数据库连接

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//最后就是Class方法了，在这里装入不同的驱动就可以与不同的数据库连接了
import java.sql.*;
public class DBTest{
static {
  try{
    Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
  }catch (Exception e){
    e.printStackTace();
  }
  public static void main(String args[]){
   String StrSQL="";
   if(args.length!=0){
     StrSQL=args[0]
     System.out.prntln("The SQL Commond you want to execute is");
     System.out.println(StrSQL);
   }else{
    System.out.println("Please input the SQL Commond");
    System.exit(0);
   }
   try{
   DBConnection DBCon = new DBCOnnection("jdbc:odbc:","","");
   Connection conn= DBCon.makeConnection();
   DisPlayResult drs = new DisPlayResult(SreSQL,conn);
   drs.show();
   }
   catch(Exception e){
     e,printStackTace();
   }
   }
}
}
运用面向对象思想，可以很好的解决代码重用，这也是面向对象的优点。

//第一步是创建连接
import java.sql.*;
public class DBConnection{
  public String url;
  public String username;
  public String password;
  public DBConnection(){
  }
  public DBConnection(String url_,String username_,String password_){
   this.url=url_;
   this.username=username_;
   this.password=password_;

   }
   public Connection makeConnection(){
   Connection conn=null;
   try{
     conn=DriverManager.getConnection(url,username,password);

    }catch (Exception e){
     e.printStackTace();
     }
     return conn;

   }

}

//把与数据库的连接分为三步，第二步就是创建一个公共的Resultset对象，用来显示查询的结果

import java.sql.*;
public class DisPlayResult{
  public Connection String conn=null;
  public String StrSQL=" SQL Language";
  public DisPlayResult(){
  }
  publicDisPlayResult(String StrSQL_,String conn){

    this.SQLStr=SQLStr_;
    this.conn=conn_;

  }
    public void show(){

    if(conn=null){
       System.out.println("You do not create a connection");
     }else{

     if(SQLStr.equals("SQL Language"))
          System.out.println("You do not input any SQL Commond");
      }else{
          try{
          Statement st=conn.createStatement();
          //create a Statement Object
          ResultSet rs = st.executeQuery(SQLStr);
          ResultSetMataData rsmd = rs.getMataData();
          int ColumnNum = rsmd.getColumnCount();
          for(int i=1;i<=ColumnNum,i++){
            System.out.println(rsmd.getColumnName(i)+"/t");
           }
           System.out.println("/n------------------------/n");
           while(rs.next()){
           String Data = "";
           for(int i=1,i<=ColumnNum,i++){
            Data+=getString(i);
            }
            System.out.println(Data);


            }
            conn.close();
          }
          catch(Exception e){
            e.printStackTace();
          }

      }

    }
}