"JDBC" uses JDBC to connect to Oracle Database (Java reflection mechanism)

Db.properties file

Driverclassname=oracle.jdbc.OracleDriverurl=jdbc:oracle:thin: @localhost: 1521: xeusername=  Systempassword=123456

db.properties

Jdbcutilproperties.java file

Encapsulation of data connections and freeing resources,

 PackageCom.xdl.util;Importjava.io.IOException;ImportJava.io.InputStream;Importjava.sql.Connection;ImportJava.sql.DriverManager;ImportJava.sql.ResultSet;Importjava.sql.SQLException;Importjava.sql.Statement;Importjava.util.Properties; Public classjdbcutilproperties { Public  StaticString Driverclassname;  Public  StaticString URL;  Public  StaticString username;  Public  StaticString password; Static {        Try {            //read the Db.properties file, the path is relative to the project's pathInputStream InputStream = jdbcutilproperties.class. getClassLoader (). getResourceAsStream ("Com/xdl/util/db.properties"); /*Properties is a key value structure*/Properties Pro=NewProperties (); Try{pro.load (InputStream); Driverclassname= Pro.getproperty ("Driverclassname"); URL= Pro.getproperty ("url"); Username= Pro.getproperty ("username"); Password= Pro.getproperty ("Password"); } Catch(IOException e) {//TODO auto-generated Catch blockE.printstacktrace ();        } class.forname (Driverclassname); } Catch(ClassNotFoundException e) {//TODO auto-generated Catch blockE.printstacktrace (); }    }      /*How to get a database connection*/     Public  StaticConnection getconnection () {Connection conn=NULL; Try{conn=drivermanager.getconnection (URL, username, password); } Catch(SQLException e) {//TODO auto-generated Catch blockE.printstacktrace (); }        returnConn; }    /*ways to release resources*/     Public  Static  voidReleaseresource (Connection conn,statement st,resultset rs) {if(rs! =NULL){            Try{rs.close (); } Catch(SQLException e) {//TODO auto-generated Catch blockE.printstacktrace (); }finally{RS=NULL; }        }        if(St! =NULL){            Try{st.close (); } Catch(SQLException e) {//TODO auto-generated Catch blockE.printstacktrace (); }finally{St=NULL; }        }        if(Conn! =NULL){            Try{conn.close (); } Catch(SQLException e) {//TODO auto-generated Catch blockE.printstacktrace (); }finally{conn=NULL; }        }    }}

Jdbcutilproperties.java

Test.java file

 Packagecom.xdl.test;ImportJava.lang.reflect.Field;Importjava.sql.Connection;ImportJava.sql.ResultSet;ImportJava.sql.ResultSetMetaData;Importjava.sql.SQLException;Importjava.sql.Statement;Importjava.util.ArrayList;Importjava.util.List;ImportCom.xdl.entity.User;Importcom.xdl.util.JDBCUtilProperties; Public classTest1 { Public Static voidMain (string[] args) {//using the tool class to get the connectionConnection conn =NULL; Statement St=NULL; ResultSet RS=NULL; //Establish a connectionconn =jdbcutilproperties.getconnection (); //get the execution Environment        Try{St=conn.createstatement (); } Catch(SQLException e) {e.printstacktrace (); }                Try{RS= St.executequery ("SELECT * from MyUser"); //While (Rs.next ()) {//the object that wants to encapsulate the data as Java user user = new user ();//User.setid (Rs.getint ("ID"));//User.setname (rs.getstring ("NAME"));//User.setpassword (rs.getstring ("PASSWORD"));//System.out.println (user);//            }                        //The above approach is a hard-coded way, and is the most commonly used method. //The following approach is the use of a soft-coded method,//using the reflection mechanism in Java,//the current file is set up and reflected in the user class and query results, respectively.//and then assemble the above function. ResultSetMetaData RSMD =Rs.getmetadata (); //get the number of columns in this ResultSet object            intcolumns =Rsmd.getcolumncount (); String Userstr= "Com.xdl.entity.User"; List<User> datas =NewArraylist<user>(); //Move the cursor forward from the current position one             while(Rs.next ()) {//it uses the underlying information wrapper object to get the class object of the user class.class<?> U =Class.forName (USERSTR); Object obj=NULL; //get the User objectobj =u.newinstance (); Field[] FS=U.getdeclaredfields ();  for(inti = 1; I <= columns; i++) {                         for(Field f:fs) {//determine if the User object has fields equal to the MyUser table                        if(F.getname (). toUpperCase (). Equals (Rsmd.getcolumnname (i))) {//the type name of the current field is number                            if(Rsmd.getcolumntypename (i). Equals ("number")) {                                //to remove access checks for the user classF.setaccessible (true); Try {                                    //Insert the corresponding value into the user objectf.setint (obj, Rs.getint (Rsmd.getcolumnname (i))); } Catch(IllegalArgumentException |illegalaccessexception e) {                                    //TODO auto-generated Catch blockE.printstacktrace (); }                            }                            //the type name of the current field is Varchar2                            if(Rsmd.getcolumntypename (i). Equals ("VARCHAR2") {f.setaccessible (true); Try{f.set (obj, rs.getstring (Rsmd.getcolumnname (i))); } Catch(IllegalArgumentException |illegalaccessexception e) {                                    //TODO auto-generated Catch blockE.printstacktrace ();                }                            }                        }                    }                                    } //stores the current user object in a user collectionDatas.add ((User) obj); }             for(user user:datas) {System.out.println (user); }        } Catch(SQLException e) {e.printstacktrace (); } Catch(ClassNotFoundException E1) {//TODO auto-generated Catch blockE1.printstacktrace (); } Catch(instantiationexception E1) {//TODO auto-generated Catch blockE1.printstacktrace (); } Catch(illegalaccessexception E1) {//TODO auto-generated Catch blockE1.printstacktrace (); } finally{jdbcutilproperties.releaseresource (conn, St, RS); }    }}

Test.java

"JDBC" uses JDBC to connect to Oracle Database (Java reflection mechanism)