Apache POI修改形状文本后修改段落报ConcurrentModificationException异常

使用Apache POI 5.2.2版本修改Word文档中矩形形状内的文本占位符，修改形状文本的代码可正常运行，但后续修改其他段落文本时，会抛出java.util.ConcurrentModificationException，异常提示为Document changed during select。

修改文本框内容的代码 #

private void replacePlaceholdersWithInAShape(XWPFParagraph paragraph) throws XmlException {

XmlCursor cursor = paragraph.getCTP().newCursor();
            cursor.selectPath("declare namespace w='http://schemas.openxmlformats.org/wordprocessingml/2006/main' .//*/w:txbxContent/w:p/w:r");
            List<XmlObject> ctrsintxtbx = new ArrayList<XmlObject>();
            while(cursor.hasNextSelection()) {
                cursor.toNextSelection();
                XmlObject obj = cursor.getObject();
                ctrsintxtbx.add(obj);
            }
            for (XmlObject obj : ctrsintxtbx) {
                CTR ctr = CTR.Factory.parse(obj.xmlText());
                XWPFRun bufferrun = new XWPFRun(ctr, (IRunBody)paragraph);
                String text = bufferrun.getText(0);
                if (text != null && !text.equalsIgnoreCase("")) {
                    if(text.contains("[{project_number}]")) {    
                        System.out.println("contains project number");
                        text = text.replace("[{project_number}]", "test");
                        bufferrun.setText("test", 0);
                    } else {                    
                        bufferrun.setText(text, 0);
                    }
                }
                obj.set(bufferrun.getCTR());
            }
}

修改段落文本的代码 #

protected void replaceParagraphPlaceholders(String paraText, XWPFParagraph paragraph, String key, String value, Map<String, Object> fields) {

    //paragraph text's empty and null check.
    String paragraphText = paragraph.getText();
    if(paragraphText!=""&&paragraphText!=null) {
        if(paragraph.getRuns().size()<=1) {
            String runText = "Sample text";
            paragraph.getRuns().get(0).setText(runText, 0);
        }
    }
}

抛出的异常 #

java.util.ConcurrentModificationException: Document changed during select
    at org.apache.xmlbeans.impl.xpath.xmlbeans.XmlbeansXPathEngine.next(XmlbeansXPathEngine.java:100)
    at org.apache.xmlbeans.impl.store.Cursor._toSelection(Cursor.java:749)
    at org.apache.xmlbeans.impl.store.Cursor._getSelectionCount(Cursor.java:764)
    at org.apache.xmlbeans.impl.store.Cursor.notifyChange(Cursor.java:697)
    at org.apache.xmlbeans.impl.store.Locale.notifyChange(Locale.java:995)
    at org.apache.xmlbeans.impl.store.Cur.moveChars(Cur.java:1772)
    at org.apache.xmlbeans.impl.store.Cur.moveNodeContents(Cur.java:2016)
    at org.apache.xmlbeans.impl.store.Cur.moveNodeContents(Cur.java:1986)
    at org.apache.xmlbeans.impl.store.Xobj.store_text(Xobj.java:1833)
    at org.apache.xmlbeans.impl.values.XmlObjectBase.set_String(XmlObjectBase.java:1106)
    at org.apache.xmlbeans.impl.values.XmlObjectBase.setStringValue(XmlObjectBase.java:1774)
    at org.apache.poi.xwpf.usermodel.XWPFRun.setText(XWPFRun.java:363)
    at net.sharesuite.formletter.builder.poibuilder.docx.PoiDocxBuilder.replaceParagraphPlaceholders(PoiDocxBuilder.java:596)
    at net.sharesuite.formletter.builder.poibuilder.docx.PoiDocxBuilder.lambda$1(PoiDocxBuilder.java:205)
    at java.base/java.util.ArrayList$Itr.forEachRemaining(ArrayList.java:1003)
    at java.base/java.util.Collections$UnmodifiableCollection$1.forEachRemaining(Collections.java:1061)
    at net.sharesuite.formletter.builder.poibuilder.docx.PoiDocxBuilder.createFormLetterFile(PoiDocxBuilder.java:175)
    at net.sharesuite.formletter.service.impl.FormLetterServiceImpl.createFormLetter(FormLetterServiceImpl.java:42)
    at net.sharesuite.test.formletter.DocumentTest.testNLBLFormletter(DocumentTest.java:646)
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:77)
    at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.base/java.lang.reflect.Method.invoke(Method.java:568)
    at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:47)
    at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
    at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:44)
    at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
    at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:26)
    at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:271)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:70)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:50)
    at org.junit.runners.ParentRunner$3.run(ParentRunner.java:238)
    at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:63)
    at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:236)
    at org.junit.runners.ParentRunner.access$000(ParentRunner.java:53)
    at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:229)
    at org.junit.runners.ParentRunner.run(ParentRunner.java:309)
    at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:93)
    at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:40)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:529)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:756)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:452)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:210)

问题根源与修复方案 #

核心原因 #

异常触发是因为XmlCursor未被关闭：遍历形状内文本节点后，XmlCursor仍持有文档的引用，后续修改文档内容时，XmlCursor的内部状态与实际文档结构不一致，触发了并发修改检测机制。

修复步骤 #

1. 关闭XmlCursor释放资源
   在replacePlaceholdersWithInAShape方法中，遍历完成后必须显式关闭XmlCursor，添加cursor.dispose();，建议放在finally块中确保执行。

2. 优化形状文本修改逻辑
   无需重新解析XML文本生成CTR对象，直接强转XmlObject为CTR即可，减少不必要的文档修改操作；同时去掉重复设置原文本的冗余代码。

修改后的replacePlaceholdersWithInAShape代码：

private void replacePlaceholdersWithInAShape(XWPFParagraph paragraph) throws XmlException {
    XmlCursor cursor = paragraph.getCTP().newCursor();
    try {
        cursor.selectPath("declare namespace w='http://schemas.openxmlformats.org/wordprocessingml/2006/main' .//*/w:txbxContent/w:p/w:r");
        List<XmlObject> ctrsintxtbx = new ArrayList<>();
        while (cursor.hasNextSelection()) {
            cursor.toNextSelection();
            XmlObject obj = cursor.getObject();
            ctrsintxtbx.add(obj);
        }
        for (XmlObject obj : ctrsintxtbx) {
            CTR ctr = (CTR) obj; // 直接强转，无需重新解析XML
            XWPFRun bufferrun = new XWPFRun(ctr, (IRunBody) paragraph);
            String text = bufferrun.getText(0);
            if (text != null && !text.isBlank()) {
                if (text.contains("[{project_number}]")) {
                    bufferrun.setText("test", 0);
                }
                // 无需重复设置原文本，避免不必要的文档变更
            }
            // 无需调用obj.set(ctr)，CTR是直接引用文档内的对象
        }
    } finally {
        cursor.dispose(); // 确保关闭cursor，释放文档引用
    }
}

3. 修复段落文本的空值判断错误
   原代码中paragraphText!=""是引用比较，会导致空字符串判断失效，改为!paragraphText.isEmpty()：

修改后的replaceParagraphPlaceholders代码片段：

String paragraphText = paragraph.getText();
if (paragraphText != null && !paragraphText.isEmpty()) {
    if (paragraph.getRuns().size() <= 1) {
        String runText = "Sample text";
        paragraph.getRuns().get(0).setText(runText, 0);
    }
}

内容的提问来源于stack exchange，提问作者Furqan Ahmed