递归实现树结构封装

刺骨的言语ヽ痛彻心扉 2021-09-01 04:45 348阅读 0赞

### 这里写自定义目录标题 ###

*  简介
 *  代码实现
 *  效果展示

# 简介 #

作为一名两年的程序猿,每每需要用到递归的都要头疼一番,所以今天就再这里写一个案例,记录一下自己递归实现树结构的封装.

# 代码实现 #

1.DataSourceTreeDomain.java用于返回给页面展示

@Data
    public class DataSourceTreeDomain {
    
        @ApiModelProperty(value = "ID")
        private Long id;
    
        @ApiModelProperty(value = "元数据名称")
        private String resourceName;
    
        @ApiModelProperty(value = "父ID")
        private Long msgParentId;
    
        @ApiModelProperty(value = "信息资源名称或分类")
        private String msgResourceName;
    
        @ApiModelProperty(value = "子树")
        List<DataSourceTreeDomain> children = new ArrayList<>();
    }

2.方法实现

public List<DataSourceTreeDomain> listTree() {
            Iterable<DataSource> dataSourceIterable = dataSourceRepository.findAll();
            List<DataSourceTreeDomain> dataSourceTreeDomainList = new ArrayList<>();
            Map<Long, List<DataSource>> dataSourceTree = new HashMap<>();
            dataSourceIterable.forEach(dataSource -> {
                if(dataSource.getMsgParentId() == null){
                    DataSourceTreeDomain dataSourceTreeDomain = new DataSourceTreeDomain();
                    BeanUtils.copyProperties(dataSource,dataSourceTreeDomain);
                    dataSourceTreeDomainList.add(dataSourceTreeDomain);
                }else{
                    List<DataSource> dataSources = dataSourceTree.get(dataSource.getMsgParentId());
                    if(dataSources == null){
                        dataSources = new ArrayList<>();
                    }
                    dataSources.add(dataSource);
                    dataSourceTree.put(dataSource.getMsgParentId(),dataSources);
                }
            });
            dataSourceTreeDomainList.forEach(dataSourceTreeDomain -> recursiveDataSource(dataSourceTreeDomain,dataSourceTree));
            return dataSourceTreeDomainList;
        }

3.封装树结构

private void recursiveDataSource(DataSourceTreeDomain dataSourceTreeDomain, Map<Long, List<DataSource>> dataSourceTree) {
            List<DataSource> dataSourceList = dataSourceTree.get(dataSourceTreeDomain.getId());
            Optional.ofNullable(dataSourceList).ifPresent(dataSources -> dataSources.forEach(dataSource -> {
                DataSourceTreeDomain dataSourceDomain = new DataSourceTreeDomain();
                BeanUtils.copyProperties(dataSource,dataSourceDomain);
                dataSourceTreeDomain.getChildren().add(dataSourceDomain);
                recursiveDataSource(dataSourceDomain,dataSourceTree);
            }));
        }

# 效果展示 #

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQzNDE5MTA1_size_16_color_FFFFFF_t_70_pic_center]

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