dbqueryframe.java

《Java实例入门》所有实例的源代码。所有的源文件都是.java文件

package test;

import java.net.URL;
import java.sql.*;
import java.util.Vector;
import java.awt.*;
import java.awt.event.*;

public class dbQueryFrame extends Frame
   implements ActionListener, ItemListener
{
   Database db;
   List Tables, Columns, SelColumns;
   Choice fields,oper, values;
   TextArea where;
   Button addAnd,addOr,clear,Search, Quit;
   public dbQueryFrame()
   {
      super("数据库查询构建器");
      //设置交互界面
      setGUI();

      db = new Database("sun.jdbc.odbc.JdbcOdbcDriver");
      db.Open("jdbc:odbc:JDBCTEST;pwd=java", "C:\\My Documents\\biblio.mdb");

      String tnames[] = db.getTableNames();
      loadList(Tables, tnames);

      String queryText ="";

      where.setText(queryText);
    }
   //------------------------------------
   private void setGUI()
   {
      setBackground(Color.lightGray);
      //界面总体分上中下三部分
      setLayout(new GridLayout(3,1));
      //上部的构件组织
      Panel pn = new Panel();
      add(pn);
      pn.setLayout(new BorderLayout());
         //添加列表框的标题
         Panel pnn=new Panel();
         pnn.setLayout(new GridLayout(1,3));
         pnn.add(new Label("所有表"));
         pnn.add(new Label("可选字段"));
         pnn.add(new Label("已选字段"));
      pn.add("North",pnn);
         //添加列表框
         Panel pnc=new Panel();
         pnc.setLayout(new GridLayout(1,3));
         pnc.add(Tables = new List(15));
         pnc.add(Columns = new List(15));
         pnc.add(SelColumns= new List(15));
      pn.add("Center",pnc);
      //中部的构件组织
      Panel pc = new Panel();
      add( pc);
      pc.setLayout(new GridLayout(3,1));
         //添加下拉列表框的标题
         Panel pcn=new Panel();
         pcn.setLayout(new GridLayout(1,3));
         pcn.add(new Label("字段"));
         pcn.add(new Label("运算符"));
         pcn.add(new Label("值"));
      pc.add(pcn);
         //添加下拉列表框
         Panel pcc=new Panel();
         pcc.setLayout(new GridLayout(1,3));
         pcc.add(fields = new Choice());
         pcc.add(oper= new Choice());
         pcc.add(values= new Choice());
      pc.add(pcc);
         //添加两个条件生成按钮
         Panel pcs=new Panel();
         pcs.add(addAnd=new Button("与"));
         pcs.add(addOr=new Button("或"));
         pcs.add(clear=new Button("清除"));
      pc.add(pcs);
      Tables.addItemListener(this);
      Columns.addActionListener(this);
      SelColumns.addActionListener(this);
      fields.addItemListener(this);
      addAnd.addActionListener(this);
      addOr.addActionListener(this);
      clear.addActionListener(this);
      oper.add("=");
      oper.add(">");
      oper.add("<");
      //下部的构件组织
      Panel ps = new Panel();
      add(ps);
      ps.add(where = new TextArea("", 3,40));
      addPanel(ps, Search = new Button("执行查询"));
      addPanel(ps, Quit = new Button("退出"));
      Search.addActionListener(this);
      Quit.addActionListener(this);
      setBounds(100, 100, 500, 300);
      setVisible(true);
   }
   //------------------------------------
   private void addPanel(Panel ps, Component c)
   {
      Panel p = new Panel();
      ps.add(p);
      p.add(c);
   }
   //------------------------------------
   private void loadChoice(Choice choice, String[] s){
      choice.removeAll();
      for (int i=0; i< s.length; i++)
          choice.add(s[i]);
   }
   //------------------------------------
   private void loadList(List list, String[] s)
   {
    list.removeAll();
    for (int i=0; i< s.length; i++)
         list.add(s[i]);
   }
   //------------------------------------
   public void actionPerformed(ActionEvent e)
   {
       Object obj = e.getSource();
      if (obj== Columns) {
          if( Columns.getSelectedIndex() ==0){
                SelColumns.removeAll();
                SelColumns.add("*");
                Columns.removeAll();
           }else{
                SelColumns.add(Columns.getSelectedItem());
                Columns.remove(Columns.getSelectedIndex());
           }
      }
      if (obj== SelColumns) {
          if( SelColumns.getSelectedItem() .trim() =="*"){
                SelColumns.removeAll();
                Columns.removeAll();
                String cnames[] = db.getColumnNames(Tables.getSelectedItem());
                loadList(Columns, cnames);
                Columns.add("*",0) ;
           }else{
                Columns.add(SelColumns.getSelectedItem());
                SelColumns.remove(SelColumns.getSelectedIndex());
           }
      }
      if(obj==addAnd){
            String strwhere=fields.getSelectedItem().trim()+oper.getSelectedItem()+"'"+values.getSelectedItem().trim()+"'";
           if(where.getText().trim() .length() ==0)
                where.setText(strwhere);
           else
               where.setText(where.getText().trim()+" and "+strwhere);
      }
      if(obj==addOr){
            String strwhere=fields.getSelectedItem().trim()+oper.getSelectedItem()+"'"+values.getSelectedItem().trim()+"'";
           if(where.getText().trim() .length() ==0)
                where.setText(strwhere);
           else
               where.setText(where.getText().trim()+" or "+strwhere);
      }
      if(obj==clear)
          where.setText("");
      if (obj == Quit)
         System.exit(0);
      if (obj == Search)
         clickedSearch();
      if (obj == clear)
         where.setText("");
   }
   //------------------------------------
   public void itemStateChanged(ItemEvent e)
   {
      Object obj = e.getSource();
      if (obj == Tables){
         showColumns();
         Columns.add("*",0);
      }
      if (obj == fields)
         showData();
   }
   //------------------------------------
   private void showColumns()
   {
      String cnames[] = db.getColumnNames(Tables.getSelectedItem());
      loadList(Columns, cnames);
      loadChoice(fields,cnames);
   }
   //------------------------------------
   private void showData()
   {
      String colname = fields.getSelectedItem();
      String colval = db.getColumnValue(Tables.getSelectedItem(), colname);
      values.setVisible(false);
      values.removeAll();
      values.setVisible(true);

      colval = db.getNextValue(fields.getSelectedItem());

      while (colval.length()>0)
         {
         values.add(colval);
         colval = db.getNextValue(fields.getSelectedItem());
         }
   }
   //------------------------------------
   private void clickedSearch()
   {
      String sql;
      sql="select ";
     for(int i=0;i<SelColumns.getItemCount() ;i++)
           sql=sql+SelColumns.getItem(i).trim()+",";
      sql=sql.substring(0,sql.length()-1);
      sql=sql+" from "+Tables.getSelectedItem().trim();
      sql=sql+" where "+where.getText().trim();
      resultSet rs = db.Execute(sql);
      queryDialog q = new queryDialog(this, rs);
      q.show();
   }
   //------------------------------------
   static public void main(String argv[])
   {
      new dbQueryFrame();
   }
}


//=====================================================
class queryDialog extends Dialog
   implements ActionListener
{
   resultSet results;
   Button OK;
   textPanel pc;
   Vector tables;

   public queryDialog(Frame f, resultSet r)
   {
   super(f, "查询结果");
   results = r;
   setLayout(new BorderLayout());
   OK = new Button("OK");
   Panel p = new Panel();
   add("South", p);
   p.add(OK);
   OK.addActionListener(this);

   pc = new textPanel();
   pc.setBackground(Color.white);
   add("Center", pc);
   makeTables();
   setBounds(100, 100, 500, 300);
   setVisible(true);
   repaint();
   }
   //-------------------------------------
   private void makeTables()
   {
      tables = new Vector();
      String t[] = results.getMetaData();
      tables.addElement( t);
      while (results.hasMoreElements())
         {
         tables.addElement(results.nextElement());
         }
   }
      //-------------------------------------
   public void actionPerformed(ActionEvent e)
   {
      setVisible(false);
   }
   //-------------------------------------
   class textPanel extends Panel
      {
      public void paint(Graphics g)
      {
     String s[];
 	int x=0;
	//计算字体的高度
 	int y =g.getFontMetrics().getHeight();
	//估算列的高度
 	int deltaX = (int)1.5f*(g.getFontMetrics().stringWidth("wwwwwwwwwwwwww"));
	//遍历表矢量
 	for (int i=0; i< tables.size(); i++)
   	{
   		s  = (String[])tables.elementAt(i);
        //绘制字符串数组中的每一行
   		for (int j =0; j< s.length; j++)
    	{
    		String st= s[j];
    		g.drawString(st, x, y);
    		x += deltaX;           	//移到下一列
    	}
   		x = 0;                 		//开始一个新行
   		y += g.getFontMetrics().getHeight();
        //列标签与列数据之间的额外空间
   		if (i == 0)
   			y += g.getFontMetrics().getHeight();
   	}
        }

   }
}