Implementing database transactions with dynamic proxies

Database sql:

1 CREATE TABLE T_user 2 (3    user_id              varchar (TEN) not            null, 4    user_name            varchar (+) not            null, 5
   password             varchar () not            null, 6    contact_tel          varchar ( 7 EMAIL)                VARCHAR (8),    create_date          DATE, 9    constraint p_key_1 primary KEY (user_id), insert INTO T_user (U ser_id, user_name, password) values (' Root ', ' system administrator ', ' root ');

Connectionmanager.java (Database connection management)

 1 package dynamicproxytransaction; 2 3 Import java.sql.Connection; 4 Import Java.sql.DriverManager; 5 Import java.sql.SQLException; 6 7 public class ConnectionManager {8 private ConnectionManager () {9}10 one private static threadlocal<c onnection> threadconn = new threadlocal<connection> (); 12 13//Get database connections from public static Connection Getconn                 Ection () {Connection conn = Threadconn.get (); + if (conn = = null) {# try {18}                         Class.forName ("Com.ibm.db2.jcc.DB2Driver"), conn = Drivermanager.getconnection (20                 "Jdbc:db2://127.0.0.1:50000/drp", "Db2admin", "619100"); catch (ClassNotFoundException e) {22             E.printstacktrace (); SQLException catch (E) {e.printstacktrace (); 25 }26 Threadconn.set (conn);}28 return conn;29}30 31//SET Transaction manual submission of public Stati c void BenigTransction (Connection conn) {All-try {conn! = null) {Conn.getautocommit () ) {Conn.setautocommit (false), PNS}38}39} catch (SQLException E ) {e.printstacktrace (); 41}42}43 44//COMMIT TRANSACTION public static void Endtransction (Connect                     Ion conn) {conn = null) {$ if (!conn.getautocommit ()) {49 Conn.commit ();}51}52} catch (SQLException e) {E.printstac Ktrace (); 54}55}56 57//Set the original state of the Connection the public static void Recovertransction (Connection conn) {5 9 try {$ if (conn! = null) {Conn.getautocommit ()) {conn             . Setautocommit (false); + N} else {conn.setautocommit (true); 65}66 }67}catch (SQLException e) {e.printstacktrace (); 69}70}71 72//Unexpected ROLLBACK transaction public static V             OID rollback (Connection conn) {conn! = null) {conn.rollback (); 77 }78} catch (SQLException e) {e.printstacktrace (); 80}81}82 83//Close the connection and             It deletes the public static void Close () {Connection conn = Threadconn.get () from the current thread, and if (conn! = null) {87             try {conn.close (); conn = null;90 threadconn.remove (); 91 } catch (SQLException e) {e.printstacktrace (); 93}94}95}96}

User.java (Entity Class)

 1 package dynamicproxytransaction; 2 3 Import java.util.Date;         4 5 public class User {6//User ID 7 private string ID; 8//User name 9 private string name;10 Login password each private string password;12//Contact phone number contact_tel;14//email 1  5 private string email;16//user creation date + private date create_date;18 public String getId ()         {id;21}22-public void setId (String id) {this.id = id;25 }26 public String GetName () {name;29}30 to public void SetName (String na Me) {this.name = name;33}34 public String GetPassword () {password ; PNs}38-public void SetPassword (String password) {This.password = password;41}4 2 public String Getcontact_tel () {Contact_tel return = = =Null?  "": contact_tel;45}46-public void Setcontact_tel (String contact_tel) {This.contact_tel = contact_tel;49}50 public String getemail () {return email = = NULL? "": email;53}54 public void Setemail (String email) {This.email = email;57}58 The public Date getcreate_date () {create_date;61}62 the public void setcreate _date (date create_date) {this.create_date = create_date;65}66}

Userdao.java (User-related database operations)

1 package dynamicproxytransaction;2 3 Import java.sql.sqlexception;4 5 public interface Userdao {6 public     User Seluser (String id) throws SQLException; 7}

Userdaoimpl.java (Userdao implementation Class)

 1 package dynamicproxytransaction; 2 3 Import java.sql.Connection; 4 Import java.sql.PreparedStatement; 5 Import Java.sql.ResultSet; 6 Import java.sql.SQLException; 7 8 public class Userdaoimpl implements Userdao {9 @Override10 public User seluser (String id) throws Sqlexceptio n {one ResultSet resu = null;12 String sql = "SELECT * from Db2admin. T_user WHERE user_id =? "; Connection conn = Connectionmanager.getconnection (); PreparedStatement pstat = Conn.preparestatement ( SQL), user user = Null;16 try {pstat.setstring (1, id); resu = Pstat.execute             Query (); + if (Resu.next ()) {user = GetUser (resu);}22} finally {23                 if (resu! = null) {resu.close ();}26 if (pstat! = null) {27 Pstat.close ();}29}30 return user;31}32//Get user PrivAte user GetUser (ResultSet resu) throws SQLException {User user = new user (); User.setid (ResU . getString ("user_id")), User.setname (resu.getstring ("user_name")), PNs User.setpassword (resu.getst Ring ("PASSWORD")), User.setcontact_tel (resu.getstring ("Contact_tel")), User.setemail (resu.gets         Tring ("EMAIL")), User.setcreate_date (Resu.gettimestamp ("Create_date")), return user;42 }43}

Usermanager.java (user management function definition)

1 package dynamicproxytransaction;2 3 public interface Usermanager {4 public     User Finduser (String id) throws Exceptio n; 5}

Usermanagerimpl.java (Usermanager implementation Class)

1 package dynamicproxytransaction;  2  3 import java.sql.SQLException; 4  5 public class Usermanagerimpl implements Usermanager {6     //This is not the same as I wrote before: I'm all written. In each method, the write attribute should be better, reducing the number of times the object was created 7     private Userdao Userdao = null;  8  9 Public     Usermanagerimpl () {         Userdao = new Userdaoimpl ();}12 public     User Finduser ( String ID) throws SQLException {         return userdao.seluser (ID);     }16}

Transactionproxy.java (Proxy implementation)

 1 package dynamicproxytransaction; 2 3 Import Java.lang.reflect.InvocationHandler; 4 Import java.lang.reflect.InvocationTargetException; 5 Import Java.lang.reflect.Method; 6 Import Java.lang.reflect.Proxy; 7 Import java.sql.Connection; 8 9 public class Transactionproxy implements Invocationhandler {Ten private Object obj = null;11//obj: class requiring proxy 1 3 public Object Newproxyinstance (object obj) {this.obj = obj;15 return Proxy.newproxyinstance (this. Obj.getclass (). getClassLoader (), This.obj.getClass (). Getinterfaces (), this);}18 @Override2 0 public Object Invoke (object proxy, Method method, object[] args) throws Throwable {22///for receiving parameters                 Number of objects param = null;24//If it is the beginning of the following method, then the agent transaction is (Method.getname (). StartsWith ("add") 26 || Method.getname (). StartsWith ("modify") 27 | | Method.getname (). StartsWith ("find") 28 | | Method.getname (). StartswitH ("Del")) {Connection conn = connectionmanager.getconnection (); try {31//Manual                 Submit Transaction connectionmanager.benigtransction (conn); param = Method.invoke (obj, args); 34                 COMMIT TRANSACTION (conn); Connectionmanager.endtransction catch (Exception e) {37 ROLLBACK TRANSACTION Connectionmanager.rollback (conn); (e instanceof Invocationtarget Exception) {InvocationTargetException INV = (invocationtargetexception) e;41st Row inv.gettargetexception (); Exception} else {The "operation failed!"); }45} finally {46//restore Status CONNECTIONMANAGER.RECOVERTRANSC tion (conn); Connectionmanager.close ();}50}51 return param;52}53}

Test.java (Test)

1 package dynamicproxytransaction; 2  3 public class Test {4 public     static void Main (string[] args) throws Exception {5         transactionproxy TRANSCT Ionproxy = new Transactionproxy (); 6  7////         Generate proxy Object 8         Usermanager Usermanager = (usermanager) Transctionproxy 9                 . Newproxyinstance (New Usermanagerimpl ()); user         user = Usermanager.finduser ("root"),         System.out.println ("username:" + user.getname ());     }13     14}

Implementing database transactions with dynamic proxies