allreader.java

java 开发的图书管理系统~~~。可以实现很多功能

package bookmanager;
import javax.swing.*;
import javax.swing.event.*;
import java.awt.event.*;
import java.awt.Point;
import java.awt.Dimension;
import java.awt.GridLayout;
import java.awt.BorderLayout;
import javax.swing.table.DefaultTableModel;
import java.util.Vector;
import java.sql.*;
public class AllReader extends JFrame implements ActionListener
{
	public AllReader(){
		setTitle("借阅者信息查询");
		setSize(200,200);
		gl=new GridLayout(1,2,20,20);
		gl2=new GridLayout(1,1,20,20);
		JPanel panel=new JPanel();
		JPanel panel2=new JPanel();
		panel.setLayout(gl);
		panel2.setLayout(gl2);
		booknamelbl=new JLabel("读者ID");
		booknametex=new JTextField("");
		selectbtn=new JButton("查询");
		model=new DefaultTableModel();
		messagetab=new JTable(model);
		model.addColumn("用户ID");
		model.addColumn("用户名");
		sp=new JScrollPane(messagetab);
		panel.add(booknamelbl);
		panel.add(booknametex);
		panel.add(selectbtn);
		panel2.add(sp);
		getContentPane().add(panel,BorderLayout.CENTER);
		getContentPane().add(panel2,BorderLayout.SOUTH);
		selectbtn.addActionListener(this);
		sql=("select * from user");
		//清除以前记录
		for(int n=model.getRowCount()-1;n>=0;n--)
		{
			model.removeRow(n);
		}
		try
		{
			rs=db.getResult(sql);
			rs.beforeFirst();
			while(rs.next()){	
				Vector tempvector=new Vector(1,1);
				tempvector.add(rs.getString(1));
				tempvector.add(rs.getString(2));
				model.addRow(tempvector);
			}
		}catch(SQLException e)
		{
			System.out.println(e);
		}
	}
	public void actionPerformed(ActionEvent e)
	{
		sql="select * from user";
		for(int n=model.getRowCount()-1;n>=0;n--)
		{
			model.removeRow(n);
		}
		String userid=booknametex.getText().trim();
		if(userid.equals(""))
		{
			JOptionPane.showMessageDialog(null,"查询请输入借阅者ID");
			return;
		}
		Long intuserid=new Long(userid);
		sql=sql+" where id="+intuserid;
		rs=db.getResult(sql);
			boolean isexist=false;
				try
				{
					//把游标指向结果集的第一行，如果没有数据则返回false
					isexist=rs.first();		
				}
				catch(SQLException w)
				{
					System.out.println(w);
				}
				//判断结果是否正确
				if(!isexist)
				{
					JOptionPane.showMessageDialog(null,"没有相关资料");
					booknametex.setText("");
					return;
				}
				try
				{
					rs.beforeFirst();
					while(rs.next()){	
					Vector tempvector=new Vector(1,1);
					tempvector.add(rs.getString(1));
					tempvector.add(rs.getString(2));
					model.addRow(tempvector);
					}
				}
				catch(SQLException e2)
				{
					System.out.println(e2);
				} 
			}
	private JLabel booknamelbl;
	private JTextField booknametex;
	private JButton selectbtn;
	private JTable messagetab;
	private DBManager db=new DBManager();
	private JScrollPane sp;
	private GridLayout gl;
	private GridLayout gl2;
	private ResultSet rs;
	private String sql;
	private DefaultTableModel model;
}