本文將完成使用SWT實(shí)現(xiàn)我們自己的RichText編輯器組件的任務(wù)。 在為我的一位客戶(hù)開(kāi)發(fā)基于桌面的應(yīng)用程序時(shí)，我遇到了這樣一個(gè)可視化組件的需求，并希望添加一項(xiàng)功能，以允許用戶(hù)使用粗體，斜體，刪除線等功能來(lái)寫(xiě)富文本注釋。 那時(shí)，我開(kāi)始研究網(wǎng)絡(luò)，以便找到一個(gè)開(kāi)放源代碼庫(kù)，該庫(kù)可以使我免于從頭開(kāi)始部署它的工作，而我遇到了“已完成”實(shí)現(xiàn)的列表 。 讓我們?cè)谶@里列出我對(duì)這種組件的需求：

• 它應(yīng)該是本地SWT組件，而不是Eclipse View或Editor，并且必須可嵌入任何SWT組合中。
• 它應(yīng)允許使用粗體，斜體，刪除線等基本格式。
• 它應(yīng)該支持剪貼板的基本操作，例如復(fù)制，剪切和粘貼。
• 它應(yīng)該使用基本HTML輸出文本。
• 它需要能夠解析所生成的基本HTML，以允許版本。

因此，我發(fā)現(xiàn)的大多數(shù)解決方案都不符合我的需求，因?yàn)樗鼈円词荅clipse Views / Editor，要么太笨拙，無(wú)法集成，要么試圖實(shí)現(xiàn)太多功能，要么與我用來(lái)為自己的企業(yè)打上烙印的圖標(biāo)集不符應(yīng)用程序（盡管這是一個(gè)小問(wèn)題，但總括來(lái)說(shuō)，這為我做出決定提供了更多原因）。 因此，最后我最終決定基于StyledText SWT標(biāo)準(zhǔn)組件從頭開(kāi)始編寫(xiě)它，并以該示例為起點(diǎn)。 RichText控件 幾乎所有的工作都將由RichText控件本身執(zhí)行。 我將添加一些支持類(lèi)，這些支持類(lèi)將用作將結(jié)果文本格式化為基本HTML的助手，以及圖像，本地化字符串等的提供者。 import java.io.IOException; import java.util.ArrayList; import java.util.Collections; import java.util.LinkedList; import java.util.List;import javax.xml.parsers.ParserConfigurationException;import org.eclipse.swt.SWT; import org.eclipse.swt.custom.CaretListener; import org.eclipse.swt.custom.ExtendedModifyEvent; import org.eclipse.swt.custom.ExtendedModifyListener; import org.eclipse.swt.custom.StyleRange; import org.eclipse.swt.custom.StyledText; import org.eclipse.swt.custom.VerifyKeyListener; import org.eclipse.swt.events.KeyAdapter; import org.eclipse.swt.events.KeyEvent; import org.eclipse.swt.events.ModifyListener; import org.eclipse.swt.events.MouseAdapter; import org.eclipse.swt.events.MouseEvent; import org.eclipse.swt.events.SelectionAdapter; import org.eclipse.swt.events.SelectionEvent; import org.eclipse.swt.events.VerifyListener; import org.eclipse.swt.graphics.Point; import org.eclipse.swt.layout.GridData; import org.eclipse.swt.layout.GridLayout; import org.eclipse.swt.widgets.Caret; import org.eclipse.swt.widgets.Composite; import org.eclipse.swt.widgets.ToolBar; import org.eclipse.swt.widgets.ToolItem; import org.xml.sax.SAXException;public class RichText extends Composite {private List cachedStyles =Collections.synchronizedList(new LinkedList());private ToolBar toolBar;private StyledText styledText;private ToolItem boldBtn;private ToolItem italicBtn;private ToolItem strikeThroughBtn;private ToolItem underlineBtn;private ToolItem pasteBtn;private ToolItem eraserBtn;public RichText(Composite parent, int style) {super(parent, style);initComponents();}public void addCaretListener(CaretListener listener) {styledText.addCaretListener(listener);}public void removeCaretListener(CaretListener listener) {styledText.removeCaretListener(listener);}public void addExtendedModifyListener(ExtendedModifyListener listener) {styledText.addExtendedModifyListener(listener);}public void removeExtendedModifyListener(ExtendedModifyListener listener) {styledText.removeExtendedModifyListener(listener);}public void addModifyListener(ModifyListener listener) {styledText.addModifyListener(listener);}public void removeModifyListener(ModifyListener listener) {styledText.removeModifyListener(listener);}public void addVerifyKeyListener(VerifyKeyListener listener) {styledText.addVerifyKeyListener(listener);}public void removeVerifyKeyListener(VerifyKeyListener listener) {styledText.removeVerifyKeyListener(listener);}public void addVerifyListener(VerifyListener listener) {styledText.addVerifyListener(listener);}public void removeVerifyListener(VerifyListener listener) {styledText.removeVerifyListener(listener);}public int getCharCount() {return styledText.getCharCount();}public Caret getCaret() {return styledText.getCaret();}public int getCaretOffset() {return styledText.getCaretOffset();}/*** Obtain an HTML formatted text from the component contents** @return an HTML formatted text*/public String getFormattedText() {String plainText = styledText.getText();RichStringBuilder builder = new RichStringBuilder();Integer[] lineBreaks = getLineBreaks();int brIdx = 0;int start = 0;int end = (lineBreaks.length > brIdx ? lineBreaks[brIdx++] : plainText.length() - 1);while (start < end) {builder.startParagraph();StyleRange[] ranges = styledText.getStyleRanges(start, (end - start));if (ranges != null && ranges.length > 0) {for (int i = 0;i < ranges.length;i++) {if (start < ranges[i].start) {builder.append(plainText.substring(start, ranges[i].start));}List styles = translateStyle(ranges[i]);builder.startFontStyles(styles.toArray(new FontStyle[styles.size()]));builder.append(plainText.substring(ranges[i].start,ranges[i].start + ranges[i].length));builder.endFontStyles(styles.size());start = (ranges[i].start + ranges[i].length) + 1;}}if (start < end) {builder.append(plainText.substring(start, end));}start = end + styledText.getLineDelimiter().length();end = (lineBreaks.length > brIdx ? lineBreaks[brIdx++] : plainText.length() - 1);builder.endParagraph();}return builder.toString();}public void setFormattedText(String text)throws ParserConfigurationException, SAXException, IOException {RichTextParser parser = RichTextParser.parse(text);styledText.setText(parser.getText());styledText.setStyleRanges(parser.getStyleRanges());}public int getLineAtOffset(int offset) {return styledText.getLineAtOffset(offset);}public int getLineCount() {return styledText.getLineCount();}public int getLineSpacing() {return styledText.getLineSpacing();}public String getText() {return styledText.getText();}protected void applyFontStyleToSelection(FontStyle style) {Point sel = styledText.getSelectionRange();if ((sel == null) || (sel.y == 0)) {return ;}StyleRange newStyle;for (int i = sel.x; i < (sel.x + sel.y); i++) {StyleRange range = styledText.getStyleRangeAtOffset(i);if (range != null) {newStyle = (StyleRange) range.clone();newStyle.start = i;newStyle.length = 1;} else {newStyle = new StyleRange(i, 1, null, null, SWT.NORMAL);}switch (style) {case BOLD:newStyle.fontStyle ^= SWT.BOLD;break;case ITALIC:newStyle.fontStyle ^= SWT.ITALIC;break;case STRIKE_THROUGH:newStyle.strikeout = !newStyle.strikeout;break;case UNDERLINE:newStyle.underline = !newStyle.underline;break;}styledText.setStyleRange(newStyle);}styledText.setSelectionRange(sel.x + sel.y, 0);}/*** Clear all styled data*/protected void clearStylesFromSelection() {Point sel = styledText.getSelectionRange();if ((sel != null) && (sel.y != 0)) {StyleRange style = new StyleRange(sel.x, sel.y, null, null, SWT.NORMAL);styledText.setStyleRange(style);}styledText.setSelectionRange(sel.x + sel.y, 0);}private Integer[] getLineBreaks() {List list = new ArrayList();int lastIdx = 0;while (lastIdx < styledText.getCharCount()) {int br = styledText.getText().indexOf(styledText.getLineDelimiter(), lastIdx);if (br >= lastIdx && !list.contains(br)) {list.add(br);}lastIdx += styledText.getLineDelimiter().length() + 1;}Collections.sort(list);return list.toArray(new Integer[list.size()]);}protected void handleCutCopy() {// Save the cut/copied style info so that during paste we will maintain// the style information. Cut/copied text is put in the clipboard in// RTF format, but is not pasted in RTF format. The other way to// handle the pasting of styles would be to access the Clipboard// directly and// parse the RTF text.cachedStyles = Collections.synchronizedList(new LinkedList());Point sel = styledText.getSelectionRange();int startX = sel.x;for (int i = sel.x; i <= sel.x + sel.y - 1; i++) {StyleRange style = styledText.getStyleRangeAtOffset(i);if (style != null) {style.start = style.start - startX;if (!cachedStyles.isEmpty()) {StyleRange lastStyle = cachedStyles.get(cachedStyles.size() - 1);if (lastStyle.similarTo(style)&& lastStyle.start + lastStyle.length == style.start) {lastStyle.length++;} else {cachedStyles.add(style);}} else {cachedStyles.add(style);}}}pasteBtn.setEnabled(true);}private void handleExtendedModified(ExtendedModifyEvent event) {if (event.length == 0) return;StyleRange style;if (event.length == 1|| styledText.getTextRange(event.start, event.length).equals(styledText.getLineDelimiter())) {// Have the new text take on the style of the text to its right// (during// typing) if no style information is active.int caretOffset = styledText.getCaretOffset();style = null;if (caretOffset < styledText.getCharCount())style = styledText.getStyleRangeAtOffset(caretOffset);if (style != null) {style = (StyleRange) style.clone();style.start = event.start;style.length = event.length;} else {style = new StyleRange(event.start, event.length, null, null,SWT.NORMAL);}if (boldBtn.getSelection())style.fontStyle |= SWT.BOLD;if (italicBtn.getSelection())style.fontStyle |= SWT.ITALIC;style.underline = underlineBtn.getSelection();style.strikeout = strikeThroughBtn.getSelection();if (!style.isUnstyled())styledText.setStyleRange(style);} else {// paste occurring, have text take on the styles it had when it was// cut/copiedfor (int i = 0; i < cachedStyles.size(); i++) {style = cachedStyles.get(i);StyleRange newStyle = (StyleRange) style.clone();newStyle.start = style.start + event.start;styledText.setStyleRange(newStyle);}}}private void handleTextSelected(SelectionEvent event) {Point sel = styledText.getSelectionRange();if ((sel != null) && (sel.y != 0)) {StyleRange[] styles = styledText.getStyleRanges(sel.x, sel.y);eraserBtn.setEnabled((styles != null) && (styles.length > 0));} else {eraserBtn.setEnabled(false);}}private void handleKeyReleased(KeyEvent event) {if ((event.keyCode == SWT.ARROW_LEFT) || (event.keyCode == SWT.ARROW_UP)|| (event.keyCode == SWT.ARROW_RIGHT) || (event.keyCode == SWT.ARROW_DOWN)) {updateStyleButtons();}}private void updateStyleButtons() {int caretOffset = styledText.getCaretOffset();StyleRange style = null;if (caretOffset >= 0 && caretOffset < styledText.getCharCount()) {style = styledText.getStyleRangeAtOffset(caretOffset);}if (style != null) {boldBtn.setSelection((style.fontStyle & SWT.BOLD) != 0);italicBtn.setSelection((style.fontStyle & SWT.ITALIC) != 0);underlineBtn.setSelection(style.underline);strikeThroughBtn.setSelection(style.strikeout);} else {boldBtn.setSelection(false);italicBtn.setSelection(false);underlineBtn.setSelection(false);strikeThroughBtn.setSelection(false);}}private void initComponents() {GridLayout layout = new GridLayout();layout.numColumns = 1;setLayout(layout);toolBar = createToolBar(this);toolBar.setLayoutData(new GridData(GridData.FILL_HORIZONTAL));styledText = new StyledText(this, SWT.BORDER | SWT.MULTI |SWT.V_SCROLL | SWT.H_SCROLL);styledText.setLayoutData(new GridData(GridData.FILL_BOTH));styledText.addKeyListener(new KeyAdapter() {@Overridepublic void keyReleased(KeyEvent e) {handleKeyReleased(e);}});styledText.addExtendedModifyListener(new ExtendedModifyListener() {@Overridepublic void modifyText(ExtendedModifyEvent event) {handleExtendedModified(event);}});styledText.addMouseListener(new MouseAdapter() {@Overridepublic void mouseUp(MouseEvent e) {updateStyleButtons();}});styledText.addSelectionListener(new SelectionAdapter() {@Overridepublic void widgetSelected(SelectionEvent event) {handleTextSelected(event);}});}private ToolBar createToolBar(Composite parent) {ToolBar toolBar = new ToolBar(parent, SWT.FLAT);boldBtn = new ToolItem(toolBar, SWT.CHECK);boldBtn.setImage(RichTextImages.IMG_BOLD);boldBtn.setToolTipText(RichTextStrings.boldBtn_tooltipText);boldBtn.addSelectionListener(new FontStyleButtonListener(FontStyle.BOLD));italicBtn = new ToolItem(toolBar, SWT.CHECK);italicBtn.setImage(RichTextImages.IMG_ITALIC);italicBtn.setToolTipText(RichTextStrings.italicBtn_tooltipText);italicBtn.addSelectionListener(new FontStyleButtonListener(FontStyle.ITALIC));underlineBtn = new ToolItem(toolBar, SWT.CHECK);underlineBtn.setImage(RichTextImages.IMG_UNDERLINE);underlineBtn.setToolTipText(RichTextStrings.underlineBtn_tooltipText);underlineBtn.addSelectionListener(new FontStyleButtonListener(FontStyle.UNDERLINE));strikeThroughBtn = new ToolItem(toolBar, SWT.CHECK);strikeThroughBtn.setImage(RichTextImages.IMG_STRIKE_THROUGH);strikeThroughBtn.setToolTipText(RichTextStrings.strikeThroughBtn_tooltipText);strikeThroughBtn.addSelectionListener(new FontStyleButtonListener(FontStyle.STRIKE_THROUGH));new ToolItem(toolBar, SWT.SEPARATOR);ToolItem cutBtn = new ToolItem(toolBar, SWT.PUSH);cutBtn.setImage(RichTextImages.IMG_CUT);cutBtn.setToolTipText(RichTextStrings.cutBtn_tooltipText);cutBtn.addSelectionListener(new SelectionAdapter() {@Overridepublic void widgetSelected(SelectionEvent e) {handleCutCopy();styledText.cut();}});ToolItem copyBtn = new ToolItem(toolBar, SWT.PUSH);copyBtn.setImage(RichTextImages.IMG_COPY);copyBtn.setToolTipText(RichTextStrings.copyBtn_tooltipText);copyBtn.addSelectionListener(new SelectionAdapter() {@Overridepublic void widgetSelected(SelectionEvent e) {handleCutCopy();styledText.copy();}});pasteBtn = new ToolItem(toolBar, SWT.PUSH);pasteBtn.setEnabled(false);pasteBtn.setImage(RichTextImages.IMG_PASTE);pasteBtn.setToolTipText(RichTextStrings.pasteBtn_tooltipText);pasteBtn.addSelectionListener(new SelectionAdapter() {@Overridepublic void widgetSelected(SelectionEvent e) {styledText.paste();}});new ToolItem(toolBar, SWT.SEPARATOR);eraserBtn = new ToolItem(toolBar, SWT.PUSH);eraserBtn.setEnabled(false);eraserBtn.setImage(RichTextImages.IMG_ERASER);eraserBtn.setToolTipText(RichTextStrings.eraserBtn_tooltipText);eraserBtn.addSelectionListener(new SelectionAdapter() {@Overridepublic void widgetSelected(SelectionEvent e) {clearStylesFromSelection();}});return toolBar;}private List translateStyle(StyleRange range) {List list = new ArrayList();if ((range.fontStyle & SWT.BOLD) != 0) {list.add(FontStyle.BOLD);}if ((range.fontStyle & SWT.ITALIC) != 0) {list.add(FontStyle.ITALIC);}if (range.strikeout) {list.add(FontStyle.STRIKE_THROUGH);}if (range.underline) {list.add(FontStyle.UNDERLINE);}return list;}private class FontStyleButtonListener extends SelectionAdapter {private FontStyle style;public FontStyleButtonListener(FontStyle style) {this.style = style;}@Overridepublic void widgetSelected(SelectionEvent e) {applyFontStyleToSelection(style);}}} 如您所見(jiàn)，我們的RichText控件基本上是ToolBar和StyledText組件的包裝，具有不同事件偵聽(tīng)器的這兩個(gè)控件都與這兩個(gè)控件掛鉤。 ? 支持班 在本節(jié)中，我將顯示用于實(shí)現(xiàn)富文本編輯器控件使用的一些支持類(lèi)的代碼。 我將在這里省略為控件提供圖像和本地化字符串的類(lèi)，因?yàn)槟抢镉刑嚓P(guān)于如何在SWT中進(jìn)行操作的示例，我將重點(diǎn)介紹格式化和解析控件的輸出/輸入所需的類(lèi)。 第一個(gè)是Java枚舉，將用于標(biāo)識(shí)支持的不同字體樣式： public enum FontStyle {BOLD, ITALIC, STRIKE_THROUGH, UNDERLINE }

下一個(gè)稱(chēng)為RichStringBuilder，它將用作幫助程序類(lèi)，以將StyledText組件的內(nèi)容格式化為基本HTML：

import java.util.Stack;public final class RichStringBuilder {public static final String LINE_DELIMITER = "<br/>";private StringBuilder builder;private Stack fontStyleStack;public RichStringBuilder() {builder = new StringBuilder();fontStyleStack = new Stack();}public RichStringBuilder append(String text) {builder.append(text);return this;}public RichStringBuilder appendLineBreak() {builder.append(LINE_DELIMITER);return this;}public RichStringBuilder startParagraph() {builder.append("<p>");return this;}public RichStringBuilder startFontStyle(FontStyle fontStyle) {fontStyleStack.push(fontStyle);internalStartFontStyle(fontStyle);return this;}public RichStringBuilder startFontStyles(FontStyle... fontStyles) {for (FontStyle fs : fontStyles) {startFontStyle(fs);}return this;}public RichStringBuilder endFontStyles(int count) {for (int i = 0;i < count;i++) {endStyle();}return this;}public RichStringBuilder endStyle() {if (fontStyleStack.size() > 0) {FontStyle style = fontStyleStack.pop();internalEndFontStyle(style);}return this;}public RichStringBuilder endParagraph() {flushStyles();builder.append("</p>");return this;}public void flushStyles() {while (fontStyleStack.size() > 0) {endStyle();}}@Overridepublic boolean equals(Object o) {if (this == o) return true;if (null == o) return false;if (!(o instanceof RichStringBuilder)) return false;return ((RichStringBuilder) o).builder.equals(builder);}@Overridepublic int hashCode() {return builder.hashCode();}@Overridepublic String toString() {return builder.toString();}private void internalStartFontStyle(FontStyle fontStyle) {switch (fontStyle) {case BOLD:builder.append("<b>");break;case ITALIC:builder.append("<i>");break;case STRIKE_THROUGH:builder.append("<del>");break;case UNDERLINE:builder.append("<ins>");break;}}private void internalEndFontStyle(FontStyle fontStyle) {switch (fontStyle) {case BOLD:builder.append("</b>");break;case ITALIC:builder.append("</i>");break;case STRIKE_THROUGH:builder.append("</del>");break;case UNDERLINE:builder.append("</ins>");break;}}}

第三個(gè)是基于SAX的內(nèi)容處理程序，它將基本HTML解析為StyledText控件時(shí)將啟動(dòng)事件：

import java.io.IOException; import java.io.StringReader; import java.util.ArrayList; import java.util.List; import java.util.Stack;import javax.xml.parsers.ParserConfigurationException; import javax.xml.parsers.SAXParser; import javax.xml.parsers.SAXParserFactory;import org.eclipse.swt.SWT; import org.eclipse.swt.custom.StyleRange; import org.xml.sax.Attributes; import org.xml.sax.InputSource; import org.xml.sax.SAXException; import org.xml.sax.helpers.DefaultHandler;public final class RichTextParser {public static RichTextParser parse(String formattedText)throws ParserConfigurationException, SAXException, IOException {return new RichTextParser(formattedText);}private StringBuilder text = new StringBuilder();private List styleRanges = new ArrayList();private RichTextParser(String formattedText)throws ParserConfigurationException, SAXException, IOException {StringReader reader = new StringReader(formattedText);SAXParserFactory factory = SAXParserFactory.newInstance();SAXParser parser = factory.newSAXParser();DefaultHandler handler = new RichTextContentHandler();parser.parse(new InputSource(reader), handler);}public String getText() {return text.toString();}public StyleRange[] getStyleRanges() {return styleRanges.toArray(new StyleRange[styleRanges.size()]);}private class RichTextContentHandler extends DefaultHandler {private Stack<List> stylesStack = new Stack<List>();private String lastTextChunk = null;@Overridepublic void characters(char[] ch, int start, int length)throws SAXException {lastTextChunk = new String(ch, start, length);}@Overridepublic void endElement(String uri, String localName, String qName)throws SAXException {// If there is not any previous text chunk parsed then returnif (lastTextChunk == null) return;// If the tag found is not a supported one then returnif (!"p".equals(qName) || !"b".equals(qName) || !"i".equals(qName) ||!"ins".equals(qName) || !"del".equals(qName)) {return;}List lastStyles = lastFontStyles(true);if (lastStyles != null) {StyleRange range = transform(lastStyles);range.start = currentIndex() + 1;range.length = lastTextChunk.length();styleRanges.add(range);}text.append(lastTextChunk);lastTextChunk = null;}@Overridepublic void startElement(String uri, String localName, String qName,Attributes atts) throws SAXException {// If the tag found is not a supported one then returnif (!"p".equals(qName) || !"b".equals(qName) || !"i".equals(qName) ||!"ins".equals(qName) || !"del".equals(qName)) {return;}List lastStyles = lastFontStyles(false);if (lastTextChunk == null) {if (lastStyles == null) {lastStyles = new ArrayList();stylesStack.add(lastStyles);}} else {if (lastStyles != null) {StyleRange range = transform(lastStyles);range.start = currentIndex() + 1;range.length = lastTextChunk.length();styleRanges.add(range);}text.append(lastTextChunk);lastTextChunk = null;}if ("b".equals(qName)) {lastStyles.add(FontStyle.BOLD);} else if ("i".equals(qName)) {lastStyles.add(FontStyle.ITALIC);} else if ("ins".equals(qName)) {lastStyles.add(FontStyle.UNDERLINE);} else {lastStyles.add(FontStyle.STRIKE_THROUGH);}}private StyleRange transform(List styles) {StyleRange range = new StyleRange();range.start = currentIndex() + 1;range.length = lastTextChunk.length();for (FontStyle fs : styles) {if (FontStyle.BOLD == fs) {range.fontStyle = (range.fontStyle & SWT.BOLD);} else if (FontStyle.ITALIC == fs) {range.fontStyle = (range.fontStyle & SWT.ITALIC);} else if (FontStyle.STRIKE_THROUGH == fs) {range.strikeout = true;} else if (FontStyle.UNDERLINE == fs) {range.underline = true;}}return range;}private List lastFontStyles(boolean remove) {List lastStyles = null;if (stylesStack.size() > 0) {if (remove) {lastStyles = stylesStack.pop();} else {lastStyles = stylesStack.peek();}}return lastStyles;}private int currentIndex() {return text.length() - 1;}}} 結(jié)論 實(shí)現(xiàn)您自己的SWT RichText控件可能不是滿(mǎn)足您需求的最佳選擇，您將需要權(quán)衡這樣做的利弊，以及是否有必要投資其中一種現(xiàn)成的商業(yè)解決方案。 但是，我想通過(guò)本文演示如何在SWT對(duì)話框和視圖中嵌入您自己的（簡(jiǎn)單且輕量級(jí)的）富文本編輯器，與從中獲得的好處相比，它很容易實(shí)現(xiàn)，并且需要花費(fèi)很少的精力。 參考：來(lái)自Code Nibbles博客的JCG合作伙伴 Alonso Dominguez的RichText編輯器組件，用于基于SWT的應(yīng)用程序 。

翻譯自: https://www.javacodegeeks.com/2012/07/richtext-editor-component-for-swt-based.html

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