Java Student Information Management system design _java

The student information for this example adds transactions to the database (you can commit the transaction, rollback the transaction, and use local thread refinement)

Main Page index.jsp

<%@ page language= "java" import= "java.util.*" pageencoding= "UTF-8"%> <%@ taglib "uri=" http://java.sun.com/jsp
 /jstl/core "prefix=" C "%>  

Get a database connection tool Connutils5.java

Package cn.hncu.utils;
Import Java.lang.reflect.InvocationHandler;
Import Java.lang.reflect.Method;
Import Java.lang.reflect.Proxy;
Import java.sql.Connection;
Import Java.sql.DriverManager;
Import java.util.ArrayList;
Import java.util.List;

Import java.util.Properties; public class ConnUtils5 {//local thread management object, for implementation: the connection obtained by the same thread is the same private static threadlocal< connection> t=new Threadloc
 Al<connection> ();
 Private final static list<connection> pool=new arraylist<connection> ();
 private static int size;//is read by the resource file private ConnUtils5 () {} static{Properties P=new properties (); try {//The following method can read a resource file under Classpath in a pure Java project, but cannot read the Java EE project.
Because Tomcat changed the system's default class loader to//p.load (Classloader.getsystemclassloader (). Getsystemresourceasstream ("jdbc.properties"));

  P.load (Classloader.getsystemresourceasstream ("jdbc.properties")); Read the resource file under the classpath of the Web project, which can be P.load (ConnUtils3.class.getClassLoader (). getResourceAsStream ("Jdbc.properties")
  ); String Driver=p.getpropeRty ("Driver");
  String url=p.getproperty ("url");
  String Name=p.getproperty ("username");
  String pwd=p.getproperty ("password");
  String ssize=p.getproperty ("size");
  Size=integer.parseint (ssize);
  Class.forName (driver);
  for (int i=0;i<size;i++) {final Connection con=drivermanager.getconnection (URL,NAME,PWD);
  System.out.println ("con==" +con); Change the Conn.close () method//Use proxy mode to generate an enhanced version of the Conn object, and its close () method to intercept the object Ncon=proxy.newproxyinstance (ConnUtils3.class.ge Tclassloader (),//Conn.getclass (). Getinterfaces (),//later this method is not possible, should be the implementation class in the driver and our current program is not in the same space (ClassLoader different) new Class[]{con  Nection.class}, new Invocationhandler () {@Override public object Invoke (Object Proxy, Method method, object[] args) throws Throwable {if (Method.getname (). Equals ("Close")) {System.out.println ("Return a Link:" + (Connection) pro
     XY);
     Pool.add ((Connection) proxy);
    return null;
    Return Method.invoke (con, args);
  }
  });
  Pool.add ((Connection) ncon); Catch (Exception e)
 {E.printstacktrace ();
 The public static synchronized Connection getconnection () {//is taken first from T, if any, take it out if it is not taken in the pool and put the object in T Connection con=t.get ();
  if (con==null) {if (Pool.size () <=0) {System.out.println ("The pool is disconnected ...");
  try {thread.sleep (1000);
  catch (Interruptedexception e) {e.printstacktrace ();
  return getconnection ();
  } con=pool.remove (0);

 T.set (con);//Put into T} return con;//take one Move one}}

Resource File Jdbc.properties

# #MySQL
driver=com.mysql.jdbc.driver
url=jdbc:mysql://127.0.0.1:3306/hncu?useunicode=true& Characterencoding=utf-8
username=root
password=1234
size=3
# #Oracle
#driver = Oracle.jdbc.driver.OracleDriver
#url =jdbc:oracle:thin:@127.0.0.1:1521:orcl
#username =scott
# Password=tiger

Value Object
Stud.java

Package cn.hncu.domain;

Import java.util.ArrayList;
Import java.util.List;
 * * * a One-to-many "one" side value object of the building method
 * * Public
class Stud {

 private String ID;
 private String name;
 ※ specifically for "many" side to add a set---embodies the "one-to-many relationship" in multiple tables
 private list<book> books=new arraylist<book> ();/Note that The collection is to be new when it is constructed or before. Public
 String GetId () {return
 ID;
 }
 public void SetId (String id) {
 this.id = ID;
 }
 Public String GetName () {return
 name;
 }
 public void SetName (String name) {
 this.name = name;
 }



 Public list<book> Getbooks () {return books
 ;
 }
 public void Setbooks (List<book> books) {
 this.books = books;
 }
 @Override public
 String toString () {return
 ' id= + ID + ', ' + name + ', ' + books;
 }

}

Book.java

Package cn.hncu.domain;
 * * * the "multi" square value object of the construction method * * Public
class Book {

 private Integer ID;
 The base data types are all declared with the wrapper class, ready to use the framework for later---wrapper classes can be compatible with the framework (because the generic framework uses class reflection)
 private String name;
 Private Double Price;
 ※ for "One" side to add a variable of the object type (note, do not studid)---embodies the "one-to-many relationship" in multiple tables
 private Stud s;//set owner
 //private String studid;// ★ Don't do this
 . Set public Integer getId () {return
 ID;
 }
 public void SetId (Integer id) {
 this.id = ID;
 }
 Public String GetName () {return
 name;
 }
 public void SetName (String name) {
 this.name = name;
 }
 Public Double GetPrice () {return price
 ;
 }
 public void Setprice (Double price) {
 This.price = Price;
 }
 Public Stud GetS () {return
 s;
 }
 public void SetS (Stud s) {
 THIS.S = s;
 }
 * * * Multiple Table association when the ToString () method to pay attention to a trap, is one side of the output of the other side, while the other side and in turn output the previous side, the formation of infinite recursion!
 * *
 @Override public
 String toString () {return
 "id= + ID +", "+ Name +", "+ price;//cannot output stud object here, no Then infinite recursion
 }

}

Stud layer of the servlet layer –queryservlet.java

Package cn.hncu.stud.servlet;
Import java.io.IOException;
Import java.util.List;

Import Java.util.Map;
Import javax.servlet.ServletException;
Import Javax.servlet.http.HttpServlet;
Import Javax.servlet.http.HttpServletRequest;

Import Javax.servlet.http.HttpServletResponse;
Import Cn.hncu.domain.Book;
Import Cn.hncu.domain.Stud;
Import Cn.hncu.stud.service.IStudService;

Import Cn.hncu.stud.service.StudServiceImpl;
 public class Queryservlet extends HttpServlet {//injection istudservice service=new Studserviceimpl (); public void doget (HttpServletRequest request, httpservletresponse response) throws Servletexception, IOException {DoP
 OST (request, response); 
 public void DoPost (HttpServletRequest request, httpservletresponse response) throws Servletexception, IOException {
 String cmd=request.getparameter ("cmd");
 System.out.println ("cmd:" +cmd);
 if ("Query". Equals (cmd)) {Query (request, response);
 }else if ("Add". Equals (cmd)) {Add (request, response); }} public void Query (HttpServletRequest request, httpservletresponse response) throws Servletexception, IOException {list<map<st
 Ring, string>> studs=service.query ();
 Request.setattribute ("studs", studs);
 Request.getrequestdispatcher ("/jsps/show.jsp"). Forward (request, response); } public void Add (HttpServletRequest request, httpservletresponse response) throws Servletexception, IOException {//1
 Collect parameter 2 organization parameters (the ID field is left in DAO to complement) String name[]=request.getparametervalues ("name");
 System.out.println (Name[0]);
 Stud s=new Stud ();
 S.setname (Name[0]);
 Library information String books[]=request.getparametervalues ("book"); Protection---Price protection should also be written, here we are lazy if (books==null| |
 books.length<=0) {return;
 } String prices[]=request.getparametervalues ("price");
  for (int i=0;i<books.length;i++) {Book b=new book ();
  B.setname (Books[i]);
  B.setprice (Double.parsedouble (prices[i));
 ※ completes the "one-to-many" relationship of two value objects Data Encapsulation S.getbooks (). Add (b);//One b.sets (s);//Multiparty}//3 invokes service layer try {service.save (s); catch (exception e) {//Guide failed Page}}}

 

The service layer of the stud layer –
Interface:

Package cn.hncu.stud.service;

Import java.util.List;
Import Java.util.Map;

Import Cn.hncu.domain.Stud;

Public interface Istudservice {public

 list<map<string, string>> query ();
 public void Save (Stud Stud);
}

Implementation class

Package cn.hncu.stud.service;
Import java.sql.Connection;
Import java.sql.SQLException;
Import java.util.List;

Import Java.util.Map;
Import Cn.hncu.domain.Stud;
Import Cn.hncu.stud.dao.BookDAO;
Import Cn.hncu.stud.dao.BookJdbcDao;
Import Cn.hncu.stud.dao.StudDAO;
Import Cn.hncu.stud.dao.StudJdbcDAO;

Import CN.HNCU.UTILS.CONNUTILS3;
 * * We will usually use a DAO standalone operation in the future development of a table, there are several entity tables in the system to write a few DAO, * after the framework is so dry, we have to do so, because the structure is good!
 * * In the case of transactions: * 1, if there is only one DAO, but to execute multiple SQL statements and involve additions and deletions, then open transaction * 2, if a service calls multiple DAO, usually also open transaction.
 * * Public class Studserviceimpl implements Istudservice {//injection Studdao dao_stud=new Studjdbcdao ();
 Bookdao dao_book=new Bookjdbcdao ();
 @Override public list<map<string, string>> query () {return dao_stud.query ();

 @Override public void Save (Stud Stud) {Connection con=null;
  try {con=connutils3.getconnection ();
  System.out.println ("Get a Link:" +con);
  Con.setautocommit (FALSE);
  Dao_stud.save (stud);

  Dao_book.save (Stud.getbooks ()); System.out.println ("Submit a transaction ...")");
 Con.commit ();
  catch (Exception e) {try {System.out.println ("Roll back a transaction ...");
  Con.rollback ();
  catch (SQLException E1) {e1.printstacktrace ();
  }finally{try {con.setautocommit (true);
  Con.close ();
  catch (SQLException e) {e.printstacktrace ();

 }
 }
 }

}

The DAO layer of the Stud layer –
Stud interface

Package Cn.hncu.stud.dao;

Import java.util.List;
Import Java.util.Map;

Import Cn.hncu.domain.Stud;

Public interface Studdao {public

 list<map<string, string>> query ();
 public void Save (Stud Stud) throws Exception;
}

Stud Implementation Class

Package Cn.hncu.stud.dao;
Import java.sql.Connection;
Import java.sql.PreparedStatement;
Import Java.sql.ResultSet;
Import java.sql.SQLException;
Import java.sql.Statement;
Import java.util.ArrayList;
Import Java.util.HashMap;
Import java.util.List;
Import Java.util.Map;

Import Java.util.UUID;
Import Cn.hncu.domain.Book;
Import Cn.hncu.domain.Stud;

Import CN.HNCU.UTILS.CONNUTILS3; public class Studjdbcdao implements Studdao {@Override public list<map<string, string>> query () {LIST&LT ;
 Map<string, string>> list=new arraylist<map<string,string>> ();
 A Map is a row of data, list<map> is the entire data table Connection Con=null;
  try {con=connutils3.getconnection ();
  Statement st=con.createstatement ();
  String sql= "SELECT * from Stud";
  ResultSet rs=st.executequery (SQL);
  while (Rs.next ()) {map<string,string> m=new hashmap<string, string> ();
  M.put ("id", (String) Rs.getobject (1));
  M.put ("Name", (String) Rs.getobject (2));
  List.add (m); Rs. Close ();
 St.close ();
 catch (SQLException e) {e.printstacktrace ();
  }finally{try {con.close ();
  catch (SQLException e) {e.printstacktrace ();
 } return list;
 @Override public void Save (Stud Stud) throws Exception {Connection con=connutils3.getconnection ();
 System.out.println ("Get a Link:" +con);
 String sql= "INSERT into stud values (?,?)";
 String Uuid=uuid.randomuuid (). toString (). Replace ("-", "");
 PreparedStatement pst=con.preparestatement (SQL);
 Stud.setid (UUID)//for "multi-party" that book can get "one side" of the ID, specialized complement pst.setstring (1, UUID);
 Pst.setstring (2, Stud.getname ());
 System.out.println ("1:" +uuid+ ", 2:" +stud.getname ());
Pst.executeupdate ();

 Con.close ()//Get the same con, there's no need to turn it off}}

Book Interface

Package Cn.hncu.stud.dao;

Import java.util.List;

Import Cn.hncu.domain.Book;

Public interface Bookdao {public

 void Save (List<book> books) throws Exception;
}

Book Implementation class

Package Cn.hncu.stud.dao;

Import java.sql.Connection;
Import java.sql.PreparedStatement;
Import java.util.List;

Import Cn.hncu.domain.Book;
Import CN.HNCU.UTILS.CONNUTILS3;

public class Bookjdbcdao implements Bookdao {

 @Override public
 void Save (List<book> books) throws Exception {
 Connection con=connutils3.getconnection ();
 System.out.println ("Get a Link:" +con);
 String sql= "INSERT INTO book (Name,price,studid) VALUES (?,?,?)";
 PreparedStatement pst=con.preparestatement (SQL);
 for (book b:books) {
  pst.setstring (1, B.getname ());
  Pst.setdouble (2, B.getprice ());
  Pst.setobject (3, "12132312");//exception (intentionally to a nonexistent foreign key field to test transaction rollback)--Measure transaction rollback
//  Pst.setobject (3, B.gets (). GetId ());
  System.out.println ("1:" +b.getname () + ", 2:" +b.getprice () + ", 3:" +b.gets (). GetId ());
  Pst.addbatch (),//Add to Batch
 }
 Pst.executebatch ()//Execute batch

//Con.close ();//Here's the same con, there's no need to close

 }

}

Show Student Information page jsps/show.jsp

<%@ page language= "java" import= "java.util.*" pageencoding= "UTF-8"%> <%@ taglib
"uri=" http:// Java.sun.com/jsp/jstl/core "prefix=" C "%>
 
 

Effect Chart:

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