Question

我正在使用datatable从数据库中检索记录。 Datatable按预期显示行上的所有项目。我想要的是如何只选择其中一个或单个，可以通过在datatable中指定项目的索引吗？还是通过SQL查询？

bean：

public JcalendarController getSelectedUser() {
    return selectedday;
}

public void setSelectedUser(JcalendarController selectedday) {
    this.selectedday = selectedday;
}

List<String> user_spinner_list = new ArrayList<String>();
List<JcalendarController> calendarlist = new ArrayList<JcalendarController>();

public void delete() {
    System.out.println("JadminBeans >> delete() ---------- id= ");
    JcalendarDAO.deleteDay(selectedday);
}

public List<JcalendarController> getMessages() {
    System.out.println("List<JcalendarController> getMessages()");
    calendarlist = JcalendarDAO.getdays();
    return calendarlist;
}

public long getId() {
    return id;
}

public void setId(long id) {
    this.id = id;
}

public String getUsername() {
    return username;
}

public void setUsername(String username) {
    this.username = username;
}

public int getDay() {
    return day;
}

public void setDay(int day) {
    this.day = day;
}

public String getText() {
    return text;
}

public void setText(String text) {
    this.text = text;
}

public UploadedFile getFile() {
    return file;
}

public void setFile(UploadedFile file) {
    this.file = file;
}

//--------------------------------------------------------------------------
//---------------------------- user_spinner() ----------------------------//
public List<String> user_spinner() {
    System.out.println("List<JcalendarBeans> user_spinner()");

    user_spinner_list = JcalendarDAO.AllUsarname_spinner();
    return user_spinner_list;
}

//---------------------------- ImageUpload() ----------------------------//
public void ImageUpload() {
    JcalendarController CC = new JcalendarController(this.username, this.day, this.file);
    System.out.println(this.username + " " + this.day + " " + this.file);
    calendarlist.add(CC);
    JcalendarDAO.add_image_DAO(CC);
}

//---------------------------- TextUpload() ----------------------------//
public void TextUpload() {
    JcalendarController CC = new JcalendarController(this.username, this.day, this.text);
    System.out.println(this.username + " " + this.day + " " + this.text);
    calendarlist.add(CC);
    JcalendarDAO.add_text_DAO(CC);
}

DAO：

public static List<JcalendarController> getdays() {

    List<JcalendarController> ccs = new ArrayList<JcalendarController>();

    try {
        Statement statement = connection.createStatement();
        ResultSet rs = statement.executeQuery("select * from calendar");

        while (rs.next()) {
            JcalendarController cc = new JcalendarController();
            cc.setId(rs.getLong("id"));
            cc.setDay(rs.getInt("day"));
            cc.setText(rs.getString("text"));
            cc.setUsername(rs.getString("username"));

        }
    } catch (SQLException e) {
        e.printStackTrace();
    }
    return ccs;
}

XHTML

<p:dataTable value="#{Jcalendar.messages}" var="o" paginator="true" selection="#{Jcalendar.selectedUser}"
             rowKey="#{o.id}" style="margin-bottom:20px"
             paginatorTemplate="{CurrentPageReport}  {FirstPageLink} {PreviousPageLink} {PageLinks} {NextPageLink} {LastPageLink} {RowsPerPageDropdown}"
             rowsPerPageTemplate="24,48,144">

    <f:facet name="header">
        <h:outputText value="Data showing from database" />
    </f:facet>

    <p:column selectionMode="single" />
    <p:column>
        <f:facet name="header">
            <h:outputText value=" Id" />
        </f:facet>

        <h:outputText value="#{o.id}" />
    </p:column>

    <p:column>
        <f:facet name="header">
            <h:outputText value="Day" />
        </f:facet>

        <h:outputText value="#{o.day}" />
    </p:column>

    <p:column>
        <f:facet name="header">
            <h:outputText value="Text" />
        </f:facet>

        <h:outputText value="#{o.text}" />
    </p:column>

    <p:column>
        <f:facet name="header">
            <h:outputText value="Username" />
        </f:facet>

        <h:outputText value="#{o.username}" />
    </p:column>

    <p:column>
        <f:facet name="header">
            <h:outputText value="Image" />
        </f:facet>

        <h:outputLink value="DisplayImage?id=#{o.id}" target="_blank">
            <h:graphicImage value="DisplayImage?id=#{o.id}" width="50" height="50"></h:graphicImage>
        </h:outputLink>
    </p:column>

    <f:facet name="footer">
        <p:commandButton value="Delete" action="#{Jcalendar.delete()}" ajax="false" update=":form:msgs"/>
    </f:facet>
</p:dataTable>

Answer 1

数据表将显示消息属性的值，因此 getMessages（）返回的列表中的任何内容都将在表内呈现。

对于您提出的问题，最好制作一个DAO方法并从数据库返回所需的记录，用你的话说，使用SQL。

一个优化提示，您应该避免在 getter 方法中使用任何逻辑，就像在单个请求的生命周期中一样，可以多次调用它。在您的情况下，它会在每次通话时联系DB。您可以查看此post了解详情，并找到更好的初始化列表的方法。

PrimeFaces在一行中显示一个列表项

1 个答案: