Struts2 addActionError时使用action标签的注意问题

我是一块硬盘 — Tue, 15 Jul 2008 22:43:00 GMT

struts.xml配置文件

     < action name ="*_*_*" class ="{0}Action" >
       < result name ="input" type ="freemarker" > /WEB-INF/template/strong/{1}/{1}_{2}_XianShi.ftl result >
       < result name ="success" type ="freemarker" > /WEB-INF/template/strong/{1}/{0}.ftl result >
     action >

登录操作Action 对应Action名为sxt_DengLu_CaoZuo 对应的input result为/WEB-INF/template/strong/sxt/sxt_DengLu_XianShi.ftl

Sxt_DengLu_CaoZuoAction.java

@Component( " sxt_DengLu_CaoZuoAction " ) // 使用了Spring 这里的意思是将本Action装配为一个ID为sxt_DengLu_CaoZuoAction的Bean
@Scope( " prototype " ) // 作用域为prototype 即每次都使用新的对象
public class Sxt_DengLu_CaoZuoAction extends ActionSupport implements ModelDriven < MYh > {

导航列表Action 对应Action名为sxt_DaoHang_XianShi 对应的success result为/WEB-INF/template/strong/sxt/sxt_DaoHang_XianShi.ftl

Sxt_DaoHang_XianShiAction.java

@Component( " sxt_DaoHang_XianShiAction " ) // 同上
@Scope( " prototype " ) // 同上
public class Sxt_DaoHang_XianShiAction extends ActionSupport implements Preparable{

sxt_DengLu_XianShi.ftl

  // 使用action标签将导航列表导入到本页面
  <@s.action name="sxt_DaoHang_XianShi" namespace="/ht" executeResult=true ignoreContextParams=true />
  <@s.form action="sxt_DengLu_CaoZuo" id="form_login" theme="simple">
    <table align="CENTER" id="table_login">
      <tr>
        <td class="td_label">登录名td>
        <td class="td_input"><@s.textfield label="${action.getText('TYH_YHDLM')}" id="yhDlm" name="yhDlm" />td>
      tr>
      <tr>
        <td class="td_label">密码td>
        <td class="td_input"><@s.password label="${action.getText('TYH_YHMM')}" id="yhMm" name="yhMm" />td>
      tr>
      <tr>
        <td class="td_label"> td>
        <td class="td_input"><p id="p_submit">
          <@s.submit value="${action.getText('PAGE_DENG_LU')}" />
          <input type="button" value="${action.getText('PAGE_TUI_CHU')}">
        p>td>
      tr>
    table>
  @s.form>

sxt_DaoHang_XianShi.ftl

Sxt_DengLu_CaoZuoAction.java 执行execute

  @Override
   public String execute() throws Exception {
     this .addActionError( " 系统错误 " );
     return INPUT;
  }

Sxt_DaoHang_XianShiAction.java 执行execute

  @Override
   public String execute() throws Exception {
    ActionContext ctx = ActionContext.getContext();
    ctx.put( " listDaoHangLieBiao " , new ArrayList());
     return SUCCESS;
  }

这个时候执行代码 freemarker会提示“

Expression listDaoHangLieBiao is undefined

”为什么会这样了？
仔细查找了相关资料发现apache的文档 http://struts.apache.org/2.x/docs/how-do-we-repopulate-controls-when-validation-fails.html中写道

When validation fails, we typically forward back to the same server page, so that the errors can be presented, and so that the client can fix the problem and resubmit the form. Of course, aside from the errors, we may also need to present rich controls, like drop down lists.

If we try to populate rich controls in an Action method, like input or execute, and validation fails, the method will not be invoked, and the controls are not populated. Two alternative ways to populate controls are the Preparable interface and the action tag.

大致的意思是但出现validation错误的时候会影响到Action的正常执行，这个时候应该实现Preparable接口中的prepare()方法，这个方法中的操作不会因为validation错误而不执行。

联想到上面的错，会不会也是因为addActionError而导致不能正常使用action标签了。为此在Sxt_DaoHang_XianShiAction中实现Preparable接口并在prepare()方法中put listDaoHangLieBiao。修改代码如下

Sxt_DaoHang_XianShiAction.java

@Component( " sxt_DaoHang_XianShiAction " )
@Scope( " prototype " )
public class Sxt_DaoHang_XianShiAction extends ActionSupport   implements Preparable{

  @Override
   public String execute() throws Exception {
     return SUCCESS;
  }

   public void prepare() throws Exception {
    ActionContext ctx = ActionContext.getContext();
    ctx.put( " listDaoHangLieBiao " , Constants.DAO_HANG_LIE_BIAO);
  }
}

再执行==成功。

总结 Struts2目前的资料相对Struts1来说是非常少的，尤其是研究的很深的资料，看来现在想学好Struts2还必须从Apache的原始资料中寻找。

另外上面使用action标签的时候是这样写的

< @s.action name = " sxt_DaoHang_XianShi " namespace = " /ht " executeResult = true ignoreContextParams = true />

注意和Struts2的标签写法略有不同，因为这里使用了Freemarker做模板，所以使用的freemarker的写法，特别的是executeResult=true ignoreContextParams=true而按照Struts2的标签应该是executeResult="true" ignoreContextParams="true"

哈哈小小两个引号害我折腾N个小时

我是一块硬盘 2008-07-16 06:43 发表评论

BlogJava-硬盘的BLOG-文章分类-Struts2

Struts2 addActionError时 使用action标签的注意问题

Struts2 addActionError时使用action标签的注意问题