hibernate级联查询的懒加载

结论: 使用迫切加载时是级联查询,只执行一条sql, 使用懒加载是执行多条sql. 和之前的认知不同

执行一条sql的前提:查询条件是id,且级联对象迫切加载

 

实体对象

@Id
    private Long id;
    private String uid;
    private Integer trade_type;
    private Integer status;
    @JsonFormat(pattern= "yyyy-MM-dd HH:mm:ss")
    private LocalDateTime deliver_time_start;
    private Long user_id;
    @ApiModelProperty("收货(配送)方式\n" +
            "0 配送\n" +
            "1 自提")
    private Integer receipt_type;
    @ApiModelProperty("应付款")
    @JsonSerialize(using = PriceToStringSerializer.class)
    private Integer pay_price;
    @ApiModelProperty("已付款")
    @JsonSerialize(using = PriceToStringSerializer.class)
    private Integer paid_price;
    @ApiModelProperty("退款金额")
    @JsonSerialize(using = PriceToStringSerializer.class)
    private Integer refund;
    private Integer refunds_dest;
    private Integer pay_type;
    @ApiModelProperty("真实的已配送商品金额,扣除订单完成前的退款金额")
    @JsonSerialize(using = PriceToStringSerializer.class)
    private Integer real_total_sale_price;

    @OneToMany(fetch = FetchType.EAGER, cascade=CascadeType.ALL)
    @JoinColumn(name = "child_order_id")
    private List orderItemDtos;

    @ManyToOne(fetch = FetchType.LAZY)
    @JsonIgnoreProperties(value = { "hibernateLazyInitializer", "handler" })
    @JoinColumn(name = "location_id")
    private LocationDto locationDto;

    @ManyToOne(fetch = FetchType.EAGER)
    @JoinColumn(name = "driver_id")
    @JsonUnwrapped
    private Employee employee;
    @JsonIgnore
    private Long deliver_range_fee_id;
    @ApiModelProperty("订单分拣编号")
    private Integer order_serial_num;
    private Boolean delivered;

    @Transient
    @ApiModelProperty("配送线路")
    private String line;
    @Transient
    @ApiModelProperty("配送线路Id")
    private Integer lineId;

    @ApiModelProperty("配送状态:0,待分拣;1,待配送;2,已完成")
    public Integer getDeliveryStatus(){
        if(status<2)
            return 0;
        if(delivered == true)
            return 2;
        return 1;
    }

    @ApiModelProperty("差额,正数代表需补款,负数代表需退款")
    @JsonSerialize(using = PriceToStringSerializer.class)
    public Integer getDetla(){
        return pay_price-paid_price;
    }

执行的sql语句

Hibernate: 
    select
        childorder0_.id as id1_0_0_,
        childorder0_.deliver_range_fee_id as deliver_2_0_0_,
        childorder0_.deliver_time_start as deliver_3_0_0_,
        childorder0_.delivered as delivere4_0_0_,
        childorder0_.driver_id as driver_17_0_0_,
        childorder0_.location_id as locatio18_0_0_,
        childorder0_.order_serial_num as order_se5_0_0_,
        childorder0_.paid_price as paid_pri6_0_0_,
        childorder0_.pay_price as pay_pric7_0_0_,
        childorder0_.pay_type as pay_type8_0_0_,
        childorder0_.real_total_sale_price as real_tot9_0_0_,
        childorder0_.receipt_type as receipt10_0_0_,
        childorder0_.refund as refund11_0_0_,
        childorder0_.refunds_dest as refunds12_0_0_,
        childorder0_.status as status13_0_0_,
        childorder0_.trade_type as trade_t14_0_0_,
        childorder0_.uid as uid15_0_0_,
        childorder0_.user_id as user_id16_0_0_,
        employee1_.id as id1_17_1_,
        employee1_.deleted as deleted3_17_1_,
        employee1_.position_id as position4_17_1_,
        employee1_.status as status5_17_1_,
        employee1_.true_name as true_nam2_17_1_,
        employee1_.user_id as user_id6_17_1_,
        employee1_.warehouse_id as warehous7_17_1_,
        orderitemd2_.child_order_id as child_or3_18_2_,
        orderitemd2_.id as id1_18_2_,
        orderitemd2_.id as id1_18_3_,
        orderitemd2_.bar_code as bar_code2_18_3_,
        orderitemd2_.child_order_id as child_or3_18_3_,
        orderitemd2_.count as count4_18_3_,
        orderitemd2_.item_id as item_id5_18_3_,
        orderitemd2_.item_uid as item_uid6_18_3_,
        orderitemd2_.procurement_item_id as procurem7_18_3_,
        orderitemd2_.real_count as real_cou8_18_3_,
        orderitemd2_.real_price as real_pri9_18_3_,
        orderitemd2_.real_weight as real_we10_18_3_,
        orderitemd2_.rejected_weight as rejecte11_18_3_,
        orderitemd2_.sale_price as sale_pr12_18_3_,
        orderitemd2_.item_specification_id as item_sp13_18_3_ 
    from
        child_order childorder0_ 
    left outer join
        manager_employee employee1_ 
            on childorder0_.driver_id=employee1_.id 
    left outer join
        order_item orderitemd2_ 
            on childorder0_.id=orderitemd2_.child_order_id 
    where
        childorder0_.id=?
Hibernate: 
    select
        locationdt0_.id as id1_13_0_,
        locationdt0_.address as address2_13_0_,
        locationdt0_.conn_person as conn_per3_13_0_,
        locationdt0_.conn_phone as conn_pho5_13_0_,
        locationdt0_.name as name4_13_0_ 
    from
        location locationdt0_ 
    where
        locationdt0_.id=?

如果把location的关联改成迫切加载, 则执行的sql为. 

Hibernate: 
    select
        childorder0_.id as id1_0_0_,
        childorder0_.deliver_range_fee_id as deliver_2_0_0_,
        childorder0_.deliver_time_start as deliver_3_0_0_,
        childorder0_.delivered as delivere4_0_0_,
        childorder0_.driver_id as driver_17_0_0_,
        childorder0_.location_id as locatio18_0_0_,
        childorder0_.order_serial_num as order_se5_0_0_,
        childorder0_.paid_price as paid_pri6_0_0_,
        childorder0_.pay_price as pay_pric7_0_0_,
        childorder0_.pay_type as pay_type8_0_0_,
        childorder0_.real_total_sale_price as real_tot9_0_0_,
        childorder0_.receipt_type as receipt10_0_0_,
        childorder0_.refund as refund11_0_0_,
        childorder0_.refunds_dest as refunds12_0_0_,
        childorder0_.status as status13_0_0_,
        childorder0_.trade_type as trade_t14_0_0_,
        childorder0_.uid as uid15_0_0_,
        childorder0_.user_id as user_id16_0_0_,
        employee1_.id as id1_17_1_,
        employee1_.deleted as deleted3_17_1_,
        employee1_.position_id as position4_17_1_,
        employee1_.status as status5_17_1_,
        employee1_.true_name as true_nam2_17_1_,
        employee1_.user_id as user_id6_17_1_,
        employee1_.warehouse_id as warehous7_17_1_,
        locationdt2_.id as id1_13_2_,
        locationdt2_.address as address2_13_2_,
        locationdt2_.conn_person as conn_per3_13_2_,
        locationdt2_.conn_phone as conn_pho5_13_2_,
        locationdt2_.name as name4_13_2_,
        orderitemd3_.child_order_id as child_or3_18_3_,
        orderitemd3_.id as id1_18_3_,
        orderitemd3_.id as id1_18_4_,
        orderitemd3_.bar_code as bar_code2_18_4_,
        orderitemd3_.child_order_id as child_or3_18_4_,
        orderitemd3_.count as count4_18_4_,
        orderitemd3_.item_id as item_id5_18_4_,
        orderitemd3_.item_uid as item_uid6_18_4_,
        orderitemd3_.procurement_item_id as procurem7_18_4_,
        orderitemd3_.real_count as real_cou8_18_4_,
        orderitemd3_.real_price as real_pri9_18_4_,
        orderitemd3_.real_weight as real_we10_18_4_,
        orderitemd3_.rejected_weight as rejecte11_18_4_,
        orderitemd3_.sale_price as sale_pr12_18_4_,
        orderitemd3_.item_specification_id as item_sp13_18_4_ 
    from
        child_order childorder0_ 
    left outer join
        manager_employee employee1_ 
            on childorder0_.driver_id=employee1_.id 
    left outer join
        location locationdt2_ 
            on childorder0_.location_id=locationdt2_.id 
    left outer join
        order_item orderitemd3_ 
            on childorder0_.id=orderitemd3_.child_order_id 
    where
        childorder0_.id=?