Java 類與JDBC用法

• 2019-03-31

import java.sql.SQLException;//捕獲問題

  import java.sql.Connection;//連接數據庫
  import java.sql.DriverManager;//DriverManager管理一組 JDBC 驅動程序的基本服務。DataSource 接口是 JDBC 2.0 API 中的新增內容，它提供了連接到數據源的另一種方法。使用 DataSource 對象是連接到數據源的首選方法。
  import java.sql.PreparedStatement;//使用preparedStatement進行增刪改查

public class JDBCUtil { public static Connection getConn() //定義靜態方法 靜態方法可以直接用調用 JDBCutil.getConn()
 //如Connection a = JDBCUtil.getconn();
 //而非靜態方法 public aa()
 // 只能用 aa b = new aa（）;
 { Connection connection=null; try { Class.forName("com.mysql.jdbc.Driver"); //返回一個類 String url ="jdbc:mysql://localhost:3306/grades?user=root&password=123"; connection =DriverManager.getConnection(url); } catch (ClassNotFoundException e) { System.out.println("JDBC connection error"); } catch (SQLException e) { //SQLException 用來捕獲問題 System.out.println("JDBC operation error"); } return connection; } public static void closeConn(PreparedStatement preStmt,Connection conn) { if(preStmt!=null) { try { preStmt.close();//關閉鏈接 } catch(SQLException e) { System.out.println("PreparedStatement close error"); } } if(conn!=null) { try { conn.close();//關閉連接避免占用過多資源 }catch(SQLException e) { System.out.println("PreparedStatement close error"); } } } }

package cn.edu.hbue.xyl.gui;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.Scanner;

public class InsertExample {
    
    public static void main(String[] args) {
        Connection connection =JDBCUtil.getConn();
        PreparedStatement preStmt =null;
        try {
            String sql ="insert into stock(orderId,sName,consignmentDate,baleName,count,money)values(?,?,?,?,?,?)";
            preStmt =connection.prepareStatement(sql);
            preStmt.setInt(1, 1235);
            preStmt.setString(2, "餅干");
            preStmt.setString(3, "2013-6-29");
            preStmt.setString(4, "小陳");
            preStmt.setInt(5, 20);
            preStmt.setDouble(6, 223);
            preStmt.executeUpdate();//返回更新的數據行數
            System.out.println("添加數據的行數為"+preStmt.getUpdateCount());
            
        }        catch (SQLException e) {
    System.out.println("JDBC operation error");
        }finally {
            JDBCUtil.closeConn(preStmt, connection);
        }
    }


}

其中execute 和 exeupDate 和 executeQuery區別參考 大佬：
https://www.cnblogs.com/angelye/p/7855906.html

 

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import java.awt.Container;
import java.awt.FlowLayout;
import java.awt.HeadlessException;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.SQLException;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JInternalFrame;
import javax.swing.JLabel;
import javax.swing.JOptionPane;
import javax.swing.JTextField;

public class InsertStockFrame extends JFrame implements ActionListener{
    private JTextField orderIdTextField; //JTextField表示的是文本框 詳情https://zhidao.baidu.com/question/288180446.html private JTextField sNameTextField;
    private JTextField consignmentDateTextField;
    private JTextField baleNameTextField;
    private JTextField countTextField;
    private JTextField moneyTextField;
    private JLabel orderLabel;//JLabel 對象可以顯示文本、圖像或同時顯示二者。 詳情http://outofmemory.cn/code-snippet/1121/swing-JLabel-explain-in-detail-yiji-usage-shili private JLabel sNameLabel;
    private JLabel dateLabel;
    private JLabel baleNameLabel;
    private JLabel countLabel;
    private JLabel moneyLabel;
    private JLabel starLabel;
    private JButton confirmButton;
    private JButton cancelButton;
    
    public InsertStockFrame(){
        
        setTitle("進貨");
        setSize(220, 300);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);//用戶單擊窗口的關閉按鈕時程序執行的操作
        
        Container cp = this.getContentPane();//this.getContentPane()的作用是初始化一個容器，用來在容器上添加一些控件
        cp.setLayout(new FlowLayout());//setLayout是對當前組件設置為流式布局.組件在窗體中從左到右依次排列
        
        orderLabel = new JLabel("訂單號");
        cp.add(orderLabel);
        orderIdTextField = new JTextField(10);
        cp.add(orderIdTextField);
        starLabel = new JLabel("*");
        cp.add(starLabel);
        
        baleNameLabel = new JLabel("商品名稱");
        cp.add(baleNameLabel);
        baleNameTextField = new JTextField(10);
        cp.add(baleNameTextField);
        starLabel = new JLabel("*");
        cp.add(starLabel);
        
        dateLabel = new JLabel("交貨日期");
        cp.add(dateLabel);
        consignmentDateTextField= new JTextField(10);
        cp.add(consignmentDateTextField);
        starLabel = new JLabel("*");
        cp.add(starLabel);
        
        sNameLabel = new JLabel("客    戶");
        cp.add(sNameLabel);
        sNameTextField = new JTextField(10);
        cp.add(sNameTextField);
        starLabel = new JLabel("*");
        cp.add(starLabel);
        

        countLabel = new JLabel("數    量");
        cp.add(countLabel);
        countTextField = new JTextField(10);
        cp.add(countTextField);
        starLabel = new JLabel("*");
        cp.add(starLabel);
        
        moneyLabel = new JLabel("金   額");
        cp.add(moneyLabel);
        moneyTextField = new JTextField(10);
        cp.add(moneyTextField);
        starLabel = new JLabel("*");
        cp.add(starLabel);
        
        confirmButton = new JButton("添加");
        confirmButton.addActionListener(this);// 建立事件監聽事件 https://blog.csdn.net/qq_41978199/article/details/80642012
        cp.add(confirmButton);
        cancelButton = new JButton("取消");
cancelButton.addActionListener(this);
        cp.add(cancelButton);
        
    }
    
    public void actionPerformed(ActionEvent e) { //actionPerformed 用於接收操作事件的偵聽器接口 if(e.getActionCommand().equals("添加")){
            //從各控件取出數據
            String orderId = orderIdTextField.getText();
            String sName = sNameTextField.getText();
            String date = consignmentDateTextField.getText();
            String baleName = baleNameTextField.getText();
            String count = countTextField.getText();
            String money = moneyTextField.getText();
            
            //此處補充代碼
            //非空或必填字段檢測
            if(orderId.equals("")){ //如果內容為空
                JOptionPane.showMessageDialog(getContentPane(), "請將帶星號的內容填寫完整！","信息提示框", JOptionPane.INFORMATION_MESSAGE);
                return ;
            }
            
            if(sName.equals("")){
                JOptionPane.showMessageDialog(getContentPane(), "請將帶星號的內容填寫完整！","信息提示框", JOptionPane.INFORMATION_MESSAGE);
                return ;
            }
            
            if(date.equals("")){
                JOptionPane.showMessageDialog(getContentPane(), "請將帶星號的內容填寫完整！","信息提示框", JOptionPane.INFORMATION_MESSAGE);
                return ;
            }

            

            if(baleName.equals("")){
                JOptionPane.showMessageDialog(getContentPane(), "請將帶星號的內容填寫完整！","信息提示框", JOptionPane.INFORMATION_MESSAGE);
                return ;
            }
            
            if(count.equals("")){
                JOptionPane.showMessageDialog(getContentPane(), "請將帶星號的內容填寫完整！","信息提示框", JOptionPane.INFORMATION_MESSAGE);
                return ;
            }
            
            if(money.equals("")){
                JOptionPane.showMessageDialog(getContentPane(), "請將帶星號的內容填寫完整！","信息提示框", JOptionPane.INFORMATION_MESSAGE);
                return ;
            }
            
            

            //此處補充代碼
            //進貨日期,數量,金額的合法性檢驗
            int c = 0;
            double m ;
            int flag = 0; //非常關鍵！！ 不然程序會重復輸出
            
            try
            {
                c = Integer.parseInt(count);//Integer.parseInt(String)的作用就是將String字符類型數據轉換為Integer整型數據
                m = Double.parseDouble(money);
            }
            catch(NumberFormatException t)
            {
                JOptionPane.showMessageDialog(getContentPane(), "請將帶星號的內容填寫完整！","信息提示框", JOptionPane.INFORMATION_MESSAGE);
                return ;
            }
            
            JDBCUtil genConnection = new JDBCUtil() ;
            Connection conn = genConnection.getConn();
            String sql = "insert into stock(orderId,sName,consignmentDate,baleName,count,money)"+
                        " values(?,?,?,?,?,?)";
            PreparedStatement preStmt = null;
            
            try {
                preStmt= conn.prepareStatement(sql);
                preStmt.setString(1, orderId);
                preStmt.setString(2, sName);
                preStmt.setString(3, date);
                preStmt.setString(4, baleName);
                preStmt.setInt(5, c);
                preStmt.setDouble(6, m);
                
                preStmt.executeUpdate();
                System.out.println("成功插入數據"+ preStmt.getUpdateCount() + "條");
                
            } catch (SQLException t) {
                flag = 1;
                t.printStackTrace();
            }finally
            {
                JDBCUtil.closeConn(preStmt, conn);
            }
            try {
                if (flag == 0)
                {
                    JOptionPane.showMessageDialog(getContentPane(), "插入成功","信息提示框", JOptionPane.INFORMATION_MESSAGE);
                    orderIdTextField.setText(""); //成功或失敗以后將文本框清零
                    sNameTextField.setText("");
                    consignmentDateTextField.setText("");
                    baleNameTextField.setText("");
                    countTextField.setText("");
                    moneyTextField.setText("");
                }
            else
            {
                JOptionPane.showMessageDialog(getContentPane(), "插入失敗","信息提示框", JOptionPane.INFORMATION_MESSAGE);
                orderIdTextField.setText(""); 
                sNameTextField.setText("");
                consignmentDateTextField.setText("");
                baleNameTextField.setText("");
                countTextField.setText("");
                moneyTextField.setText("");
        }
            }
       catch(HeadlessException t) 
        {
            t.printStackTrace();
        }
        }
        else
        {
         System.exit(0); //直接退出程序
        }
        }
            
    public static void main(String[] args){
        InsertStockFrame insert = new InsertStockFrame(); //調用前面方法
        insert.setVisible(true);
    }
}


實現如下

 

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package cn.edu.hbue.xyl.gui;   


import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;



public class get {
    
    public static void main(String[] args) {
    
    Connection conn = JDBCUtil.getConn();
    String sql = "select * from stock where consignmentDate= '2018-03-22' ";//where id = 1； 如果是日期得加上單引號''
    PreparedStatement preStmt = null;
    ResultSet rs = null;
    
    try {
    preStmt = conn.prepareStatement(sql);
    rs = preStmt.executeQuery(); //執行后返回代表查詢結果的ResultSet對象。 while(rs.next()) {
        System.out.println("訂單號=" + rs.getInt(2));
        System.out.println("貨品名稱:" + rs.getString(3));
        System.out.println("交貨日期:" + rs.getDate(4));
        System.out.println("數量:" + rs.getInt("count"));
        System.out.println("金額=" + rs.getDouble("money"));
    }
    }catch(SQLException e) {
        e.printStackTrace();
    }
    
    }
    
}

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• package cn.edu.hbue.xyl.gui;
  
  import java.sql.Array;
  import java.sql.Connection;
  import java.sql.PreparedStatement;
  import java.sql.ResultSet;
  import java.sql.SQLException;
  import java.util.ArrayList;
  
  import javax.swing.table.AbstractTableModel;
  
  public class AllDataValues extends AbstractTableModel { //JTable用法 https://blog.csdn.net/edc3001/article/details/83386713
  	Object[][] values ;
  	String[] headerNames = {"訂單號", "客戶" ,"交貨日期", "貨物名稱", "數量","金額"};
  	public AllDataValues(){
  		getValues();
  	}
  	
  	private void getValues(){
  		
  		Connection conn = JDBCUtil.getConn();
  		PreparedStatement stmt= null;
  		ResultSet rs = null;
  		PreparedStatement preStmt = null; //使用 preparedStatement對象 preStmt來進行增刪改查
  		ArrayList list ;//多維數組
  		String sql = "select * from stock ";
  		String countSql = "select count(id) from stock";  
  		try {
  			stmt = conn.prepareStatement(countSql);
  			rs = stmt.executeQuery();//執行查詢；要用statement類的executeQuery()方法來下達select指令以查詢數據庫，executeQuery()方法會把數據庫響應的查詢結果存放在ResultSet類對象中供我們使用。即語句：ResultSet rs=s.executeQuery(sql);
  			int rows = 0;
  			while(rs.next())
  			   rows = rs.getInt(1);
  			values = new Object[rows][];
  			stmt = conn.prepareStatement(sql);
  			rs = stmt.executeQuery();
  			int i =0;
  			while(rs.next()){
  				list = new ArrayList();// 動態數組 有點類似於set<string> https://www.cnblogs.com/rickie/articles/67978.html
  				String orderId = rs.getString("orderId");
  				list.add(orderId);
  				String sName = rs.getString("sName");
  				list.add(sName);
  				java.sql.Date consignmentDate = rs.getDate("consignmentDate");
  				list.add(consignmentDate);
  				String baleName = rs.getString("baleName");
  				list.add(baleName);
  				Integer count = rs.getInt("count");
  				list.add(count);
  				Double money = rs.getDouble("money");
  				list.add(money);
  				
  				values[i] = new Object[list.size()];
  				values[i] = list.toArray();
  				i++;
  			}
  			
  		} catch (SQLException e) {
  			e.printStackTrace();
  		}finally{
  			JDBCUtil.closeConn(preStmt, conn);
  		}
  	}
  	
  	public int getColumnCount() {
  		return values[0].length;
  	}
  
  	public int getRowCount() {
  		return values.length;
  	}
  
  	public Object getValueAt(int row, int col) {
  		return values[row][col];
  	}
  
  	public String  getColumnName(int col){
  		return headerNames[col];
  	}
  }
  
  

  package cn.edu.hbue.xyl.gui;    //調用前面方法

  import java.awt.Container; 
  import java.awt.FlowLayout;

  import javax.swing.JFrame;
  import javax.swing.JScrollPane;
  import javax.swing.JTable;

  public class ShowDataFrame extends JFrame {
  protected JTable table;
  
  public ShowDataFrame(){
  setSize(500,200);
  setTitle("貨物一覽表");
  Container pane = getContentPane();
  pane.setLayout(new FlowLayout());
  AllDataValues dv = new AllDataValues();
  table = new JTable(dv);
  pane.add(new JScrollPane(table));
  this.pack();
  }
  public static void main(String[] args){
  ShowDataFrame s = new ShowDataFrame();
  s.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
  s.setSize(500,200);
  s.setVisible(true);
  }
  }

  

  　　

 

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• 一般情況下程序直接寫在 main方法底下
• 當有extends或者implements其他接口的時候  用public 寫 比如: public Insert（）然后在底下的main方法中調用 insert如： insert a = new insert（）；
• 寫其他的方法時候如 actionperformed 時候  用public void
• JFrame是調用窗口指令 記得最后要加上關閉窗口和setvisib（true） 不然窗口不可見或者無法關閉