Extraction of DAO operations, Basedao

Common steps for DAO Operations:

0.    Write SQL statement 1.    Gets the connection 2.    Create stmt3.    Execute sqla)    update b)    query 4.    Close/exception

Code:

Basedao

/*** General DAO, all DAO written by himself inherits this class; * This class defines 2 common methods: * 1. Update * 2. Enquiry *@authorJie.yuan **/ Public classBasedao {//Initialize Parameters    PrivateConnection con; PrivatePreparedStatement pstmt; PrivateResultSet rs; /*** General method of updating *@paramSQL Update for SQL statement (update/insert/delete) *@paramParamsvalue The value of the placeholder in the SQL statement (if there is no placeholder, pass in null)*/     Public voidupdate (String sql,object[] paramsvalue) {Try {            //Get ConnectionsCon =jdbcutil.getconnection (); //to create a stmt object that executes a commandPSTMT =con.preparestatement (SQL); //parameter metadata: Gets the number of placeholder parameters            intCount =pstmt.getparametermetadata (). GetParameterCount (); //set the value of a placeholder parameter            if(Paramsvalue! =NULL&& paramsvalue.length > 0) {                //loop to assign a value to a parameter                 for(inti=0;i<count;i++) {Pstmt.setobject (i+1, Paramsvalue[i]); }            }            //Perform the updatepstmt.executeupdate (); } Catch(Exception e) {Throw NewRuntimeException (e); } finally{Jdbcutil.closeall (con, pstmt,NULL); }    }        /*** General method of query *@paramSQL *@paramParamsvalue*/     Public<T> list<t> query (String sql, object[] paramsvalue,class<t>clazz) {                Try {            //the returned collectionlist<t> list =NewArraylist<t>(); //ObjectT t =NULL; //1. Get the connectionCon =jdbcutil.getconnection (); //2. Create a stmt objectPSTMT =con.preparestatement (SQL); //3. Get the number of placeholder parameters and set the value of each parameter            intCount =pstmt.getparametermetadata (). GetParameterCount (); if(Paramsvalue! =NULL&& paramsvalue.length > 0) {                 for(inti=0; i<paramsvalue.length; i++) {Pstmt.setobject (i+1, Paramsvalue[i]); }            }            //4. Execute the queryrs =Pstmt.executequery (); //5. Get result set metadataResultSetMetaData RSMD =Rs.getmetadata (); //---> Get the number of columns            intColumnCount =Rsmd.getcolumncount (); //6. Traverse RS             while(Rs.next ()) {//the object to encapsulatet =clazz.newinstance (); //7. Traverse each column of each row to encapsulate the data                 for(inti=0; i<columncount; i++) {                    //get column names for each columnString columnName = rsmd.getcolumnname (i + 1); //gets the column name for each column, corresponding to the valueObject value =Rs.getobject (columnName); //encapsulation: Set to the properties of the T object "beanutils component"Beanutils.copyproperty (t, columnName, value); }                                //Add the Encapsulated object to the list collectionList.add (t); }                        returnlist; } Catch(Exception e) {Throw NewRuntimeException (e); } finally{Jdbcutil.closeall (Con, pstmt, RS); }    }}

Admindao:

 Public classAdmindaoextendsBasedao {//Delete     Public voidDeleteintID) {String SQL= "Delete from admin where id=?"; Object[] Paramsvalue={ID}; Super. Update (SQL, paramsvalue); }    //Insert     Public voidSave (Admin admin) {String SQL= "INSERT into admin (username,pwd) VALUES (?,?)"; Object[] Paramsvalue={admin.getusername (), Admin.getpwd ()}; Super. Update (SQL, paramsvalue); }        //Search All     PublicList<admin>GetAll () {String SQL= "SELECT * from admin"; List<Admin> list =Super. query (SQL,NULL, Admin.class); returnlist; }        //Query by criteria (primary key)     PublicAdmin FindByID (intID) {String SQL= "SELECT * from admin where id=?"; List<Admin> list =Super. query (SQL,NewObject[]{id}, Admin.class); return(list!=NULL&&list.size () >0)? List.get (0):NULL; }    }

Extraction of DAO operations, Basedao