背景
之前在 使用spire.doc匯出支援編輯Latex公式的標準格式word 部落格中寫過，使用spire.doc來生成word，不得不說spire.doc的api操作起來還是比較方便，但是使用的過程中還是發生了一些異常，如∑求和公式會報錯，類似 \limit \widehat \sideset \overline \leqslant \geqslant \textcircled 均遇到了問題，類似解析失敗無法渲染、求和公式設定上下限報空指標異常等，使用同樣的方式轉換MathML之後還是同樣的問題，無法解決，一個兩個還能以圖片的形式顯示，隨著這麼多問題的出現，終究不是辦法
POI匯出Latex至word
POI轉Latex轉WORD過程是 Latex → MathML(數學標記語言) → OMML(Word公式)
Latex轉MathML問題
POI支援MathML，我基本上生成的都是數學試卷，Latex公式有了，但是需要轉換為MathML，一開始準備使用fmath三件套，這裡需要吐槽一下，這個官網的下載連結已經失效，搜了一下看到很久沒去的CSDN有資源，一下載50積分沒了，貌似不管啥資源都是50分起步，看來CSDN已經不是我等P民可以混跡的存在了
但是實驗了一下，fmath匯出的複雜公式在word中顯示偶爾有問題，可能是因為版本太老了，在StackOverflow上看到有人推薦使用snuggletex-core這個類庫，我就更換了實現方式，我來找了大量的數學公式latex，先看下效果
POM依賴
<!-- https://mvnrepository.com/artifact/de.rototor.snuggletex/snuggletex-core -->
<dependency>
<groupId>de.rototor.snuggletex</groupId>
<artifactId>snuggletex-core</artifactId>
<version>1.3.0</version>
</dependency>
<!-- https://mvnrepository.com/artifact/org.apache.poi/poi -->
<dependency>
<groupId>org.apache.poi</groupId>
<artifactId>poi</artifactId>
<version>4.1.2</version>
</dependency>
<!-- https://mvnrepository.com/artifact/org.apache.poi/ooxml-schemas -->
<dependency>
<groupId>org.apache.poi</groupId>
<artifactId>ooxml-schemas</artifactId>
<version>1.4</version>
</dependency>
<!-- https://mvnrepository.com/artifact/org.apache.poi/poi-ooxml -->
<dependency>
<groupId>org.apache.poi</groupId>
<artifactId>poi-ooxml</artifactId>
<version>4.1.2</version>
</dependency>
<dependency>
<groupId>commons-io</groupId>
<artifactId>commons-io</artifactId>
<version>2.11.0</version>
</dependency>
snuggletex-core轉換Latex為MathML
注意：這裡的latex必須用$$包裹，否則在轉換MathML的時候會報錯
@SneakyThrows
public static void addLatex(String latex, XWPFParagraph paragraph) {
paragraph.setAlignment(ParagraphAlignment.LEFT);
paragraph.setFontAlignment(ParagraphAlignment.LEFT.getValue());
SnuggleEngine engine = new uk.ac.ed.ph.snuggletex.SnuggleEngine();
SnuggleSession session = engine.createSession();
SnuggleInput input = new uk.ac.ed.ph.snuggletex.SnuggleInput(latex);
session.parseInput(input);
String mathML = session.buildXMLString();
CTOMath ctOMath = getOMML(mathML);
CTP ctp = paragraph.getCTP();
CTOMath ctoMath = ctp.addNewOMath();
ctoMath.set(ctOMath);
}
MathML轉OMML
MML2OMML.XSL在windows的Office安裝目錄裡面直接搜就能拿到
private static File stylesheet = new File("D:\\MML2OMML.XSL");
private static TransformerFactory tFactory = TransformerFactory.newInstance();
private static StreamSource stylesource = new StreamSource(stylesheet);
private static CTOMath getOMML(String mathML) throws Exception {
Transformer transformer = tFactory.newTransformer(stylesource);
StringReader stringreader = new StringReader(mathML);
StreamSource source = new StreamSource(stringreader);
StringWriter stringwriter = new StringWriter();
StreamResult result = new StreamResult(stringwriter);
transformer.transform(source, result);
String ooML = stringwriter.toString();
stringwriter.close();
CTOMathPara ctOMathPara = CTOMathPara.Factory.parse(ooML);
CTOMath ctOMath = ctOMathPara.getOMathArray(0);
//for making this to work with Office 2007 Word also, special font settings are necessary
XmlCursor xmlcursor = ctOMath.newCursor();
while (xmlcursor.hasNextToken()) {
XmlCursor.TokenType tokentype = xmlcursor.toNextToken();
if (tokentype.isStart()) {
if (xmlcursor.getObject() instanceof CTR) {
CTR cTR = (CTR) xmlcursor.getObject();
cTR.addNewRPr2().addNewRFonts().setAscii("Cambria Math");
cTR.getRPr2().getRFonts().setHAnsi("Cambria Math"); // up to apache poi 4.1.2
//cTR.getRPr2().getRFontsArray(0).setHAnsi("Cambria Math"); // since apache poi 5.0.0
}
}
}
return ctOMath;
}
已發現無法識別的符號（目前沒有找到解決方案）
嘗試了很多中元件，spire.doc 、fmath 等都無法渲染 \textcircled ,這個是latex標準支援的公式，效果文字外面圈一個圈類似①這樣的效果，這裡嘗試無果之後只能暫時以比較噁心的方式解決這個問題，方法latexFilter，我這裡只有①②③④這個四個出現的比較多，其他的都沒有出現，如果要使用這個地方需要注意一下
private static String latexFilter(String latex){
if(!latex.contains("textcircled")){
return latex;
}
return TextCircledEnum.replaceTextCircled(latex);
}
private enum TextCircledEnum{
Zero("\\\\textcircled\\{0\\}","⓪"),
One("\\\\textcircled\\{1\\}","①"),
Two("\\\\textcircled\\{2\\}","②"),
Three("\\\\textcircled\\{3\\}","③"),
Four("\\\\textcircled\\{4\\}","④"),
Five("\\\\textcircled\\{5\\}","⑤"),
Six("\\\\textcircled\\{6\\}","⑥"),
Seven("\\\\textcircled\\{7\\}","⑦"),
Eight("\\\\textcircled\\{8\\}","⑧"),
Nine("\\\\textcircled\\{9\\}","⑨"),
Ten("\\\\textcircled\\{10\\}","⑩")
;
TextCircledEnum(String code, String v) {
this.code = code;
this.v = v;
}
public final String code;
public final String v;
public static String replaceTextCircled(String latex){
for (TextCircledEnum c : TextCircledEnum.values()) {
latex = latex.replaceAll(c.code,c.v);
}
return latex;
}
}
測試程式碼，附帶大量latex公式
public static void main(String[] args) throws Exception {
XWPFDocument document = new XWPFDocument();
XWPFParagraph paragraph = document.createParagraph();
paragraph.setAlignment(ParagraphAlignment.LEFT);
List<String> latexList = Arrays.asList("$\\frac{\\sum\\limits_{i=1}^{n}({x}_{i}−\\overline{x})({y}_{i}−\\overline{y})}{\\sum\\limits_{i=1}^{n}({x}_{i}−\\overline{x}{)}^{2}}$"
, "$\\frac{ \\sum _{i=1}^{n} (x_ {i}-\\overline {x})(y_ {i}-\\overline {y})}{\\sqrt { \\sum _{i=1}^{n} (x_ {i-x})^ {2} \\sum _{i=1}^{n} (y_ {i}-y)^ {2}}}$"
, "$\\widehat{y}$"
, "$s_{x}^ {2}$"
, "$\\sum _{i=1}^{n}$"
, "$\\frac%…7B(a+b)(c+d)(a+c)(b+d)}$"
, "$0 \\geqslant x\\leqslant 5 \\widehat{A} \\hat{A} \\sideset{^1_2}{^3_4}Y \\sideset{^1_2}{^3_4}Y $"
, "$\\textcircled{1}$"
, "$\\textcircled1$"
, "$\\f\\relax{x} = \\int_{-\\infty}^\\infty \\f\\hat\\xi\\,e^{2 \\pi i \\xi x} \\,d\\xi$"
, "$a_{1} \\quad x^2 \\quad e^{- \\alpha t} \\quad b^{3}_{ij} \\quad e^{2}\\neq {e^x}^2$"
, "$\\sqrt{x} \\quad \\sqrt[3]{x} \\quad \\sqrt{x^{2}+ \\sqrt{y}}$"
, "$\\frac{x^2}{k+1} \\quad x^{\\frac{2}{k+1}} \\quad x^{1/2}$"
, "$\\vec a \\qquad \\overrightarrow{AB} \\qquad \\overleftarrow{AB}$"
, "$\\sum_{i=1}^{n} \\quad \\int_{0}^{\\frac{\\pi}{2}} \\quad \\prod_{\\epsilon}$"
, "$\\alpha \\beta \\gamma \\sigma \\omega \\delta \\pi \\rho \\epsilon \\eta \\lambda \\mu \\xi \\tau \\kappa \\zeta \\phi \\chi$"
, "$\\le \\ge \\ne \\approx \\sim \\subseteq \\in \\notin \\times \\div \\pm \\Rightarrow \\rightarrow \\infty \\partial \\angle \\triangle$"
, "$\\left\\{ \n" +
" \\begin{array}{**lr**} \n" +
" x=\\dfrac{3\\pi}{2}(1+2t)\\cos(\\dfrac{3\\pi}{2}(1+2t)), & \\\\ \n" +
" y=s, & 0\\leq s\\leq L,|t|\\leq1.\\\\ \n" +
" z=\\dfrac{3\\pi}{2}(1+2t)\\sin(\\dfrac{3\\pi}{2}(1+2t)), & \n" +
" \\end{array} \n" +
"\\right. \n$"
,"$F^{HLLC}=\\left\\{\n" +
"\\begin{array}{rcl}\n" +
"F_L & & {0 < S_L}\\\\\n" +
"F^*_L & & {S_L \\leq 0 < S_M}\\\\\n" +
"F^*_R & & {S_M \\leq 0 < S_R}\\\\\n" +
"F_R & & {S_R \\leq 0}\n" +
"\\end{array} \\right. $"
,"$\\Bigg ( \\bigg [ \\Big \\{\\big \\langle \\left \\vert \\parallel \\frac{a}{b} \\parallel \\right \\vert \\big \\rangle \\Big \\} \\bigg ] \\Bigg )$"
);
latexList.forEach(latex -> addLatex(latexFilter(latex), document.createParagraph()));
FileOutputStream out = new FileOutputStream("CreateWordFormulaFromMathML.docx");
document.write(out);
out.close();
document.close();
}
fmath轉換Latex為MathML（棄用）
上面的公式用fmath三件套的轉換的時候有報錯地方，而且轉換後的效果有不及預期的，所以就棄用了，下面是fmath轉換的程式碼
@SneakyThrows
public static void addLatexByFMath(String latex, XWPFParagraph paragraph) {
String mathML = fmath.conversion.ConvertFromLatexToMathML.convertToMathML(latex);
mathML = mathML.replaceFirst("<math ", "<math xmlns=\"http://www.w3.org/1998/Math/MathML\" ");
mathML = mathML.replaceAll("±", "±");
CTOMath ctOMath = getOMML(mathML);
CTP ctp = paragraph.getCTP();
CTOMath ctoMath = ctp.addNewOMath();
ctoMath.set(ctOMath);
}
POI生成Word程式碼API介紹
生成段落
private XWPFParagraph newParagraph(XWPFDocument document) {
XWPFParagraph paragraph = document.createParagraph();
paragraph.setSpacingLineRule(LineSpacingRule.AUTO);
paragraph.setSpacingBefore(30);
paragraph.setAlignment(ParagraphAlignment.LEFT);
return paragraph;
}
新增文字
注：POI不支援 \r \n 之類的換行符，如果需要換行顯示呼叫 xwpfRun.addBreak() 來實現換行
public void addText(String text, XWPFParagraph paragraph) {
if (StringUtils.isEmpty(text)) {
return;
}
XWPFRun xwpfRun = paragraph.createRun();
String[] lines = text.split("\n");
if (lines.length < 1) {
return;
}
xwpfRun.setText(lines[0], 0);
for (int m = 1; m < lines.length; m++) {
xwpfRun.addBreak();
xwpfRun.setText(lines[m]);
}
if (text.endsWith("\n")) {
xwpfRun.addBreak();
}
}
Table渲染
注：這裡在渲染的時候把table行數和列數全部都已計算好（這個不涉及單元格合併功能），table.setWidth() 也是POI4.X版本才支援傳入字串設定百分比
private void parse2Table(WordInnerPojo innerPojo, XWPFParagraph paragraph) {
XWPFTable table = paragraph.getDocument().createTable(innerPojo.rows, innerPojo.lines);
table.setWidth("100%");
for (int i = 0; i < innerPojo.rowLines.size(); i++) {
List<String> rowLine = innerPojo.rowLines.get(i);
for (int j = 0; j < rowLine.size(); j++) {
XWPFTableCell cell = table.getRow(i).getCell(j);
XWPFParagraph innerParagraph = cell.getParagraphs().size() > 0 ? cell.getParagraphs().get(0) : cell.addParagraph();
innerParagraph.setSpacingBefore(0);
innerParagraph.setVerticalAlignment(TextAlignment.CENTER);
innerParagraph.setAlignment(ParagraphAlignment.LEFT);
addContent(rowLine.get(j), innerParagraph);
}
}
paragraph.getDocument().createParagraph();
}
插入圖片
注：單位需要轉換為em，直接呼叫org.apache.poi.util.Units的toEMU方法即可，這樣的寫法直接在文字的後面增加圖片，不換行
paragraph.createRun().addPicture(new ByteArrayInputStream(innerPojo.image),
XWPFDocument.PICTURE_TYPE_JPEG, "",
Units.toEMU(width.intValue()),
Units.toEMU(height.intValue()));
word公式渲染POJO類和渲染邏輯
一段原始的html文字需要分段解析的，文字、公式、表格、圖片等，需要解析抽象生成一個POJO類，把這些非文字的型別提出來並標記好佔位符，用於替換和渲染
POJO類
private static class WordInnerPojo {
protected static final int LATEX_TYPE = 0;
protected static final int IMG_TYPE = 1;
protected static final int TABLE_TYPE = 2;
private int type;
private byte[] image;
private String latex;
private String imageUrl;
private int rows;
private int lines;
private List<List<String>> rowLines;
private BufferedImage imageTemp;
@SneakyThrows
BufferedImage readImage() {
if (this.imageTemp == null) {
this.imageTemp = ImageIO.read(new ByteArrayInputStream(this.image));
}
return imageTemp;
}
private Integer getImageWidth() {
return readImage().getWidth();
}
private Integer getImageHeight() {
return readImage().getHeight();
}
}
渲染邏輯
@SneakyThrows
private void appendWordInnerPojo(WordInnerPojo innerPojo, XWPFParagraph paragraph) {
switch (innerPojo.type) {
case WordInnerPojo.LATEX_TYPE:
addLatex(latexFilter(MessageFormat.format("${0}$", URLDecoder.decode(innerPojo.latex, "UTF-8")))), paragraph);
break;
case WordInnerPojo.IMG_TYPE:
log.info("imageUrl:{}", innerPojo.imageUrl);
/* 控制word中的圖片渲染大小，不要太大 */
Float width = Float.valueOf(innerPojo.getImageWidth());
Float height = Float.valueOf(innerPojo.getImageHeight());
if (width > 300 && width > height) {
BigDecimal rate = BigDecimal.valueOf(300).divide(BigDecimal.valueOf(width), 8, BigDecimal.ROUND_DOWN);
height = height * rate.floatValue();
width = 300f;
} else if (height > 200 && height > width) {
BigDecimal rate = BigDecimal.valueOf(200).divide(BigDecimal.valueOf(height), 8, BigDecimal.ROUND_DOWN);
width = width * rate.floatValue();
height = 200f;
}
paragraph.createRun().addPicture(new ByteArrayInputStream(innerPojo.image), XWPFDocument.PICTURE_TYPE_JPEG, "", Units.toEMU(width.intValue()), Units.toEMU(height.intValue()));
paragraph.createRun().addBreak();
break;
case WordInnerPojo.TABLE_TYPE:
parse2Table(innerPojo, paragraph);
break;
}
}
搞定！匯出的部分樣例如下：
參考連結
https://stackoverflow.com/questions/46623554/add-latex-type-equation-in-word-docx-using-apache-poi