JDBC实例 Statement,PreparedStatement,CallableStatement三个方法的实例

大西瓜 — Fri, 23 Feb 2007 13:05:00 GMT

public void ListStudents() throws SQLException{
  int i, NoofColumns;
  String StNo, StFName, StLName;
  //初始化并加载JDBC-ODBC驱动程序
  Class.forName("jdbc.odbc.JdbcOdbcDriver");
  //创建连接对象
  Connection Ex1Con = DriverManager.getConnection("jdbc:odbc:StudentDB";uid="admin";pw="sa");
  //创建一个简单的Statement对象
  Statement Ex1Stmt = Ex1Con.createStatement();
  //创建SQL串，传送到DBMS并执行SQL语句
  ResultSet Ex1rs = Ex1Stmt.executeQuery("SELECT StudentID, FirstName, LastName FROM Students");
  //处理每一个数据行，直到不再有数据行
  System.out.println("Student Number     First Name     Last Name");
  while(Ex1rs.next()){
   //将列值保存到java变量中
   StNo = Ex1rs.getString(1);
   StFName = Ex1rs.getString(2);
   StLName = Ex1rs.getString(3);
   System.out.println(StNo, StFName, StLName);
  }
}

public void UpdateStudentName(String StFName, String StLName, String StNo) throws SQLException, ClassNotFoundException
{
  int RetValue;
  //初始化并加载JDBC-ODBC驱动程序
  Class.forName("jdbc.odbc.JdbcOdbcDriver");
  //创建连接对象
  Connection Ex1Con = DriverManager.getConnection("jdbc:odbc:StudentDB";uid="admin";pw="sa");
  //创建一个简单的Statement对象
  Statement Ex1Stmt = Ex1Con.createStatement();
  //创建SQL串，传送到DBMS并执行该SQL语句
  String SQLBuffer = "UPDATE Students SET FirstName = " +
   StFName + ",LastName = " + StLName +
   "WHERE StudentNumber = " + StNo;
  RetValue = Ex1Stmt.executeUpdate(SQLBuffer);
  System.out.println("Updated" + RetValue + "rows in the Database.");
}

//使用PreparedStatement改进实例
//Declare class variables
Connection Con;
PreparedStatement PrepStmt;
boolean Initialized = false;
public void InitConnection() throws SQLException, ClassNotFoundException{
  //Initialize and load the JDBC-ODBC driver.
  Class.forName("jdbc.odbc.JdbcOdbcDriver");
  //Make the connection object.
  Con = DriverManager.getConnection("jdbc:odbc:StudentDB";uid="admin";pw="sa");
  //Create a prepared Statement object.
  PrepStmt = Con.prepareStatement("SELECT ClassName, Location, DaysAndTimes FROM Classes WHERE ClassName = ?");
  Initialized = true;
}
public void ListOneClass(String ListClassName) throws SQLException, ClassNotFoundException{
  int i, NoOfColumns;
  String ClassName, ClassLocation, ClassSchedule;
  if(!Initialized){
   InitConnection();
  }

  //Set the SQL parameter to the one passed into this method
  PrepStmt.setString(1, ListClassName);
  ResultSet Ex1rs = PrepStmt.executeQuery();
  //Process each row until there are no more rows and display the results on the console.
  System.out.println("Class Location Schedule");
  while(Ex1rs.next()){
   ClassName = Ex1rs.getString(1);
   ClassLocation = Ex1rs.getString(2);
   ClassSchedule = Ex1rs.getString(3);
   System.out.println(ClassName,ClassLocation,ClassSchedule);
  }
}

//使用CallableStatement显示成绩
//预先定义好的存储过程的调用形式为：studentGrade = getStudentGrade(StudentID, ClassID)
public void DisplayGrade(String StudentID, String ClassID) throws SQLException
{
  int Grade;
  //Initialize and load the JDBC-ODBC dirver.
  Class.forName("jdbc.odbc.JdbcOdbcDriver");
  //Make the connection object;
  Connection Con = DriverManager.getConnection("jdbc:odbc:studentDB";uid="admin";pw="sa");
  //Create a Callable Statement object;
  CallableStatement CStmt = Con.prepareCall({? = call getStudentGrade[?,?]});

  //Now tie the placeholders with actual parameters.
  //Register the return value from the stored procedure
  //as an integer type so that the driver knows how to handle it.
  //Note the type is defined in the java.sql.Types.
  CStmt.registerOutParameter(1,java.sql.Types.INTEGER);

  //Set the In parameters (which are inherited from the PreparedStatement class)
  CStmt.setString(1,StudentID);
  CStmt.setString(2,ClassID);

  //Now we are ready to call the stored procedure

  int RetVal = CStmt.excuteUpdate();

  //Get the OUT Parameter from the registered parameter
  //Note that we get the result from the CallableStatement object
  Grade = CStmt.getInt(1);

  //And display the results on the console;
  System.out.println("The Grade is:" + Grade);
}

大西瓜 2007-02-23 21:05 发表评论

使用java.net.socket类创建socket的例子

大西瓜 — Mon, 05 Feb 2007 13:29:00 GMT

SOCKET客户端：

try{
Socket netspace = new Socket("www.netspace.org", 7);
BufferedReader input = new BufferedReader(new InputStreamReader(netspace.getInputStream()));
PrintWriter output = new PrintWriter(netspace.getOutputStream(), true);

}catch(UnknownHostException expt){
System.err.println("Unknown host:" + except);
System.exit(1);
}catch(IOException excpt){
System.err.println("Failed I/O:" + excpt);
System.exit(1);
}

output.println("test");
String testResponse = input.readLine();

SOCKET服务器端

try{
ServerSocket server = new ServerSocket(2222);
Socket clientConn = server.accept();

BufferedReader input = new BufferedReader(new InputStreamReader(clientConn.getInputStream()));
PrintWriter output = new PrintWriter(clientConn.getOutputStream(), true);
}catch(IOException excpt){
System.err.println("Failed I/O:" + excpt);
System.exit(1);
}

大西瓜 2007-02-05 21:29 发表评论

应用程序与小应用程序的转换

大西瓜 — Tue, 16 Jan 2007 13:31:00 GMT

应用程序向小应用程序转换的最简单的一个方法是：

　　扩展java.applet.Applet和在init()方法中调用main方法，如，

public void init(){
　　　main(null);
　　}

如果应用程序有命令行参数，那么，

　　public void init(){
　　String args[] = new String[2];
　　args[1] = getParameter("param1");
　　args[2] = getParameter("param2");
　　main(args);
　　｝

小应用程序向应用程序转换的方法是：

　　添加main()方法
　　在main()方法的最后需要调用init(), start()方法。

大西瓜 2007-01-16 21:31 发表评论

在java中main()方法必须是静态的和公共的。

大西瓜 — Tue, 16 Jan 2007 12:00:00 GMT

在java中main()方法必须是静态的和公共的。

Integer.parseInt() parseInt(String) 为了把字符串转换成整数型数值需要使用Integer类的parseInt(String)方法

大西瓜 2007-01-16 20:00 发表评论

IT博客-Think and Grow rich－－－－－－－－－－－－－－－－－－－－－－－-随笔分类-Java Notes

JDBC实例 Statement,PreparedStatement,CallableStatement三个方法的实例

使用java.net.socket类创建socket的例子

应用程序与小应用程序的转换

在java中main()方法必须是静态的和公共的。