Package org.apache.struts2.components

Class Component

java.lang.Object
org.apache.struts2.components.Component
Direct Known Subclasses:
ContextBean, Else, ElseIf, I18n, If, Include, OptGroup, Param, Property, Push, UIBean
public class Component extends Object
Base class to extend for UI components.
This class is a good extension point when building reusable UI components.

  • Field Details

    • COMPONENT_STACK

      public static final String COMPONENT_STACK
      See Also:

    • standardAttributesMap

      protected static ConcurrentMap<Class<?>,Collection<String>> standardAttributesMap
      Caches information about common tag's attributes to reduce scanning for annotation @StrutsTagAttribute

    • devMode

      protected boolean devMode

    • escapeHtmlBody

      protected boolean escapeHtmlBody

    • stack

      protected ValueStack stack

    • attributes

      protected Map<String,Object> attributes

    • actionMapper

      protected ActionMapper actionMapper

    • throwExceptionOnELFailure

      protected boolean throwExceptionOnELFailure

    • performClearTagStateForTagPoolingServers

      protected boolean performClearTagStateForTagPoolingServers

  • Constructor Details

    • Component

      public Component(ValueStack stack)
      Constructor.
      Parameters:
      stack - OGNL value stack.

  • Method Details

    • setDevMode

      public void setDevMode(String devMode)

    • setActionMapper

      public void setActionMapper(ActionMapper mapper)

    • setThrowExceptionsOnELFailure

      public void setThrowExceptionsOnELFailure(String throwException)

    • setEscapeHtmlBody

      public void setEscapeHtmlBody(String escapeHtmlBody)

    • setUrlHelper

      public void setUrlHelper(UrlHelper urlHelper)

    • setNotExcludedAcceptedPatterns

      public void setNotExcludedAcceptedPatterns(NotExcludedAcceptedPatternsChecker notExcludedAcceptedPatterns)

    • getStack

      public ValueStack getStack()
      Gets the OGNL value stack associated with this component.
      Returns:
      the OGNL value stack associated with this component.

    • getComponentStack

      public Stack<Component> getComponentStack()
      Gets the component stack of this component.
      Returns:
      the component stack of this component, never null.

    • start

      public boolean start(Writer writer)
      Callback for the start tag of this component. Should the body be evaluated?
      Parameters:
      writer - the output writer.
      Returns:
      true if the body should be evaluated

    • end

      public boolean end(Writer writer, String body)
      Callback for the end tag of this component. Should the body be evaluated again?
      NOTE: will pop component stack.
      Parameters:
      writer - the output writer.
      body - the rendered body.
      Returns:
      true if the body should be evaluated again

    • end

      protected boolean end(Writer writer, String body, boolean popComponentStack)
      Callback for the start tag of this component. Should the body be evaluated again?
      NOTE: has a parameter to determine to pop the component stack.
      Parameters:
      writer - the output writer.
      body - the rendered body.
      popComponentStack - should the component stack be popped?
      Returns:
      true if the body should be evaluated again

    • popComponentStack

      protected void popComponentStack()
      Pops the component stack.

    • findAncestor

      protected Component findAncestor(Class<?> clazz)
      Finds the nearest ancestor of this component stack.
      Parameters:
      clazz - the class to look for, or if assignable from.
      Returns:
      the component if found, null if not.

    • findString

      protected String findString(String expr)
      Evaluates the OGNL stack to find a String value.
      Parameters:
      expr - OGNL expression.
      Returns:
      the String value found.

    • findString

      protected String findString(String expr, String field, String errorMsg)
      Evaluates the OGNL stack to find a String value.
      If the given expression is null a error is logged and a RuntimeException is thrown constructed with a messaged based on the given field and errorMsg parameter.
      Parameters:
      expr - OGNL expression.
      field - field name used when throwing RuntimeException.
      errorMsg - error message used when throwing RuntimeException.
      Returns:
      the String value found.
      Throws:
      StrutsException - is thrown in case of expression is null.

    • fieldError

      protected StrutsException fieldError(String field, String errorMsg, Exception e)
      Constructs a RuntimeException based on the given information.
      A message is constructed and logged at ERROR level before being returned as a RuntimeException.
      Parameters:
      field - field name used when throwing RuntimeException.
      errorMsg - error message used when throwing RuntimeException.
      e - the caused exception, can be null.
      Returns:
      the constructed StrutsException.

    • findValue

      protected Object findValue(String expression)
      Finds a value from the OGNL stack based on the given expression. Will always evaluate expr against stack except when expr is null. If %{...} is applied, simply strip it off.
      Parameters:
      expression - the expression. Returns null if expr is null.
      Returns:
      the value, null if not found.

    • stripExpression

      protected String stripExpression(String expression)
      If %{...} is applied, simply strip the "%{" and "}" off.
      Parameters:
      expression - the expression (must be not null)
      Returns:
      the stripped expression

    • completeExpression

      protected String completeExpression(String expr)
      Adds the surrounding %{ } to the expression for proper processing.
      Parameters:
      expr - the expression.
      Returns:
      the modified expression wrapped with %{...}

    • findValue

      protected Object findValue(String expr, String field, String errorMsg)

      Evaluates the OGNL stack to find an Object value.

      Function just like findValue(String) except that if the given expression is null a error is logged and a RuntimeException is thrown constructed with a messaged based on the given field and errorMsg parameter.

      Parameters:
      expr - OGNL expression.
      field - field name used when throwing RuntimeException.
      errorMsg - error message used when throwing RuntimeException.
      Returns:
      the Object found, is never null.
      Throws:
      StrutsException - is thrown in case of not found in the OGNL stack, or expression is null.

    • findValue

      protected Object findValue(String expression, Class<?> toType)
      Evaluates the OGNL stack to find an Object of the given type. Will evaluate expression the portion wrapped with %{...} against stack if evaluating to String.class, else the whole expression is evaluated against the stack.
      Parameters:
      expression - OGNL expression.
      toType - the type expected to find.
      Returns:
      the Object found, or null if not found.

    • determineActionURL

      protected String determineActionURL(String action, String namespace, String method, jakarta.servlet.http.HttpServletRequest req, jakarta.servlet.http.HttpServletResponse res, Map<String,Object> parameters, String scheme, boolean includeContext, boolean encodeResult, boolean forceAddSchemeHostAndPort, boolean escapeAmp)
      Renders an action URL by consulting the ActionMapper.
      Parameters:
      action - the action
      namespace - the namespace
      method - the method
      req - HTTP request
      res - HTTP response
      parameters - parameters
      scheme - http or https
      includeContext - should the context path be included or not
      encodeResult - should the url be encoded
      forceAddSchemeHostAndPort - should the scheme host and port be forced
      escapeAmp - should ampersand (&) be escaped to &amp;
      Returns:
      the action url.

    • determineNamespace

      protected String determineNamespace(String namespace, ValueStack stack, jakarta.servlet.http.HttpServletRequest req)
      Determines the namespace of the current page being renderdd. Useful for Form, URL, and href generations.
      Parameters:
      namespace - the namespace
      stack - OGNL value stack
      req - HTTP request
      Returns:
      the namepsace of the current page being rendered, is never null.

    • getNamespace

      protected String getNamespace(ValueStack stack)

    • copyAttributes

      public void copyAttributes(Map<String,Object> attributesToCopy)
      Pushes this component's parameter Map as well as the component itself on to the stack and then copies the supplied parameters over. Because the component's parameter Map is pushed before the component itself, any key-value pair that can't be assigned to component will be set in the parameters Map.
      Parameters:
      attributesToCopy - the attributes to copy.

    • toString

      protected String toString(Throwable t)
      Constructs a string representation of the given exception.
      Parameters:
      t - the exception
      Returns:
      the exception as a string.

    • getAttributes

      public Map<String,Object> getAttributes()
      Gets the attributes.
      Returns:
      the attributes. It's never null.

    • addAllAttributes

      public void addAllAttributes(Map<String,Object> additionalAttributes)
      Adds all the given attributes to this component's own attributes.
      Parameters:
      additionalAttributes - the attributes to add.

    • addParameter

      public void addParameter(String key, Object value)
      Adds the given key and value to this component's own parameter.
      If the provided key is null nothing happens. If the provided value is null any existing parameter with the given key name is removed.
      Parameters:
      key - the key of the new parameter to add.
      value - the value associated with the key.

    • usesBody

      public boolean usesBody()
      Overwrite to set if body should be used.
      Returns:
      always false for this component.

    • escapeHtmlBody

      public boolean escapeHtmlBody()
      Override to set if body content should be HTML-escaped.
      Returns:
      always true (default) for this component.
      Since:
      6.0.0

    • isValidTagAttribute

      public boolean isValidTagAttribute(String attrName)
      Checks if provided name is a valid tag's attribute
      Parameters:
      attrName - String name of attribute
      Returns:
      true if attribute with the same name was already defined

    • getStandardAttributes

      protected Collection<String> getStandardAttributes()
      If needed caches all methods annotated by given annotation to avoid further scans
      Returns:
      list of attributes

    • setPerformClearTagStateForTagPoolingServers

      public void setPerformClearTagStateForTagPoolingServers(boolean performClearTagStateForTagPoolingServers)
      Request that the tag state be cleared during StrutsBodyTagSupport.doEndTag() processing, which may help with certain edge cases with tag logic running on servers that implement JSP Tag Pooling. Note: All Tag classes that extend StrutsBodyTagSupport must implement a setter for this attribute (same name), and it must be defined at the Tag class level. Defining a setter in the superclass alone is insufficient (results in "Cannot find a setter method for the attribute").

      See for additional details.

      Parameters:
      performClearTagStateForTagPoolingServers - true if tag state should be cleared, false otherwise.

    • getPerformClearTagStateForTagPoolingServers

      public boolean getPerformClearTagStateForTagPoolingServers()

    • isAcceptableExpression

      protected boolean isAcceptableExpression(String expression)
      Checks if expression doesn't contain vulnerable code
      Parameters:
      expression - of the component
      Returns:
      true|false
      Since:
      6.0.0