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Vaadin系列（二）应用开发：Table 组件

Table 用来显示一个二维表，Table算是Vaadin提供的功能最强大的组件，每个单元格既可以显示字符串也可以显示其它的UI组件。你可以实现可编辑的表格，比如点击某个单元格后将其变为可编辑的文本框。
Table关联的数据采用Vaadin 的Container数据模型。从而使得Table可以直接绑定数据库的表或查询。Table只载入当前需要显示的数据，当数据载入时，Table会给出提示正在显示的数据表的范围和全部记录的数目。
Table中每行数据对应Vaadin数据模型的Item接口，每个字段对应到Property接口，每行数据由Item标识符（IID）唯一指定，而字段由Property标识符（PID）指定。
创建一个Table，首先使用addContainerProperty 定义表的字段。这个方法有两种调用方式。简单方式是使用Property ID 做为字段的标题。而复杂方式可以分别制定Property ID和字段的标题，这种方式使得应用本地化成为可能。

复杂方式也支持使用图标资源显示字段标题。在定义表的字段时，可以提供一个“缺省值”用在该字段没有赋值的情况下。Table基本用法如下：

[java]
// Create the table with a caption.
Table table = new Table("This is my Table");

// Define the names and data types of columns.
// The "default value" parameter is meaningless here.
table.addContainerProperty("First Name", String.class, null);
table.addContainerProperty("Last Name", String.class, null);
table.addContainerProperty("Year",       Integer.class, null);

// Add a few items in the table.
table.addItem(new Object[] {
    "Nicolaus","Copernicus",new Integer(1473)}, new Integer(1));
table.addItem(new Object[] {
    "Tycho",   "Brahe",     new Integer(1546)}, new Integer(2));
table.addItem(new Object[] {
    "Giordano","Bruno",     new Integer(1548)}, new Integer(3));
table.addItem(new Object[] {
    "Galileo", "Galilei",   new Integer(1564)}, new Integer(4));
table.addItem(new Object[] {
    "Johannes","Kepler",    new Integer(1571)}, new Integer(5));
table.addItem(new Object[] {
    "Isaac",   "Newton",    new Integer(1643)}, new Integer(6));

// Create the table with a caption.
Table table = new Table("This is my Table");

// Define the names and data types of columns.
// The "default value" parameter is meaningless here.
table.addContainerProperty("First Name", String.class, null);
table.addContainerProperty("Last Name", String.class, null);
table.addContainerProperty("Year", Integer.class, null);

// Add a few items in the table.
table.addItem(new Object[] {
    "Nicolaus","Copernicus",new Integer(1473)}, new Integer(1));
table.addItem(new Object[] {
    "Tycho",   "Brahe",     new Integer(1546)}, new Integer(2));
table.addItem(new Object[] {
    "Giordano","Bruno",     new Integer(1548)}, new Integer(3));
table.addItem(new Object[] {
    "Galileo", "Galilei",   new Integer(1564)}, new Integer(4));
table.addItem(new Object[] {
    "Johannes","Kepler",    new Integer(1571)}, new Integer(5));
table.addItem(new Object[] {
    "Isaac",   "Newton",    new Integer(1643)}, new Integer(6));

在这个例子中，使用了整数值作为Item的IID，作为第二个参数传给addItem, 每行实际的数据为一个Object数组，采用和表字段定义同样的顺序，并且必须采用和由addContainerProperty定义的同样的数据类型。

Table 支持的数据规模取决于Container的实现，缺省的Container在更新数据时可能会由于数据规模过大而造成问题。因此推荐使用优化过的Container类型。Table本身不限制记录的数目，但当前滚动实现有一个50万条记录的限制。

选择Table中的项，Table允许用户选择表格中的某个或多个数据项，当用户选取某个Item时，Item的IID会作为ValueChangeEvent 的Property传入。要使Table支持选取，必须通过方法setSelectable 将Table设为支持选取。同时需将setImmediate 设为True。

例如：

[java]
// Allow selecting items from the table.
table.setSelectable(true);

// Send changes in selection immediately to server.
table.setImmediate(true);

// Shows feedback from selection.
final Label current = new Label("Selected: -");

// Handle selection change.
table.addListener(new Property.ValueChangeListener() {
    public void valueChange(ValueChangeEvent event) {
        current.setValue("Selected: " + table.getValue());
    }
});

// Allow selecting items from the table.
table.setSelectable(true);

// Send changes in selection immediately to server.
table.setImmediate(true);

// Shows feedback from selection.
final Label current = new Label("Selected: -");

// Handle selection change.
table.addListener(new Property.ValueChangeListener() {
    public void valueChange(ValueChangeEvent event) {
        current.setValue("Selected: " + table.getValue());
    }
});

通常用户再次点击已选取的数据行时会取消该行的选取，如果你想修改这种行为，可以将setNullSelectionAllowed 设为False.
如果需要Table支持多行选取，可以将setMultiSelect 设为True, 此时可以通过按下Ctrl/Shift来实现多选。

Table缺省支持滚动条，当所显示记录数大于Table可见行数时在Table右边显示滚动条。可以通过setPageLength 修改Table可以区域。将PageLength设为0，取消分页，显示所有记录数。
表个字段宽度可以通过setColumnWidth 来修改，用户也可以通过拖动字段边界更改字段宽度，并会触发ColumnResizeEvent 事件。
如果设置setColumnReorderingAllowed(true) ，则允许用户重新排列字段的顺序。
setColumnCollapsingAllowed (true) 允许用户展开或隐藏某些字段。
以上Table单元格中都显示的是简单的字符串，Table单元格也可以显示UI组件。此时如果Table缺省风格的行高不够的话，你需要使用自定义的风格定义合适的行高。
如果需要响应Table单元格中某个UI组件的事件，需要知道其对应的Item标识IID。简单的方法是使用setData 方法将某个对象附加到该UI组件上。
如下例使用了Label，TextField, CheckBox, Button 作为Table单元格元素显示。

[java]
// Create a table and add a style to allow setting the row height in theme.
final Table table = new Table();
table.addStyleName("components-inside");

//Define the names and data types of columns.
// The "default value" parameter is meaningless here.
table.addContainerProperty("Sum",            Label.class,     null);
table.addContainerProperty("Is Transferred", CheckBox.class, null);
table.addContainerProperty("Comments",       TextField.class, null);
table.addContainerProperty("Details",        Button.class,    null);

// Add a few items in the table.
for (int i=0; i<100; i++) {
    // Create the fields for the current table row
    Label sumField = new Label(String.format(
                   "Sum is $%04.2f
(VAT incl.)",
                   new Object[] {new Double(Math.random()*1000)}),
                               Label.CONTENT_XHTML);
    CheckBox transferredField = new CheckBox("is transferred");

    // Multiline text field. This required modifying the
    // height of the table row.
    TextField commentsField = new TextField();
    commentsField.setRows(3);

    // The Table item identifier for the row.
    Integer itemId = new Integer(i);

    // Create a button and handle its click. A Button does not
    // know the item it is contained in, so we have to store the
    // item ID as user-defined data.
    Button detailsField = new Button("show details");
    detailsField.setData(itemId);
    detailsField.addListener(new Button.ClickListener() {
        public void buttonClick(ClickEvent event) {
            // Get the item identifier from the user-defined data.
            Integer itemId = (Integer)event.getButton().getData();
            getWindow().showNotification("Link "+
                                   itemId.intValue()+" clicked.");
        }
    });
    detailsField.addStyleName("link");

    // Create the table row.
    table.addItem(new Object[] {sumField, transferredField,
                                commentsField, detailsField},
                  itemId);
}

// Show just three rows because they are so high.
table.setPageLength(3);

// Create a table and add a style to allow setting the row height in theme.
final Table table = new Table();
table.addStyleName("components-inside");

//Define the names and data types of columns.
// The "default value" parameter is meaningless here.
table.addContainerProperty("Sum",            Label.class,     null);
table.addContainerProperty("Is Transferred", CheckBox.class, null);
table.addContainerProperty("Comments",       TextField.class, null);
table.addContainerProperty("Details",        Button.class,    null);

// Add a few items in the table.
for (int i=0; i<100; i++) {
    // Create the fields for the current table row
    Label sumField = new Label(String.format(
                   "Sum is $%04.2f
(VAT incl.)",
                   new Object[] {new Double(Math.random()*1000)}),
                               Label.CONTENT_XHTML);
    CheckBox transferredField = new CheckBox("is transferred");

    // Multiline text field. This required modifying the
    // height of the table row.
    TextField commentsField = new TextField();
    commentsField.setRows(3);

// The Table item identifier for the row.
Integer itemId = new Integer(i);

    // Create a button and handle its click. A Button does not
    // know the item it is contained in, so we have to store the
    // item ID as user-defined data.
    Button detailsField = new Button("show details");
    detailsField.setData(itemId);
    detailsField.addListener(new Button.ClickListener() {
        public void buttonClick(ClickEvent event) {
            // Get the item identifier from the user-defined data.
            Integer itemId = (Integer)event.getButton().getData();
            getWindow().showNotification("Link "+
                                   itemId.intValue()+" clicked.");
        }
    });
    detailsField.addStyleName("link");

    // Create the table row.
    table.addItem(new Object[] {sumField, transferredField,
                                commentsField, detailsField},
                  itemId);
}

// Show just three rows because they are so high.
table.setPageLength(3);

通常情况下Table以文本形式显示单元格，如果想让Table支持编辑功能，一是使用上面UI组件的方式，或者简单的调用setEditable(true)自动将表格变为可编辑。
setColumnHeader 为表格定义表头，setColumnFooter 定义表尾。Table的表头和表尾也接受点击事件。
下例显示了一个自定义的表尾显示平均值。

[java]
// Have a table with a numeric column
Table table = new Table("Custom Table Footer");
table.addContainerProperty("Name", String.class, null);
table.addContainerProperty("Died At Age", Integer.class, null);

// Insert some data
Object people[][] = {{"Galileo", 77},
                     {"Monnier", 83},
                     {"Vaisala", 79},
                     {"Oterma",   86}};
for (int i=0; i     table.addItem(people[i], new Integer(i));

// Calculate the average of the numeric column
double avgAge = 0;
for (int i=0; i     avgAge += (Integer) people[i][1];
avgAge /= people.length;

// Set the footers
table.setFooterVisible(true);
table.setColumnFooter("Name", "Average");
table.setColumnFooter("Died At Age", String.valueOf(avgAge));

// Adjust the table height a bit
table.setPageLength(table.size());

// Have a table with a numeric column
Table table = new Table("Custom Table Footer");
table.addContainerProperty("Name", String.class, null);
table.addContainerProperty("Died At Age", Integer.class, null);

// Insert some data
Object people[][] = {{"Galileo", 77},
                     {"Monnier", 83},
                     {"Vaisala", 79},
                     {"Oterma",   86}};
for (int i=0; i     table.addItem(people[i], new Integer(i));

// Calculate the average of the numeric column
double avgAge = 0;
for (int i=0; i avgAge += (Integer) people[i][1];
avgAge /= people.length;

// Set the footers
table.setFooterVisible(true);
table.setColumnFooter("Name", "Average");
table.setColumnFooter("Died At Age", String.valueOf(avgAge));

// Adjust the table height a bit
table.setPageLength(table.size());

Table Item的双击事件，我可是搜索好多资料才找到的哦，在此分享一下：