【
IT168技术文档】
Tapestry中构建选择列表需要使用IPropertySelectionModel，Model可以映射选择列表中的Label和Option，Tapestry中已经提供一个常用的StringSelectonModel,具体组件使用如下：
Html代码
java 代码
"@PropertySelection" model="ognl:@com.myexample.DetailsPage@GENDER_MODEL"
value="ognl:gender"/>
Java代码
public abstract class DetailsPage extends BasePage ...{
public static final IPropertySelectionModel GENDER_MODEL =
new StringPropertySelectionModel(new String[] ...{ "Unspecified", "Female", "Male" });
public abstract String getGender();
public void formSubmit(IRequestCycle cycle) ...{
// Process form submission
String genderSelection = getGender();
...
}
}
开发中比较常见的选择列表就是类别的选择，，一般是新建一个类别的SelectionModel，例如如下代码
java 代码
public class TypeSelectionModel implements IPropertySelectionModel, Serializable ...{
private List TypeList;
public ItemSelectionModel(List typeList) ...{
this. typeList = typeList;
}
public int getOptionCount() ...{ return typeList.size(); }
public Object getOption(int index) ...{
return ((Type)typeList.get(index)).getId();
}
public String getLabel(int index) ...{
return ((Type) typeList.get(index)).getName();
}
public String getValue(int index) ...{ return Integer.toString(index); }
public Object translateValue(String value) ...{
return getOption(Integer.parseInt(value));
}
}
这只是传统方法，开发中的类别如果多了，每一个都要新建一个SelectionModel。
【
IT168技术文档】
下面是在Tapestry JumpStart里看到的通用的SelectionModel，感觉比较不错，现介绍给大家，具体代码如下：
java 代码
package com.javaeye.tapestrying.selectionModel;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.ArrayList;
import java.util.List;
import org.apache.tapestry.form.IPropertySelectionModel;
public class ObjectPropertySelectionModel implements IPropertySelectionModel ...{
private List _list;
private Method _methodToGetLabel = null;
private Method _methodToGetOption = null;
private boolean _allowNoSelection = false;
private String _noSelectionMessage = null;
private int _offset = 0;
public ObjectPropertySelectionModel() ...{
_list = new ArrayList();
throw new UnsupportedOperationException("Do not use the default constructor.");
}
/**//**
*
* @param list
* the list of objects to represent in a PropertySelection
* component. WARNING: The objects in the list MUST implement
* equals(Object obj) and hashCode(), and if they are EJB3
* Entities those methods MUST return the same thing for
* different instances of the same detached entity (eg. by
* matching on Id only).
* @param clazz
* the class of objects in the list.
* @param nameOfMethodToGetLabel
* the name of the method that PropertySelection must invoke on
* each object in the list to get its label to display in the
* list on the page. For example, the method name might be
* "getShortName".
* @param nameOfMethodToGetOption
* the name of the method that PropertySelection must invoke on
* an object when it has been selected. The result is put into
* the property named in the "value" parameter of the
* PropertySelection. For example, the method name might be
* "getKey". If you want the result to be the the whole object
* then set this argument to null.
*
*/
public ObjectPropertySelectionModel(Listextends Object> list,
Class clazz, String nameOfMethodToGetLabel,
String nameOfMethodToGetOption) ...{
this(list, clazz, nameOfMethodToGetLabel, nameOfMethodToGetOption, false, null);
}
/**//**
*
* @param list
* the list of objects to represent in a PropertySelection
* component. WARNING: The objects in the list MUST implement
* equals(Object obj) and hashCode(), and if they are EJB3
* Entities those methods MUST return the same thing for
* different instances of the same detached entity (eg. by
* matching on Id only).
* @param clazz
* the class of objects in the list.
* @param nameOfMethodToGetLabel
* the name of the method that PropertySelection must invoke on
* each object in the list to get its label to display in the
* list on the page. For example, the method name might be
* "getShortName".
* @param nameOfMethodToGetOption
* the name of the method that PropertySelection must invoke on
* an object when it has been selected. The result is put into
* the property named in the "value" parameter of the
* PropertySelection. For example, the method name might be
* "getKey". If you want the result to be the the whole object
* then set this argument to null.
* @param allowNoSelection
* If true then adds an element to the start of the list. Its
* option is null.
* @param noSelectionLabel
* If null then no label. A typical label might be "Select...".
*
*/
public ObjectPropertySelectionModel(Listextends Object> list, Class clazz,
String nameOfMethodToGetLabel,
String nameOfMethodToGetOption, boolean allowNoSelection,
String noSelectionLabel) ...{
try ...{
_list = list;
_methodToGetLabel = clazz.getMethod(nameOfMethodToGetLabel,
(Class[]) null);
if (nameOfMethodToGetOption != null) ...{
_methodToGetOption = clazz.getMethod(nameOfMethodToGetOption,
(Class[]) null);
}
_allowNoSelection = allowNoSelection;
if (_allowNoSelection) ...{
_noSelectionMessage = noSelectionLabel;
_offset = 1;
}
}
catch (SecurityException e) ...{
throw new IllegalStateException(e);
}
catch (NoSuchMethodException e) ...{
throw new IllegalArgumentException("Given nameOfMethodToGetLabel=
\"" + nameOfMethodToGetLabel + "\", nameOfMethodToGetOption=\""
+ nameOfMethodToGetOption + "\", class=\"" + clazz + "\".", e);
}
}
public int getOptionCount() ...{
return _list.size() + _offset;
}
public Object getOption(int index) ...{
if (_allowNoSelection) ...{
if (index < _offset) ...{
return null;
}
}
Object o = _list.get(index - _offset);
if (_methodToGetOption == null) ...{
return o;
}
else ...{
try ...{
Object option = _methodToGetOption.invoke(o, (Object[]) null);
return option;
}
catch (IllegalArgumentException e) ...{
throw new IllegalStateException("Problem with the given
methodToGetOption \"" + _methodToGetOption + "\": ", e);
}
catch (IllegalAccessException e) ...{
throw new IllegalStateException("Problem with the given
methodToGetOption \"" + _methodToGetOption + "\": ", e);
}
catch (InvocationTargetException e) ...{
throw new IllegalStateException("Problem with the
given methodToGetOption \"" + _methodToGetOption + "\": ", e);
}
}
}
public String getLabel(int index) ...{
if (_allowNoSelection) ...{
if (index < _offset) ...{
return _noSelectionMessage;
}
}
Object o = _list.get(index - _offset);
try ...{
String label = _methodToGetLabel.invoke(o, (Object[]) null).toString();
return label;
}
catch (IllegalArgumentException e) ...{
throw new IllegalStateException("Problem with the given
methodToGetLabel \"" + _methodToGetOption + "\": ", e);
}
catch (IllegalAccessException e) ...{
throw new IllegalStateException("Problem with the given
methodToGetLabel \"" + _methodToGetOption + "\": ", e);
}
catch (InvocationTargetException e) ...{
throw new IllegalStateException ("Problem with the given
methodToGetLabel \"" + _methodToGetOption + "\": ", e);
}
}
public String getValue(int index) ...{
return Integer.toString(index);
}
public Object translateValue(String value) ...{
return value == null ? null : getOption(Integer.parseInt(value));
}
}
【
IT168技术文档】
具体使用如下，假如现在有一个配件类型的类
java 代码
public class FittingType ...{
private Long id;
private String name;
private Set fittings = new HashSet();
//getter and setter
}
创建配件类时，需要选择配件类型
java 代码
private IPropertySelectionModel fittingTypeSelectionModel;
public IPropertySelectionModel getFittingTypeSelectionModel() ...{
if (fittingTypeSelectionModel == null) ...{
List fittingTypes = getFittingTypeService().findAll();
fittingTypeSelectionModel = new ObjectPropertySelectionModel(
fittingTypes, FittingType.class, "getName", "getId", true,
"选择分类");
}
return fittingTypeSelectionModel;
}
public abstract Long getFittingTypeId();
public ILink onSave() ...{
//其他
if (getFittingTypeId() != null) ...{
fitting.setType(getFittingTypeService()
.findByID(getFittingTypeId()));
}
//其他
}
Html中定义组件
java 代码
"type@PropertySelection" model="ognl:fittingTypeSelectionModel"
value="ognl:fittingTypeId" displayName="配件类型"/>
具体定义中
fittingTypeSelectionModel = new ObjectPropertySelectionModel(
fittingTypes, FittingType.class, "getName", "getId", true,
"选择分类");
}
参数1：候选的List
参数2：类别
参数3：label的getter方法
参数4：option的getter方法
参数5：是否允许没有选项
参数6：没有选项时的label
