java访问mysql数据库资源-CSDN文库

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Java 访问 MySQL 数据库是开发应用程序时常见的需求，Swing 是 Java 提供的一个用于创建图形用户界面（GUI）的库。在这个项目中，我们利用 Swing 构建了一个界面，通过 JDBC（Java Database Connectivity）来连接和操作 MySQL 数据库。下面将详细讲解这个过程中的关键知识点。我们需要了解 JDBC，它是 Java 与数据库交互的标准接口。JDBC 提供了一组接口和类，使得 Java 应用程序可以连接到各种类型的数据库，包括 MySQL。在程序中，我们需要引入 MySQL 的 JDBC 驱动，通常使用以下依赖： ```xml <dependency> <groupId>mysql</groupId> <artifactId>mysql-connector-java</artifactId> <version>8.0.23</version> </dependency> ``` 接下来，我们需要编写代码来连接数据库。这通常涉及到以下几个步骤： 1. 加载驱动：`Class.forName("com.mysql.cj.jdbc.Driver");` 2. 创建连接：`Connection conn = DriverManager.getConnection(url, username, password);` 3. 创建 Statement 或 PreparedStatement 对象，用于执行 SQL 语句。 4. 执行 SQL 查询、更新等操作。 5. 处理结果集（ResultSet），如果查询返回数据的话。 6. 关闭连接、Statement 和 ResultSet。例如，一个简单的查询操作可能如下所示： ```java String url = "jdbc:mysql://localhost:3306/mydatabase"; String username = "root"; String password = "mypassword"; try (Connection conn = DriverManager.getConnection(url, username, password); Statement stmt = conn.createStatement(); ResultSet rs = stmt.executeQuery("SELECT * FROM mytable")) { while (rs.next()) { // 处理每一行数据 String column1 = rs.getString("column1"); int column2 = rs.getInt("column2"); // ... } } catch (SQLException e) { e.printStackTrace(); } ``` Swing 用于创建 GUI 的部分，主要包括组件（JButton, JTextField, JLabel 等）、布局管理器和事件监听器。例如，你可以创建一个 `JFrame` 作为窗口，添加 `JButton` 用于触发数据库操作，`JTextField` 用于输入查询条件，然后在按钮的点击事件中执行相应的 SQL 语句。 ```java import javax.swing.*; import java.awt.*; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; public class InensShow extends JFrame { private JButton queryButton; private JTextField conditionField; public InensShow() { // 初始化组件 queryButton = new JButton("查询"); conditionField = new JTextField(20); // 设置布局 setLayout(new FlowLayout()); // 添加组件 add(conditionField); add(queryButton); // 添加事件监听 queryButton.addActionListener(new ActionListener() { @Override public void actionPerformed(ActionEvent e) { String condition = conditionField.getText(); // 在这里编写查询逻辑，使用 condition 来构建 SQL } }); // 其他设置，如大小、位置等 } public static void main(String[] args) { SwingUtilities.invokeLater(() -> new InensShow().setVisible(true)); } } ``` 在实际项目中，为了提高代码的可维护性和可扩展性，通常会使用 MVC（Model-View-Controller）设计模式，将数据操作逻辑、视图显示和用户交互分离。模型（Model）负责处理数据库操作，视图（View）展示数据，控制器（Controller）处理用户输入并协调模型和视图。 `inensshow.java` 文件可能是这个 Swing 应用程序的主类，它包含了创建 GUI 并设置事件监听的代码。如果你需要进一步了解具体实现，建议查看该文件的源代码。这个项目结合了 Java 的 GUI 编程和数据库访问能力，通过 Swing 实现用户界面，使用 JDBC 连接并操作 MySQL 数据库。学习这些知识点对于开发任何基于 Java 的数据库应用都是非常有帮助的。

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Java_MySQL.rar （1个子文件）

inensshow.java 8KB

import java.sql.*; import javax.swing.*; import javax.swing.border.*; import java.awt.*; import java.awt.event.*; import java.util.*; public class inensshow extends JFrame { /*********************************** * ***********************************/ private static final long serialVersionUID = 1L; private Connection connection; private Statement statement; private ResultSet resultSet; //private ResultSetMetaData rsMetaData; //GUI变量定义 private JTable table; private JButton submitQuery; private JTextField fromYear; private JTextField fromMonth; private JTextField fromDay; private JTextField fromHour; private JTextField fromMinute; private JTextField fromSecond; private JTextField toYear; private JTextField toMonth; private JTextField toDay; private JTextField toHour; private JTextField toMinute; private JTextField toSecond; public inensshow() { super("Information search"); String url = "jdbc:mysql://localhost:3306/elevator"; String username = "root"; String password = "881026"; //加载驱动程序以连接数据库 try { Class.forName("org.gjt.mm.mysql.Driver"); connection = DriverManager.getConnection(url, username, password ); } //捕获加载驱动程序异常 catch ( ClassNotFoundException cnfex ) { System.err.println("装载 JDBC/ODBC 驱动程序失败。" ); //cnfex.printStackTrace(); System.exit(1); // terminate program } //捕获连接数据库异常 catch ( SQLException sqlex ) { System.err.println( "无法连接数据库" ); //sqlex.printStackTrace(); System.exit(1); // terminate program } //如果数据库连接成功，则建立GUI //SQL语句 submitQuery = new JButton( "查询" ); //Button事件 submitQuery.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent e) { //TO DO search(); } }); fromYear = new JTextField(); fromYear.setBorder(new TitledBorder("Year")); fromMonth = new JTextField(); fromMonth.setBorder(new TitledBorder("Month")); fromDay = new JTextField(); fromDay.setBorder(new TitledBorder("Day")); fromHour = new JTextField(); fromHour.setBorder(new TitledBorder("Hour")); fromMinute = new JTextField(); fromMinute.setBorder(new TitledBorder("Minute")); fromSecond = new JTextField(); fromSecond.setBorder(new TitledBorder("Second")); toYear = new JTextField(); toYear.setBorder(new TitledBorder("Year")); toMonth = new JTextField(); toMonth.setBorder(new TitledBorder("Month")); toDay = new JTextField(); toDay.setBorder(new TitledBorder("Day")); toHour = new JTextField(); toHour.setBorder(new TitledBorder("Hour")); toMinute = new JTextField(); toMinute.setBorder(new TitledBorder("Minute")); toSecond = new JTextField(); toSecond.setBorder(new TitledBorder("Second")); JPanel topLeftPanel = new JPanel(); topLeftPanel.setBorder(new TitledBorder("From time")); topLeftPanel.setLayout(new GridLayout(2,3)); topLeftPanel.add(fromYear); topLeftPanel.add(fromMonth); topLeftPanel.add(fromDay); topLeftPanel.add(fromHour); topLeftPanel.add(fromMinute); topLeftPanel.add(fromSecond); JPanel topRightPanel = new JPanel(); topRightPanel.setBorder(new TitledBorder("To time")); topRightPanel.setLayout(new GridLayout(2,3)); topRightPanel.add(toYear); topRightPanel.add(toMonth); topRightPanel.add(toDay); topRightPanel.add(toHour); topRightPanel.add(toMinute); topRightPanel.add(toSecond); JPanel topUpPanel = new JPanel(); topUpPanel.setLayout(new GridLayout(1,2)); topUpPanel.add(topLeftPanel); topUpPanel.add(topRightPanel); JPanel topPanel = new JPanel(); topPanel.setLayout(new BorderLayout()); //将"输入查询"编辑框布置到 "CENTER" topPanel.add(topUpPanel, BorderLayout.CENTER ); //将"提交查询"按钮布置到 "SOUTH" topPanel.add( submitQuery, BorderLayout.SOUTH ); table = new JTable(); Container c = getContentPane(); c.setLayout(new BorderLayout()); //将"topPanel"编辑框布置到 "NORTH" c.add(topPanel, BorderLayout.NORTH); //将"table"编辑框布置到 "CENTER" c.add(table, BorderLayout.CENTER); setSize(500, 300); setLocation(200,200); setVisible(true); //显示Form } public void insert(int year,int month,int day, int hour,int minute,int second,String message){ String str ="insert into log values('"; str += year+"'," + "'"+month+"','"+day+"','"; str += hour+"','"+minute+"','"+second+"','"; str += message+"')"; execute(str, false, true); } public void search() { int fromYear = 0; int fromMonth = 0; int fromDay = 0; int fromHour = 0; int fromMinute = 0; int fromSecond = 0; int toYear = 0; int toMonth = 0; int toDay = 0; int toHour = 0; int toMinute = 0; int toSecond = 0; try { fromYear = Integer.parseInt(this.fromYear.getText()); fromMonth = Integer.parseInt(this.fromMonth.getText()); fromDay = Integer.parseInt(this.fromDay.getText()); fromHour = Integer.parseInt(this.fromHour.getText()); fromMinute = Integer.parseInt(this.fromMinute.getText()); fromSecond = Integer.parseInt(this.fromSecond.getText()); toYear = Integer.parseInt(this.toYear.getText()); toMonth = Integer.parseInt(this.toMonth.getText()); toDay = Integer.parseInt(this.toDay.getText()); toHour = Integer.parseInt(this.toHour.getText()); toMinute = Integer.parseInt(this.toMinute.getText()); toSecond = Integer.parseInt(this.toSecond.getText()); }catch (Exception e){ JOptionPane.showMessageDialog(this, "数值错误!", "错误", 0); return; } String str = "select * from log where "; str += "year > " + fromYear + " and year < " + toYear + " and "; str += "month > " + fromMonth + " and month < " + toMonth + " and "; str += "day > " + fromDay + " and day < " + toDay + " and "; str += "hour > " + fromHour + " and hour < " + toHour + " and "; str += "minute > " + fromMinute + " and minute < " + toMinute + " and "; str += "second > " + fromSecond + " and second < " + toSecond + ";"; execute(str, true, false); } public void execute(String query, boolean display, boolean update) { try { //执行SQL语句 //String query = inputQuery.getText(); statement = connection.createStatement(); if(update) statement.executeUpdate(query); else resultSet = statement.executeQuery(query); //如果需要，则在表格中显示结果 if (display) displayResultSet(resultSet); }catch (SQLException sqlex) { sqlex.printStackTrace(); JOptionPane.showMessageDialog(this, "SQL错误!", "错误", 0); } } @SuppressWarnings("unchecked") private void displayResultSet(ResultSet rs)throws SQLException { //定位到达第一条记录 boolean moreRecords = rs.next(); //如果没有记录，则提示一条消息 if (!moreRecords) { JOptionPane.showMessageDialog(this,"无记录", "警告", 2); return; } Vector columnHeads = new Vector(); Vector rows = new Vector(); try { //获取字段的名称 ResultSetMetaData rsmd = rs.getMetaData(); for ( int i = 1; i <= rsmd.getColumnCount(); ++i ) columnHeads.addElement( rsmd.getColumnName( i ) ); //获取记录集 do { rows.addElement( getNextRow( rs, rsmd ) ); } while ( rs.next() ); //在表格中显示查询结果 table = new JTable( rows, columnHeads ); JScrollPane scroller = new JScrollPane( table ); Container c = getContentPane(); c.remove(1); c.add(scroller, BorderLayout.CENTER); //刷新Table c.validate(); }catch ( SQLException sqlex ) { //sqlex.printStackTrace(); } } @SuppressWarnings("unchecked") private Vector getNextRow(ResultSet rs,ResultSetMetaData rsmd) throws SQLException { Vector currentRow = new Vector(); for ( int

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