public abstract class JspContext extends Object
 JspContext serves as the base class for the
 PageContext class and abstracts all information that is not specific
 to servlets.  This allows for Simple Tag Extensions to be used
 outside of the context of a request/response Servlet.
 
The JspContext provides a number of facilities to the page/component author and page implementor, including:
Methods Intended for Container Generated Code
 The following methods enable the management of nested JspWriter
 streams to implement Tag Extensions: pushBody() and
 popBody()
 
Methods Intended for JSP authors
 Some methods provide uniform access to the diverse objects
 representing scopes.
 The implementation must use the underlying machinery
 corresponding to that scope, so information can be passed back and
 forth between the underlying environment (e.g. Servlets) and JSP pages.
 The methods are:
 setAttribute(),  getAttribute(),
 findAttribute(),  removeAttribute(),
 getAttributesScope() and
 getAttributeNamesInScope().
 
 The following methods provide convenient access to implicit objects:
 getOut()
 
 The following methods provide programmatic access to the
 Expression Language evaluator:
 getExpressionEvaluator(), getVariableResolver()
| Constructor and Description | 
|---|
| JspContext()Sole constructor. | 
| Modifier and Type | Method and Description | 
|---|---|
| abstract Object | findAttribute(String name)Searches for the named attribute in page, request, session (if valid),
 and application scope(s) in order and returns the value associated or
 null. | 
| abstract Object | getAttribute(String name)Returns the object associated with the name in the page scope or null
 if not found. | 
| abstract Object | getAttribute(String name,
            int scope)Return the object associated with the name in the specified
 scope or null if not found. | 
| abstract Enumeration<String> | getAttributeNamesInScope(int scope)Enumerate all the attributes in a given scope. | 
| abstract int | getAttributesScope(String name)Get the scope where a given attribute is defined. | 
| abstract ELContext | getELContext() | 
| abstract ExpressionEvaluator | getExpressionEvaluator()Deprecated. 
 As of JSP 2.1, replaced by
             JspApplicationContext.getExpressionFactory() | 
| abstract JspWriter | getOut()The current value of the out object (a JspWriter). | 
| abstract VariableResolver | getVariableResolver()Deprecated. 
 As of JSP 2.1,
             replaced by javax.el.ELContext.getELResolver()
             which can be obtained by
             jspContext.getELContext().getELResolver() | 
| JspWriter | popBody()Return the previous JspWriter "out" saved by the matching
 pushBody(), and update the value of the "out" attribute in
 the page scope attribute namespace of the JspContext. | 
| JspWriter | pushBody(Writer writer)Return a new JspWriter object that sends output to the
 provided Writer. | 
| abstract void | removeAttribute(String name)Remove the object reference associated with the given name
 from all scopes. | 
| abstract void | removeAttribute(String name,
               int scope)Remove the object reference associated with the specified name
 in the given scope. | 
| abstract void | setAttribute(String name,
            Object value)Register the name and value specified with page scope semantics. | 
| abstract void | setAttribute(String name,
            Object value,
            int scope)Register the name and value specified with appropriate
 scope semantics. | 
public JspContext()
public abstract void setAttribute(String name, Object value)
null, this has the same
 effect as calling
 removeAttribute( name, PageContext.PAGE_SCOPE ).name - the name of the attribute to setvalue - the value to associate with the name, or null if the
     attribute is to be removed from the page scope.NullPointerException - if the name is nullpublic abstract void setAttribute(String name, Object value, int scope)
null,
 this has the same effect as calling
 removeAttribute( name, scope ).name - the name of the attribute to setvalue - the object to associate with the name, or null if
     the attribute is to be removed from the specified scope.scope - the scope with which to associate the name/objectNullPointerException - if the name is nullIllegalArgumentException - if the scope is invalidIllegalStateException - if the scope is
     PageContext.SESSION_SCOPE but the page that was requested
     does not participate in a session or the session has been
     invalidated.public abstract Object getAttribute(String name)
name - the name of the attribute to getNullPointerException - if the name is nullpublic abstract Object getAttribute(String name, int scope)
name - the name of the attribute to setscope - the scope with which to associate the name/objectNullPointerException - if the name is nullIllegalArgumentException - if the scope is invalidIllegalStateException - if the scope is
     PageContext.SESSION_SCOPE but the page that was requested
     does not participate in a session or the session has been
     invalidated.public abstract Object findAttribute(String name)
name - the name of the attribute to search forNullPointerException - if the name is nullpublic abstract void removeAttribute(String name)
name - The name of the object to remove.NullPointerException - if the name is nullpublic abstract void removeAttribute(String name, int scope)
name - The name of the object to remove.scope - The scope where to look.IllegalArgumentException - if the scope is invalidIllegalStateException - if the scope is
     PageContext.SESSION_SCOPE but the page that was requested
     does not participate in a session or the session has been
     invalidated.NullPointerException - if the name is nullpublic abstract int getAttributesScope(String name)
name - the name of the attribute to return the scope forNullPointerException - if the name is nullpublic abstract Enumeration<String> getAttributeNamesInScope(int scope)
scope - the scope to enumerate all the attributes forIllegalArgumentException - if the scope is invalidIllegalStateException - if the scope is
     PageContext.SESSION_SCOPE but the page that was requested
     does not participate in a session or the session has been
     invalidated.public abstract JspWriter getOut()
public abstract ExpressionEvaluator getExpressionEvaluator()
public abstract ELContext getELContext()
public abstract VariableResolver getVariableResolver()
public JspWriter pushBody(Writer writer)
The returned JspWriter must implement all methods and behave as though it were unbuffered. More specifically:
writer - The Writer for the returned JspWriter to send
     output to.public JspWriter popBody()
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