java - 如何使用 Vaadin 8.1 在树形网格中设置多个级别？

Question

我需要在 vaadin 树形网格中显示三个级别。根据 vaadin 文档，我使用“setItems”方法将值设置为树状网格。如何为网格设置第三个嵌套级别。

    TreeGrid<Project> treeGrid = new TreeGrid<>();
    treeGrid.setItems(getProjects(), Project::getSubProjects);
    treeGrid.addColumn(Project::getName).setCaption("Name");
    treeGrid.addColumn(Project::getStatus).setCaption("Status");

我遵循了 vaadin 8.1 文档中的代码片段 https://vaadin.com/docs/-/part/framework/components/components-treegrid.html

Answer 1

您有 2 个选择。假设您有类似于以下内容的内容:

public class Project {
    private List<Project> subProjects;

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

• 第一个也是最简单的解决方案是向树提供一个根项目列表和一个子项提供程序(一种检索给定项目的子项目的方法):treeGrid.setItems(rootProjects, Project::getSubProjects);

• 或者，如果确实需要，您可以为每个子项列表指定父项，但您可能需要递归地执行此操作。来自documentation link you provided : data.addItems(newProject, newProject.getChildren());(或 treeGrid.getTreeData().addItems(newProject, newProject.getSubProjects()))

---

功能齐全sscce使用第一种方法(从 Vaadin sampler 中窃取):

public class BasicTreeGrid extends VerticalLayout {

    // used to generate some random data
    private final Random random = new Random();

    public BasicTreeGrid() {
        // basic tree setup
        TreeGrid<Project> treeGrid = new TreeGrid<>();
        addComponent(treeGrid);
        treeGrid.addColumn(Project::getName).setCaption("Project Name").setId("name-column");
        treeGrid.addColumn(Project::getHoursDone).setCaption("Hours Done");
        treeGrid.addColumn(Project::getLastModified).setCaption("Last Modified");

        // some listeners for interaction
        treeGrid.addCollapseListener(event -> Notification
                .show("Project '" + event.getCollapsedItem().getName() + "' collapsed.", Notification.Type.TRAY_NOTIFICATION));
        treeGrid.addExpandListener(event -> Notification
                .show("Project '" + event.getExpandedItem().getName() + "' expanded.", Notification.Type.TRAY_NOTIFICATION));


        // add the list of root projects and specify a provider of sub-projects
        treeGrid.setItems(generateProjectsForYears(2010, 2016), Project::getSubProjects);
    }

    // generate some random projects
    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;
    }


    // basic parent (or intermediate child) bean used for easy binding
    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);
        }
    }


    // basic final child (can not have other children) bean used for easy binding
    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;
        }
    }
}

结果: