db.java

设备管理系统：三种管理员：普通员工、设备管理员、超级管理员。可进行设备添加删除维修等基本操作。运行此需要netbeans+sql2005

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package upd;



import java.sql.*;
import java.sql.DriverManager;

public class DB {
    private Connection con;
    private Statement stm;
    private ResultSet rs;
    private String classname="com.microsoft.jdbc.sqlserver.SQLServerDriver";
    private String url="jdbc:microsoft:sqlserver://localhost:1433;DatabaseName=db_database07";

    public DB(){}
    public Connection getCon(){
    	try{
    		Class.forName(classname);
    	}
    	catch(ClassNotFoundException e){
    		e.printStackTrace();
    	}
    	try{
    	    con=DriverManager.getConnection(url,"sa","1234");
    	}
    	catch(Exception e){
    	    e.printStackTrace(System.err);
    		con=null;
    	}
    	return con;
    }
    public Statement getStm(){
  	  try{
  	     con=getCon();
  	     stm=con.createStatement();
  	  }catch(Exception e){e.printStackTrace(System.err);}
  	   return stm;
  	}
  	public Statement getStmed(){
  	  try{
  	     con=getCon();
  	     stm=con.createStatement(ResultSet.TYPE_SCROLL_INSENSITIVE,ResultSet.CONCUR_READ_ONLY);
  	  }catch(Exception e){e.printStackTrace(System.err);}
  	  return stm;
    }
  	public ResultSet getRs(String sql){
   		if(sql==null)sql="";
		try{
			stm=getStm();
			rs=stm.executeQuery(sql);
		}
		catch(SQLException e){e.printStackTrace();}
		return rs;
	}

    public int update(String sql){
        int num=-1;
        if(sql==null)sql="";
        System.out.println("sql:"+sql);
         	try{
                 FileBean be=new FileBean();
      if(be.writeStr("更新: "+sql)){
         	    stm=getStmed();
         	    num=stm.executeUpdate(sql);}
        	}
         	catch(Exception e){e.printStackTrace();num=-1;}
         	return num;
    }
    public int insert(String sql){
      int num=-1;
      if(sql==null)sql="";
       	try{
             FileBean be=new FileBean();
      if(be.writeStr("插入: "+sql)){
       	    stm=getStmed();
       	    num=stm.executeUpdate(sql);}
      	}
       	catch(Exception e){e.printStackTrace();num=-1;}
       	return num;
    }
    public int delete(String sql){
    	int num=0;
    	if(sql==null)sql="";
    	try{
             FileBean be=new FileBean();
      if(be.writeStr("删除: "+sql)){
    	  	stm=getStmed();
    	   	num=stm.executeUpdate(sql);}
    	}
    	catch(Exception e){e.printStackTrace();num=-1;}
    	return num;
    }
  	public void closed(){
  		try{
    		if(rs!=null)rs.close();
    	}
    	catch(Exception e){e.printStackTrace();}
    	try{
    		if(stm!=null)stm.close();
    	}
    	catch(Exception e){e.printStackTrace();}
  		try{
    		if(con!=null)con.close();
    	}
    	catch(Exception e){e.printStackTrace();}
    }
}