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我是 Java EE 的新手，遵循边做边学的方法。在一个非常简单的 Mysql 数据库中，Netbeans 7.3.1 有一个 Patient 表与一个 Person 表相关，我无法理解 Netbeans 生成的代码。我想创建一个事务，其中应该创建一个 Person 和一个 Patient 并保持回滚的可能性。我是否应该创建一个单独的控制器来处理此类事务。请帮助提供一些类似示例代码的链接。Netbeans 生成的代码如下。（删除了一些导入和冗余代码）

人.java

package entity;

import java.io.Serializable;
import java.util.Collection;
import java.util.Date;
import javax.persistence.Basic;
import javax.persistence.CascadeType;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.NamedQueries;
import javax.persistence.NamedQuery;
import javax.persistence.OneToMany;
import javax.persistence.Table;
import javax.persistence.Temporal;
import javax.persistence.TemporalType;
import javax.validation.constraints.NotNull;
import javax.validation.constraints.Size;
import javax.xml.bind.annotation.XmlRootElement;
import javax.xml.bind.annotation.XmlTransient;

@Entity
@Table(name = "person")
@XmlRootElement

public class Person implements Serializable {
    private static final long serialVersionUID = 1L;
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Basic(optional = false)
    @Column(name = "id")
    private Integer id;
    @Basic(optional = false)
    @NotNull
    @Size(min = 1, max = 45)
    @Column(name = "firstname")
    private String firstname;

    @Size(max = 255)
    @Column(name = "email")
    private String email;
    @Size(max = 15)
    @Column(name = "mobile")
    private String mobile;
    @Size(max = 15)
    @Column(name = "residence")
    private String residence;
    @Size(max = 15)
    @Column(name = "office")
    private String office;
    @Size(max = 255)
    @Column(name = "address")
    private String address;
    @Size(max = 20)
    @Column(name = "nic")
    private String nic;
    @Basic(optional = false)
    @NotNull
    @Column(name = "regdate")
    @Temporal(TemporalType.DATE)
    private Date regdate;
    @Basic(optional = false)
    @NotNull
    @Column(name = "dob")
    @Temporal(TemporalType.DATE)
    private Date dob;
    @Basic(optional = false)
    @NotNull
    @Size(min = 1, max = 45)
    @Column(name = "lastname")
    private String lastname;
    @Basic(optional = false)
    @NotNull
    @Size(min = 1, max = 25)
    @Column(name = "city")
    private String city;
    @OneToMany(cascade = CascadeType.ALL, mappedBy = "personid")
    private Collection<Patient> patientCollection;

    public Person() {
    }

    public Person(Integer id) {
        this.id = id;
    }

    public Person(Integer id, String firstname, Date regdate, Date dob, String lastname, String city) {
        this.id = id;
        this.firstname = firstname;
        this.regdate = regdate;
        this.dob = dob;
        this.lastname = lastname;
        this.city = city;
    }

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public String getFirstname() {
        return firstname;
    }

    public void setFirstname(String firstname) {
        this.firstname = firstname;
    }

    public String getEmail() {
        return email;
    }

    public void setEmail(String email) {
        this.email = email;
    }

    public String getMobile() {
        return mobile;
    }

    public void setMobile(String mobile) {
        this.mobile = mobile;
    }

    public String getResidence() {
        return residence;
    }

    public void setResidence(String residence) {
        this.residence = residence;
    }

    public String getOffice() {
        return office;
    }

    public void setOffice(String office) {
        this.office = office;
    }

    public String getAddress() {
        return address;
    }

    public void setAddress(String address) {
        this.address = address;
    }

    public String getNic() {
        return nic;
    }

    public void setNic(String nic) {
        this.nic = nic;
    }

    public Date getRegdate() {
        return regdate;
    }

    public void setRegdate(Date regdate) {
        this.regdate = regdate;
    }

    public Date getDob() {
        return dob;
    }

    public void setDob(Date dob) {
        this.dob = dob;
    }

    public String getLastname() {
        return lastname;
    }

    public void setLastname(String lastname) {
        this.lastname = lastname;
    }

    public String getCity() {
        return city;
    }

    public void setCity(String city) {
        this.city = city;
    }

    @XmlTransient
    public Collection<Patient> getPatientCollection() {
        return patientCollection;
    }

    public void setPatientCollection(Collection<Patient> patientCollection) {
        this.patientCollection = patientCollection;
    }


}

病人.java

package entity;

import java.io.Serializable;
import javax.persistence.Basic;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.ManyToOne;
import javax.persistence.NamedQueries;
import javax.persistence.NamedQuery;
import javax.persistence.Table;
import javax.validation.constraints.NotNull;
import javax.validation.constraints.Size;
import javax.xml.bind.annotation.XmlRootElement;

@Entity
@Table(name = "patient")
@XmlRootElement
@NamedQueries({
@NamedQuery(name = "Patient.findAll", query = "SELECT p FROM Patient p"),
@NamedQuery(name = "Patient.findById", query = "SELECT p FROM Patient p WHERE p.id = :id"),
@NamedQuery(name = "Patient.findByPatientcode", query = "SELECT p FROM Patient p WHERE p.patientcode = :patientcode"),
@NamedQuery(name = "Patient.findByHistory", query = "SELECT p FROM Patient p WHERE p.history = :history"),
@NamedQuery(name = "Patient.findByExtPatientCode", query = "SELECT p FROM Patient p    WHERE p.extPatientCode = :extPatientCode")})
public class Patient implements Serializable {
private static final long serialVersionUID = 1L;
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
@Basic(optional = false)
@Column(name = "id")
private Integer id;
@Basic(optional = false)
@NotNull
@Size(min = 1, max = 20)
@Column(name = "patientcode")
private String patientcode;
@Size(max = 255)
@Column(name = "history")
private String history;
@Size(max = 20)
@Column(name = "ExtPatientCode")
private String extPatientCode;
@JoinColumn(name = "personid", referencedColumnName = "id")
@ManyToOne(optional = false)
private Person personid;

public Patient() {
}

public Patient(Integer id) {
    this.id = id;
}

public Patient(Integer id, String patientcode) {
    this.id = id;
    this.patientcode = patientcode;
}

public Integer getId() {
    return id;
}

public void setId(Integer id) {
    this.id = id;
}

public String getPatientcode() {
    return patientcode;
}

public void setPatientcode(String patientcode) {
    this.patientcode = patientcode;
}

public String getHistory() {
    return history;
}

public void setHistory(String history) {
    this.history = history;
}

public String getExtPatientCode() {
    return extPatientCode;
}

public void setExtPatientCode(String extPatientCode) {
    this.extPatientCode = extPatientCode;
}

public Person getPersonid() {
    return personid;
}

public void setPersonid(Person personid) {
    this.personid = personid;
}

}

AbstractFacade.java

package session;

import java.util.List;
import javax.persistence.EntityManager;

public abstract class AbstractFacade<T> {
private Class<T> entityClass;

public AbstractFacade(Class<T> entityClass) {
    this.entityClass = entityClass;
}

protected abstract EntityManager getEntityManager();

public void create(T entity) {
    getEntityManager().persist(entity);
}

public void edit(T entity) {
    getEntityManager().merge(entity);
}

public void remove(T entity) {
    getEntityManager().remove(getEntityManager().merge(entity));
}

public T find(Object id) {
    return getEntityManager().find(entityClass, id);
}

public List<T> findAll() {
    javax.persistence.criteria.CriteriaQuery cq = getEntityManager().getCriteriaBuilder().createQuery();
    cq.select(cq.from(entityClass));
    return getEntityManager().createQuery(cq).getResultList();
}

public List<T> findRange(int[] range) {
    javax.persistence.criteria.CriteriaQuery cq = getEntityManager().getCriteriaBuilder().createQuery();
    cq.select(cq.from(entityClass));
    javax.persistence.Query q = getEntityManager().createQuery(cq);
    q.setMaxResults(range[1] - range[0]);
    q.setFirstResult(range[0]);
    return q.getResultList();
}

}

PatientFacade.java

package session;

import entity.Patient;
import javax.ejb.Stateless;
import javax.persistence.EntityManager;
import javax.persistence.PersistenceContext;

@Stateless
public class PatientFacade extends AbstractFacade<Patient> {
@PersistenceContext(unitName = "WebApplication4PU")
private EntityManager em;

@Override
protected EntityManager getEntityManager() {
    return em;
}

public PatientFacade() {
    super(Patient.class);
}

}

PersonFacade.java

package session;

import entity.Person;
import javax.ejb.Stateless;
import javax.persistence.EntityManager;
import javax.persistence.PersistenceContext;


@Stateless
public class PersonFacade extends AbstractFacade<Person> {
@PersistenceContext(unitName = "WebApplication4PU")
private EntityManager em;

@Override
protected EntityManager getEntityManager() {
    return em;
}

public PersonFacade() {
    super(Person.class);
}

}

人控制器.java

    package controllers;

import entity.Person;
import controllers.util.JsfUtil;
import controllers.util.PaginationHelper;
import session.PersonFacade;

import java.io.Serializable;
import java.util.ResourceBundle;
import javax.ejb.EJB;
import javax.inject.Named;
import javax.enterprise.context.SessionScoped;
import javax.faces.component.UIComponent;
import javax.faces.context.FacesContext;
import javax.faces.convert.Converter;
import javax.faces.convert.FacesConverter;
import javax.faces.model.DataModel;
import javax.faces.model.ListDataModel;
import javax.faces.model.SelectItem;

@Named("personController")
@SessionScoped
public class PersonController implements Serializable {

    private Person current;
    private DataModel items = null;
    @EJB
    private session.PersonFacade ejbFacade;
    private PaginationHelper pagination;
    private int selectedItemIndex;

    public PersonController() {
    }

    public Person getSelected() {
        if (current == null) {
            current = new Person();
            selectedItemIndex = -1;
        }
        return current;
    }

    private PersonFacade getFacade() {
        return ejbFacade;
    }

    public PaginationHelper getPagination() {
        if (pagination == null) {
            pagination = new PaginationHelper(10) {
                @Override
                public int getItemsCount() {
                    return getFacade().count();
                }

                @Override
                public DataModel createPageDataModel() {
                    return new ListDataModel(getFacade().findRange(new int[]{getPageFirstItem(), getPageFirstItem() + getPageSize()}));
                }
            };
        }
        return pagination;
    }

    public String prepareList() {
        recreateModel();
        return "List";
    }

    public String prepareView() {
        current = (Person) getItems().getRowData();
        selectedItemIndex = pagination.getPageFirstItem() + getItems().getRowIndex();
        return "View";
    }

    public String prepareCreate() {
        current = new Person();
        selectedItemIndex = -1;
        return "Create";
    }

    public String create() {
        try {
            getFacade().create(current);
            JsfUtil.addSuccessMessage(ResourceBundle.getBundle("/Bundle").getString("PersonCreated"));
            return prepareCreate();
        } catch (Exception e) {
            JsfUtil.addErrorMessage(e, ResourceBundle.getBundle("/Bundle").getString("PersistenceErrorOccured"));
            return null;
        }
    }

    public String prepareEdit() {
        current = (Person) getItems().getRowData();
        selectedItemIndex = pagination.getPageFirstItem() + getItems().getRowIndex();
        return "Edit";
    }

    public String update() {
        try {
            getFacade().edit(current);
            JsfUtil.addSuccessMessage(ResourceBundle.getBundle("/Bundle").getString("PersonUpdated"));
            return "View";
        } catch (Exception e) {
            JsfUtil.addErrorMessage(e, ResourceBundle.getBundle("/Bundle").getString("PersistenceErrorOccured"));
            return null;
        }
    }

    public String destroy() {
        current = (Person) getItems().getRowData();
        selectedItemIndex = pagination.getPageFirstItem() + getItems().getRowIndex();
        performDestroy();
        recreatePagination();
        recreateModel();
        return "List";
    }

    public String destroyAndView() {
        performDestroy();
        recreateModel();
        updateCurrentItem();
        if (selectedItemIndex >= 0) {
            return "View";
        } else {
            // all items were removed - go back to list
            recreateModel();
            return "List";
        }
    }

    private void performDestroy() {
        try {
            getFacade().remove(current);
            JsfUtil.addSuccessMessage(ResourceBundle.getBundle("/Bundle").getString("PersonDeleted"));
        } catch (Exception e) {
            JsfUtil.addErrorMessage(e, ResourceBundle.getBundle("/Bundle").getString("PersistenceErrorOccured"));
        }
    }

    private void updateCurrentItem() {
        int count = getFacade().count();
        if (selectedItemIndex >= count) {
            // selected index cannot be bigger than number of items:
            selectedItemIndex = count - 1;
            // go to previous page if last page disappeared:
            if (pagination.getPageFirstItem() >= count) {
                pagination.previousPage();
            }
        }
        if (selectedItemIndex >= 0) {
            current = getFacade().findRange(new int[]{selectedItemIndex, selectedItemIndex + 1}).get(0);
        }
    }

    public DataModel getItems() {
        if (items == null) {
            items = getPagination().createPageDataModel();
        }
        return items;
    }

    private void recreateModel() {
        items = null;
    }

    private void recreatePagination() {
        pagination = null;
    }

    public String next() {
        getPagination().nextPage();
        recreateModel();
        return "List";
    }

    public String previous() {
        getPagination().previousPage();
        recreateModel();
        return "List";
    }

    public SelectItem[] getItemsAvailableSelectMany() {
        return JsfUtil.getSelectItems(ejbFacade.findAll(), false);
    }

    public SelectItem[] getItemsAvailableSelectOne() {
        return JsfUtil.getSelectItems(ejbFacade.findAll(), true);
    }

    public Person getPerson(java.lang.Integer id) {
        return ejbFacade.find(id);
    }

    @FacesConverter(forClass = Person.class)
    public static class PersonControllerConverter implements Converter {

        @Override
        public Object getAsObject(FacesContext facesContext, UIComponent component, String value) {
            if (value == null || value.length() == 0) {
                return null;
            }
            PersonController controller = (PersonController) facesContext.getApplication().getELResolver().
                    getValue(facesContext.getELContext(), null, "personController");
            return controller.getPerson(getKey(value));
        }

        java.lang.Integer getKey(String value) {
            java.lang.Integer key;
            key = Integer.valueOf(value);
            return key;
        }

        String getStringKey(java.lang.Integer value) {
            StringBuilder sb = new StringBuilder();
            sb.append(value);
            return sb.toString();
        }


    }
}

病人控制器.java

    package controllers;

import entity.Patient;
import controllers.util.JsfUtil;
import controllers.util.PaginationHelper;
import session.PatientFacade;

import java.io.Serializable;
import java.util.ResourceBundle;
import javax.ejb.EJB;
import javax.inject.Named;
import javax.enterprise.context.SessionScoped;
import javax.faces.component.UIComponent;
import javax.faces.context.FacesContext;
import javax.faces.convert.Converter;
import javax.faces.convert.FacesConverter;
import javax.faces.model.DataModel;
import javax.faces.model.ListDataModel;
import javax.faces.model.SelectItem;

@Named("patientController")
@SessionScoped
public class PatientController implements Serializable {

    private Patient current;
    private DataModel items = null;
    @EJB
    private session.PatientFacade ejbFacade;
    private PaginationHelper pagination;
    private int selectedItemIndex;

    public PatientController() {
    }

    public Patient getSelected() {
        if (current == null) {
            current = new Patient();
            selectedItemIndex = -1;
        }
        return current;
    }

    private PatientFacade getFacade() {
        return ejbFacade;
    }

    public PaginationHelper getPagination() {
        if (pagination == null) {
            pagination = new PaginationHelper(10) {
                @Override
                public int getItemsCount() {
                    return getFacade().count();
                }

                @Override
                public DataModel createPageDataModel() {
                    return new ListDataModel(getFacade().findRange(new int[]{getPageFirstItem(), getPageFirstItem() + getPageSize()}));
                }
            };
        }
        return pagination;
    }

    public String prepareList() {
        recreateModel();
        return "List";
    }

    public String prepareView() {
        current = (Patient) getItems().getRowData();
        selectedItemIndex = pagination.getPageFirstItem() + getItems().getRowIndex();
        return "View";
    }

    public String prepareCreate() {
        current = new Patient();
        selectedItemIndex = -1;
        return "Create";
    }

    public String create() {
        try {
            getFacade().create(current);
            JsfUtil.addSuccessMessage(ResourceBundle.getBundle("/Bundle").getString("PatientCreated"));
            return prepareCreate();
        } catch (Exception e) {
            JsfUtil.addErrorMessage(e, ResourceBundle.getBundle("/Bundle").getString("PersistenceErrorOccured"));
            return null;
        }
    }

    public String prepareEdit() {
        current = (Patient) getItems().getRowData();
        selectedItemIndex = pagination.getPageFirstItem() + getItems().getRowIndex();
        return "Edit";
    }

    public String update() {
        try {
            getFacade().edit(current);
            JsfUtil.addSuccessMessage(ResourceBundle.getBundle("/Bundle").getString("PatientUpdated"));
            return "View";
        } catch (Exception e) {
            JsfUtil.addErrorMessage(e, ResourceBundle.getBundle("/Bundle").getString("PersistenceErrorOccured"));
            return null;
        }
    }

    public String destroy() {
        current = (Patient) getItems().getRowData();
        selectedItemIndex = pagination.getPageFirstItem() + getItems().getRowIndex();
        performDestroy();
        recreatePagination();
        recreateModel();
        return "List";
    }

    public String destroyAndView() {
        performDestroy();
        recreateModel();
        updateCurrentItem();
        if (selectedItemIndex >= 0) {
            return "View";
        } else {
            // all items were removed - go back to list
            recreateModel();
            return "List";
        }
    }

    private void performDestroy() {
        try {
            getFacade().remove(current);
            JsfUtil.addSuccessMessage(ResourceBundle.getBundle("/Bundle").getString("PatientDeleted"));
        } catch (Exception e) {
            JsfUtil.addErrorMessage(e, ResourceBundle.getBundle("/Bundle").getString("PersistenceErrorOccured"));
        }
    }

    private void updateCurrentItem() {
        int count = getFacade().count();
        if (selectedItemIndex >= count) {
            // selected index cannot be bigger than number of items:
            selectedItemIndex = count - 1;
            // go to previous page if last page disappeared:
            if (pagination.getPageFirstItem() >= count) {
                pagination.previousPage();
            }
        }
        if (selectedItemIndex >= 0) {
            current = getFacade().findRange(new int[]{selectedItemIndex, selectedItemIndex + 1}).get(0);
        }
    }

    public DataModel getItems() {
        if (items == null) {
            items = getPagination().createPageDataModel();
        }
        return items;
    }

    private void recreateModel() {
        items = null;
    }

    private void recreatePagination() {
        pagination = null;
    }

    public String next() {
        getPagination().nextPage();
        recreateModel();
        return "List";
    }

    public String previous() {
        getPagination().previousPage();
        recreateModel();
        return "List";
    }

    public SelectItem[] getItemsAvailableSelectMany() {
        return JsfUtil.getSelectItems(ejbFacade.findAll(), false);
    }

    public SelectItem[] getItemsAvailableSelectOne() {
        return JsfUtil.getSelectItems(ejbFacade.findAll(), true);
    }

    public Patient getPatient(java.lang.Integer id) {
        return ejbFacade.find(id);
    }

    @FacesConverter(forClass = Patient.class)
    public static class PatientControllerConverter implements Converter {

        @Override
        public Object getAsObject(FacesContext facesContext, UIComponent component, String value) {
            if (value == null || value.length() == 0) {
                return null;
            }
            PatientController controller = (PatientController) facesContext.getApplication().getELResolver().
                    getValue(facesContext.getELContext(), null, "patientController");
            return controller.getPatient(getKey(value));
        }

        java.lang.Integer getKey(String value) {
            java.lang.Integer key;
            key = Integer.valueOf(value);
            return key;
        }

        String getStringKey(java.lang.Integer value) {
            StringBuilder sb = new StringBuilder();
            sb.append(value);
            return sb.toString();
        }

        @Override
        public String getAsString(FacesContext facesContext, UIComponent component, Object object) {
            if (object == null) {
                return null;
            }
            if (object instanceof Patient) {
                Patient o = (Patient) object;
                return getStringKey(o.getId());
            } else {
                throw new IllegalArgumentException("object " + object + " is of type " + object.getClass().getName() + "; expected type: " + Patient.class.getName());
            }
        }
    }
}

提前致谢。

4

1 回答 1

1

事实：单个@StatelessEJB 方法调用算作单个完整事务。

只要利用这个事实。在 EJB 中创建一个新方法，该方法@Stateless一次执行所有必要的查询，然后让您的 JSF 支持 bean 准确调用该单一方法。

顺便说一下，这正是 EJB 存在的主要原因之一：透明的事务管理。在学习 Java EE 时，您似乎错过了这个并非不重要的事实。

于 2013-12-02T11:06:49.403 回答