在Tapestry 5 Web应用程序中编辑复杂的Java对象

我正在使用Tapestry 5.3.6作为Web应用程序,我希望用户使用Web表单(立即建议使用beaneditform)编辑Java类的实例(“bean”或POJO) – 但是Java要编辑的类具有相当复杂的结构.我正在寻找Tapestry 5中最简单的方法.

首先,让我们定义一些实用程序类,例如

public class ModelObject {
  private URI uri;
  private boolean modified;
  // the usual constructors, getters and setters ...
}

public class Literal<T> extends ModelObject {
  private Class<?> valueClass;
  private T value;
  public Literal(Class<?> valueClass) {
    this.valueClass = valueClass;
  }
  public Literal(Class<?> valueClass, T value) {
    this.valueClass = valueClass;
    this.value = value;
  }
  // the usual getters and setters ...
}

public class Link<T extends ModelObject> extends ModelObject {
  private Class<?> targetClass;
  private T target;
  public Link(Class<?> targetClass) {
    this.targetClass = targetClass;
  }
  public Link(Class<?> targetClass, T target) {
    this.targetClass = targetClass;
    this.target = target;
  }
  // the usual getters and setters ...
}

现在您可以创建一些相当复杂的数据结构,例如：

public class HumanBeing extends ModelObject {
  private Literal<String> name;
  // ... other stuff
  public HumanBeing() {
    name = new Literal<String>(String.class);
  }
  // the usual getters and setters ...
}

public class Project extends ModelObject {
  private Literal<String> projectName;
  private Literal<Date> startDate;
  private Literal<Date> endDate;
  private Literal<Integer> someCounter;
  private Link<HumanBeing> projectLeader;
  private Link<HumanBeing> projectManager;
  // ... other stuff, including lists of things, that may be Literals or
  // Links ... e.g. (ModelObjectList is an enhanced ArrayList that remembers
  // the type(s) of the objects it contains - to get around type erasure ...
  private ModelObjectList<Link<HumanBeing>> projectMembers;
  private ModelObjectList<Link<Project>> relatedProjects;
  private ModelObjectList<Literal<String>> projectAliases;
  // the usual constructors, getters and setters for all of the above ...
  public Project() {
    projectName = new Literal<String>(String.class);
    startDate = new Literal<Date>(Date.class);
    endDate = new Literal<Date>(Date.class);
    someCounter = new Literal<Integer>(Integer.class);
    projectLeader = new Link<HumanBeing>(HumanBeing.class);
    projectManager = new Link<HumanBeing>(HumanBeing.class);
    projectMembers = new ModelObjectList<Link<HumanBeing>>(Link.class, HumanBeing.class);
    // ... more ...
  }
}

如果你将beaneditform指向Project.class的一个实例,那么在你必须提供很多自定义coercers,translators,valueencoders等之前你就不会走得太远 – 然后你仍然会遇到不能使用泛型的问题当“贡献”表示coercers,translators,valueencoders等.

然后我开始编写自己的组件来解决这些问题(例如ModelObjectDisplay和ModelObjectEdit),但是这需要我理解Tapestry的更多内容而不是我有时间学习…感觉就像我可能能够使用标准组件和自由使用“委托”等来做我想做的事.任何人都可以看到一条简单的路径供我使用吗？

感谢您阅读这篇文章.

PS：如果你想知道为什么我做了这样的事情,那是因为模型代表来自RDF图数据库(又称三重存储)的链接数据 – 我需要记住每一位数据的URI及其相关性(链接到其他位数据(欢迎您提出更好的方法)—)

编辑：

@uklance建议使用显示和编辑块 – 这是我已经尝试过的：

首先,我在AppPropertyDisplayBlocks.tml中有以下内容……

    <t:block id="literal">
        <t:delegate to="literalType" t:value="literalValue" />
    </t:block>

    <t:block id="link">
        <t:delegate to="linkType" t:value="linkValue" />
    </t:block>

并在AppPropertyDisplayBlocks.java中…

    public Block getLiteralType() {
        Literal<?> literal = (Literal<?>) context.getPropertyValue();

        Class<?> valueClass = literal.getValueClass();
        if (!AppModule.modelTypes.containsKey(valueClass))
            return null;

        String blockId = AppModule.modelTypes.get(valueClass);
        return resources.getBlock(blockId);
    }

    public Object getLiteralValue() {
        Literal<?> literal = (Literal<?>) context.getPropertyValue();
        return literal.getValue();
    }

    public Block getLinkType() {
        Link<?> link = (Link<?>) context.getPropertyValue();

        Class<?> targetClass = link.getTargetClass();
        if (!AppModule.modelTypes.containsKey(targetClass))
            return null;

        String blockId = AppModule.modelTypes.get(targetClass);
        return resources.getBlock(blockId);
    }

    public Object getLinkValue() {
        Link<?> link = (Link<?>) context.getPropertyValue();
        return link.getTarget();
    }

AppModule.modelTypes是从java类到Tapestry要使用的String的映射,例如： Link.class – > “link”和Literal.class – > “literal”…在AppModule中我有以下代码……

    public static void contributeDefaultDataTypeAnalyzer(
            MappedConfiguration<Class<?>, String> configuration) {
        for (Class<?> type : modelTypes.keySet()) {
            String name = modelTypes.get(type);
            configuration.add(type, name);
        }
    }

    public static void contributeBeanBlockSource(
            Configuration<BeanBlockContribution> configuration) {

        // using HashSet removes duplicates ...
        for (String name : new HashSet<String>(modelTypes.values())) {
            configuration.add(new DisplayBlockContribution(name,
                    "blocks/AppPropertyDisplayBlocks", name));
            configuration.add(new EditBlockContribution(name,
                    "blocks/AppPropertyEditBlocks", name));
        }
    }

我有类似的编辑块代码…但是这些似乎都不起作用 – 我认为因为原始对象被传递给“委托”而不是被引用的对象,该对象是存储在文字中的值或者对象链接指向(hmm …应该是上面的[Ll] inkTarget,而不是[Ll] inkValue).我也一直遇到错误,Tapestry找不到合适的“翻译”,“价值编码器”或“coercer”…我在一段时间的压力下因此很难跟随这些曲折的段落以便离开迷宫 ：-)

解决方法:

我建议在你想通过BeanEditForm编辑的对象周围构建一个瘦包装器并将它们传递给它.所以类似于：

public class TapestryProject {

   private Project project;

   public TapestryProject(Project proj){
      this.project = proj;
   }

   public String getName(){
      this.project.getProjectName().getValue();
   }

   public void setName(String name){
      this.project.getProjectName().setValue(name);
   }

   etc...
}

这样,挂毯将处理它所知道的所有类型,让您不必创建自己的版本(顺便说一句,这本身就很简单).

标签：java,web-applications,tapestry,rdfstore
来源： https://codeday.me/bug/20190625/1285628.html