Vaadin 8.1 TreeGrid中Collapseitems和ExpandItems的替换

this similar feature request for the older TreeTable component 自2011年以来一直处于开放状态。

无论哪种方式,即使它们可能不是最佳解决方案,您也可以使用一些变通方法来实现此行为。我是 无耻地 vaadin-sampler for TreeGrid .

public class RecursiveExpansionTreeGrid extends VerticalLayout {

    private Random random = new Random();

    public RecursiveExpansionTreeGrid() {
        // common setup with some dummy data
        TreeGrid<Project> treeGrid = new TreeGrid<>();
        treeGrid.setItems(generateProjectsForYears(2010, 2016), Project::getSubProjects);
        treeGrid.addColumn(Project::getName).setCaption("Project Name").setId("name-column");
        treeGrid.addColumn(Project::getHoursDone).setCaption("Hours Done");
        treeGrid.addColumn(Project::getLastModified).setCaption("Last Modified");
        addComponent(treeGrid);
    }

    // generate some dummy data to display in the tree grid
    private List<Project> generateProjectsForYears(int startYear, int endYear) {
        List<Project> projects = new ArrayList<>();

        for (int year = startYear; year <= endYear; year++) {
            Project yearProject = new Project("Year " + year);

            for (int i = 1; i < 2 + random.nextInt(5); i++) {
                Project customerProject = new Project("Customer Project " + i);
                customerProject.setSubProjects(Arrays.asList(
                        new LeafProject("Implementation", random.nextInt(100), year),
                        new LeafProject("Planning", random.nextInt(10), year),
                        new LeafProject("Prototyping", random.nextInt(20), year)));
                yearProject.addSubProject(customerProject);
            }
            projects.add(yearProject);
        }
        return projects;
    }

    // POJO for easy binding
    public class Project {
        private List<Project> subProjects = new ArrayList<>();
        private String name;

        public Project(String name) {
            this.name = name;
        }

        public String getName() {
            return name;
        }

        public List<Project> getSubProjects() {
            return subProjects;
        }

        public void setSubProjects(List<Project> subProjects) {
            this.subProjects = subProjects;
        }

        public void addSubProject(Project subProject) {
            subProjects.add(subProject);
        }

        public int getHoursDone() {
            return getSubProjects().stream().map(project -> project.getHoursDone()).reduce(0, Integer::sum);
        }

        public Date getLastModified() {
            return getSubProjects().stream().map(project -> project.getLastModified()).max(Date::compareTo).orElse(null);
        }
    }

    // Second POJO for easy binding
    public class LeafProject extends Project {
        private int hoursDone;
        private Date lastModified;

        public LeafProject(String name, int hoursDone, int year) {
            super(name);
            this.hoursDone = hoursDone;
            lastModified = new Date(year - 1900, random.nextInt(12), random.nextInt(10));
        }

        @Override
        public int getHoursDone() {
            return hoursDone;
        }

        @Override
        public Date getLastModified() {
            return lastModified;
        }
    }
}

压平 将层次结构转换为节点列表,并调用适当的方法, expand(List<T> items) expand(T ... items) (第二种方法代表第一种方法,可能是一种方便的方法,例如 expand(myItem)

flatten 我们的方法 Project 实施如果由于某种原因不能这样做,那么创建一个递归方法,该方法创建一个从所选节点开始的列表,并包括所有子节点、子节点和子节点……好吧,你明白了。

public Stream<Project> flatten() {
    return Stream.concat(Stream.of(this), getSubProjects().stream().flatMap(Project::flatten));
}

可能的情况:

1. 在展开根时自动展开整个层次结构-添加侦听器,并展开/折叠整个层次结构 等级制度:

treeGrid.addCollapseListener(event -> {
    if (event.isUserOriginated()) {
        // event is triggered by all collapse calls, so only do it the first time, when the user clicks in the UI
        // and ignore the programmatic calls
        treeGrid.collapse(event.getCollapsedItem().flatten().collect(Collectors.toList()));
    }
});
treeGrid.addExpandListener(event -> {
    if (event.isUserOriginated()) {
        // event is triggered by all expand calls, so only do it the first time, when the user clicks in the UI
        // and ignore the programmatic calls
        treeGrid.expand(event.getExpandedItem().flatten().collect(Collectors.toList()));
    }
});

2. 使用自定义操作(如关联菜单)扩展层次结构或其一部分

GridContextMenu<Project> contextMenu = new GridContextMenu<>(treeGrid);
contextMenu.addGridBodyContextMenuListener(contextEvent -> {
    contextMenu.removeItems();
    if (contextEvent.getItem() != null) {
        Project project = (Project) contextEvent.getItem();
        // update selection
        treeGrid.select(project);

        // show option for expanding
        contextMenu.addItem("Expand all", VaadinIcons.PLUS, event -> treeGrid.expand((project).flatten().collect(Collectors.toList())));

        // show option for collapsing
        contextMenu.addItem("Collapse all", VaadinIcons.MINUS, event -> treeGrid.collapse((project).flatten().collect(Collectors.toList())));
    }
});

最后,你应该得到这样的效果:

docs for treegrid ,您可以使用这些方法, collapse 和 expand

treeGrid.expand(someTreeGridItem1, someTreeGridItem2);
treeGrid.collapse(someTreeGridItem1);

同样值得注意的是,有一节展示了 prevent certain items from ever being collapsed