Mysql数据库 (JTree应用)

 package com.databases.jtree;

 import java.awt.FlowLayout;
 import java.awt.GridLayout;
 import java.awt.event.MouseAdapter;
 import java.awt.event.MouseEvent;
 import java.awt.event.MouseListener;
 import java.sql.Connection;
 import java.sql.DriverManager;
 import java.sql.ResultSet;
 import java.sql.ResultSetMetaData;
 import java.sql.SQLException;
 import java.sql.Statement;
 import java.util.ArrayList;

 import javax.swing.JFrame;
 import javax.swing.JOptionPane;
 import javax.swing.JPanel;
 import javax.swing.JScrollPane;
 import javax.swing.JTable;
 import javax.swing.JTree;
 import javax.swing.plaf.PanelUI;
 import javax.swing.table.DefaultTableModel;
 import javax.swing.tree.DefaultMutableTreeNode;
 import javax.swing.tree.TreePath;

 public class MainFrame extends JFrame {
     private Connection conn; // 数据库连接对象
     ResultSet rs;
     Statement st;
     private JTree tree;
     ArrayList<String> list = new ArrayList<>();
     private DefaultMutableTreeNode databases;
     public static JTable jtable;
     public static JScrollPane jScrollPane;

     public static JPanel p1 = new JPanel();
     public static JPanel p2 = new JPanel();
     public static JPanel p3 = new JPanel();

     public static void main(String[] args) throws SQLException {
         new MainFrame();
     }

     public MainFrame() throws SQLException {
         super("数据库管理");
         this.setBounds(400, 300, 780, 480);
         this.setDefaultCloseOperation(EXIT_ON_CLOSE);
         this.getContentPane().setLayout(new FlowLayout(FlowLayout.LEFT));
         databases = new DefaultMutableTreeNode("数据库管理                         ");
         tree = new JTree(databases);
         tree.setSize(600, 600);
         tree.setLocation(400, 300);

         p2.add(new JScrollPane(tree));
         p3.add(jScrollPane = new JScrollPane(jtable));
         p1.setLayout(new GridLayout(1, 2));
         p1.add(p2);
         p1.add(p3);
         this.add(p1);

         conDB("information_schema");
         String sql = "SELECT SCHEMA_NAME FROM information_schema.SCHEMATA";
         rs = st.executeQuery(sql);
         while (rs.next()) {
             System.out.println(rs.getString("SCHEMA_NAME"));
             list.add(rs.getString("SCHEMA_NAME"));
         }
         closeDB();

         for (int i = 0; i < list.size(); i++) {
             DefaultMutableTreeNode roots = new DefaultMutableTreeNode(list.get(i));
             databases.add(roots);
             conDB("information_schema");
             String sql1 = "SELECT TABLE_NAME FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_SCHEMA = '" + list.get(i)
                     + "';";
             rs = st.executeQuery(sql1);
             while (rs.next()) {
                 System.out.println(rs.getString("TABLE_NAME"));
                 DefaultMutableTreeNode tables = new DefaultMutableTreeNode(rs.getString("TABLE_NAME"));
                 roots.add(tables);
             }
             closeDB();
         }
         MouseListener ml = new MouseAdapter() {
             public void mousePressed(MouseEvent e) {
                 int selRow = tree.getRowForLocation(e.getX(), e.getY());
                 TreePath selPath = tree.getPathForLocation(e.getX(), e.getY());
                 if (selRow != -1) {
                     if (e.getClickCount() == 1) {
                         try {
                             mySingleClick(selRow, selPath);
                         } catch (SQLException e1) {
                             e1.printStackTrace();
                         }
                         System.out.println("长度" + selPath.getPathCount());
                     }
                 }
             }
         };

         tree.addMouseListener(ml);
         this.setVisible(true);
     }
     public void mySingleClick(int selRow, TreePath selPath) throws SQLException {
         if (selPath.getPathCount() == 3) {
             String tableName = selPath.getLastPathComponent().toString();
             String databasesName = selPath.getPathComponent(1).toString();
             conDB(databasesName);
             JTable jtable = new JTable();
             jtable= query(tableName);
             p3.removeAll();
             jScrollPane = new JScrollPane(jtable);
             p3.add(MainFrame.jScrollPane);
             p3.updateUI();
             closeDB();
         }
     }
     // 以下是连接数据库
     public void conDB(String DBName) {
         try {
             // 加载数据库驱动
             Class.forName("com.mysql.jdbc.Driver");
         } catch (ClassNotFoundException e) {
             JOptionPane.showMessageDialog(null, "数据库加载失败！");
         }
         try {
             // 连接数据库
             String url = "jdbc:mysql://localhost:3306/" + DBName + "";
             System.out.println(url);
             String user = "root";
             String passwd = "10521";
             conn = DriverManager.getConnection(url, user, passwd);
             st = conn.createStatement();
         } catch (SQLException e) {
             JOptionPane.showMessageDialog(null, "数据库连接失败！");
         }
     }

     // 以下是关闭数据库
     public void closeDB() {
         try {
             conn.close();
         } catch (SQLException e) {
             JOptionPane.showMessageDialog(null, "数据库关闭失败！");
         }
     }

     public JTable query(String table) throws SQLException {
         DefaultTableModel tablemodel = new DefaultTableModel();
         String sql = "SELECT * FROM " + table + ";";
         Statement stmt = this.conn.createStatement(); // 创建语句对象
         ResultSet rest = stmt.executeQuery(sql); // 执行数据查询SELECT语句
         ResultSetMetaData rsmd = rest.getMetaData(); // 返回表属性对象
         int count = rsmd.getColumnCount(); // 获得列数
         for (int j = 1; j <= count; j++) // 将各列名添加到表格模型作为标题，列序号>=1
             tablemodel.addColumn(rsmd.getColumnLabel(j)); // 将结果集中各行数据添加到表格模型
         Object[] columns = new Object[count]; // 创建对象数组，数组长度为列数
         while (rest.next()) // 迭代遍历结果集，从前向后访问每行
         {
             for (int j = 1; j <= columns.length; j++) // 获得每行各列值
                 columns[j - 1] = rest.getString(j);
             tablemodel.addRow(columns); // 表格模型添加一行，参数指明各列值
         }
         rest.close();
         stmt.close();
         return new JTable(tablemodel);
     }
 }