studentbean.java

java的一系列产品中包括jsme,jmse,j2ee,本文件提供j2ee实现的源代码.

package sessionEntity;

import java.rmi.RemoteException;
import java.sql.*;
import java.util.*;
import javax.ejb.*;
import javax.naming.*;
import javax.sql.DataSource;

public class StudentBean implements EntityBean {
  private EntityContext ctx;
  private DataSource dataSource;
  private String tableName;

  private String name;
  private Integer ssn; // primary key
  private int grade;
  public void setEntityContext(EntityContext c) {
    ctx = c;
    try {
      Context envCtx = (Context) new InitialContext().lookup("java:/comp/env");
      tableName = (String) envCtx.lookup("tableName");      
      String poolName = (String) envCtx.lookup("poolName");
      dataSource = (DataSource) envCtx.lookup("/jdbc/"+poolName);
    } catch (NamingException ne){
      // EJB was not deployed properly
      throw new EJBException(ne);
    }
  }

  public void unsetEntityContext(){
    ctx = null;
  }

  public Integer ejbCreate(String name, int ssn, int grade){
    this.name   = name;
    this.ssn    = new Integer(ssn);
    this.grade  = grade;
    Connection  con = null;
    PreparedStatement ps = null;
    Statement stmt=null;
    try {
      con = dataSource.getConnection();
			System.out.println("Connect successful");
      ps = con.prepareStatement("insert into "+tableName+
        " (name,ssn,grade) values (?,?,?)");
      ps.setString(1,name);
      ps.setInt(2,ssn);
      ps.setInt(3,grade);
      ps.executeUpdate();
      //when use no-transaction sataSource add follow:
      //con.commit();
      return this.ssn;
    } catch (SQLException sqe){
      try {
        ejbFindByPrimaryKey(this.ssn);
        throw new DuplicateKeyException("A student with social "+
                 "security number: "+ssn+" already exists.");
      } catch (Exception Ignore){}
      	System.out.println("Insert failed");
      	sqe.printStackTrace();
      	throw new EJBException(sqe);
    } finally {
      try {
        if (ps != null) ps.close();
        if (con != null) con.close();
      } catch (Exception ignore) {}
    }
  }

  public void ejbPostCreate(String name, int ssn, int grade) {}
  public void ejbRemove() throws RemoveException{
    Connection con = null;
    PreparedStatement ps = null;
    try {
      con = dataSource.getConnection();
      ps  = con.prepareStatement("delete from "+tableName+
        " where ssn=?");
      ps.setInt(1, ssn.intValue());
      if (ps.executeUpdate() < 1) {
        throw new RemoveException ("Error removing Student with ssn: "+ssn);
      }
    } catch (SQLException sqe) {
      throw new EJBException (sqe);
    } finally{
      try {
        if(ps != null) ps.close();
        if(con != null) con.close();
      } catch (Exception ignore) {}
    }
  }

  public void ejbLoad() {
    ssn = (Integer) ctx.getPrimaryKey();
    Connection con       = null;
    PreparedStatement ps = null;
    ResultSet rs         = null;
    try {
      con = dataSource.getConnection();
      ps  = con.prepareStatement("select name, grade from "
        +tableName+ " where ssn=?");
      ps.setInt(1, ssn.intValue());
      ps.executeQuery();
      rs = ps.getResultSet();

      if (rs.next()) {
        name  = rs.getString(1);
        grade = rs.getInt(2);
      } else {
        throw new NoSuchEntityException("Student with social "+
          "security number: "+ssn+" no longer exists.");
      }
    } catch (SQLException sqe) {
      throw new EJBException(sqe);
    } finally {
      try {
        if (rs != null) rs.close();
        if (ps != null) ps.close();
        if (con != null) con.close();
      } catch (Exception ignore) {}
    }
  }

  public void ejbStore(){
    Connection con       = null;
    PreparedStatement ps = null;
    try {
      con = dataSource.getConnection();
      ps  = con.prepareStatement("update "+tableName+
        " SET name=?, grade=? where ssn=?");
      ps.setString(1, name);
      ps.setInt(2, grade);
      ps.setInt(3, ssn.intValue());
      ps.executeUpdate();
    } catch (SQLException sqe) {
      throw new EJBException(sqe);
    } finally {
      try {
        if (ps != null) ps.close();
        if (con != null) con.close();
      } catch (Exception ignore) {}
    }
  }

  public void ejbActivate() {}
  public void ejbPassivate() {}
  public Integer ejbFindByPrimaryKey(Integer pk) throws ObjectNotFoundException
  {
    Connection con       = null;
    PreparedStatement ps = null;
    ResultSet rs         = null;
    try {
      con = dataSource.getConnection();
      ps  = con.prepareStatement("select ssn from "+tableName+
        " where ssn=?");
      ps.setInt(1, pk.intValue());
      ps.executeQuery();

      rs = ps.getResultSet();

      if (rs.next()) {
        return pk;
      } else {
        throw new ObjectNotFoundException ("Student with social "+
          "security number: "+ssn+" no longer exists.");
      }
    } catch (SQLException sqe) {
      throw new EJBException (sqe);
    } finally {
      try {
        if(rs != null) rs.close();
        if(ps != null) ps.close();
        if(con != null) con.close();
      } catch (Exception ignore) {}
    }
  }
  public Collection ejbFindStudentsInGrade(int gradeValue) {
    Connection con       = null;
    PreparedStatement ps = null;
    ResultSet rs         = null;

    ArrayList keys = new ArrayList();
    try {
      con = dataSource.getConnection();
      ps  = con.prepareStatement("select ssn from "+tableName+
        " where grade=?");
      ps.setInt(1, gradeValue);
      ps.executeQuery();

      rs = ps.getResultSet();
      while (rs.next()) {
        keys.add(new Integer(rs.getInt(1)));
      }
      return keys;
    } catch (SQLException sqe) {
      throw new EJBException (sqe);
    } finally {
      try {
        if(rs != null) rs.close();
        if(ps != null) ps.close();
        if(con != null) con.close();
      } catch (Exception ignore) {}
    }
  }
  public String getName() { return name; }
  public Integer getSsn() { return ssn; }
  public int getGrade() { return grade; }
  public void setGrade(int grade) { this.grade = grade; }
}