Java SWT/JFace：如何在TableViewerColumn中设置最大文本长度

如何设置JFace

TableViewerColumn

中输入的最大字符数？有没有办法获取包含的控件并将其强制转换

下面是（几乎）完整的课程：

public class CustomerTab extends Composite implements ITableLabelProvider {
    org.eclipse.swt.layout.GridLayout layout = null;

    Table table = null;

    GridData griddata = null;

    TableViewer viewer = null;

    private CustomerSearchFilter filter;

    public CustomerTab(Composite arg1, int arg2) throws SQLException {
        super(arg1, arg2);

        layout = new org.eclipse.swt.layout.GridLayout(GridData.FILL_BOTH,
                false);
        layout.numColumns = 1;

        this.setLayout(layout);

        Button button = new Button(this, SWT.PUSH);
        button.setText("New customer");
        button.addSelectionListener(new SelectionAdapter() {
            public void widgetSelected(SelectionEvent e) {

                WizardDialog wizardDialog = new WizardDialog(ApplicationRunner
                        .getApp().getShell(), new NewCustomerWizard());
                if (wizardDialog.open() == Window.OK) {
                    System.out.println("Ok pressed");
                    try {
                        viewer.setInput(CustomerDAO.getInstance().getAll());
                        viewer.refresh();
                    } catch (SQLException e1) {
                        // TODO something
                    }

                } else {
                    System.out.println("Cancel pressed");
                }
            }
        });

        final Text searchText = new Text(this, SWT.BORDER | SWT.SEARCH);
        searchText.setLayoutData(new GridData(GridData.GRAB_HORIZONTAL
                | GridData.HORIZONTAL_ALIGN_FILL));

        addTable();

        // Support the search
        searchText.addKeyListener(new KeyAdapter() {
            public void keyReleased(KeyEvent ke) {
                filter.setSearchText(searchText.getText());
                viewer.refresh();
            }

        });
        filter = new CustomerSearchFilter();
        viewer.addFilter(filter);
    }

    public void addTable() throws SQLException {

        viewer = new TableViewer(this, SWT.BORDER | SWT.MULTI
                | SWT.FULL_SELECTION);

        final Table table = viewer.getTable();
        table.setHeaderVisible(true);
        table.setLinesVisible(true);

        createColumns(this, viewer);

        viewer.setContentProvider(new ArrayContentProvider());
        viewer.setInput(CustomerDAO.getInstance().getAll());

        GridData gridData = new GridData();
        gridData.verticalAlignment = GridData.FILL;
        gridData.horizontalSpan = 2;
        gridData.grabExcessHorizontalSpace = true;
        gridData.grabExcessVerticalSpace = true;
        gridData.horizontalAlignment = GridData.FILL;
        viewer.getControl().setLayoutData(gridData);
    }

    private void createColumns(final Composite parent, final TableViewer viewer) {
        String[] titles = { "ID", "Firma", "Anrede", "Vorname", "Nachname",
                "Strasse", "Plz", "Ort", "Tel. privat", "Tel. gesch.", " " };
        int[] bounds = { 30, 130, 50, 100, 100, 100, 50, 100, 100, 100, 30 };



        // Col 1, ID
        TableViewerColumn col = createTableViewerColumn(titles[0], bounds[0], 0);
        col.setLabelProvider(new ColumnLabelProvider() {
            @Override
            public String getText(Object element) {
                Customer p = (Customer) element;
                return String.valueOf(p.getId());
            }
        });
        col.setEditingSupport(new TestFirstNameEditingSupport(viewer));


        // other columns here...

        // Col 4, Firstname
        col = createTableViewerColumn(titles[3], bounds[3], 3);
        col.setLabelProvider(new ColumnLabelProvider() {
            @Override
            public String getText(Object element) {
                Customer p = (Customer) element;
                return p.getFirstname();
            }
        });
        col.setEditingSupport(new TestFirstNameEditingSupport(viewer));

        // and the rest of the columns here

    }

    private TableViewerColumn createTableViewerColumn(String title, int bound,
            final int colNumber) {
        final TableViewerColumn viewerColumn = new TableViewerColumn(viewer,
                SWT.NONE);
        final TableColumn column = viewerColumn.getColumn();
        column.setText(title);
        column.setWidth(bound);
        column.setResizable(true);
        column.setMoveable(true);
        return viewerColumn;
    }

    // LabelProvider
    @Override
    public void addListener(ILabelProviderListener arg0) {
    }

    @Override
    public boolean isLabelProperty(Object arg0, String arg1) {
        return false;
    }

    @Override
    public void removeListener(ILabelProviderListener arg0) {
    }

    @Override
    public Image getColumnImage(Object arg0, int arg1) {
        return null;
    }

    @Override
    public String getColumnText(Object arg0, int arg1) {

        String result = "";
        switch (arg1) {
        case 0:
            result = "ID";
            break;
        ...

        case 4:
            result = "Firstname";
            break;
        ...

        default:
            // should not get here
            result = "";
        }
        return result;
    }

    static class TestFirstNameEditingSupport extends EditingSupport {

        private final TableViewer viewer;
        private TextCellEditor editor = null;

        public TestFirstNameEditingSupport(TableViewer viewer) {
            super(viewer);
            this.viewer = viewer;
            editor = new TextCellEditor(viewer.getTable());

            Text text = (Text) editor.getControl();

            //  set maximal length HERE
            text.setTextLimit(3);
        }

        public CellEditor getMyCellEditor(Object element) {
            return editor;
        }

        @Override
        protected CellEditor getCellEditor(Object element) {
            return new TextCellEditor(viewer.getTable());
        }

        @Override
        protected boolean canEdit(Object element) {
            return true;
        }

        @Override
        protected Object getValue(Object element) {
            return ((de.devision.data.bean.Customer) element).getVorname();
        }

        @Override
        protected void setValue(Object element, Object value) {

            if (String.valueOf(value).length() <= 2 || String.valueOf(value).equals("")) {
                MessageDialog.openInformation(ApplicationRunner.getApp().getShell(), "to short!", "at least 3 characters!");
                return;
            }

            ((Customer) element).setVorname(String.valueOf(value));

            try {
                CustomerDAO.getInstance().update(((Customer) element));
            } catch (SQLException e) {
                // TODO maybe later
            }
            viewer.refresh();
        }
    }
}

公共类CustomerTab扩展了复合实现ITableLabelProvider{
org.eclipse.swt.layout.GridLayout=null；
Table=null；
GridData GridData=null；
TableViewer=null；
私人客户搜索过滤器；
公共CustomerTab（复合arg1，int arg2）引发SQLException{
超级（arg1，arg2）；
layout=neworg.eclipse.swt.layout.GridLayout（GridData.FILL_两者，
假）；
layout.numColumns=1；
这个.setLayout（布局）；
按钮=新按钮（此按钮为SWT.按钮）；
button.setText（“新客户”）；
addSelectionListener（新建SelectionAdapter（）{
公共无效WidgeSelected（SelectionEvent e）{
向导对话框=新建向导对话框（ApplicationRunner）
.getApp（）.getShell（），新的CustomerWizard（））；
如果（wizardDialog.open（）==Window.OK）{
System.out.println（“按下Ok”）；
试一试{
setInput（CustomerDAO.getInstance（）.getAll（））；
viewer.refresh（）；
}捕获（SQLException e1）{
//做点什么
}
}否则{
系统输出打印项次（“取消按下”）；
}
}
});
最终文本搜索文本=新文本（此，SWT.BORDER | SWT.SEARCH）；
searchText.setLayoutData（新的GridData（GridData.GRAB）)
|GridData.HORIZONTAL_ALIGN_FILL））；
addTable（）；
//支持搜索
addKeyListener（新的KeyAdapter（）{
公开无效密钥已释放（密钥事件）{
filter.setSearchText（searchText.getText（））；
viewer.refresh（）；
}
});
过滤器=新客户搜索过滤器（）；
viewer.addFilter（filter）；
}
public void addTable（）引发SQLException{
查看器=新的TableViewer（此，SWT.BORDER | SWT.MULTI
|SWT.全方位选择）；
final Table Table=viewer.getTable（）；
表.setheadervible（true）；
表.setLinesVisible（真）；
createColumns（这个，查看器）；
setContentProvider（新的ArrayContentProvider（））；
setInput（CustomerDAO.getInstance（）.getAll（））；
GridData GridData=新的GridData（）；
gridData.verticalAlignment=gridData.FILL；
gridData.horizontalSpan=2；
gridData.grabExcessHorizontalSpace=true；
gridData.grabExcessVerticalSpace=true；
gridData.horizontalAlignment=gridData.FILL；
viewer.getControl（）.setLayoutData（gridData）；
}
私有void createColumns（最终复合父级、最终TableViewer）{
String[]titles={“ID”、“Firma”、“Anrede”、“Vorname”、“Nachname”，
“Strasse”、“Plz”、“Ort”、“Tel.privat”、“Tel.gesch.”、“}；
int[]边界={30,130,50,100,100,100,50,100,100,100,30}；
//第1列，ID
TableViewerColumn col=createTableViewerColumn（标题[0]，边界[0]，0）；
col.setLabelProvider（新ColumnLabelProvider（）{
@凌驾
公共字符串getText（对象元素）{
客户p=（客户）要素；
返回字符串.valueOf（p.getId（））；
}
});
col.setEditingSupport（新的TestFirstNameEditingSupport（查看器））；
//这里的其他专栏。。。
//第4列，名字
col=createTableViewerColumn（标题[3]，边界[3]，3]；
col.setLabelProvider（新ColumnLabelProvider（）{
@凌驾
公共字符串getText（对象元素）{
客户p=（客户）要素；
返回p.getFirstname（）；
}
});
col.setEditingSupport（新的TestFirstNameEditingSupport（查看器））；
//还有这里的其他专栏
}
私有TableViewerColumn createTableViewerColumn（字符串标题，int-bound，
最终整数（整数）{
最终TableViewerColumn viewerColumn=新的TableViewerColumn（查看器，
SWT（无）；
final TableColumn column=viewerColumn.getColumn（）；
列.setText（标题）；
column.setWidth（绑定）；
column.setResizeable（true）；
column.setMoveable（true）；
返回viewerColumn；
}
//标签提供者
@凌驾
public void addListener（ILabelProviderListener arg0）{
}
@凌驾
公共布尔isLabelProperty（对象arg0，字符串arg1）{
返回false；
}
@凌驾
公共void RemovelListener（ILabelProviderListener arg0）{
}
@凌驾
公共映像getColumnImage（对象arg0，int arg1）{
返回null；
}
@凌驾
公共字符串getColumnText（对象arg0，int arg1）{
字符串结果=”；
开关（arg1）{
案例0：
结果=“ID”；
打破
...
案例4：
result=“Firstname”；
打破
...
违约：
//我不应该到这里
结果=”；
}
返回结果；
}
静态类TestFirstNameEditingSupport扩展了EditingSupport{
私有最终表格查看器；
私有TextCellEditor=null；
公共TestFirstNameEditingSupport（TableViewer）{
超级（观众）；
this.viewer=查看器；
editor=newtextcelleditor（viewer.getTable（））；
Text Text=（Text）editor.getControl（）；
//在此处设置最大长度
text.setTextLimit（3）；
}
公共CellEditor getMyCellEditor（对象元素）{
返回
private static void createViewer(Composite parent) {
    viewer = new TableViewer(parent, SWT.MULTI | SWT.H_SCROLL
            | SWT.V_SCROLL | SWT.FULL_SELECTION | SWT.BORDER);
    createColumns(parent, viewer);
    final Table table = viewer.getTable();
    table.setHeaderVisible(true);
    table.setLinesVisible(true);

    viewer.setContentProvider(new ArrayContentProvider());
    // Get the content for the viewer, setInput will call getElements in the
    // contentProvider
    viewer.setInput(ModelProvider.INSTANCE.getPersons());
    // Set the sorter for the table

    // Layout the viewer
    GridData gridData = new GridData();
    gridData.verticalAlignment = GridData.FILL;
    gridData.horizontalSpan = 2;
    gridData.grabExcessHorizontalSpace = true;
    gridData.grabExcessVerticalSpace = true;
    gridData.horizontalAlignment = GridData.FILL;
    viewer.getControl().setLayoutData(gridData);

    comparator = new PersonViewerComparator();
    viewer.setComparator(comparator);
}

// This will create the columns for the table
private static void createColumns(final Composite parent,
        final TableViewer viewer) {
    String[] titles = { "First name", "Last name", "Gender", "Married" };
    int[] bounds = { 100, 100, 100, 100 };

    // First column is for the first name
    TableViewerColumn col = createTableViewerColumn(titles[0], bounds[0], 0);
    col.setLabelProvider(new ColumnLabelProvider() {
        @Override
        public String getText(Object element) {
            Person p = (Person) element;
            return p.getFirstName();
        }
    });

    col.setEditingSupport(new CheckLengthEditingSupport(viewer)); 

    // Second column is for the last name
    col = createTableViewerColumn(titles[1], bounds[1], 1);
    col.setLabelProvider(new ColumnLabelProvider() {
        @Override
        public String getText(Object element) {
            Person p = (Person) element;
            return p.getLastName();
        }
    });

    // Now the gender
    col = createTableViewerColumn(titles[2], bounds[2], 2);
    col.setLabelProvider(new ColumnLabelProvider() {
        @Override
        public String getText(Object element) {
            Person p = (Person) element;
            return p.getGender();
        }
    });

    // // Now the status married
    col = createTableViewerColumn(titles[3], bounds[3], 3);
    col.setLabelProvider(new ColumnLabelProvider() {
        @Override
        public String getText(Object element) {
            return "";
        }

        @Override
        public Image getImage(Object element) {
            if (((Person) element).isMarried()) {
                return CHECKED;
            } else {
                return UNCHECKED;
            }
        }
    });
}

static class CheckLengthEditingSupport extends EditingSupport {

    private final TableViewer viewer;
    private TextCellEditor editor = null;

    public FirstNameEditingSupport(TableViewer viewer) {
        super(viewer);
        this.viewer = viewer;
        editor = new TextCellEditor(viewer.getTable());

        Text text = (Text) editor.getControl();

        //  set maximal length HERE
        text.setTextLimit(3);
    }

    @Override
    protected CellEditor getCellEditor(Object element) {
        return editor;
    }

    @Override
    protected boolean canEdit(Object element) {
        return true;
    }

    @Override
    protected Object getValue(Object element) {
        return ((YourObject) element).getName();
    }

    @Override
    protected void setValue(Object element, Object value) {
        ((YourObject) element).setName(String.valueOf(value));
        viewer.update(element, null);
    }
}