Java+Swing: 数据回显和修改功能的实现 整理14
1. 数据回显
其实数据回显就是为修改功能的实现做准备的
1.1 在MainView类中，创建一个方法获取选中行的id
// 获取选中的行的id
public int[] getSelectedRowIds() {
int[] selectedRows = mainViewTable.getSelectedRows();
int[] ids = new int[selectedRows.length]; // 用来存储id
for (int i = 0; i < selectedRows.length; i++) {
int selectedRowIndex = selectedRows[i];
Object idObj = mainViewTable.getValueAt(selectedRowIndex, 0);
ids[i]= Integer.parseInt(idObj.toString()); // toString()是将转为字符串的类型
}
return ids;
}1.2 给按钮添加点击事件
1.3 在MainViewHandler进行相应的处理
if ("修改".equals(text)){
int[] selectedRowIds = mainView.getSelectedRowIds();
if (selectedRowIds.length != 1) {
JOptionPane.showMessageDialog(mainView, "请选择一条记录！");
return;
}
new UpdateStudentView(mainView, selectedRowIds[0]);
}
1.4 编写UpdateStudentView界面代码
与上一篇博客中的添加数据界面相同，直接给出代码了
package com.student_view;
import com.entity.Student;
import com.handler.UpdateStudentViewHandler;
import com.service.Impl.StudentServiceImpl;
import javax.swing.*;
import java.awt.*;
/**
* @Author：xiexu
* @Date：2023/12/16 21:52
*/
public class UpdateStudentView extends JDialog {
// 声明一系列组件
JPanel jPanel = new JPanel(new FlowLayout(FlowLayout.CENTER, 10, 20));
JLabel idLabel = new JLabel("学号", JLabel.RIGHT);
JTextField idTextField = new JTextField();
JLabel nameLabel = new JLabel("姓名", JLabel.RIGHT); // 第二个参数表示水平的排列方式
JTextField nameTextField = new JTextField();
JLabel noLabel = new JLabel("学号", JLabel.RIGHT);
JTextField noTextField = new JTextField();
JLabel homeLabel = new JLabel("家乡", JLabel.RIGHT);
JTextField homeTextField = new JTextField();
JLabel chineseLabel = new JLabel("语文成绩", JLabel.RIGHT);
JTextField chineseTextField = new JTextField();
JLabel mathLabel = new JLabel("数学成绩", JLabel.RIGHT);
JTextField mathTextField = new JTextField();
JLabel englishLabel = new JLabel("英语成绩", JLabel.RIGHT);
JTextField englishTextField = new JTextField();
JButton updateBtn = new JButton("修改");
public UpdateStudentView(MainView mainView, int selectedRowId) {
super(mainView, "修改学生信息",true);
// 添加各组件到面板上
idLabel.setPreferredSize(new Dimension(80, 30));
jPanel.add(idLabel);
idTextField.setPreferredSize(new Dimension(200, 30));
jPanel.add(idTextField);
nameLabel.setPreferredSize(new Dimension(80, 30));
jPanel.add(nameLabel);
nameTextField.setPreferredSize(new Dimension(200, 30));
jPanel.add(nameTextField);
noLabel.setPreferredSize(new Dimension(80, 30));
jPanel.add(noLabel);
noTextField.setPreferredSize(new Dimension(200, 30));
jPanel.add(noTextField);
homeLabel.setPreferredSize(new Dimension(80, 30));
jPanel.add(homeLabel);
homeTextField.setPreferredSize(new Dimension(200, 30));
jPanel.add(homeTextField);
chineseLabel.setPreferredSize(new Dimension(80, 30));
jPanel.add(chineseLabel);
chineseTextField.setPreferredSize(new Dimension(200, 30));
jPanel.add(chineseTextField);
mathLabel.setPreferredSize(new Dimension(80, 30));
jPanel.add(mathLabel);
mathTextField.setPreferredSize(new Dimension(200, 30));
jPanel.add(mathTextField);
englishLabel.setPreferredSize(new Dimension(80, 30));
jPanel.add(englishLabel);
englishTextField.setPreferredSize(new Dimension(200, 30));
jPanel.add(englishTextField);
jPanel.add(updateBtn);
Container contentPane = getContentPane();
contentPane.add(jPanel);
setSize(350, 500);
setLocationRelativeTo(null);
// DISPOSE_ON_CLOSE 只销毁当前窗体
setDefaultCloseOperation(DISPOSE_ON_CLOSE);
setResizable(false);
setVisible(true);
}
}
1.5 实现数据回显
就是根据传过来的id值，查询数据库，在展示到对应的表单中
1.5.1 接口
Student getById(int selectedRowId);1.5.2 实现类
// 根据 id 查询
@Override
public Student getById(int selectedRowId) {
StringBuilder sql = new StringBuilder();
sql.append("select * from detail where id = ?");
// 执行
Connection connection = null;
PreparedStatement preparedStatement = null;
ResultSet resultSet = null;
Student student = new Student();// 返回的数据
try {
connection = DBUtil.getConnection();
preparedStatement = connection.prepareStatement(sql.toString());
preparedStatement.setInt(1, selectedRowId);
resultSet = preparedStatement.executeQuery(); // 执行查询返回结果集
while (resultSet.next()) {
// 遍历查询的每一条记录
int id = resultSet.getInt("id");
String name = resultSet.getString("name");
String no = resultSet.getString("no");
String homeTown = resultSet.getString("homeTown");
double chinese = resultSet.getDouble("chinese");
double math = resultSet.getDouble("math");
double english = resultSet.getDouble("english");
student.setId(id);
student.setName(name);
student.setNo(no);
student.setHomeTown(homeTown);
student.setChinese(chinese);
student.setMath(math);
student.setEnglish(english);
}
return student;
}catch (Exception e) {
e.printStackTrace();
} finally {
DBUtil.closeRS(resultSet);
DBUtil.closePS(preparedStatement);
DBUtil.closeConnection(connection);
}
return null;
}1.5.3 在updateStudentView中对返回的结果进行相应的处理
// 查询selectedRowIds对应的数据并回显
StudentServiceImpl studentService = new StudentServiceImpl();
Student selectedStudent = studentService.getById(selectedRowId);把返回的结果设置到相应的表单中，注意id需设为不可编辑 ，这里只给出了部分，其他的组件也是一样的写法
1.5.4 效果
2. 修改数据
在上面的基础上，对修改数据的模态框进行处理
2.1 给模态框中的修改按钮添加点击事件
2.2 编写事件处理类updateStudentViewHandler
以下代码中给出了框架，具体的逻辑还没实现，具体的实现继续往下看
package com.handler;
import com.entity.Student;
import com.service.Impl.StudentServiceImpl;
import com.student_view.MainView;
import com.student_view.UpdateStudentView;
import javax.swing.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
/**
* @Author：xiexu
* @Date：2023/12/18 17:33
*/
public class UpdateStudentViewHandler implements ActionListener {
private UpdateStudentView updateStudentView;
private MainView mainView;
public UpdateStudentViewHandler(UpdateStudentView updateStudentView, MainView mainView) {
this.updateStudentView = updateStudentView;
this.mainView = mainView;
}
@Override
public void actionPerformed(ActionEvent e) {
JButton jButton = (JButton) e.getSource();
String text = jButton.getText();
if ("修改".equals(text)) {
.......
if (...) {
// 重新加载表格查到最新数据
mainView.reloadTable();
updateStudentView.dispose();
} else {
// 添加错误，给出提示
JOptionPane.showMessageDialog(updateStudentView, "添加失败");
}
}
}
}
2.3 在updateStudentView中实例化
需要传递两个参数，这边将mainView传过去，是便于修改数据成功后，调用reloadTable方法，重新加载表格。
UpdateStudentViewHandler updateStudentViewHandler;
updateStudentViewHandler = new UpdateStudentViewHandler(this, mainView);
2.4 实现数据的修改操作逻辑
2.4.1 接口
boolean update(Student student);2.4.2 实现类
// 修改/更新
@Override
public boolean update(Student student) {
StringBuilder sql = new StringBuilder();
sql.append("update detail set name=?, no=?, homeTown=?, chinese=?, math=?, english=?");
sql.append("where id = ?");
// 执行
Connection connection = null;
PreparedStatement preparedStatement = null;
ResultSet resultSet = null;
TableDTO tableDTO = new TableDTO(); // 返回的数据
try {
connection = DBUtil.getConnection();
preparedStatement = connection.prepareStatement(sql.toString());
preparedStatement.setString(1, student.getName());
preparedStatement.setString(2, student.getNo());
preparedStatement.setString(3, student.getHomeTown());
preparedStatement.setDouble(4, student.getChinese());
preparedStatement.setDouble(5, student.getMath());
preparedStatement.setDouble(6, student.getEnglish());
preparedStatement.setInt(7,student.getId());
return preparedStatement.executeUpdate() == 1; // 执行查询返回结果集
}catch (Exception e) {
e.printStackTrace();
} finally {
DBUtil.closeRS(resultSet);
DBUtil.closePS(preparedStatement);
DBUtil.closeConnection(connection);
}
return false;
}2.4.3 补全上述的代码
2.4.4 上述也是需要一个方法将属性值封装成一个对象
public Student builStudent() {
Student student = new Student();
student.setId(Integer.valueOf(idTextField.getText()));
student.setName(nameTextField.getText());
student.setNo(noTextField.getText());
student.setHomeTown(homeTextField.getText());
student.setChinese(Double.parseDouble(chineseTextField.getText()));
student.setMath(Double.parseDouble(mathTextField.getText()));
student.setEnglish(Double.parseDouble(englishTextField.getText()));
return student;
}