<c:if>显示了unkonwn tag

如果您在使用 `<c:if>` 标签时出现了 `unknown tag` 错误，这可能是由于缺少 JSTL（JavaServer Pages Standard Tag Library）标签库的支持。为了使用 JSTL 标签库，您需要将 JSTL 的相关 JAR 包添加到您的项目中，并在 JSP 页面中引入 JSTL 标签库的命名空间。

以下是一个引入 JSTL 标签库的示例代码：

<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>

<!-- 在这里使用 <c:if> 标签 -->
<c:if test="${userRule == 0}">
    <li> <a href="users.jsp">用户管理</a></li>
</c:if>

在上述代码中，我们使用了 JSP 页面中的 `taglib` 指令来引入 JSTL 标签库的命名空间，并在 `<c:if>` 标签中使用了 EL 表达式来引用我们从 Java Servlet 中传递过来的 `userRule` 变量。

如果您仍然遇到了 `unknown tag` 错误，请确保您已经正确地添加了 JSTL 相关的 JAR 包，并在 JSP 页面中正确地引入了 JSTL 标签库的命名空间。

相关问题

objectarx二次开发自定义实体，实体数据是一个结构体tag，结构体tag中包含另外一个结构体map、一个类指针Class*、一个bool,而结构体map保存的是一个long long int数据和一个vector<wstring>.类指针class中有一个vector<class2*>, class2是个基类,使用时会根据class中的int型的参数判断强制转换成不同子类进行绘制，子类中的数据也不相同，class2中包含了vector<AcGePoint3D>以及字符串、int等数据，请问如何保存读取这些数据到dwg

为了保存自定义实体及其数据到DWG文件中，您需要使用AutoCAD提供的ObjectARX API进行开发。下面是大致的步骤：

1. 定义自定义实体类，其中包含tag结构体、Class类指针、bool变量等成员变量。

class MyEntity : public AcDbEntity
{
public:
    ACDB_DECLARE_MEMBERS(MyEntity);

    MyEntity();
    virtual ~MyEntity();

    // Overridden methods from AcDbEntity
    virtual Adesk::Boolean subWorldDraw(AcGiWorldDraw* pWd);
    virtual Acad::ErrorStatus dwgOutFields(AcDbDwgFiler* pFiler) const;
    virtual Acad::ErrorStatus dwgInFields(AcDbDwgFiler* pFiler);

private:
    tag m_tag;
    Class* m_pClass;
    bool m_bFlag;
};

2. 在实体类中实现`dwgOutFields`和`dwgInFields`方法，用于保存和读取实体数据到DWG文件中。

Acad::ErrorStatus MyEntity::dwgOutFields(AcDbDwgFiler* pFiler) const
{
    Acad::ErrorStatus es = AcDbEntity::dwgOutFields(pFiler);
    if (es != Acad::eOk) return es;

    // Write tag data
    pFiler->writeInt32(m_tag.map.size());
    for (auto it = m_tag.map.begin(); it != m_tag.map.end(); ++it)
    {
        pFiler->writeInt64(it->first);
        pFiler->writeInt32(it->second.size());
        for (const auto& str : it->second)
        {
            pFiler->writeBChunk(str.c_str(), str.size() * sizeof(wchar_t));
        }
    }
    pFiler->writeInt64(reinterpret_cast<AcDbUIntPtr>(m_tag.ClassPtr));
    pFiler->writeBool(m_tag.bFlag);

    // Write Class data
    pFiler->writeInt32(m_pClass->vec2.size());
    for (const auto& pClass2 : m_pClass->vec2)
    {
        pFiler->writeInt32(pClass2->getType()); // Save type information
        pFiler->writeBChunk(&pClass2->ptVec[0], pClass2->ptVec.size() * sizeof(AcGePoint3d));
        pFiler->writeBChunk(pClass2->str.c_str(), pClass2->str.size() * sizeof(wchar_t));
        pFiler->writeInt32(pClass2->n);
    }

    return pFiler->filerStatus();
}

Acad::ErrorStatus MyEntity::dwgInFields(AcDbDwgFiler* pFiler)
{
    Acad::ErrorStatus es = AcDbEntity::dwgInFields(pFiler);
    if (es != Acad::eOk) return es;

    // Read tag data
    int nSize = 0;
    pFiler->readInt32(&nSize);
    for (int i = 0; i < nSize; ++i)
    {
        long long llKey = 0;
        pFiler->readInt64(&llKey);
        int nVecSize = 0;
        pFiler->readInt32(&nVecSize);
        std::vector<std::wstring> vecStr;
        for (int j = 0; j < nVecSize; ++j)
        {
            char* pBuf = nullptr;
            int nLen = 0;
            pFiler->readBChunk(&pBuf, &nLen);
            vecStr.emplace_back(reinterpret_cast<wchar_t*>(pBuf), nLen / sizeof(wchar_t));
            acutDelString(pBuf);
        }
        m_tag.map[llKey] = vecStr;
    }
    AcDbUIntPtr nPtr = 0;
    pFiler->readInt64(reinterpret_cast<AcDbUIntPtr*>(&nPtr));
    m_tag.ClassPtr = reinterpret_cast<Class*>(nPtr);
    pFiler->readBool(&m_tag.bFlag);

    // Read Class data
    pFiler->readInt32(&nSize);
    for (int i = 0; i < nSize; ++i)
    {
        int nType = 0;
        pFiler->readInt32(&nType);
        class2* pClass2 = nullptr;
        if (nType == 1)
        {
            pClass2 = new class2A;
        }
        else if (nType == 2)
        {
            pClass2 = new class2B;
        }
        else
        {
            // Unknown type, skip
            continue;
        }
        char* pBuf = nullptr;
        int nLen = 0;
        pFiler->readBChunk(&pClass2->ptVec[0], pClass2->ptVec.size() * sizeof(AcGePoint3d));
        pFiler->readBChunk(&pBuf, &nLen);
        pClass2->str = std::wstring(reinterpret_cast<wchar_t*>(pBuf), nLen / sizeof(wchar_t));
        acutDelString(pBuf);
        pFiler->readInt32(&pClass2->n);
        m_pClass->vec2.emplace_back(pClass2);
    }

    return pFiler->filerStatus();
}

3. 在自定义实体的构造函数中初始化成员变量。

MyEntity::MyEntity()
{
    m_tag.ClassPtr = nullptr;
    m_tag.bFlag = false;
    m_pClass = new Class;
}

4. 在实体类中实现`subWorldDraw`方法，用于绘制实体。

Adesk::Boolean MyEntity::subWorldDraw(AcGiWorldDraw* pWd)
{
    // Draw entity using OpenGL
    // ...

    // Draw Class data
    for (const auto& pClass2 : m_pClass->vec2)
    {
        if (auto pClass2A = dynamic_cast<class2A*>(pClass2))
        {
            // Draw class2A using OpenGL
            // ...
        }
        else if (auto pClass2B = dynamic_cast<class2B*>(pClass2))
        {
            // Draw class2B using OpenGL
            // ...
        }
        else
        {
            // Unknown type, skip
            continue;
        }
    }

    return Adesk::kTrue;
}

在AutoCAD中使用自定义实体时，可以使用下列代码进行创建并添加到当前图形数据库中：

MyEntity* pEnt = new MyEntity;
AcDbObjectId objId;
Acad::ErrorStatus es = acdbHostApplicationServices()->workingDatabase()->addAcDbEntity(objId, pEnt);
if (es == Acad::eOk)
{
    // Set entity properties
    // ...

    // Add entity to current space
    AcDbBlockTableRecord* pBTR = nullptr;
    es = acdbHostApplicationServices()->workingDatabase()->getModelSpace(pBTR, AcDb::kForWrite);
    if (es == Acad::eOk)
    {
        es = pBTR->appendAcDbEntity(objId, pEnt);
        pBTR->close();
    }
}
else
{
    delete pEnt;
}

当从DWG文件中读取自定义实体时，可以使用下列代码进行获取：

AcDbObjectIdArray objIds;
acdbGetObjectsOfType(objIds, MyEntity::desc());
for (const auto& objId : objIds)
{
    MyEntity* pEnt = nullptr;
    Acad::ErrorStatus es = acdbOpenAcDbEntity(reinterpret_cast<AcDbEntity*&>(pEnt), objId, AcDb::kForRead);
    if (es == Acad::eOk)
    {
        // Get entity properties
        // ...

        pEnt->close();
    }
}

2023-06-17 23:47:22.786162: W tensorflow/stream_executor/platform/default/dso_loader.cc:64] Could not load dynamic library 'cudart64_110.dll'; dlerror: cudart64_110.dll not found 2023-06-17 23:47:22.786281: I tensorflow/stream_executor/cuda/cudart_stub.cc:29] Ignore above cudart dlerror if you do not have a GPU set up on your machine. 2023-06-17 23:47:24.419330: W tensorflow/stream_executor/platform/default/dso_loader.cc:64] Could not load dynamic library 'nvcuda.dll'; dlerror: nvcuda.dll not found 2023-06-17 23:47:24.419809: W tensorflow/stream_executor/cuda/cuda_driver.cc:263] failed call to cuInit: UNKNOWN ERROR (303) 2023-06-17 23:47:24.426229: I tensorflow/stream_executor/cuda/cuda_diagnostics.cc:169] retrieving CUDA diagnostic information for host: ����� 2023-06-17 23:47:24.426345: I tensorflow/stream_executor/cuda/cuda_diagnostics.cc:176] hostname: ����� 2023-06-17 23:47:24.430552: I tensorflow/core/platform/cpu_feature_guard.cc:193] This TensorFlow binary is optimized with oneAPI Deep Neural Network Library (oneDNN) to use the following CPU instructions in performance-critical operations: AVX AVX2 To enable them in other operations, rebuild TensorFlow with the appropriate compiler flags. Traceback (most recent call last): File "C:\Users\10290\Desktop\test\writer.py", line 20, in <module> write_reward_tb(summary_writer, rewards[i], i) File "C:\Users\10290\Desktop\test\writer.py", line 9, in write_reward_tb summary = tf.Summary(value=[tf.Summary.Value(tag='reward', simple_value=reward)]) AttributeError: module 'tensorflow' has no attribute 'Summary'分析错误原因

这个错误是由于TensorFlow 2.x版本中`tf.Summary`已被弃用所致。相反，你应该使用`tf.summary.Summary`。你需要将代码更新为：

summary = tf.summary.Summary(value=[tf.summary.Summary.Value(tag='reward', simple_value=reward)])

这样就可以避免这个错误了。另外，还需要注意，TensorFlow 2.x版本中`tf.summary.FileWriter`已经被弃用，应该使用`tf.summary.create_file_writer`来创建一个`tf.summary.FileWriter`的实例。