當結果類型為Struts2中的重定向操作時，prepare（）方法將被調用兩次

Question

我有以下動作課：

@Namespace("/admin_side")
@ResultPath("/WEB-INF/content")
@ParentPackage(value="struts-default")
public final class FabricAction extends ActionSupport implements Serializable, ValidationAware, Preparable, ModelDriven<Fabric>
{
    @Autowired
    private final transient FabricService fabricService=null;
    private static final long serialVersionUID = 1L;

    private int pageSize=5;
    private Long id;
    private Boolean deleteOneRow;
    private Boolean deleteMultipleRows;
    private String message;
    private List<Long>chk;
    private Long deleteId;

    private Long begin;
    private Long end;
    private Long currentPage=1L;
    private Long rowCount;
    private Long totalPages;
    private Integer status;

    private Fabric entity=new Fabric();
    private List<Fabric>fabrics=new ArrayList<Fabric>();

    //Getters & Setters.

    @Action(value = "Fabric",
            results = {
                @Result(name=ActionSupport.SUCCESS, location="Fabric.jsp"),
                @Result(name = ActionSupport.INPUT, location = "Fabric.jsp")},
            interceptorRefs={
                @InterceptorRef(value="paramsPrepareParamsStack", params={"params.acceptParamNames", "id, currentPage, rowCount, totalPages, message, status", "validation.validateAnnotatedMethodOnly", "true", "validation.excludeMethods", "load"})})
    public String load() throws Exception
    {
        //Invokes, when the page is loaded.
        return ActionSupport.SUCCESS;
    }

    @Action(value = "FabricPage",
        results = {@Result(name=ActionSupport.SUCCESS, location="Fabric.jsp", params={"namespace", "/admin_side", "actionName", "Fabric", "currentPage", "${currentPage}"}),
        @Result(name = ActionSupport.INPUT, location = "Fabric.jsp")},
        interceptorRefs={
            @InterceptorRef(value="conversionError"),
            @InterceptorRef(value="paramsPrepareParamsStack", params={"params.acceptParamNames", "currentPage", "validation.validateAnnotatedMethodOnly", "true"})})
    public String page()
    {
        //Invokes, when a page link is clicked.
        return ActionSupport.SUCCESS;
    }

    @Validations(
            requiredStrings={
                @RequiredStringValidator(fieldName="fabricName", type= ValidatorType.FIELD, key = "fabric.name.required")},
            stringLengthFields={
                @StringLengthFieldValidator(fieldName="fabricName", type= ValidatorType.FIELD, minLength="2", maxLength="45", key="fabric.name.length", messageParams={"2", "45"})})
    @Action(value = "AddFabric",
        results = {
            @Result(name=ActionSupport.SUCCESS, type="redirectAction", location="Fabric.jsp", params={"namespace", "/admin_side", "actionName", "Fabric", "currentPage", "${currentPage}", "message", "${message}", "id", "${id}", "status", "${status}"}),
            @Result(name = ActionSupport.INPUT, location = "Fabric.jsp")},
        interceptorRefs={
            @InterceptorRef(value="conversionError"),
            @InterceptorRef(value="paramsPrepareParamsStack", params={"params.acceptParamNames", "id, fabricId, fabricName, currentPage, rowCount, totalPages, status", "validation.validateAnnotatedMethodOnly", "true"})
        })
    public String insert()
    {
        //Handles insert and update operations.
        return ActionSupport.SUCCESS;
    }

    @Action(value = "EditFabric",
            results = {
                @Result(name=ActionSupport.SUCCESS, location="Fabric.jsp"),
                @Result(name = ActionSupport.INPUT, location = "Fabric.jsp")},
            interceptorRefs={
                @InterceptorRef(value="paramsPrepareParamsStack", params={"params.acceptParamNames", "id, fabricId, fabricName, currentPage", "validation.validateAnnotatedMethodOnly", "true"}),
                @InterceptorRef(value="conversionError")})
    public String edit()
    {
        //Invokes, when an edit link is clicked.
        return ActionSupport.SUCCESS;
    }

    @Validations(
            fieldExpressions={@FieldExpressionValidator(fieldName="deleteOneRow", expression="deleteOneRow==true", shortCircuit=true, key="delete.row.reject")})
    @Action(value = "DeleteFabric",
            results = {
                @Result(name=ActionSupport.SUCCESS, type="redirectAction", location="Fabric.action", params={"currentPage", "${currentPage}", "message", "${message}", "status", "${status}"}),
                @Result(name = ActionSupport.INPUT, location = "Fabric.jsp")},
            interceptorRefs={
                @InterceptorRef(value="paramsPrepareParamsStack", params={"params.acceptParamNames", "deleteId, deleteOneRow, currentPage, status", "validation.validateAnnotatedMethodOnly", "true"}),
                @InterceptorRef(value="conversionError")})
    public String deleteSingleRow()
    {
        //Handles deletion of a single row.
        return ActionSupport.SUCCESS;
    }

    @Validations(
            requiredFields={
                @RequiredFieldValidator(type= ValidatorType.FIELD, fieldName="chk", key="delete.multiple.alert"),
                @RequiredFieldValidator(type= ValidatorType.FIELD, fieldName="deleteMultipleRows", key="delete.multiple.confirm")})
    @Action(value = "DeleteFabrics",
            results = {
                @Result(name=ActionSupport.SUCCESS, type="redirectAction", location="Fabric.jsp", params={"namespace", "/admin_side", "actionName", "Fabric", "currentPage", "${currentPage}", "message", "${message}", "status", "${status}"}),
                @Result(name = ActionSupport.INPUT, location = "Fabric.jsp")},
            interceptorRefs={
                @InterceptorRef(value="paramsPrepareParamsStack", params={"params.acceptParamNames", "deleteMultipleRows, chk, currentPage, rowCount, totalPages", "validation.validateAnnotatedMethodOnly", "true"}),
                @InterceptorRef(value="conversionError")})
    public String deleteMultipleRows()
    {
        //Handles deletion of multiple rows.
        return ActionSupport.SUCCESS;
    }

    public Fabric getEntity() {
        return entity;
    }

    public void setEntity(Fabric entity) {
        this.entity = entity;
    }

    public List<Fabric> getFabrics()
    {
        return fabrics;
    }

    @Override
    public Fabric getModel()
    {
        return entity;
    }

    @Override
    public void prepare() throws Exception
    {
        fabrics= fabricService.getList((int)(currentPage-1)*pageSize, pageSize);
    }
}

在執行除與insert()方法關聯的insert和update以外的所有操作（它們都與被映射到<s:submit>動作的insert()關聯）時， prepare()方法僅執行一次。

在執行插入或更新時，可以看到prepare()方法被調用了兩次。 為什么會這樣？

如果@Result()的type="redirectAction" ，則prepare()方法將執行兩次。 @Result type設置為redirectAction時，是否有一種方法可以防止prepare()方法執行兩次？

Answer 1

選擇結果type或location出錯。 因為"Fabric.jsp"或"Fabric.action"不是有效的動作名稱。

@Result(name=ActionSupport.SUCCESS, type="redirectAction", location="Fabric.jsp",

應該是dispatcher結果

@Result(name=ActionSupport.SUCCESS, location="Fabric.jsp",

或redirectAction結果

@Result(name=ActionSupport.SUCCESS, type="redirectAction", location="Fabric"

如果使用redirectAction結果類型，則默認情況下會創建新的動作類實例，在該實例中，在動作之前執行prepare方法。 如果打印的hashCode()應該不同（即使動作名稱不同hashCode()也可以進行檢查。 因此，沒有調用兩次的prepare方法，因為它僅在每個動作的堆棧中prepare攔截器。 另一方面，如果使用paramsPrepareParamsStack ，則兩次調用params攔截器：在prepare攔截器之前和之后。

Answer 2

我遇到了同樣的問題，最終發現我在多個地方引用了一個攔截器堆棧。 就您而言，您似乎在課程級別上：

@ParentPackage(value="struts-default") ，我相信它使用默認堆棧。

然后在@Act​​ion級別，您可以引用paramsPrepareParamsStack ：

interceptorRefs={
            @InterceptorRef(value="paramsPrepareParamsStack"...)})

在我的特定情況下，我的Action類擴展了BaseAction類。 我在兩個地方都聲明了@InterceptorRef批注。 BaseAction（已引用第一個攔截器堆棧）：

@Namespace("/")
@InterceptorRef("myCustomStack")
@Results({ @Result(name = "cancel", location = "${previousPageLink}", type = "redirectAction", params = {
 }) })
public class BaseAction extends ActionSupport implements ServletRequestAware, ParameterAware,
SessionAware { 
...
}

然后，在動作類中，我再次有了攔截器ref（“ myCustomStack”）。 在我的HomeAction類中刪除攔截器引用堆棧對我來說解決了這個問題。

@Namespace("/")
@InterceptorRefs({
@InterceptorRef(value = "store", params = {"operationMode", "RETRIEVE"}) })
/*@InterceptorRef("myCustomStack") })*/
@Results({ @Result(name = "success", location = "home.def", type = "tiles")
})
public class HomeAction extends BaseAction implements Preparable {
...
}

最后，這是我的struts.xml，其default.parent.package設置為“ default”：

<struts>
  <constant name="struts.convention.action.packages" value="com.myapp.action" />
  <constant name="struts.convention.default.parent.package" value="default" />
  <constant name="struts.action.extension" value="action" />
  <constant name="struts.enable.DynamicMethodInvocation" value="false" />
  <constant name="struts.ognl.allowStaticMethodAccess" value="true" />
  <package name="default" namespace="/" extends="tiles-default,json-default">
    <interceptors>
      <interceptor-stack name="myCustomStack">
        <interceptor-ref name="basicStack" />
        <interceptor-ref name="staticParams" />
        <interceptor-ref name="validation">
          <param name="excludeMethods">input,back,cancel,browse</param>
        </interceptor-ref>
        <interceptor-ref name="workflow">
          <param name="excludeMethods">input,back,cancel,browse</param>
        </interceptor-ref>
      </interceptor-stack>
    </interceptors>
  </package>
</struts>