The DBHelper of JAVA-JDBC

Package Com.myit.util;import Java.lang.reflect.field;import Java.sql.connection;import Java.sql.DriverManager; Import Java.sql.preparedstatement;import Java.sql.resultset;import Java.sql.resultsetmetadata;import Java.sql.sqlexception;import Java.util.arraylist;import Java.util.list;public class DBHelper {private static final Str    ing driver= "COM.MYSQL.JDBC";    private static final String url= "Jdbc:mysql://localhost:3306/dvd";    private static final String user= "root";        private static final String password= "root";        /** * Connect database * @return Linked Database object */public Connection getconnection () {Connection conn=null;        try {class.forname (DRIVER);        } catch (ClassNotFoundException e) {//TODO auto-generated catch block E.printstacktrace ();        } try {conn=drivermanager.getconnection (URL, USER, PASSWORD); } catch (SQLException e) {//TODO auto-generated catch block e.printstAcktrace ();    } return conn; /** * Release the appropriate resources * @param RS * @param pstmt * @param conn */public void CloseAll (ResultSet r            S,preparedstatement pstmt,connection conn) {try {if (rs!=null) {rs.close ();            } if (Pstmt!=null) {pstmt.close ();            } if (Conn!=null) {conn.close ();        }} catch (SQLException e) {//TODO auto-generated catch block E.printstacktrace (); }}/** * This method can be done to add and revise all operations * @param SQL * @param params * @return true or false */public        The number of rows affected by the Boolean excuteupdate (String sql,list<object> params) {int res=0;//Connection conn=null;        PreparedStatement pstmt = null;        ResultSet Rs=null;            try {conn=getconnection (); Pstmt=conn.preparestatement (SQL);//Load SQL statement if (params!=null) {//join have? Placeholderbit, before execution?                Placeholder replace for (int i=0;i<params.size (); i++) {Pstmt.setobject (i+1, Params.get (i));                    }} res=pstmt.executeupdate ();        } catch (SQLException e) {//TODO auto-generated catch block E.printstacktrace ();        }finally{CloseAll (RS, PSTMT, conn);    } return res>0?true:false; }/** * encapsulated using generic method and reflection mechanism * @param SQL * @param params * @param CLS * @return */Public &L T T> list<t> executeQuery (String sql,list<object> params,class<t> cls) throws exception{Connect        Ion Conn=null;        PreparedStatement pstmt = null;        ResultSet Rs=null;        List<t> data=new arraylist<t> ();            try {conn=getconnection (); Pstmt=conn.preparestatement (SQL);//Load SQL statement if (params!=null) {//join have? placeholder, put in before executing? Placeholder replace for (int i=0;i<parAms.size (); i++) {Pstmt.setobject (i+1, Params.get (i));            }} rs=pstmt.executequery ();            The query is encapsulated into the corresponding entity class object ResultSetMetaData Rsd=rs.getmetadata ();//Get the Column object, this object can get the structure of the table, including, column name, number of columns, the data type of the column                while (Rs.next ()) {T m=cls.newinstance ();                    for (int i=0;i<rsd.getcolumncount (); i++) {String col_name=rsd.getcolumnname (i+1);//Get Column name                    Object Value=rs.getobject (col_name);//Gets the value of the column corresponding to Field Field=cls.getdeclaredfield (col_name);                 Field.setaccessible (TRUE);//Give the private property an accessible Field.set (m, value);//Assign a value to the object's private property}            Data.add (m); }} catch (SQLException e) {//TODO auto-generated catch block E.printstacktrace        ();        }finally{CloseAll (RS, PSTMT, conn);    } return data; }} 

　　

The DBHelper of JAVA-JDBC