java - 使用 hibernate 和 seam 保持多对多关系

Question

我有一个与现有数据库通信的程序。有一个复合表，其中一个员工和一个车辆作为其复合键。在编辑或添加员工页面上，有一个下拉框，用于选择员工喜欢的车辆，然后将车辆列表存储在员工类的哈希表中。但是，该列表不会保留或存储在复合表中。我是接缝新手，花了一整天的时间试图弄清楚这一点。任何帮助将不胜感激。

以下是我的一些类(class):员工:

@Entity
@Table(name = "flower_store_employee", schema = "dbo", catalog = "tyler")
public class FlowerStoreEmployee implements java.io.Serializable, Comparable<FlowerStoreEmployee> {

/**
 * 
 */
private static final long serialVersionUID = -1727355085366851150L;
@Id
@GeneratedValue(strategy=GenerationType.IDENTITY)
@Column(name = "employee_id", unique = true, nullable = false)
private Integer employeeId;
@ManyToOne(fetch = FetchType.LAZY)
@JoinColumn(name = "address_id")
private FlowerStoreAddress flowerStoreAddress;
@Column(name = "name_first", length = 25)
@Length(max = 25)
private String nameFirst;
@Column(name = "name_last", length = 25)
@Length(max = 25)
private String nameLast;
@Column(name = "ssn")
private String ssn;
@Column(name = "phone")
private String phone;
@Column(name = "pay")
private int pay;
@OneToMany(fetch = FetchType.LAZY, mappedBy = "flowerStoreEmployee")
private Set<FlowerStoreDelivery> flowerStoreDeliveries = new HashSet<FlowerStoreDelivery>(
        0);
@Cascade({org.hibernate.annotations.CascadeType.ALL })
@ManyToMany(fetch = FetchType.LAZY, mappedBy = "flowerStoreEmployees")
//@JoinTable(name = "flower_store_emp_vehicle", schema = "dbo", catalog = "tyler", joinColumns = { @JoinColumn(name = "vehicle_id", nullable = false, updatable = true) }, inverseJoinColumns = { @JoinColumn(name = "employee_id", nullable = false, updatable = true) })
private Set<FlowerStoreVehicle> flowerStoreVehicles = new HashSet<FlowerStoreVehicle>(
        0);
public FlowerStoreEmployee() {
}

public FlowerStoreEmployee(int employeeId) {
    this.employeeId = employeeId;
}

public FlowerStoreEmployee(FlowerStoreAddress flowerStoreAddress, String nameFirst,
        String nameLast, String ssn, String phone, int pay,
        Set<FlowerStoreDelivery> flowerStoreDeliveries,
        Set<FlowerStoreVehicle> flowerStoreVehicles) {
    this.employeeId = employeeId;
    this.flowerStoreAddress = flowerStoreAddress;
    this.nameFirst = nameFirst;
    this.nameLast = nameLast;
    this.ssn = ssn;
    this.phone = phone;
    this.pay = pay;
    this.flowerStoreDeliveries = flowerStoreDeliveries;
    this.flowerStoreVehicles = flowerStoreVehicles;
}


public int getEmployeeId() {
    return this.employeeId;
}

public void setEmployeeId(int employeeId) {
    this.employeeId = employeeId;
}


public FlowerStoreAddress getFlowerStoreAddress() {
    return this.flowerStoreAddress;
}

public void setFlowerStoreAddress(FlowerStoreAddress flowerStoreAddress) {
    this.flowerStoreAddress = flowerStoreAddress;
}


public String getNameFirst() {
    return this.nameFirst;
}

public void setNameFirst(String nameFirst) {
    this.nameFirst = nameFirst;
}


public String getNameLast() {
    return this.nameLast;
}

public void setNameLast(String nameLast) {
    this.nameLast = nameLast;
}


public String getSsn() {
    return this.ssn;
}

public void setSsn(String ssn) {
    this.ssn = ssn;
}


public String getPhone() {
    return this.phone;
}

public void setPhone(String phone) {
    this.phone = phone;
}


public int getPay() {

    return this.pay;
}

public void setPay(int pay) {
    this.pay = pay;
}

public void setPay(String pay){
    this.pay = Integer.parseInt(pay);
}

public Set<FlowerStoreDelivery> getFlowerStoreDeliveries() {
    return this.flowerStoreDeliveries;
}

public void setFlowerStoreDeliveries(
        Set<FlowerStoreDelivery> flowerStoreDeliveries) {
    this.flowerStoreDeliveries = flowerStoreDeliveries;
}


public Set<FlowerStoreVehicle> getFlowerStoreVehicles() {
    return this.flowerStoreVehicles;
}

public void setFlowerStoreVehicles(
        Set<FlowerStoreVehicle> flowerStoreVehicles) {
    this.flowerStoreVehicles = flowerStoreVehicles;
}

public int compareTo(FlowerStoreEmployee emp) {
    if(this.employeeId > emp.employeeId){
        return 1;
    }
    else 
        if(this.employeeId < emp.employeeId){
                return -1;
        }
    else{
        return 0;
    }
}

车辆:

@Entity
@Table(name = "flower_store_vehicle", schema = "dbo", catalog = "tyler")
public class FlowerStoreVehicle implements java.io.Serializable {

/**
 * 
 */
private static final long serialVersionUID = 5349431404739349258L;
@Id
@GeneratedValue(strategy=GenerationType.IDENTITY)
@Column(name = "vehicle_id", unique = true, nullable = false)
private int vehicleId;
@Column(name = "vin", length = 17)
@Length(max = 17)
private String vin;
@Column(name = "license", length = 10)
@Length(max = 10)
private String license;
@Column(name = "make", length = 15)
@Length(max = 15)
private String make;
@Column(name = "model", length = 20)
@Length(max = 20)
private String model;
@Column(name = "color", length = 20)
@Length(max = 20)
private String color;
@OneToMany(fetch = FetchType.LAZY, mappedBy = "flowerStoreVehicle")
private Set<FlowerStoreDelivery> flowerStoreDeliveries = new HashSet<FlowerStoreDelivery>(
        0);
@ManyToMany(fetch = FetchType.LAZY)
@JoinTable(name = "flower_store_emp_vehicle", schema = "dbo", catalog = "tyler", joinColumns = { @JoinColumn(name = "vehicle_id", nullable = false, updatable = false) }, inverseJoinColumns = { @JoinColumn(name = "employee_id", nullable = false, updatable = false) })
private Set<FlowerStoreEmployee> flowerStoreEmployees = new HashSet<FlowerStoreEmployee>(
        0);

public FlowerStoreVehicle() {
}

public FlowerStoreVehicle(int vehicleId) {
    this.vehicleId = vehicleId;
}

public FlowerStoreVehicle(int vehicleId, String vin, String license,
        String make, String model, String color,
        Set<FlowerStoreDelivery> flowerStoreDeliveries,
        Set<FlowerStoreEmployee> flowerStoreEmployees) {
    this.vehicleId = vehicleId;
    this.vin = vin;
    this.license = license;
    this.make = make;
    this.model = model;
    this.color = color;
    this.flowerStoreDeliveries = flowerStoreDeliveries;
    this.flowerStoreEmployees = flowerStoreEmployees;
}

public int getVehicleId() {
    return this.vehicleId;
}

public void setVehicleId(int vehicleId) {
    this.vehicleId = vehicleId;
}

public String getVin() {
    return this.vin;
}

public void setVin(String vin) {
    this.vin = vin;
}

public String getLicense() {
    return this.license;
}

public void setLicense(String license) {
    this.license = license;
}

public String getMake() {
    return this.make;
}

public void setMake(String make) {
    this.make = make;
}

public String getModel() {
    return this.model;
}

public void setModel(String model) {
    this.model = model;
}

public String getColor() {
    return this.color;
}

public void setColor(String color) {
    this.color = color;
}


public Set<FlowerStoreDelivery> getFlowerStoreDeliveries() {
    return this.flowerStoreDeliveries;
}

public void setFlowerStoreDeliveries(
        Set<FlowerStoreDelivery> flowerStoreDeliveries) {
    this.flowerStoreDeliveries = flowerStoreDeliveries;
}

public Set<FlowerStoreEmployee> getFlowerStoreEmployees() {
    return this.flowerStoreEmployees;
}

public void setFlowerStoreEmployees(
        Set<FlowerStoreEmployee> flowerStoreEmployees) {
    this.flowerStoreEmployees = flowerStoreEmployees;
}

}

复合表ID:

/**
 * FlowerStoreEmpVehicleId generated by hbm2java
 */
@Embeddable
public class FlowerStoreEmpVehicleId implements java.io.Serializable {

private int vehicleId;
private int employeeId;

public FlowerStoreEmpVehicleId() {
}

public FlowerStoreEmpVehicleId(int vehicleId, int employeeId) {
    this.vehicleId = vehicleId;
    this.employeeId = employeeId;
}

@Column(name = "vehicle_id", nullable = false)
public int getVehicleId() {
    return this.vehicleId;
}

public void setVehicleId(int vehicleId) {
    this.vehicleId = vehicleId;
}

@Column(name = "employee_id", nullable = false)
public int getEmployeeId() {
    return this.employeeId;
}

public void setEmployeeId(int employeeId) {
    this.employeeId = employeeId;
}

public boolean equals(Object other) {
    if ((this == other))
        return true;
    if ((other == null))
        return false;
    if (!(other instanceof FlowerStoreEmpVehicleId))
        return false;
    FlowerStoreEmpVehicleId castOther = (FlowerStoreEmpVehicleId) other;

    return (this.getVehicleId() == castOther.getVehicleId())
            && (this.getEmployeeId() == castOther.getEmployeeId());
}

public int hashCode() {
    int result = 17;

    result = 37 * result + this.getVehicleId();
    result = 37 * result + this.getEmployeeId();
    return result;
}

}

复合表:

@Entity
@Table(name = "flower_store_emp_vehicle", schema = "dbo", catalog = "tyler")
public class FlowerStoreEmpVehicle implements java.io.Serializable {

private FlowerStoreEmpVehicleId id;

public FlowerStoreEmpVehicle() {
}

public FlowerStoreEmpVehicle(FlowerStoreEmpVehicleId id) {
    this.id = id;
}

@EmbeddedId
@AttributeOverrides({
        @AttributeOverride(name = "vehicleId", column = @Column(name = "vehicle_id", nullable = false)),
        @AttributeOverride(name = "employeeId", column = @Column(name = "employee_id", nullable = false)) })
@NotNull
public FlowerStoreEmpVehicleId getId() {
    return this.id;
}

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

}

这是保存员工的代码:

public String addEmployee(){
    Set<FlowerStoreVehicle> vehicleSet = new HashSet<FlowerStoreVehicle>();
    FlowerStoreEmployee n = new FlowerStoreEmployee();
    if(first!=null && first!=""){
        n.setNameFirst(first);
    }
    if(last!=null && last!=""){
        n.setNameLast(last);
    }
    if(pay!=null && pay!=""){
        int intPay = (int)(Double.parseDouble(pay)*100);
        n.setPay(intPay);
    }
    if(phone!=null && phone!=""){
        n.setPhone(phone);
    }
    if(ssn!=null && ssn!=""){
        n.setSsn(ssn);
    }
    if(vehicle!=null && vehicle!=""){
        String[] vehStr = vehicle.split(" ");
        for(int i = 0; i < vehStr.length; i++){
            int vehId = Integer.parseInt(vehStr[i]);
            vehicleSet.add(entityManager.find(FlowerStoreVehicle.class, vehId));
        }
    }
    if(!vehicleSet.isEmpty()){
        n.setFlowerStoreVehicles(vehicleSet);
    }
    entityManager.persist(n);
    if(zip!=null && zip!=""){
        FlowerStoreZip zipCode = entityManager.find(FlowerStoreZip.class, Integer.parseInt(zip));
        if(zipCode==null){
            zipCode = new FlowerStoreZip();
            if(zip!=null && zip!=""){
                zipCode.setZipCode(Integer.parseInt(zip));
        }
        if(city!=null && city!=""){
            zipCode.setCity(city);
        }
        if(state!=null && city!=""){
            zipCode.setState(state);
        }
        entityManager.persist(zipCode);
        }
    }
    FlowerStoreAddress add = new FlowerStoreAddress();
    if(house!=null && house!=""){
        add.setHouseNumber(Integer.parseInt(house));
    }
    if(street!=null && street!=""){
        add.setStreet(street);
    }
    if(zip!=null && zip!=""){
        add.setFlowerStoreZip(entityManager.find(FlowerStoreZip.class, Integer.parseInt(zip)));
    }
    return "/employee.xhtml";
}

如果需要更多信息，请告诉我。任何帮助将不胜感激。谢谢

Answer 1

首先，检查你的代码，你有很多错误的指令:在 Java 中，你使用 equals() 方法比较字符串，而不是这样:ssn != ""。

问题的根源不是Seam本身，而是Hibernate。首先，通过 n.getFlowerStoreVehicles().add(...) 将元素添加到车辆集合中，不要使用 n.setFlowerStoreVehicles(...) 重新分配整个集合(这在实体创建期间可能不是问题，但在实体持久化后修改集合时会成为问题。

关系未正确持久化的原因是 FlowerStoreEmployee 是关系的“弱”侧(注释中具有“mappedBy”属性的一侧)。将 @JoinTable 注解移动到 FlowerStoreEmployee 类并将其从 FlowerStoreVehicle 中删除，从 FlowerStoreEmployee 中删除 mappedBy 并将其放入 FlowerStoreVehicle (mappedBy="flowerStoreVehicles")。由于关系是双向的，因此分配给关系的双方:

FlowerStoreVehicle veh = entityManager.find(FlowerStoreVehicle.class, vehId);
veh.getFlowerStoreEmployees().add(n); // one direction: vehicle -> employee
n.getFlowerStoreVehicles().add(veh);  // the other direction: employee -> vehicle