studentquery.java

综合测评管理系统——完成班级的综合测评工作

import java.sql.*; 
import javax.swing.*; 
import java.awt.*; 
import java.awt.event.*; 
import java.util.*; 

public class StudentQuery extends JFrame{
	private Connection dbConn;
	private PreparedStatement ps;
	private ResultSet rs;
	private ResultSetMetaData rsMetaData;
	
	//GUI变量定义
	private JTable table;
	private JTextArea inputQuery; 
	private JButton submitQuery;
	Container c=getContentPane();
	JButton query_button=new JButton("查询");
	JButton exit_button=new JButton("退出");
	
	String[] comboboxStr={"2006-2007","2007-2008","2008-2009","2009-2010"};
	JLabel term_label=new JLabel("学年: ");
	final JComboBox term_combobox=new JComboBox(comboboxStr);  
	JLabel studentno_label=new JLabel("学生学号: ");
	final JTextField studentno_textfield=new JTextField();
	JLabel studentname_label=new JLabel("学生姓名: ");
	final JTextField studentname_textfield=new JTextField();
	   
	JLabel userinfo_label=new JLabel("各科成绩:");
	
	public StudentQuery() 
	{
		//Form的标题 
		super("成绩查询"); 
		
		final String dbURL="jdbc:sqlserver://localhost:1433; DatabaseName=sample"; 
		final String username="sa"; 
		final String password="2005"; 
		//加载驱动程序以连接数据库
		try{
			Class.forName("com.microsoft.sqlserver.jdbc.SQLServerDriver"); 
			dbConn=DriverManager.getConnection(dbURL,username,password);
		}catch(ClassNotFoundException cnfex){
			System.err.println("装载 JDBC/ODBC 驱动程序失败。");
			cnfex.printStackTrace();
			System.exit(1); // terminate program
		}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
		String test="select cname as '课程名',grade as '成绩' from student_course,course where student_course.cno=course.cno";
		
		JPanel topPanel = new JPanel();
		GridBagLayout lay=new GridBagLayout();
		GridBagConstraints constraints=new GridBagConstraints();
		topPanel.setLayout(lay);
	     
	  constraints.anchor=GridBagConstraints.CENTER;
	  
	  constraints.gridx=0;
	  constraints.gridy=0;
	  constraints.weightx=1;
	  constraints.weighty=1;
	  constraints.gridwidth=1;
	  constraints.gridheight=1;
	  constraints.fill=GridBagConstraints.NONE;
	  constraints.anchor=GridBagConstraints.EAST;
	  topPanel.add(studentno_label,constraints);
	      
	  constraints.gridx=1;
	  constraints.gridy=0;
	  constraints.weightx=1;
	  constraints.weighty=2;
	  constraints.gridwidth=1;
	  constraints.gridheight=1;
	  constraints.fill=GridBagConstraints.BOTH;
	  constraints.anchor=GridBagConstraints.CENTER;
	  topPanel.add(studentno_textfield,constraints);
	  
	  constraints.gridx=2;
	  constraints.gridy=0;
	  constraints.weightx=1;
	  constraints.weighty=1;
	  constraints.gridwidth=1;
	  constraints.gridheight=1;
	  constraints.fill=GridBagConstraints.NONE;
	  constraints.anchor=GridBagConstraints.CENTER;
	  topPanel.add(query_button,constraints);
	  
	  constraints.gridx=0;
	  constraints.gridy=1;
	  constraints.weightx=1;
	  constraints.weighty=1;
	  constraints.gridwidth=1;
	  constraints.gridheight=1;
	  constraints.fill=GridBagConstraints.NONE;
	  constraints.anchor=GridBagConstraints.EAST;
	  topPanel.add(studentname_label,constraints);
	      
	  constraints.gridx=1;
	  constraints.gridy=1;
	  constraints.weightx=1;
	  constraints.weighty=2;
	  constraints.gridwidth=1;
	  constraints.gridheight=1;
	  constraints.fill=GridBagConstraints.BOTH;
	  constraints.anchor=GridBagConstraints.CENTER;
	  topPanel.add(studentname_textfield,constraints);
	     
	  constraints.gridx=2;
	  constraints.gridy=1;
	  constraints.weightx=1;
	  constraints.weighty=2;
	  constraints.gridwidth=1;
	  constraints.gridheight=1;
	  constraints.fill=GridBagConstraints.NONE;
	  constraints.anchor=GridBagConstraints.CENTER;
	  topPanel.add(exit_button,constraints);
	           
	  constraints.gridx=0;
	  constraints.gridy=2;
	  constraints.weightx=1;
	  constraints.weighty=1;
	  constraints.gridwidth=1;
	  constraints.gridheight=1;
	  constraints.fill=GridBagConstraints.NONE;
	  constraints.anchor=GridBagConstraints.EAST;
	  topPanel.add(term_label,constraints);
	     
	  constraints.gridx=1;
	  constraints.gridy=2;
	  constraints.weightx=1;
	  constraints.weighty=2;
	  constraints.gridwidth=1;
	  constraints.gridheight=1;
	  constraints.fill=GridBagConstraints.BOTH;
	  constraints.anchor=GridBagConstraints.CENTER;
	  topPanel.add(term_combobox,constraints);
	  
	  //按钮的单击事件处理
	  query_button.addActionListener(new ActionListener(){
	  	public void actionPerformed(ActionEvent e){
	  		table.selectAll();
			  table.clearSelection();
	  		rs=null;
	  		String[] temp={"",""};
	  		temp[0]=studentno_textfield.getText();
	  		temp[1]=studentname_textfield.getText();
	  		if(temp[0].equals("")&&temp[1].equals("")){
	  			JOptionPane.showMessageDialog(new JFrame(),"空值,不合法","警告",JOptionPane.WARNING_MESSAGE);
	  		}else if(!temp[0].equals("")&&temp[0].length()!=11){
	  			JOptionPane.showMessageDialog(new JFrame(),"学号,不合法","警告",JOptionPane.WARNING_MESSAGE);
	  		}else{
	  		  try{
	  		    dbConn=DriverManager.getConnection(dbURL,username,password);
	  				String selectStr="select * from student WHERE sno=? or sname=?";
	  				ps=dbConn.prepareStatement(selectStr);
	  				ps.setString(1,studentno_textfield.getText());
	  				ps.setString(2,studentname_textfield.getText());
	  				rs=ps.executeQuery();
	  				if(rs.next()){
	  					String snoStr=rs.getString("sno");
	  					//studentno_textfield.setText(rs.getString("sno"));
	  					//studentname_textfield.setText(rs.getString("sname"));
	  					selectStr="select cname as '课程名',grade as '成绩' from student_course,course where student_course.cno=course.cno and sno=? and academic_year=?";
	  					ps=dbConn.prepareStatement(selectStr);
	  				  ps.setString(1,snoStr);
	  				  ps.setString(2,(String)term_combobox.getSelectedItem());
	  				  rs=ps.executeQuery();
	  				  displayResultSet(rs);
	  			  }else{
	  			  	JOptionPane.showMessageDialog(new JFrame(),"此人不存在","警告",JOptionPane.WARNING_MESSAGE);
	  			  }
	  			}catch(SQLException exc){
	  			  exc.printStackTrace();
	  			}finally{
	  			  if(ps!=null)try{ps.close();}catch(SQLException ignore){}
	  			  if(dbConn!=null)try{dbConn.close();}catch(SQLException ignore){}
	  			}
	  	  }
	  	}
	  });
	  
	  exit_button.addActionListener(new ActionListener(){
	  	public void actionPerformed(ActionEvent e){
	  		dispose();	  	
	  	}
	  });
	  
	  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 ); 
	  getTable(); 
	  setSize( 500, 300 );
	  //显示Frame 
	  show();
	  
	  Toolkit kit=Toolkit.getDefaultToolkit();
	  Dimension screenSize=kit.getScreenSize();
	  int width=screenSize.width;
	  int height=screenSize.height;
	  setLocation((width-getWidth())/2,(height-getHeight())/2);
	} 
	
	private void getTable()
	{
		/*try{
			//执行SQL语句 
			String query="select cname as '课程名',grade as '成绩' from student_course,course where student_course.cno=course.cno"; 
			ps=dbConn.prepareStatement(query);
			rs=ps.executeQuery(); 
			//在表格中显示查询结果
			displayResultSet(rs);
		}catch(SQLException sqlex){
			sqlex.printStackTrace();
		}*/
	}
	
	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(new JFrame(),"无记录","警告",JOptionPane.WARNING_MESSAGE);
			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 );
			
			c.remove(1);
			c.add( scroller, BorderLayout.CENTER );
			//刷新Table
			c.validate();
		}catch(SQLException sqlex){
			sqlex.printStackTrace();
		}
	} 
	
	private Vector getNextRow(ResultSet rs,ResultSetMetaData rsmd)throws SQLException{
		Vector currentRow = new Vector();
		for ( int i = 1; i <= rsmd.getColumnCount(); ++i )
		  currentRow.addElement( rs.getString( i ) );
		  //返回一条记录
		  return currentRow;
	}
}