failed to lazily initialize a collection of role 异常

　　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)

　　举个栗子：

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;

    }

}

这个实体类里，对应有四个一对多的外键关系，每一个一对多的关系查询的时候都涉及到一个懒加载，所以说，每一个OneToMany上都要添加fetch=FetchType.EAGER

巴特西

failed to lazily initialize a collection of role 异常

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