使用java类更改jsp中textarea的属性

Question

我想使用java类更改这些文本区域的属性。正如您所看到的，文本区域在默认情况下是禁用的。如果用户在数据库中找不到注册的TIN，我想启用此功能。这是我的代码：

jsp:

<label style="font-size: 17px;">Registered Name</label><br><br>         
<textarea disabled id="tpName" name="tpName" style="margin-top: -9px; width: 275px; height: 40px;">${name}</textarea>   
<br><br>
<label style="font-size: 17px;">Address</label><br><br>         
<textarea disabled id="tpAddress" name="tpAddress" style="margin-top: -9px; width: 275px; height: 40px;">${address}</textarea>

类别：

private String tpTin;
private String tpName;  
private String tpAddress;
private TblTaxPayment tbltaxpayment;
public String getTpTin() {
    return tpTin;
}
public String getTpName() {
    return tpName;
}
public String getTpAddress() {
    return tpAddress;
}
public void setTpTin(String tpTin) {
    this.tpTin = tpTin;
}
public void setTpName(String tpName) {
    this.tpName = tpName;
}
public void setTpAddress(String tpAddress) {
    this.tpAddress = tpAddress;
}
private HttpServletRequest request;
public void setServletRequest(HttpServletRequest request){
    this.request = request;
}
public TblTaxPayment getTblTaxPayment() {
    return tbltaxpayment;
}
public void setTblTaxPayment(TblTaxPayment tbltaxpayment) {
    this.tbltaxpayment = tbltaxpayment;
}
@SuppressWarnings("unused")
public String execute() throws Exception {
    Debugger.border();
    Debugger.startDebug(this.getClass().toString());
    String tax = request.getParameter("tpTin");
    TblTaxPaymentDAO tdao = DAOFactory.getDaoManager(TblTaxPayment.class);
    TblTaxPayment t = null;
    t = tdao.findbyTIN(tax.replace("-", ""));
    tbltaxpayment = (TblTaxPayment) t;
    try{
            Debugger.print("TIN : "+tax);
            if(tax != null) {
                tpTin = tbltaxpayment.getTpTin();                                       
                tpName = tbltaxpayment.getTpName();
                tpAddress = tbltaxpayment.getTpAddress();
                String tin = tpTin;
                String name = tpName;
                String address = tpAddress;
                request.setAttribute("tin", tin);
                request.setAttribute("name", name);
                request.setAttribute("address", address);
                return SUCCESS;
            }else{
                request.setAttribute("name", true);
                request.setAttribute("address", true);              
                return SUCCESS;
            }

    }catch(Exception e){
        e.printStackTrace();
        Debugger.endDebug(this.getClass().toString());
        Debugger.border();
        return ERROR;
    }
}

}

我做了什么。我将属性设置为true，以便能够更改jsp中文本区域的属性/属性。

Answer 1

如果Java类包含决定是否启用文本区域的逻辑，则必须首先将该状态的Java类存储在JSP可以访问的地方。您有许多选项：您可以将其设置为请求属性，例如

request.setAttribute("nameRequired", true /* or false */); 
request.setAttribute("addressRequired", true /* or false */);

您可以将标志存储在Java类中，并通过getters使其可用：

boolean nameRequired;
boolean addressRequired;
public String execute () throws Exception {
    ...
    nameRequired = true /* or false */;
    addressRequired = true /* or false */;
    ...
}
public boolean isNameRequired () {
    return nameRequired;
}
public boolean isAddressRequired () {
    return addressRequired;
}

对于以上任何一种情况，您还可以通过让类返回业务状态并让UI决定是否需要名称或地址来进一步将业务逻辑与UI隔离开来，例如。；

request.setAttribute("haveTaxInfo", false /* or true */); 

或者其他什么——语义。

在任何情况下，JSP确定文本区域状态所需的信息现在都可以由JSP访问。然后，在JSP中，您只需适当地编写disabled属性：

<%
// option 1: if you used request attributes:
boolean nameRequired = Boolean.TRUE.equals(request.getAttribute("nameRequired")); 
boolean addressRequired = Boolean.TRUE.equals(request.getAttribute("addressRequired"));
// option 2: or, if you used class fields:
boolean nameRequired = businessClass.isNameRequired(); 
boolean addressRequired = businessClass.isAddressRequired();
// option 3: or,if you used the business state in a request attribute: 
boolean haveTaxInfo = Boolean.TRUE.equals(request.getAttribute("haveTaxInfo"));
boolean nameRequired = !haveTaxInfo;    // if we don't have the tax info then the name
boolean addressRequired = !haveTaxInfo; // and address are required.
%>
<textarea <%=(nameRequired?"":"disabled")%> id="tpName" name="tpName" style="margin-top: -9px; width: 275px; height: 40px;">${name}</textarea>   
<textarea <%=(addressRequired?"":"disabled")%> id="tpAddress" name="tpAddress" style="margin-top: -9px; width: 275px; height: 40px;">${address}</textarea>

这里需要重点说明的是，您可以使用<%= ... %> JSP标记来控制是否在输出中写入"disabled"。您可以在这些标记中使用基于某个布尔值的条件表达式，并且该布尔值必须以某种方式从您的业务类传递到JSP（通过请求属性、getter或其他方式）。

希望能有所帮助。