Statement object
Statement sqlState = conn.createStatement();
// This is the query I'm sending to the database
String selectStuff = "SELECT `name`, `charity`, `amount` FROM `charity`.`donations` ";
// A ResultSet contains a table of data representing the
// results of the query. It can not be changed and can
// only be read in one direction
rows = sqlState.executeQuery(selectStuff);
// Temporarily holds the row results
Object[] tempRow;
// next is used to iterate through the results of a query
while(rows.next()){
// Gets the column values based on class type expected
tempRow = new Object[]{rows.getString(1), rows.getString(2), rows.getDouble(3) };
// Adds the row of data to the end of the model
dTableModel.addRow(tempRow);
}
// Successfully loaded, message the user
message1.setText("<html><font color='red'>Database Info Loaded</font>");
message2.setText("");
}
catch (SQLException ex)
{
// String describing the error
System.out.println("SQLException: " + ex.getMessage());
// Vendor specific error code
System.out.println("VendorError: " + ex.getErrorCode());
}
catch (ClassNotFoundException e)
{
// Executes if the driver can't be found
System.out.println("Driver Cannot be found");
e.printStackTrace();
}
// Create a JTable using the custom DefaultTableModel
JTable table = new JTable(dTableModel);
// Increase the font size for the cells in the table
table.setFont(new Font("Serif", Font.PLAIN, 16));
// Increase the size of the cells to allow for bigger fonts
table.setRowHeight(table.getRowHeight()+5);
// Allows the user to sort the data
table.setAutoCreateRowSorter(true);
// right justify amount column
TableColumn tc = table.getColumn("amount");
RightTableCellRenderer rightRenderer = new RightTableCellRenderer();
tc.setCellRenderer(rightRenderer);
// Disable auto resizing
table.setAutoResizeMode(JTable.AUTO_RESIZE_OFF);
// Set the width for the columns
TableColumn col1 = table.getColumnModel().getColumn(0);
col1.setPreferredWidth(200);
TableColumn col2 = table.getColumnModel().getColumn(1);
col2.setPreferredWidth(275);
TableColumn col3 = table.getColumnModel().getColumn(2);
col3.setPreferredWidth(75);
// Put the table in a scrollpane and add scrollpane to the frame
JScrollPane scrollPane = new JScrollPane(table);
scrollPane.setPreferredSize(new Dimension(552, 400));
this.add(scrollPane, BorderLayout.CENTER);
}
// To change justification to the right
class RightTableCellRenderer extends DefaultTableCellRenderer {
public RightTableCellRenderer() {
setHorizontalAlignment(JLabel.RIGHT);
}
}
JButton btnLoad=newjbutton（“加载文件”）
私有void GetAction（）
{
ActionHandler=新的ActionHandler（）；
btnLoad.addActionListener（处理程序）；
}
私有类ActionHandler实现ActionListener
{
已执行的公共无效操作（操作事件evt）
{
字符串incmd=evt.getActionCommand（）；
if（incmd.equals（“加载文件”）//如果按下加载文件按钮
数据库加载（）；
else if（incmd.equals（“Exit”）//如果按下Exit按钮
系统出口（0）；
}
}
私有void数据库加载（）
{
尝试
{
//该驱动程序允许您使用Java查询数据库
//forName为您动态加载类
Class.forName（“com.mysql.jdbc.Driver”）；
//DriverManager用于处理一组JDBC驱动程序
//getConnection建立到数据库的连接
//您还必须传递数据库的用户ID和密码
String url=“jdbc:mysql://localhost:3306/charity";
conn=DriverManager.getConnection（url，“根”，“密码”）；
//语句对象执行SQL查询
//createStatement返回一个语句对象
语句sqlState=conn.createStatement（）；
//这是我发送到数据库的查询
String selectStuff=“选择'name'、'charity'、'amount`来自'charity`.'investments`”；
//ResultSet包含一个数据表，表示
//查询的结果。它不能更改，并且可以
//只能从一个方向读取
rows=sqlState.executeQuery（selectStuff）；
//暂时保存行结果
对象[]临时行；
//next用于遍历查询结果
while（rows.next（））{
//根据预期的类类型获取列值
tempRow=newobject[]{rows.getString（1），rows.getString（2），rows.getDouble（3）}；
//将数据行添加到模型的末尾
dTableModel.addRow（tempRow）；
}
//已成功加载，请向用户发送消息
message1.setText（“加载的数据库信息”）；
message2.setText（“”）；
}
catch（SQLException-ex）
{
//描述错误的字符串
System.out.println（“SQLException:+ex.getMessage（））；
//供应商特定错误代码
System.out.println（“vendoerror:+ex.getErrorCode（））；
}
catch（classnotfounde异常）
{
//如果找不到驱动程序，则执行
System.out.println（“找不到驱动程序”）；
e、 printStackTrace（）；
}
//使用自定义DefaultTableModel创建JTable
JTable table=新的JTable（dTableModel）；
//增加表格中单元格的字体大小
表.setFont（新字体（“衬线”，Font.PLAIN，16））；
//增加单元格的大小以允许使用更大的字体
table.setRowHeight（table.getRowHeight（）+5）；
//允许用户对数据进行排序
表.setAutoCreateRowSorter（真）；
//右对齐金额列
TableColumn tc=table.getColumn（“金额”）；
RightTableCellRenderer rightRenderer=新的RightTableCellRenderer（）；
tc.setCellRenderer（右渲染器）；
//禁用自动调整大小
table.setAutoResizeMode（JTable.AUTO_RESIZE_OFF）；
//设置列的宽度
TableColumn col1=table.getColumnModel（）.getColumn（0）；
col1.设置首选宽度（200）；
TableColumn col2=table.getColumnModel（）.getColumn（1）；
col2.设置首选宽度（275）；
TableColumn col3=table.getColumnModel（）.getColumn（2）；
col3.设置首选宽度（75）；
//将表格放在滚动窗格中，并将滚动窗格添加到框架中
JScrollPane scrollPane=新的JScrollPane（表）；
scrollPane.setPreferredSize（新维度（552400））；
添加（滚动窗格，BorderLayout.CENTER）；
}
//右转
类RightTableCellRenderer扩展了DefaultTableCellRenderer{
public RightTableCellRenderer（）{
设置水平对齐（JLabel.RIGHT）；
}
}
JButton btnLoad = new JButton("Load File")
private void GetAction()
{
ActionHandler handler = new ActionHandler();
btnLoad.addActionListener(handler);
}
private class ActionHandler implements ActionListener
{
public void actionPerformed(ActionEvent evt)
{
String incmd = evt.getActionCommand();
if (incmd.equals("Load File")) // If Load File button is pressed
DatabaseLoad();
else if (incmd.equals("Exit")) // If Exit button is pressed
System.exit(0);
}
}
private void DatabaseLoad()
{
try
{
// The driver allows you to query the database with Java
// forName dynamically loads the class for you
Class.forName("com.mysql.jdbc.Driver");
// DriverManager is used to handle a set of JDBC drivers
// getConnection establishes a connection to the database
// You must also pass the userid and password for the database
String url = "jdbc:mysql://localhost:3306/charity";
conn = DriverManager.getConnection (url,"root","password");
// Statement objects executes a SQL query
// createStatement returns a Statement object
Statement sqlState = conn.createStatement();
// This is the query I'm sending to the database
String selectStuff = "SELECT `name`, `charity`, `amount` FROM `charity`.`donations` ";
// A ResultSet contains a table of data representing the
// results of the query. It can not be changed and can
// only be read in one direction
rows = sqlState.executeQuery(selectStuff);
// Temporarily holds the row results
Object[] tempRow;
// next is used to iterate through the results of a query
while(rows.next()){
// Gets the column values based on class type expected
tempRow = new Object[]{rows.getString(1), rows.getString(2), rows.getDouble(3) };
// Adds the row of data to the end of the model
dTableModel.addRow(tempRow);
}
// Successfully loaded, message the user
message1.setText("<html><font color='red'>Database Info Loaded</font>");
message2.setText("");
}
catch (SQLException ex)
{
// String describing the error
System.out.println("SQLException: " + ex.getMessage());
// Vendor specific error code
System.out.println("VendorError: " + ex.getErrorCode());
}
catch (ClassNotFoundException e)
{
// Executes if the driver can't be found
System.out.println("Driver Cannot be found");
e.printStackTrace();
}
// Create a JTable using the custom DefaultTableModel
JTable table = new JTable(dTableModel);
// Increase the font size for the cells in the table
table.setFont(new Font("Serif", Font.PLAIN, 16));
// Increase the size of the cells to allow for bigger fonts
table.setRowHeight(table.getRowHeight()+5);
// Allows the user to sort the data
table.setAutoCreateRowSorter(true);
// right justify amount column
TableColumn tc = table.getColumn("amount");
RightTableCellRenderer rightRenderer = new RightTableCellRenderer();
tc.setCellRenderer(rightRenderer);
// Disable auto resizing
table.setAutoResizeMode(JTable.AUTO_RESIZE_OFF);
// Set the width for the columns
TableColumn col1 = table.getColumnModel().getColumn(0);
col1.setPreferredWidth(200);
TableColumn col2 = table.getColumnModel().getColumn(1);
col2.setPreferredWidth(275);
TableColumn col3 = table.getColumnModel().getColumn(2);
col3.setPreferredWidth(75);
// Put the table in a scrollpane and add scrollpane to the frame
JScrollPane scrollPane = new JScrollPane(table);
scrollPane.setPreferredSize(new Dimension(552, 400));
this.add(scrollPane, BorderLayout.CENTER);
}
// To change justification to the right
class RightTableCellRenderer extends DefaultTableCellRenderer {
public RightTableCellRenderer() {
setHorizontalAlignment(JLabel.RIGHT);
}
}
table.setModel( updatedModel );
JButton btnLoad = new JButton("Load File")
private void GetAction()
{
ActionHandler handler = new ActionHandler();
btnLoad.addActionListener(handler);
}
private class ActionHandler implements ActionListener
{
public void actionPerformed(ActionEvent evt)
{
String incmd = evt.getActionCommand();
if (incmd.equals("Load File")) // If Load File button is pressed
DatabaseLoad();
else if (incmd.equals("Exit")) // If Exit button is pressed
System.exit(0);
}
}
private void DatabaseLoad()
{
try
{
// The driver allows you to query the database with Java
// forName dynamically loads the class for you
Class.forName("com.mysql.jdbc.Driver");
// DriverManager is used to handle a set of JDBC drivers
// getConnection establishes a connection to the database
// You must also pass the userid and password for the database
String url = "jdbc:mysql://localhost:3306/charity";
conn = DriverManager.getConnection (url,"root","password");
// Statement objects executes a SQL query
// createStatement returns a Statement object
Statement sqlState = conn.createStatement();
// This is the query I'm sending to the database
String selectStuff = "SELECT `name`, `charity`, `amount` FROM `charity`.`donations` ";
// A ResultSet contains a table of data representing the
// results of the query. It can not be changed and can
// only be read in one direction
rows = sqlState.executeQuery(selectStuff);
// Temporarily holds the row results
Object[] tempRow;
// next is used to iterate through the results of a query
while(rows.next()){
// Gets the column values based on class type expected
tempRow = new Object[]{rows.getString(1), rows.getString(2), rows.getDouble(3) };
// Adds the row of data to the end of the model
dTableModel.addRow(tempRow);
}
// Successfully loaded, message the user
message1.setText("<html><font color='red'>Database Info Loaded</font>");
message2.setText("");
}
catch (SQLException ex)
{
// String describing the error
System.out.println("SQLException: " + ex.getMessage());
// Vendor specific error code
System.out.println("VendorError: " + ex.getErrorCode());
}
catch (ClassNotFoundException e)
{
// Executes if the driver can't be found
System.out.println("Driver Cannot be found");
e.printStackTrace();
}
// Create a JTable using the custom DefaultTableModel
JTable table = new JTable(dTableModel);
// Increase the font size for the cells in the table
table.setFont(new Font("Serif", Font.PLAIN, 16));
// Increase the size of the cells to allow for bigger fonts
table.setRowHeight(table.getRowHeight()+5);
// Allows the user to sort the data
table.setAutoCreateRowSorter(true);
// right justify amount column
TableColumn tc = table.getColumn("amount");
RightTableCellRenderer rightRenderer = new RightTableCellRenderer();
tc.setCellRenderer(rightRenderer);
// Disable auto resizing
table.setAutoResizeMode(JTable.AUTO_RESIZE_OFF);
// Set the width for the columns
TableColumn col1 = table.getColumnModel().getColumn(0);
col1.setPreferredWidth(200);
TableColumn col2 = table.getColumnModel().getColumn(1);
col2.setPreferredWidth(275);
TableColumn col3 = table.getColumnModel().getColumn(2);
col3.setPreferredWidth(75);
// Put the table in a scrollpane and add scrollpane to the frame
JScrollPane scrollPane = new JScrollPane(table);
scrollPane.setPreferredSize(new Dimension(552, 400));
this.add(scrollPane, BorderLayout.CENTER);
}
// To change justification to the right
class RightTableCellRenderer extends DefaultTableCellRenderer {
public RightTableCellRenderer() {
setHorizontalAlignment(JLabel.RIGHT);
}
}
table.setModel( updatedModel );
你能发布显示你的
ActionListenerJButtonActionListenerJButton