eXtremeComponents（簡稱ec）是一系列提供高級顯示的開源JSP定制標簽，當前的包含的組件為eXtremeTable，用于以表形式顯示數(shù)據(jù)。

其本質是jsp的自定義標簽，抓住這一點就抓住了ec的本源。

1. Table定義

我們先看一下標簽的定義：extremComponents.tld，其中table的標簽定義如下：

<tag><name>table</name><tag-class>org.extremecomponents.table.tag.TableTag</tag-class><body-content>JSP</body-content><display-name>TableTag</display-name><description><![CDATA[The container which holds all the main table information. Will also hold global information if needed. The table tag is copied into the Table and encapsulated in the Model.]]></description><attribute><name>action</name><required>false</required><rtexprvalue>true</rtexprvalue><description><![CDATA[The URI that will be called when the filter, sort and pagination is used.]]></description></attribute><attribute><name>autoIncludeParameters</name><required>false</required><rtexprvalue>true</rtexprvalue><description><![CDATA[Specify whether or not to automatically include the parameters, as hidden inputs, passed into the JSP.]]></description></attribute><attribute><name>border</name><required>false</required><rtexprvalue>true</rtexprvalue><description><![CDATA[The table border attribute. The default is 0.]]></description></attribute><attribute><name>bufferView</name><required>false</required><rtexprvalue>true</rtexprvalue><description><![CDATA[Whether of not to buffer the view. Boolean value with the default being false.]]></description></attribute><attribute><name>cellpadding</name><required>false</required><rtexprvalue>true</rtexprvalue><description><![CDATA[The table cellpadding attribute. The default is 0.]]></description></attribute><attribute><name>cellspacing</name><required>false</required><rtexprvalue>true</rtexprvalue><description><![CDATA[The table cellspacing attribute. The default is 0.]]></description></attribute><attribute><name>filterable</name><required>false</required><rtexprvalue>true</rtexprvalue><description><![CDATA[Specify whether or not the table is filterable. Boolean value with the default being true.]]></description></attribute><attribute><name>filterRowsCallback</name><required>false</required><rtexprvalue>true</rtexprvalue><description><![CDATA[A fully qualified class name to a custom FilterRowsCallback implementation. Could also be a named type in the preferences. Used to filter the Collection of Beans or Collection of Maps.]]></description></attribute><attribute><name>form</name><required>false</required><rtexprvalue>true</rtexprvalue><description><![CDATA[The reference to a surrounding form element.]]></description></attribute><attribute><name>imagePath</name><required>false</required><rtexprvalue>true</rtexprvalue><description><![CDATA[The path to find the images. For example imagePath=/extremesite/images/*.png is saying look in the image directory for the .png images.]]></description></attribute><attribute><name>interceptor</name><required>false</required><rtexprvalue>true</rtexprvalue><description><![CDATA[A fully qualified class name to a custom InterceptTable implementation. Could also be a named type in the preferences. Used to add table attributes.]]></description></attribute><attribute><name>items</name><required>false</required><rtexprvalue>true</rtexprvalue><description><![CDATA[Reference the collection that will be retrieved.]]></description></attribute><attribute><name>locale</name><required>false</required><rtexprvalue>true</rtexprvalue><description><![CDATA[The locale for this table. For example fr_FR is used for the French translation.]]></description></attribute><attribute><name>method</name><required>false</required><rtexprvalue>true</rtexprvalue><description><![CDATA[Used to invoke the table action using a POST or GET.]]></description></attribute><attribute><name>onInvokeAction</name><required>false</required><rtexprvalue>true</rtexprvalue><description><![CDATA[The javascript that will be invoked when a table action enabled.]]></description></attribute><attribute><name>retrieveRowsCallback</name><required>false</required><rtexprvalue>true</rtexprvalue><description><![CDATA[A fully qualified class name to a custom RetrieveRowsCallback implementation. Could also be a named type in the preferences. Used to retrieve the Collection of Beans or Collection of Maps.]]></description></attribute><attribute><name>rowsDisplayed</name><required>false</required><rtexprvalue>true</rtexprvalue><description><![CDATA[The number of rows to display in the table.]]></description></attribute><attribute><name>scope</name><required>false</required><rtexprvalue>true</rtexprvalue><description><![CDATA[The scope (page, request, session, or application) to find the Collection of beans or Collection of Maps defined by the collection attribute.]]></description></attribute><attribute><name>showPagination</name><required>false</required><rtexprvalue>true</rtexprvalue><description><![CDATA[Specify whether or not the table should use pagination. Boolean value with the default being true.]]></description></attribute><attribute><name>showExports</name><required>false</required><rtexprvalue>true</rtexprvalue><description><![CDATA[Specify whether or not the table should use the exports. Boolean value with the default being true.]]></description></attribute><attribute><name>showStatusBar</name><required>false</required><rtexprvalue>true</rtexprvalue><description><![CDATA[Specify whether or not the table should use the status bar. Boolean value with the default being true.]]></description></attribute><attribute><name>showTitle</name><required>false</required><rtexprvalue>true</rtexprvalue><description><![CDATA[Specify whether or not to show the title. Boolean value with the default being true.]]></description></attribute><attribute><name>showTooltips</name><required>false</required><rtexprvalue>true</rtexprvalue><description><![CDATA[Specify whether or not to show the tooltips. Boolean value with the default being true.]]></description></attribute><attribute><name>sortRowsCallback</name><required>false</required><rtexprvalue>true</rtexprvalue><description><![CDATA[A fully qualified class name to a custom SortRowsCallback implementation. Could also be a named type in the preferences. Used to sort the Collection of Beans or Collection of Maps.]]></description></attribute><attribute><name>sortable</name><required>false</required><rtexprvalue>true</rtexprvalue><description><![CDATA[Specify whether or not the table is sortable. Boolean value with the default being true.]]></description></attribute><attribute><name>state</name><required>false</required><rtexprvalue>true</rtexprvalue><description><![CDATA[The table state to use when returning to a table. Acceptable values are default, notifyToDefault, persist, notifyToPersist.]]></description></attribute><attribute><name>stateAttr</name><required>false</required><rtexprvalue>true</rtexprvalue><description><![CDATA[The table attribute used to invoke the state change of the table.]]></description></attribute><attribute><name>style</name><required>false</required><rtexprvalue>true</rtexprvalue><description><![CDATA[The css inline style sheet.]]></description></attribute><attribute><name>styleClass</name><required>false</required><rtexprvalue>true</rtexprvalue><description><![CDATA[The css class style sheet.]]></description></attribute><attribute><name>tableId</name><required>false</required><rtexprvalue>true</rtexprvalue><description><![CDATA[The unique identifier for the table.]]></description></attribute><attribute><name>theme</name><required>false</required><rtexprvalue>true</rtexprvalue><description><![CDATA[The theme to style the table. The default is eXtremeTable.]]></description></attribute><attribute><name>title</name><required>false</required><rtexprvalue>true</rtexprvalue><description><![CDATA[The title of the table. The title will display above the table.]]></description></attribute><attribute><name>var</name><required>false</required><rtexprvalue>true</rtexprvalue><description><![CDATA[The name of the variable to hold the current row bean.]]></description></attribute><attribute><name>view</name><required>false</required><rtexprvalue>true</rtexprvalue><description><![CDATA[Generates the output. The default is the HtmlView to generate the HTML. Also used by the exports to generate XLS-FO, POI, and CSV.]]></description></attribute><attribute><name>width</name><required>false</required><rtexprvalue>true</rtexprvalue><description><![CDATA[Width of the table.]]></description></attribute></tag>

從上面我們可以看到，先定義了table標簽的實現(xiàn)類：org.extremecomponents.table.tag.TableTag，其作用是：

The container which holds all the main table information. Will also hold global information if needed. The table tag is copied into the Table and encapsulated in the Model.

一句話：保存table的信息及一些全局信息，通過table封裝到Model中。

然后定義了table的一些屬性，這些屬性和org.extremecomponents.table.bean.Table一致。

public class Table extends Attributes {private TableModel model;private String action;private Boolean autoIncludeParameters;private String border;private Boolean bufferView;private String cellpadding;private String cellspacing;private Boolean filterable;private String filterRowsCallback;private String form;private String imagePath;private String interceptor;private Object items;private String locale;private int maxRowsDisplayed;private int medianRowsDisplayed;private String method;private String onInvokeAction;private String retrieveRowsCallback;private int rowsDisplayed;private Boolean saveFilterSort;private String scope;private Boolean showExports;private Boolean showPagination;private Boolean showStatusBar;private Boolean showTitle;private Boolean showTooltips;private String sortRowsCallback;private Boolean sortable;private String state;private String stateAttr;private String style;private String styleClass;private String tableId;private String title;private String theme;private String var;private String view;private String width;public Table(TableModel model) {this.model = model;} // setter and getter }

2. TableTag實現(xiàn)

我們來看一下TableTage如何實現(xiàn)table標簽？首先：TableTage繼承了TagSupport：

web容器執(zhí)行自定義標簽的過程如下
初始化時調用setPageContent()方法，完了在調用setParent方法
2.1 ?web容器首先執(zhí)行自定義標簽的開始標記，同時調用doStartTag方法。
2.2 ?如果doStartTag方法返回EVAL_BODY_INCLUDE，web容器在執(zhí)行完標簽體的內容后，會調用標簽類得doAfterBody方法；
　　如果doStartTag方法返回SKIP_BODY,doAfterBody方法不會調用，web容器會直接調用標簽類得doEndTag方法
2.3 如果doAfterBody方法被調用，并且方法返回EVAL_BODY_AGIN,web容器會再次執(zhí)行標簽體的內容；
　　如果doAfterBody方法返回SKIP_BODY,web容器會調用標簽類的doEndTag方法
2.4 如果doEndTag方法返回EVAL_PAGE,web容器會執(zhí)行標簽后面的內容；
　　如果doEndTag方法返回SKIP_PAGE,web容器會忽略自定義標簽后面的內容

public int doStartTag() throws JspException {try {// initialize the attributesiterator = null;pageContext.setAttribute(TableConstants.ROWCOUNT, "0");// fire up the model with the context, preferences and messagesmodel = new TableModelImpl(new JspPageContext(pageContext), TagUtils.evaluateExpressionAsString("locale", this.locale, this, pageContext));// make the tableTable table = new Table(model);table.setAction(TagUtils.evaluateExpressionAsString("action", action, this, pageContext));table.setAutoIncludeParameters(TagUtils.evaluateExpressionAsBoolean("autoIncludeParameters", this.autoIncludeParameters, this, pageContext));table.setBorder(TagUtils.evaluateExpressionAsString("border", this.border, this, pageContext));table.setBufferView(TagUtils.evaluateExpressionAsBoolean("bufferView", this.bufferView, this, pageContext));table.setCellpadding(TagUtils.evaluateExpressionAsString("cellpadding", this.cellpadding, this, pageContext));table.setCellspacing(TagUtils.evaluateExpressionAsString("cellspacing", this.cellspacing, this, pageContext));table.setFilterable(TagUtils.evaluateExpressionAsBoolean("filterable", this.filterable, this, pageContext));table.setFilterRowsCallback(TagUtils.evaluateExpressionAsString("filterRowsCallback", this.filterRowsCallback, this, pageContext));table.setForm(TagUtils.evaluateExpressionAsString("form", this.form, this, pageContext));table.setImagePath(TagUtils.evaluateExpressionAsString("imagePath", this.imagePath, this, pageContext));table.setInterceptor(TagUtils.evaluateExpressionAsString("interceptor", this.interceptor, this, pageContext));table.setItems(TagUtils.evaluateExpressionAsObject("items", this.items, this, pageContext));table.setLocale(TagUtils.evaluateExpressionAsString("locale", this.locale, this, pageContext));table.setMethod(TagUtils.evaluateExpressionAsString("method", this.method, this, pageContext));table.setOnInvokeAction(TagUtils.evaluateExpressionAsString("onInvokeAction", this.onInvokeAction, this, pageContext));table.setRetrieveRowsCallback(TagUtils.evaluateExpressionAsString("retrieveRowsCallback", this.retrieveRowsCallback, this, pageContext));table.setRowsDisplayed(TagUtils.evaluateExpressionAsInt("rowsDisplayed", this.rowsDisplayed, this, pageContext));table.setScope(TagUtils.evaluateExpressionAsString("scope", scope, this, pageContext));table.setShowExports(TagUtils.evaluateExpressionAsBoolean("showExports", this.showExports, this, pageContext));table.setShowPagination(TagUtils.evaluateExpressionAsBoolean("showPagination", this.showPagination, this, pageContext));table.setShowStatusBar(TagUtils.evaluateExpressionAsBoolean("showStatusBar", this.showStatusBar, this, pageContext));table.setShowTitle(TagUtils.evaluateExpressionAsBoolean("showTitle", this.showTitle, this, pageContext));table.setShowTooltips(TagUtils.evaluateExpressionAsBoolean("showTooltips", this.showTooltips, this, pageContext));table.setSortRowsCallback(TagUtils.evaluateExpressionAsString("sortRowsCallback", this.sortRowsCallback, this, pageContext));table.setSortable(TagUtils.evaluateExpressionAsBoolean("sortable", this.sortable, this, pageContext));table.setState(TagUtils.evaluateExpressionAsString("state", this.state, this, pageContext));table.setStateAttr(TagUtils.evaluateExpressionAsString("stateAttr", this.stateAttr, this, pageContext));table.setStyle(TagUtils.evaluateExpressionAsString("style", style, this, pageContext));table.setStyleClass(TagUtils.evaluateExpressionAsString("styleClass", this.styleClass, this, pageContext));table.setTableId(TagUtils.evaluateExpressionAsString("tableId", tableId, this, pageContext));table.setTheme(TagUtils.evaluateExpressionAsString("theme", this.theme, this, pageContext));table.setTitle(TagUtils.evaluateExpressionAsString("title", this.title, this, pageContext));table.setVar(TagUtils.evaluateExpressionAsString("var", this.var, this, pageContext));table.setView(TagUtils.evaluateExpressionAsString("view", this.view, this, pageContext));table.setWidth(TagUtils.evaluateExpressionAsString("width", this.width, this, pageContext));addTableAttributes(model, table);model.addTable(table);} catch (Exception e) {throw new JspException("TableTag.doStartTag() Problem: " + ExceptionUtils.formatStackTrace(e));}return EVAL_BODY_INCLUDE;}/*** Two things need to be accomplished here. First, need to iterate once over* the columns to load up all the attributes. Second, need to iterate over* the columns as many times as specified by the rowsDisplayed attribute so* the columns row can be resolved. On each iteration over the columns the* current bean in the collection is passed via the pageScope.*/public int doAfterBody() throws JspException {try {if (iterator == null) { iterator = model.execute().iterator();}if (iterator != null && iterator.hasNext()) {Object bean = iterator.next();model.setCurrentRowBean(bean);return EVAL_BODY_AGAIN;}} catch (Exception e) {throw new JspException("TableTag.doAfterBody() Problem: " + ExceptionUtils.formatStackTrace(e));}return SKIP_BODY;}public int doEndTag() throws JspException {try {pageContext.getOut().println(model.getViewData());} catch (Exception e) {throw new JspException("TableTag.doEndTag() Problem: " + ExceptionUtils.formatStackTrace(e));}return EVAL_PAGE;}

3. 深入追蹤到TableModel

? ? 在doAfterBody()方法中調用了TableModel的excute方法：

public Collection execute() throws Exception {
　　　　　 //1. 查詢記錄Collection rows = TableModelUtils.retrieveRows(this);rows = new ArrayList(rows); // copy for thread safetythis.collectionOfBeans = rows;//2. 過濾和排序記錄rows = TableModelUtils.filterRows(this, rows);rows = TableModelUtils.sortRows(this, rows);this.collectionOfFilteredBeans = rows;// 3. 獲取記錄總數(shù)和pagesizeInteger totalRows = getTableHandler().getTotalRows();
　　　　int defaultRowsDisplayed = getTableHandler().getTable().getRowsDisplayed();if (totalRows != null) {
　　　　　　　//4. 設置記錄總數(shù)和默認pagesize limit.setRowAttributes(totalRows.intValue(), defaultRowsDisplayed);} else {limit.setRowAttributes(rows.size(), defaultRowsDisplayed);}if (logger.isDebugEnabled()) {logger.debug(limit.toString());}//5. 獲取本次顯示的記錄rows = TableModelUtils.getCurrentRows(this, rows);this.collectionOfPageBeans = rows;//6. 視圖顯示 viewHandler.setView();return rows;}

4. 視圖顯示

?　默認定義了三種視圖模式：extremetable.properties

table.view.compact=org.extremecomponents.table.view.CompactView
table.view.limit=org.extremecomponents.table.view.LimitView
table.view.html=org.extremecomponents.table.view.HtmlView

public void setView() throws Exception {boolean isExported = model.getLimit().isExported();String currentView = null;if (isExported) {currentView = model.getExportHandler().getCurrentExport().getView();String preference = model.getPreferences().getPreference(PreferencesConstants.EXPORT_VIEW + currentView);if (StringUtils.isNotBlank(preference)) {currentView = preference;}} else {currentView = model.getTableHandler().getTable().getView();String preference = model.getPreferences().getPreference(PreferencesConstants.TABLE_VIEW + currentView);if (StringUtils.isNotBlank(preference)) {currentView = preference;}}Class classDefinition = Class.forName(currentView);this.view = (View) classDefinition.newInstance();getView().beforeBody(model);}

調用抽象類的beforeBody方法：

public final void beforeBody(TableModel model) {this.model = model;bufferView = model.getTableHandler().getTable().isBufferView();if (bufferView) {html = new HtmlBuilder();} else {html = new HtmlBuilder(model.getContext().getWriter());}formBuilder = new FormBuilder(html, model);init(html, model);formBuilder.formStart();tableBuilder.themeStart(); beforeBodyInternal(model);}

調用HtmlView的beforeBodyInternal處理

protected void beforeBodyInternal(TableModel model) {toolbar(getHtmlBuilder(), getTableModel());getTableBuilder().tableStart();getTableBuilder().theadStart();statusBar(getHtmlBuilder(), getTableModel());getTableBuilder().filterRow();getTableBuilder().headerRow();getTableBuilder().theadEnd();getTableBuilder().tbodyStart();}

工具欄：

protected void toolbar(HtmlBuilder html, TableModel model) {
　　　　//layout 布局new DefaultToolbar(html, model).layout();}

左右布局格式：

public void layout() {if (!showLayout(model)) {return;}html.table(0).border("0").cellPadding("0").cellSpacing("0");Table table = model.getTableHandler().getTable();html.width(table.getWidth()).close();html.tr(1).close();// layout area leftcolumnLeft(html, model);// layout area right columnRight(html, model);html.trEnd(1);html.tableEnd(0);html.newline();}

布局的實現(xiàn)：

protected void columnLeft(HtmlBuilder html, TableModel model) {html.td(2).close();new TableBuilder(html, model).title();html.tdEnd();}protected void columnRight(HtmlBuilder html, TableModel model) {boolean showPagination = BuilderUtils.showPagination(model);boolean showExports = BuilderUtils.showExports(model);ToolbarBuilder toolbarBuilder = new ToolbarBuilder(html, model);html.td(2).align("right").close();html.table(2).border("0").cellPadding("0").cellSpacing("1").styleClass(BuilderConstants.TOOLBAR_CSS).close();html.tr(3).close();if (showPagination) {html.td(4).close();toolbarBuilder.firstPageItemAsImage();html.tdEnd();html.td(4).close();toolbarBuilder.prevPageItemAsImage();html.tdEnd();html.td(4).close();toolbarBuilder.nextPageItemAsImage();html.tdEnd();html.td(4).close();toolbarBuilder.lastPageItemAsImage();html.tdEnd();html.td(4).close();toolbarBuilder.separator();html.tdEnd();html.td(4).style("width:20px").close();html.newline();html.tabs(4);toolbarBuilder.rowsDisplayedDroplist();html.img();html.src(BuilderUtils.getImage(model, BuilderConstants.TOOLBAR_ROWS_DISPLAYED_IMAGE));html.style("border:0");html.alt("Rows Displayed");html.xclose();html.tdEnd();if (showExports) {html.td(4).close();toolbarBuilder.separator();html.tdEnd();}}if (showExports) {Iterator iterator = model.getExportHandler().getExports().iterator();for (Iterator iter = iterator; iter.hasNext();) {html.td(4).close();Export export = (Export) iter.next();toolbarBuilder.exportItemAsImage(export);html.tdEnd();}}html.trEnd(3);html.tableEnd(2);html.newline();html.tabs(2);html.tdEnd();}

狀態(tài)欄和工具欄類似，就不一一贅述了。

5. 動作觸發(fā)

以下一頁來理解ectable中是如何觸發(fā)事件的：

public void nextPageItemAsImage() {
ImageItem item = new ImageItem();
item.setTooltip(messages.getMessage(BuilderConstants.TOOLBAR_NEXT_PAGE_TOOLTIP));
item.setDisabledImage(BuilderUtils.getImage(model, BuilderConstants.TOOLBAR_NEXT_PAGE_DISABLED_IMAGE));
item.setImage(BuilderUtils.getImage(model, BuilderConstants.TOOLBAR_NEXT_PAGE_IMAGE));
item.setAlt(messages.getMessage(BuilderConstants.TOOLBAR_NEXT_PAGE_TEXT));
item.setStyle("border:0");
ToolbarItemUtils.buildNextPage(html, model, item);
}

下一頁的構建

public static void buildNextPage(HtmlBuilder html, TableModel model, ToolbarItem item) {int page = model.getLimit().getPage();String action = new TableActions(model).getPageAction(page + 1);item.setAction(action);int totalPages = BuilderUtils.getTotalPages(model);if (!BuilderUtils.isNextPageEnabled(page, totalPages)) {item.disabled(html);} else {item.enabled(html, model);}}

觸發(fā)動作，js實現(xiàn)

public String getPageAction(int page) {StringBuffer action = new StringBuffer("javascript:");action.append(getClearedExportTableIdParameters());action.append(getFormParameter(TableConstants.PAGE, "" + page));action.append(getOnInvokeAction());return action.toString();}

一個完整的table示例如下：

<table border="0" cellpadding="0" cellspacing="0" width="60%" ><tr><td><span class="title" >persons</span></td><td align="right" ><table border="0" cellpadding="0" cellspacing="1" class="toolbar" ><tr><td><img src="/address-book/public/images/table/firstPageDisabled.gif" style="border:0" alt="第一頁" /></td><td><img src="/address-book/public/images/table/prevPageDisabled.gif" style="border:0" alt="上一頁" /></td><td><img src="/address-book/public/images/table/nextPageDisabled.gif" style="border:0" alt="下一頁" /></td><td><img src="/address-book/public/images/table/lastPageDisabled.gif" style="border:0" alt="最后頁" /></td><td><img src="/address-book/public/images/table/separator.gif" style="border:0" alt="Separator" /></td><td style="width:20px" ><select name="ec_rd" onchange="javascript:document.forms.ec.ec_crd.value=this.options[this.selectedIndex].value;document.forms.ec.ec_p.value='1';document.forms.ec.setAttribute('action','/address-book/person/list');document.forms.ec.setAttribute('method','post');document.forms.ec.submit()" ><option value="5" selected="selected">5</option><option value="50" >50</option><option value="100" >100</option></select><img src="/address-book/public/images/table/rowsDisplayed.gif" style="border:0" alt="Rows Displayed" /></td></tr></table></td></tr> </table>

6. 小結：

? ?eXtremeComponents為jsp開發(fā)table提供了比較好的支持，它的源碼可以作為學習jsp tag的一個很好示例，研究該源碼可以加深對jsp的理解，通過對上述源碼進行合適的擴展后可以作為組件庫使用。

參考文獻：

1.?http://liuna718-163-com.iteye.com/blog/1318991

2.?http://www.51cto.com/specbook/11/57761.htm

?

轉載于:https://www.cnblogs.com/davidwang456/p/4401742.html

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