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javax.servlet.jsp
abstract public class: JspContext [javadoc | source]
java.lang.Object
   javax.servlet.jsp.JspContext

Direct Known Subclasses:
    PageContext

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:
 public JspContext() 
Method from javax.servlet.jsp.JspContext Summary:
findAttribute,   getAttribute,   getAttribute,   getAttributeNamesInScope,   getAttributesScope,   getELContext,   getExpressionEvaluator,   getOut,   getVariableResolver,   popBody,   pushBody,   removeAttribute,   removeAttribute,   setAttribute,   setAttribute
Methods from java.lang.Object:
clone,   equals,   finalize,   getClass,   hashCode,   notify,   notifyAll,   toString,   wait,   wait,   wait
Method from javax.servlet.jsp.JspContext Detail:
 abstract public 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 public Object getAttribute(String name)
    Returns the object associated with the name in the page scope or null if not found.
 abstract public Object getAttribute(String name,
    int scope)
    Return the object associated with the name in the specified scope or null if not found.
 abstract public Enumeration<String> getAttributeNamesInScope(int scope)
    Enumerate all the attributes in a given scope.
 abstract public int getAttributesScope(String name)
    Get the scope where a given attribute is defined.
 abstract public ELContext getELContext()
 abstract public ExpressionEvaluator getExpressionEvaluator()Deprecated! As -  of JSP 2.1, replaced by
            JspApplicationContext.getExpressionFactory()

    Provides programmatic access to the ExpressionEvaluator. The JSP Container must return a valid instance of an ExpressionEvaluator that can parse EL expressions.
 abstract public JspWriter getOut()
    The current value of the out object (a JspWriter).
 abstract public VariableResolver getVariableResolver()Deprecated! As -  of JSP 2.1,
            replaced by javax.el.ELContext.getELResolver()
            which can be obtained by
            jspContext.getELContext().getELResolver()

    Returns an instance of a VariableResolver that provides access to the implicit objects specified in the JSP specification using this JspContext as the context object.
 public 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.
 public JspWriter pushBody(Writer writer) 
    Return a new JspWriter object that sends output to the provided Writer. Saves the current "out" JspWriter, and updates the value of the "out" attribute in the page scope attribute namespace of the JspContext.

    The returned JspWriter must implement all methods and behave as though it were unbuffered. More specifically:

    • clear() must throw an IOException
    • clearBuffer() does nothing
    • getBufferSize() always returns 0
    • getRemaining() always returns 0

 abstract public  void removeAttribute(String name)
    Remove the object reference associated with the given name from all scopes. Does nothing if there is no such object.
 abstract public  void removeAttribute(String name,
    int scope)
    Remove the object reference associated with the specified name in the given scope. Does nothing if there is no such object.
 abstract public  void setAttribute(String name,
    Object value)
    Register the name and value specified with page scope semantics. If the value passed in is null, this has the same effect as calling removeAttribute( name, PageContext.PAGE_SCOPE ).
 abstract public  void setAttribute(String name,
    Object value,
    int scope)
    Register the name and value specified with appropriate scope semantics. If the value passed in is null, this has the same effect as calling removeAttribute( name, scope ).