java樹形菜單實現 JPA實現樹形菜單

基於springboot + JPA

方法一：

樹結構：

@Setter
@Getter
public class TreeNode<T> {

    @ApiModelProperty(value = "id", notes = "id")
    public Long id;

    @ApiModelProperty(value = "父ID", notes = "父ID")
    private Long parentId;

    @ApiModelProperty(value = "子節點", notes = "子節點")
    private List<T> children = new ArrayList<>();

}

部門：

@Entity
@Table(name = "department")
@Getter
@Setter
public class Department  {

    public static final int STATUS_DISABLED = 0;

    public static final int STATUS_ENABLED = 1;


    @Column(nullable = false, columnDefinition="bigint COMMENT '唯一標識'")
    @Id
    private Long id;

    @Column(nullable = false, columnDefinition = "varchar(255) COMMENT '部門名稱'")
    private String departmentName;

    @Column(nullable = false, columnDefinition = "varchar(1000) COMMENT '部門描述'")
    private String departmentDesc;

    @Column(nullable = false, columnDefinition = "tinyint(1) DEFAULT 1 COMMENT '狀態（1：可用，0：禁用）'")
    private Integer status;

    @Column(nullable = false, columnDefinition = "bigint(20) COMMENT '歸屬人ID'")
    private Long userId;

    @Column(columnDefinition = "bigint(20) COMMENT '父ID'")
    private Long parentId;

}

部門VO：

@Getter
@Setter
@ApiModel(value = "部門VO")
public class DepartmentVO extends TreeNode<DepartmentVO> implements Serializable {

    @ApiModelProperty(value = "部門名稱", notes = "部門名稱")
    public String departmentName;

    @ApiModelProperty(value = "部門描述", notes = "部門描述")
    private String departmentDesc;
}

方法實現

private List<DepartmentVO> getTree(List<DepartmentVO> list) {
        Map<Long, DepartmentVO> dtoMap = new HashMap<>();
        for (DepartmentVO node : list) {
            dtoMap.put(node.getId(), node);
        }
        List<DepartmentVO> resultList = new ArrayList<>();
        for (Map.Entry<Long, DepartmentVO> entry : dtoMap.entrySet()) {
            DepartmentVO node = entry.getValue();
            if (node.getParentId() == null) {
                // 如果是頂層節點，直接添加到結果集合中
                resultList.add(node);
            } else {
                // 如果不是頂層節點，找其父節點，並且添加到父節點的子節點集合中
                if (dtoMap.get(Long.valueOf(node.getParentId())) != null) {
                    dtoMap.get(Long.valueOf(node.getParentId())).getChildren().add(node);
                }
            }
        }
        return resultList;
    }

調用

        List<Department> list = departmentRepository.findByUserIdAndStatus(userVO.getParentId(), Department.STATUS_ENABLED);
        //重寫工具類實現，就是把數組從 對象-> 對象VO 數組
        List<DepartmentVO> result = BeanUtils.copyProperties(list, DepartmentVO.class);
        result = getTree(result);

方法二：

對數據庫壓力有點大，查詢多次，建議用方法一

因先使用方法二實現，後改用方法一，所以方法二調用需要自己測試。

部門實體

@Entity
@Table(name = "epartment")
@Getter
@Setter
public class Department{

    public static final int STATUS_DISABLED = 0;

    public static final int STATUS_ENABLED = 1;

    @Column(nullable = false, columnDefinition="bigint COMMENT '唯一標識'")
    @Id
    private Long id;


    @Column(nullable = false, columnDefinition = "varchar(255) COMMENT '部門名稱'")
    private String departmentName;

    @Column(nullable = false, columnDefinition = "varchar(1000) COMMENT '部門描述'")
    private String departmentDesc;

    @Column(nullable = false, columnDefinition = "tinyint(1) DEFAULT 1 COMMENT '狀態（1：可用，0：禁用）'")
    private Integer status;


    @Column(nullable = false, columnDefinition = "bigint(20) COMMENT '歸屬人ID'")
    private Long userId;

    @ManyToOne(cascade = CascadeType.ALL, fetch = FetchType.EAGER)
    @JoinColumn(name = "PARENT_ID", columnDefinition = "bigint(20) COMMENT '父ID'")
    private Department parent;

    @OneToMany(cascade = CascadeType.ALL, mappedBy = "parent", fetch = FetchType.EAGER)
    private List<Department> children = new ArrayList<>();


}

調用方法 

//通過某個用戶拿出該用戶所有主部門數據，就會帶出來子節點
//最好初始化一個主節點ID爲0 
Department department = new Department();
department.setId(0L);
List<Department> list = departmentRepository.findByUserIdAndParent(userId,department);