mysql - 使用 JSF 中的预准备语句更新数据库

Question

我有mainpage.xhtml，它显示数据库中的整个记录​​并允许我编辑它们。如果单击 Edit 按钮，它会调用 mainPageController.edit() 函数，该函数填充 MainPageConroller 类中的 _bilgi 变量，然后重定向到 edit.xhtml 页面。

在edit.xhtml页面中，它基本上显示之前在MainPageController类中填充的_bilgi值。到这里为止没有问题(可能有但我不知道。)

当我想要更新其中一个变量(例如 baslik)时，我在 MainPageController 中创建了一个方法，该方法在 updateBilgi(_bilgi) 中调用 < strong>bilgiDAO 类。

在 UpdateBilgi 中，它的作用非常清楚，但它并没有更新表。对我来说有趣的是，当我调试并跟踪变量时，一切都很顺利，但最终它没有更新。

另一件事是，当我在 BilgilerDAO 中只放入一个字符串时，例如 ps.setString(1, "aqa1") 它可以工作，但是 ps.setString(2, bilgi.getBaslik() ) 甚至 bilgi.getBaslik() 也不会返回更改后的值。

可能出了什么问题？感谢您提前的答复。

我希望我说得足够清楚。

编辑:我发现了故障。在 BilgilerDAO 中，函数 updateBilgi(Bilgi bilgi)变量 bilgi 不会从 _bilgi 获取 id，而是获取其他变量。为什么取不到id？

ma​​inpage.xhtml

<h:form id="bilgiForm">
    <h:dataTable id="bilgiTable" value="#{mainPageController.bilgiListesi}"
        var="bilgiler" border="1">
        <h:column>
            <f:facet name="header">
                <h:outputText value="Başlık" />
            </f:facet>
            <h:outputText value="#{bilgiler.baslik}" />
            <f:facet name="footer">
                <h:outputText value="Başlık" />
            </f:facet>
        </h:column>

        <h:column>
            <f:facet name="header">
                <h:outputText value="Bilgi Metni" />
            </f:facet>
            <h:outputText value="#{bilgiler.bilgi}" />
            <f:facet name="footer">
                <h:outputText value="Bilgi Metni" />
            </f:facet>
        </h:column>


        <h:column>
            <f:facet name="header">
                <h:outputText value="Bilgi Metni" />
            </f:facet>
            <h:outputText value="#{bilgiler.bilgi}" />
            <f:facet name="footer">
                <h:outputText value="Bilgi Metni" />
            </f:facet>
        </h:column>

        <h:column>
            <f:facet name="header">
                <h:outputText value="Bilgi Metni" />
            </f:facet>
            <h:graphicImage
                value="https://canakkale.000webhostapp.com/showImage.php/?name=#{bilgiler.img.name}" />
            <f:facet name="footer">
                <h:outputText value="Bilgi Metni" />
            </f:facet>
        </h:column>

        <h:column>
            <fcore:facet name="header">Edit</fcore:facet>
            <h:commandButton action="edit" value="Edit"
                actionListener="#{mainPageController.edit()}">
                <fcore:param name="id" value="#{bilgiler.id}" />
            </h:commandButton>
        </h:column>
    </h:dataTable>
</h:form>




    <fcore:view>
        <h:form>
            <fcore:view>
                <h:form>
                    <h1>Update</h1>
                    <h:panelGrid border="" cellpadding="20" cellspacing="20"
                        columns="3">
                        <h:outputLabel value="Bilgi ID" />
                        <h:inputText value="#{mainPageController._bilgi.id}"
                            readonly="true" required="true" requiredMessage="Id is Required"
                            id="bilgiID">
                        </h:inputText>
                        <h:message for="bilgiID" />

                        <h:outputLabel value="Tag" />
                        <h:inputText value="#{mainPageController._bilgi.tag}"
                            readonly="true" required="true"
                            requiredMessage="Tag Girmeniz Gereklidir." id="bilgiTag">
                        </h:inputText>
                        <h:message for="bilgiTag" />
                        <h:outputLabel value="Başlık" />
                        <h:inputText value="#{mainPageController._bilgi.baslik}"
                            required="true" requiredMessage="Başlık Girmeniz Gereklidir."
                            id="bilgiBaslik">
                        </h:inputText>
                        <h:message for="bilgiBaslik" />


                        <h:outputLabel value="Bilgi Metni" />
                        <h:inputTextarea value="#{mainPageController._bilgi.bilgi}"
                            required="true" requiredMessage="Başlık Girmeniz Gereklidir."
                            id="bilgiBilgi">
                        </h:inputTextarea>
                        <h:message for="bilgiBilgi" />


                        <h:outputLabel value="Image URL" />
                        <h:inputText value="#{mainPageController._bilgi.img.name}"
                            required="true" requiredMessage="Başlık Girmeniz Gereklidir."
                            readonly="true" id="bilgiImgName">
                        </h:inputText>
                        <h:message for="bilgiImgName" />

                        <h:outputLabel value="Başlık" />
                        <input type="file" value="#{mainPageController._bilgi.img.image}" />
                        <h:commandButton action="#{mainPageController.updateRecord()}"
                            value="Update">
                        </h:commandButton>
                    </h:panelGrid>
                </h:form>
            </fcore:view>


        </h:form>
    </fcore:view>
</h:body>
</html>

MainPageController类

 @ManagedBean
    public class MainPageController implements Serializable {

        List<Bilgi> bilgiListesi = new ArrayList<Bilgi>();
        private Bilgi _bilgi = new Bilgi();
        private static final long serialVersionUID = 1L;

        BilgilerDAO bilgiDao = new BilgilerDAO();
        ImageDAO imgDao = new ImageDAO();

        public MainPageController() {// Default Constructor
            try {
                bilgiListesi = showAllRecords();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }

        public List<Bilgi> showAllRecords() throws SQLException {
            return bilgiDao.getAllBilgiler();
        }

        public List<Image> showAllImages() throws Exception {
            return imgDao.getAllImages();

        }

        public void updateRecord() {
            try {
                bilgiDao.updateBilgi(_bilgi);
                //imgDao.updateImage(_bilgi.getImg());
            } catch (Exception e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }

        }

        public void edit() {
            FacesContext fc = FacesContext.getCurrentInstance();
            int id;
            HttpServletRequest request = (HttpServletRequest) fc.getExternalContext().getRequest();
            id = Integer.parseInt(request.getParameter("id"));
            try {
                bilgiListesi = bilgiDao.getAllBilgiler();
            } catch (SQLException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
            for (Bilgi bilgi : bilgiListesi) {
                if (bilgi.getId() == id) {
                    _bilgi.setBaslik(bilgi.getBaslik());
                    _bilgi.setBilgi(bilgi.getBilgi());
                    _bilgi.setImg(bilgi.getImg());
                    _bilgi.setTag(bilgi.getTag());
                    _bilgi.setId(bilgi.getId());
                }

            }
        }

        public void edit(Bilgi bilgi) {
            for (Bilgi existing : getBilgiListesi()) {
                existing.setEditable(false);
            }
            bilgi.setEditable(true);
        }


    }

BilgilerDAO

@Override
    public String updateBilgi(Bilgi bilgi) throws Exception {
        String sql = "UPDATE bilgiler SET bilgi=?, baslik =? WHERE id=? ";
        ps = DatabaseConnection.getConnection().prepareStatement(sql);

        ps.setString(1, "aqa1");
        ps.setString(2, bilgi.getBaslik());
        ps.setInt(3, bilgi.getId());

        int ex = ps.executeUpdate();
        if (ex > 0) {
            System.err.println("coodld");
        }
        ps.close();
        return "mainpage";

    }

Answer 1

我已经解决了这个问题。

<h:inputText value="#{mainPageController._bilgi.id}" readonly="true" required="true" requiredMessage="Id is Required" id="bilgiID">

在此 xhtml 行中 readonly="true" 导致它返回 null。我现在将其删除，它按我想要的方式工作。不过，我仍然希望它们显示但不可编辑。