GWT CellList MutilSelect

package com.cn.client;

import java.util.ArrayList;
import java.util.List;

import com.google.gwt.cell.client.AbstractCell;
import com.google.gwt.cell.client.Cell;
import com.google.gwt.cell.client.CheckboxCell;
import com.google.gwt.cell.client.CompositeCell;
import com.google.gwt.cell.client.FieldUpdater;
import com.google.gwt.cell.client.HasCell;
import com.google.gwt.core.client.EntryPoint;
import com.google.gwt.dom.client.Element;
import com.google.gwt.event.dom.client.ClickEvent;
import com.google.gwt.event.dom.client.ClickHandler;
import com.google.gwt.safehtml.shared.SafeHtmlBuilder;
import com.google.gwt.user.cellview.client.CellList;
import com.google.gwt.user.client.Window;
import com.google.gwt.user.client.ui.Button;
import com.google.gwt.user.client.ui.HorizontalPanel;
import com.google.gwt.user.client.ui.Label;
import com.google.gwt.user.client.ui.RootPanel;
import com.google.gwt.user.client.ui.VerticalPanel;
import com.google.gwt.view.client.DefaultSelectionEventManager;
import com.google.gwt.view.client.MultiSelectionModel;
import com.google.gwt.view.client.ProvidesKey;
import com.google.gwt.view.client.SelectionChangeEvent;
/**
* Entry point classes define <code>onModuleLoad()</code>.
*/
public class CellTest implements EntryPoint {

private Cell<Department> contactCell;
private Label selectedLabel = new Label();

public void onModuleLoad() {

List<Department> depts = new ArrayList<Department>();
Department c = new Department("项目部");
  c.setId(1);
  Department c1 = new Department("财务部");
  c1.setId(2);
  Department c2 = new Department("开发部");
  c2.setId(3);
  Department c3 = new Department("测试部");
  c3.setId(149);
  depts.add(c);
  depts.add(c1);
  depts.add(c2);
  depts.add(c3);
  final DefaultSelectionEventManager<Department> selectionManager = DefaultSelectionEventManager.createCheckboxManager();
  final MultiSelectionModel<Department> selectionModel = new MultiSelectionModel<Department>(DepartmentCell.KEY_PROVIDER);
  selectionModel.addSelectionChangeHandler(
          new SelectionChangeEvent.Handler() {
            public void onSelectionChange(SelectionChangeEvent event) {
              StringBuilder sb = new StringBuilder();
              boolean first = true;
              List<Department> selected = new ArrayList<Department>(
                  selectionModel.getSelectedSet());
              for (Department value : selected) {
                if (first) {
                first = false;
                } else {
                sb.append(",");
                }
                sb.append(value.getName());
              }
              selectedLabel.setText("选择："+sb.toString());
            }
          });
    List<HasCell<Department, ?>> hasCells = new ArrayList<HasCell<Department, ?>>();
    hasCells.add(new HasCell<Department, Boolean>() {
      private CheckboxCell cell = new CheckboxCell(true, false);
      public Cell<Boolean> getCell() {
        return cell;
      }

      public FieldUpdater<Department, Boolean> getFieldUpdater() {
        return null;
      }

      public Boolean getValue(Department object) {
        return selectionModel.isSelected(object);
      }
    });
    hasCells.add(new HasCell<Department, Department>() {
      private DepartmentCell cell = new DepartmentCell();
      public Cell<Department> getCell() {
        return cell;
      }

      public FieldUpdater<Department, Department> getFieldUpdater() {
        return null;
      }

      public Department getValue(Department object) {
        return object;
      }
    });
    contactCell = new CompositeCell<Department>(hasCells) {
      @Override
      public void render(Context context, Department value, SafeHtmlBuilder sb) {
        sb.appendHtmlConstant("<table><tbody><tr>");
        super.render(context, value, sb);
        sb.appendHtmlConstant("</tr></tbody></table>");
      }
      @Override
      protected Element getContainerElement(Element parent) {
        return parent.getFirstChildElement().getFirstChildElement().getFirstChildElement();
      }
      @Override
      protected <X> void render(Context context, Department value,
          SafeHtmlBuilder sb, HasCell<Department, X> hasCell) {
        Cell<X> cell = hasCell.getCell();
        sb.appendHtmlConstant("<td>");
        cell.render(context, hasCell.getValue(value), sb);
        sb.appendHtmlConstant("</td>");
      }
    };

    final CellList<Department> cellList = new CellList<Department>(contactCell);
    cellList.setRowData(depts);
    cellList.setSelectionModel(selectionModel,selectionManager);
    HorizontalPanel hpanel = new HorizontalPanel();
    VerticalPanel vpanel = new VerticalPanel();
    vpanel.add(cellList);
    vpanel.add(selectedLabel);
    Button submitButton = new Button("提交");
    submitButton.addClickHandler(new ClickHandler() {
@Override
public void onClick(ClickEvent event) {
if(selectedLabel.getText() == null && selectedLabel.getText().equals("")){
Window.alert("没有选择!");
}else{
Window.alert(selectedLabel.getText());
}
}
});
    hpanel.add(vpanel);
    hpanel.add(submitButton);
    RootPanel.get("root").add(hpanel);
}

private static class DepartmentCell extends AbstractCell<Department> {
@Override
public void render(Context context,Department value, SafeHtmlBuilder sb) {
if (value == null) {
return;
}
sb.appendHtmlConstant("<table>");
sb.appendHtmlConstant("<td style='font-size:95%;'>");
    sb.appendEscaped(value.getName());
    sb.appendHtmlConstant("</td></tr></table>");
}

public static final ProvidesKey<Department> KEY_PROVIDER = new ProvidesKey<Department>() {
@Override
public Object getKey(Department item) {
    return item == null ? null : item.getId();
  }
};
}

private class Department implements Comparable<Department> {
private int id;
private String name;

public Department(String name) {
super();
this.name = name;
}

public int getId() {
return id;
}

public void setId(int id) {
this.id = id;
}

public String getName() {
return name;
}

public void setName(String name) {
this.name = name;
}

@Override
public int compareTo(Department o) {
return (o == null || o.name == null) ? -1 : -o.name.compareTo(name);
}

@Override
    public boolean equals(Object o) {
      if (o instanceof Department) {
        return id == ((Department) o).id;
      }
      return false;
    }
}
}

要实现单选则：cellList.setSelectionModel(selectionModel);
要实现多选则：cellList.setSelectionModel(selectionModel,selectionManager);