jdbcutil.java

出试卷系统（包括前台教师出卷系统

package util;
import java.sql.*;
	

	public class JdbcUtil
	{    private static Connection con;
	
	private static String[] props = { "com.mysql.jdbc.Driver",
		"jdbc:mysql://127.0.0.1:3306/exam", "root", "tarena" };
		//1、加载驱动
	    static{
		  try{
		    Class.forName(props[0]);
		  }catch(Exception e){
		    e.printStackTrace();
		  }
		}
		//2、获取连接
		public static Connection getConnection(){
		  //Connection con = null;
		  try{
		    con = DriverManager.getConnection(
				props[1],props[2],props[3]);
		  }catch(Exception e){
		    e.printStackTrace();
		  }
		  return con;
		}
		//3、释放资源
		public static void release(Object o){
		   try{
		     if(o instanceof ResultSet){
				 ((ResultSet)o).close();
		     }else if(o instanceof Statement){
			   ((Statement)o).close();
			 }else if(o instanceof Connection){
			   ((Connection)o).close();
			 }
		   }catch(Exception e){
		     e.printStackTrace();
		   }
		}
		public static void release(
			ResultSet rs,Statement stmt,Connection con){
	      if(rs!=null){
		    try{
			  rs.close();
			}catch(Exception e){
			  e.printStackTrace();
			}
		  }

		  if(stmt!=null){
		    try{
			  stmt.close();
			}catch(Exception e){
			  e.printStackTrace();
			}
		  }

		  if(con!=null){
		    try{
			  con.close();
			}catch(Exception e){
			  e.printStackTrace();
			}
		  }

		}
		public static void printRs(ResultSet rs){
		  if(rs==null) return;
		  try{
		   ResultSetMetaData md = rs.getMetaData();
		   int num = md.getColumnCount();
		   StringBuffer sb = new StringBuffer();
		   for(int i=1;i<=num;i++){
		    int size = md.getColumnDisplaySize(i);
			if(size!=0){
			  String cname = md.getColumnName(i);
			  int blank = (size-cname.length())/2;
			  for(int j=0;j<blank;j++) sb.append(" ");
			  sb.append(cname);
			  if((size-cname.length())%2!=0) blank++;
			  for(int j=0;j<blank;j++) sb.append(" ");
		    }
		   }
		   sb.append("\n");
		   while(rs.next()){
		    for(int i=1;i<=num;i++){
		       int size = md.getColumnDisplaySize(i);
			   if(size!=0){
			     String value = rs.getString(i);
			     int blank = (size-value.length())/2;
			     for(int j=0;j<blank;j++) sb.append(" ");
			     sb.append(value);
			     if((size-value.length())%2!=0) blank++;
			     for(int j=0;j<blank;j++) sb.append(" ");
		       }
			}
			sb.append("\n");
		   }
		   System.out.println(sb.toString());
		  }catch(Exception e){
		   e.printStackTrace();
		  }
		}
		public static void main(String[] args) {
		   System.out.println(getConnection());
		}
	}