failed to lazily initialize a collection of role 异常

系统管理员 2022-03-09 07:16 152阅读 0赞

最近在通过配置实体类的方式，正向自动扫描注解方式配置的hibernate类文件来生成数据库的方法搭建环境，遇到了许多问题。

通过数据库配置hibernate的时候，大家都知道是在实体类对应生成的.hbm.xml文件中查看一对多和多对多的关系。

当报failed to lazily initialize a collection of role异常的时候，往往是因为懒加载的问题导致的。

可以在.hbm.xml文件中，将lazy=“false”，这样就不会报这个异常了。

但是在自动扫描注解方式配置的hibernate类文件时，如何将懒加载改为false呢？

只需要一句话，在注解上添加fetch=FetchType.EAGER便可

@OneToMany(mappedBy="user",fetch=FetchType.EAGER)

举个例子：

package com.maya.entity;
    
    import java.util.ArrayList;
    import java.util.List;
    
    import javax.persistence.Column;
    import javax.persistence.Entity;
    import javax.persistence.FetchType;
    import javax.persistence.GeneratedValue;
    import javax.persistence.Id;
    import javax.persistence.JoinColumn;
    import javax.persistence.ManyToOne;
    import javax.persistence.OneToMany;
    import javax.persistence.Table;
    
    import org.hibernate.annotations.GenericGenerator;
    import org.springframework.context.annotation.Lazy;
    
    @Entity
    @Table(name="t_user")
    
    public class User {
    
        private Integer id;
        private String password;
        private String ename;
        private String sex;
        //private String dept;
        //private Dept dept;
        private String tel;
        private String description;
        
        private List<WarehouseMain> warehouseMainList=new ArrayList<WarehouseMain>();
        private List<ReWarehouseMain> reWarehouseMainList=new ArrayList<ReWarehouseMain>();
        private List<SellMain> sellMainList=new ArrayList<SellMain>();
        private List<ReSellMain> reSellMainList=new ArrayList<ReSellMain>();
        
        @Id
        @GenericGenerator(name = "generator", strategy = "native")
        @GeneratedValue(generator = "generator")
        @Column(name = "id", length=11)
        public Integer getId() {
            return id;
        }
        public void setId(Integer id) {
            this.id = id;
        }
        @Column(name = "password", length = 20)
        public String getPassword() {
            return password;
        }
        public void setPassword(String password) {
            this.password = password;
        }
        @Column(name = "ename", length = 20)
        public String getEname() {
            return ename;
        }
        
        public void setEname(String ename) {
            this.ename = ename;
        }
        @Column(name = "sex", length = 10)
        public String getSex() {
            return sex;
        }
        public void setSex(String sex) {
            this.sex = sex;
        }
        /*
        @ManyToOne
        @JoinColumn(name="dept_id")
        public Dept getDept() {
            return dept;
        }
        public void setDept(Dept dept) {
            this.dept = dept;
        }*/
        @Column(name = "tel", length = 20)
        public String getTel() {
            return tel;
        }
        public void setTel(String tel) {
            this.tel = tel;
        }
        @Column(name = "description", length = 100)
        public String getDescription() {
            return description;
        }
        public void setDescription(String description) {
            this.description = description;
        }
        @OneToMany(mappedBy="user",fetch=FetchType.EAGER)
        public List<WarehouseMain> getWarehouseMainList() {
            return warehouseMainList;
        }
        public void setWarehouseMainList(List<WarehouseMain> warehouseMainList) {
            this.warehouseMainList = warehouseMainList;
        }
        @OneToMany(mappedBy="user",fetch=FetchType.EAGER)
        public List<ReWarehouseMain> getReWarehouseMainList() {
            return reWarehouseMainList;
        }
        public void setReWarehouseMainList(List<ReWarehouseMain> reWarehouseMainList) {
            this.reWarehouseMainList = reWarehouseMainList;
        }
        @OneToMany(mappedBy="user",fetch=FetchType.EAGER)
        public List<SellMain> getSellMainList() {
            return sellMainList;
        }
        public void setSellMainList(List<SellMain> sellMainList) {
            this.sellMainList = sellMainList;
        }
        @OneToMany(mappedBy="user",fetch=FetchType.EAGER)
        public List<ReSellMain> getReSellMainList() {
            return reSellMainList;
        }
        public void setReSellMainList(List<ReSellMain> reSellMainList) {
            this.reSellMainList = reSellMainList;
        }
        
        
    }