实体：product
@Entity
public class Product {
private String productNo;
private String name;
private String chandi;
private ProductType productType;
@Id
public String getProductNo() {
return productNo;
}
public void setProductNo(String productNo) {
this.productNo = productNo;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getChandi() {
return chandi;
}
public void setChandi(String chandi) {
this.chandi = chandi;
}
@ManyToOne(cascade ="CascadeType.All")
@JoinColumn(name="productType_id")
public ProductType getProductType() {
return productType;
}
public void setProductType(ProductType productType) {
this.productType = productType;
}
}
实体类ProductType
@Entity
public class ProductType {
private String typeNo;
private String Name;
private Set<Product> products;
@Id
public String getTypeNo() {
return typeNo;
}
public void setTypeNo(String typeNo) {
this.typeNo = typeNo;
}
public String getName() {
return Name;
}
public void setName(String name) {
Name = name;
}
@OneToMany(mappedBy="productType")
public Set<Product> getProducts() {
return products;
}
public void setProducts(Set<Product> products) {
this.products = products;
}
}
如果关联查询：createQuery("select p.chandit.name from Product p left join p.productType t group by p.productType ")会返回object类型要想对实体处理可以采取如下措施：
1、增加一个类(字段名为查询的字段名，要生成对应的geter seter方法，并且一定要有构造函数，且构造函数的参数是查询的字段)
public class ProductAndType {
private String name;
private String chandi;
public Product(String name, String chandi) {
this.name = name;
this.chandi = chandi;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getChandi() {
return chandi;
}
public void setChandi(String chandi) {
this.chandi = chandi;
}
}
2、修改查询语句createQuery("select new 包名.ProductAndType( p.chandi t.name )from Product p left join p.productType t group by p.productType ")这样即可转为ProductAndType类型，可对其操作。