通过实例可以更好的了解java

23-例子1
import java.sql.*;
public class Example23_1
{public static void main(String args[])
  { String name,xuehao;Date date; int math,physics,english;
    Connection con;Statement sql; ResultSet rs;
    try{Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");  }
    catch(ClassNotFoundException e){}
    try
      { 
         con=DriverManager.getConnection("jdbc:odbc:redsun","snow","ookk");
         sql=con.createStatement();
         rs=sql.executeQuery("SELECT * FROM chengjibiao");
       while(rs.next())
        {   name=rs.getString(2);  xuehao=rs.getString(1);
          date  =rs.getDate(3);    math=rs.getInt("数学");
          physics=rs.getInt("物理"); english=rs.getInt("英语");
          System.out.println("姓名："+name);
          System.out.println("学号："+xuehao);  
          System.out.println("出生："+date.toString());
          System.out.println("数学："+math);
          System.out.println("物理："+physics);  
    System.out.println("英语："+english);
       }
con.close();
     }
   catch(SQLException e1) {}
  } 
}  
23-例子2
import java.sql.*;
public class Example23_2
{public static void main(String args[])
  { String name,xuehao;Date date; int math,physics,english;
    Connection con;Statement sql; ResultSet rs;
    try{Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");  }
    catch(ClassNotFoundException e){}
    try
      { 
     con=DriverManager.getConnection("jdbc:odbc:redsun","snow","ookk");
     sql=con.createStatement();
      rs=sql.executeQuery("SELECT * FROM chengjibiao WHERE 学号 = '4' ");
       while(rs.next())
        { name=rs.getString(2); xuehao=rs.getString(1);
          date =rs.getDate(3);   math=rs.getInt("数学");
          physics=rs.getInt("物理");english=rs.getInt("英语");
          System.out.println("姓名："+name);
          System.out.println("学号："+xuehao);  
          System.out.println("出生："+date.toString());
          System.out.println("数学："+math);
          System.out.println("物理："+physics);  
          System.out.println("英语："+english);
                 }
       con.close(); 
     }
   catch(SQLException e1) {}
  } 
}
23-例子3
import java.sql.*;
public class Example23_3
{public static void main(String args[])
  { String name,xuehao;Date date; int math,physics,english;
    Connection con;Statement sql; ResultSet rs;
    try{Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");  }
    catch(ClassNotFoundException e){}
    try
   { con=DriverManager.getConnection("jdbc:odbc:redsun","snow","ookk");
    sql=con.createStatement();
   rs=sql.executeQuery("SELECT * FROM chengjibiao WHERE 英语 >= 90 ");
     while(rs.next())
      {   name=rs.getString(2); xuehao=rs.getString(1);
      date=rs.getDate(3); math=rs.getInt("数学");
    physics=rs.getInt("物理"); english=rs.getInt("英语");
    System.out.println("姓名："+name); System.out.println("学号："+xuehao);
      System.out.println("出生："+date.toString());
      System.out.println("数学："+math);
      System.out.println("物理："+physics);  
      System.out.println("英语："+english);
       }
       con.close(); 
     }
   catch(SQLException e1) {}
 } 
}



23-例子4
import java.awt.*;import java.net.*;
import java.sql.*; import java.awt.event.*;
class Window extends Frame implements ActionListener
 { TextArea text;Panel panel;TextField xingming;
   Button button1,button2;
   Window()
  { super("成绩查询");
    setLayout(new BorderLayout()); setBackground(Color.cyan);
    setBounds(150,150,300,120); setVisible(true);
text=new TextArea();button1=new Button("确定");
button2=new Button("查询所有人的成绩");
    xingming=new TextField(16); panel=new Panel();
panel.add(new Label("输入被查询的学生的姓名："));
panel.add(xingming);panel.add(button1);
    add("North",panel); add(text,"Center");add(button2,"South");
    text.setEditable(false);text.setBackground(Color.pink);
    button1.addActionListener(this);button2.addActionListener(this);
    addWindowListener(new WindowAdapter()
     {public void windowClosing(WindowEvent e)
        { setVisible(false);System.exit(0);  } } );
 }
 public void actionPerformed(ActionEvent e)
  { if(e.getSource()==button1)
    {  text.setText("查询结果"+'\n');
       try{ Liststudent1();}
       catch(SQLException ee) {}
    }
    else if(e.getSource()==button2)
    {  text.setText("查询结果"+'\n');
       try{ Liststudent2();}
       catch(SQLException ee) {}
    }
  }
 public  void Liststudent1() throws SQLException
  {  String name;int math,english,physics,sum;
     try{Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");}
     catch(ClassNotFoundException e){}
     Connection con=DriverManager.getConnection("jdbc:odbc:redsun","chengjibiao","ookk");
    Statement sql=con.createStatement();
    ResultSet rs=sql.executeQuery("SELECT * FROM chengjibiao");  
    while(rs.next())
    {      name=rs.getString("姓名");  math=rs.getInt("数学");
           physics=rs.getInt("物理");  english=rs.getInt("英语");
           sum=english+math+physics; 
    if((name.trim()).equals(xingming.getText().trim()))
      {text.append("***"+"\n"+name+"的成绩: "+"\n"+"数学："+math+" 英语：
       "+english+"物理:"+physics+"总分："+sum+'\n');   
      } 
    }
   if((text.getText().trim()).equals("查询结果")) 
      {text.setText("没有该人的成绩");  }
 }
 public  void Liststudent2() throws SQLException
  { String name; int math,english,physics ,sum;
     try{Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");}
     catch(ClassNotFoundException e){}
    Connection con=DriverManager.getConnection("jdbc:odbc:redsun","snow","ookk");
    Statement sql=con.createStatement();
    ResultSet rs=sql.executeQuery("SELECT * FROM chengjibiao");  
    while(rs.next())
    { 
      name=rs.getString(2); math=rs.getInt("数学");
      physics=rs.getInt("物理");english=rs.getInt("英语");
      sum=english+math+physics;
     text.append("***"+"\n"+name+"的成绩: "+"\n"+"数学："+math+" 英语：
"+english+"物理:"+physics+"总分："+sum+'\n');    
    }
  }
}
public class Example23_4
{ public static void main(String args[])
  {Window window=new Window();window.pack();
  }
}



23-例子5
import java.awt.*;import java.net.*;
import java.sql.*;import java.awt.event.*;
class DataWindow extends Frame implements ActionListener
 { TextField   待查英文单词_文本条,汉语解释_文本条,
                 更新英文单词_文本条,更新汉语解释_文本条,
                 填加英文单词_文本条,填加汉语解释_文本条; 
   Button       查询按扭,更新按扭,填加按扭;
   int 查询记录=0;
   Connection Con=null;Statement Stmt=null;
  DataWindow()
  {  super("英汉小词典");
     setBounds(150,150,300,120); 
     setVisible(true);setLayout(new GridLayout(3,1));
     try{Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");}
     catch(ClassNotFoundException e){}
      try{
Con=DriverManager.getConnection("jdbc:odbc:moon","gxy","ookk");
           Stmt=Con.createStatement();
         }
      catch(SQLException ee) {}
      待查英文单词_文本条=new TextField(16);
汉语解释_文本条=new TextField(16);
      更新英文单词_文本条=new TextField(16);
更新汉语解释_文本条=new TextField(16);
      填加英文单词_文本条=new TextField(16);
填加汉语解释_文本条=new TextField(16); 
      查询按扭=new Button("查询");
      更新按扭=new Button("更新");
      填加按扭=new Button("填加");
     Panel p1=new Panel(),p2=new Panel(),p3=new Panel();
     p1.add(new Label("输入要查询的英语单词:"));
p1.add( 待查英文单词_文本条);
     p1.add(new Label("显示英语单词的汉语解释:"));
p1.add(汉语解释_文本条);
     p1.add(查询按扭);
     p2.add(new Label("输入英语单词:"));p2.add( 更新英文单词_文本条);
     p2.add(new Label("输入该单词更新的汉语解释:"));
p2.add(更新汉语解释_文本条);
     p2.add(更新按扭);
     p3.add(new Label("输入英语单词:"));p3.add(  填加英文单词_文本条);
     p3.add(new Label("输入汉语解释:"));p3.add(填加汉语解释_文本条);
     p3.add(填加按扭);
     add(p1);add(p2);add(p3);
     查询按扭.addActionListener(this);更新按扭.addActionListener(this);
     填加按扭.addActionListener(this);
     addWindowListener(new WindowAdapter()
     {public void windowClosing(WindowEvent e)
     {setVisible(false);System.exit(0);  } } );
  }
 public void actionPerformed(ActionEvent e)
  {if(e.getSource()==查询按扭)
    {  查询记录=0;
       try{ 查询();}
       catch(SQLException ee) {}
    }
   else if(e.getSource()==更新按扭)
    {  try{ 更新();}
       catch(SQLException ee) {}
    }
   else if(e.getSource()==填加按扭)
    {  try{ 填加();}
       catch(SQLException ee) {}
    }
  }
 public  void 查询() throws SQLException
  { String cname,ename;
Con=DriverManager.getConnection("jdbc:odbc:moon","gxy","ookk");
    ResultSet rs=Stmt.executeQuery("SELECT * FROM 表1 ");  
    while (rs.next())
     {ename=rs.getString("单词"); cname=rs.getString("解释");
       if(ename.equals( 待查英文单词_文本条.getText().trim()))
       {汉语解释_文本条.setText(cname);查询记录=1; break;
       } 
     }
     Con.close();
   if(查询记录==0)
     {汉语解释_文本条.setText("没有该单词");  
     }
 }
 public void 更新() throws SQLException
 {  String s1="'"+更新英文单词_文本条.getText().trim()+"'",
           s2="'"+更新汉语解释_文本条.getText().trim()+"'";
    String t=" 'womendouhao' ";
   String temp="UPDATE 表1 SET 解释 ="+s2+" WHERE 单词 = "+s1 ;
   Con=DriverManager.getConnection("jdbc:odbc:moon","gxy","ookk");
   Stmt.executeUpdate(temp);  Con.close();
 } 
 public void 填加() throws SQLException
 {  String s1="'"+填加英文单词_文本条.getText().trim()+"'",
           s2="'"+填加汉语解释_文本条.getText().trim()+"'";
    String temp="INSERT INTO 表1 VALUES ("+s1+","+s2+")";
    Con=DriverManager.getConnection("jdbc:odbc:moon","gxy","ookk");
    Stmt.executeUpdate(temp); 
    Con.close();
 }
}
public class Database
{ public static void main(String args[])
    {DataWindow window=new DataWindow();window.pack();
  }
}





23-例子6
(1) 客户端程序:
import java.net.*;import java.io.*;
import java.awt.*;import java.awt.event.*;
import java.applet.*;