Class Ognl

java.lang.Object
ognl.Ognl
public abstract class Ognl extends Object
This class provides static methods for parsing and interpreting OGNL expressions. The simplest use of the Ognl class is to get the value of an expression from an object, without extra context or pre-parsing. 
import ognl.Ognl; import ognl.OgnlException; try { result = Ognl.getValue(expression, root); }
catch (OgnlException ex) { // Report error or recover }

This will parse the expression given and evaluate it against the root object given, returning the result. If there is an error in the expression, such as the property is not found, the exception is encapsulated into an OgnlException.

Other more sophisticated uses of Ognl can pre-parse expressions. This provides two advantages: in the case of user-supplied expressions it allows you to catch parse errors before evaluation and it allows you to cache parsed expressions into an AST for better speed during repeated use. The pre-parsed expression is always returned as an Object to simplify use for programs that just wish to store the value for repeated use and do not care that it is an AST. If it does care it can always safely cast the value to an AST type.

The Ognl class also takes a context map as one of the parameters to the set and get methods. This allows you to put your own variables into the available namespace for OGNL expressions. The default context contains only the #root and #context keys, which are required to be present. The addDefaultContext(Object, Map) method will alter an existing Map to put the defaults in. Here is an example that shows how to extract the documentName property out of the root object and append a string with the current user name in parens: 

private Map context = new HashMap(); public void setUserName(String value) {
context.put("userName", value); } try { // get value using our own custom context map result =
Ognl.getValue("documentName + \" (\" + ((#userName == null) ? \"<nobody>\" : #userName) +
\")\"", context, root); } catch (OgnlException ex) { // Report error or recover }

  • Field Details

    • expressionMaxLength

      private static volatile Integer expressionMaxLength

    • expressionMaxLengthFrozen

      private static volatile Boolean expressionMaxLengthFrozen

  • Constructor Details

    • Ognl

      private Ognl()
      You can't make one of these.

  • Method Details

    • applyExpressionMaxLength

      public static void applyExpressionMaxLength(Integer expressionMaxLength)
      Applies a maximum allowed length on OGNL expressions for security reasons.
      Parameters:
      expressionMaxLength - the OGNL expressions maximum allowed length. Use null (default) to disable this functionality.
      Throws:
      SecurityException - if the caller is inside OGNL expression itself.
      IllegalStateException - if the expression maximum allowed length is frozen.
      IllegalArgumentException - if the provided expressionMaxLength is < 0.
      Since:
      3.1.26

    • freezeExpressionMaxLength

      public static void freezeExpressionMaxLength()
      Freezes (prevents updates to) the maximum allowed length on OGNL expressions at the current value. This makes it clear to other OGNL callers that the value should not be changed.
      Throws:
      SecurityException - if the caller is inside OGNL expression itself.
      Since:
      3.1.26

    • thawExpressionMaxLength

      public static void thawExpressionMaxLength()
      Thaws (allows updates to) the maximum allowed length on OGNL expressions. This makes it clear to other OGNL callers that the value can (again) be changed.
      Throws:
      SecurityException - if the caller is inside OGNL expression itself.
      Since:
      3.1.26

    • parseExpression

      public static Object parseExpression(String expression) throws OgnlException
      Parses the given OGNL expression and returns a tree representation of the expression that can be used by Ognl static methods.
      Parameters:
      expression - the OGNL expression to be parsed
      Returns:
      a tree representation of the expression
      Throws:
      ExpressionSyntaxException - if the expression is malformed
      OgnlException - if there is a pathological environmental problem

    • compileExpression

      public static Node compileExpression(OgnlContext context, Object root, String expression) throws Exception
      Parses and compiles the given expression using the OgnlExpressionCompiler returned from OgnlRuntime.getCompiler().
      Parameters:
      context - The context to use.
      root - The root object for the given expression.
      expression - The expression to compile.
      Returns:
      The node with a compiled accessor set on Node.getAccessor() if compilation was successfull. In instances where compilation wasn't possible because of a partially null expression the ExpressionAccessor instance may be null and the compilation of this expression still possible at some as yet indertermined point in the future.
      Throws:
      Exception - If a compilation error occurs.

    • createDefaultContext

      public static OgnlContext createDefaultContext(Object root)
      Creates and returns a new standard naming context for evaluating an OGNL expression.
      Parameters:
      root - the root of the object graph
      Returns:
      a new OgnlContext with the keys root and context set appropriately

    • createDefaultContext

      public static OgnlContext createDefaultContext(Object root, Map<String,Object> values)
      Creates and returns a new standard naming context for evaluating an OGNL expression.
      Parameters:
      root - the root of the object graph
      Returns:
      a new OgnlContext with the keys root and context set appropriately

    • createDefaultContext

      public static OgnlContext createDefaultContext(Object root, ClassResolver classResolver)
      Creates and returns a new standard naming context for evaluating an OGNL expression.
      Parameters:
      root - The root of the object graph.
      classResolver - The resolver used to instantiate Class instances referenced in the expression.
      Returns:
      a new OgnlContext with the keys root and context set appropriately

    • createDefaultContext

      public static OgnlContext createDefaultContext(Object root, ClassResolver classResolver, TypeConverter converter)
      Creates and returns a new standard naming context for evaluating an OGNL expression.
      Parameters:
      root - The root of the object graph.
      classResolver - The resolver used to instantiate Class instances referenced in the expression.
      converter - Converter used to convert return types of an expression in to their desired types.
      Returns:
      a new OgnlContext with the keys root and context set appropriately

    • createDefaultContext

      public static OgnlContext createDefaultContext(Object root, MemberAccess memberAccess, ClassResolver classResolver, TypeConverter converter)
      Creates and returns a new standard naming context for evaluating an OGNL expression.
      Parameters:
      root - The root of the object graph.
      memberAccess - Java security handling object to determine semantics for accessing normally private/protected methods / fields.
      classResolver - The resolver used to instantiate Class instances referenced in the expression.
      converter - Converter used to convert return types of an expression in to their desired types.
      Returns:
      a new OgnlContext with the keys root and context set appropriately

    • createDefaultContext

      public static OgnlContext createDefaultContext(Object root, MemberAccess memberAccess)
      Creates and returns a new standard naming context for evaluating an OGNL expression.
      Parameters:
      root - The root of the object graph.
      memberAccess - Java security handling object to determine semantics for accessing normally private/protected methods / fields.
      Returns:
      a new OgnlContext with the keys root and context set appropriately

    • addDefaultContext

      public static OgnlContext addDefaultContext(Object root, OgnlContext context)
      Appends the standard naming context for evaluating an OGNL expression into the context given so that cached maps can be used as a context.
      Parameters:
      root - the root of the object graph
      context - the context to which OGNL context will be added.
      Returns:
      OgnlContext with the keys root and context set appropriately

    • addDefaultContext

      public static OgnlContext addDefaultContext(Object root, ClassResolver classResolver, OgnlContext context)
      Appends the standard naming context for evaluating an OGNL expression into the context given so that cached maps can be used as a context.
      Parameters:
      root - The root of the object graph.
      classResolver - The resolver used to instantiate Class instances referenced in the expression.
      context - The context to which OGNL context will be added.
      Returns:
      Context Map with the keys root and context set appropriately

    • addDefaultContext

      public static OgnlContext addDefaultContext(Object root, ClassResolver classResolver, TypeConverter converter, OgnlContext context)
      Appends the standard naming context for evaluating an OGNL expression into the context given so that cached maps can be used as a context.
      Parameters:
      root - The root of the object graph.
      classResolver - The resolver used to instantiate Class instances referenced in the expression.
      converter - Converter used to convert return types of an expression in to their desired types.
      context - The context to which OGNL context will be added.
      Returns:
      Context Map with the keys root and context set appropriately

    • addDefaultContext

      public static OgnlContext addDefaultContext(Object root, MemberAccess memberAccess, ClassResolver classResolver, TypeConverter converter, OgnlContext initialContext)
      Appends the standard naming context for evaluating an OGNL expression into the context given so that cached maps can be used as a context.
      Parameters:
      root - the root of the object graph
      memberAccess - Definition for handling private/protected access.
      classResolver - The class loading resolver that should be used to resolve class references.
      converter - The type converter to be used by default.
      initialContext - Default context to use, if not an OgnlContext will be dumped into a new OgnlContext object.
      Returns:
      Context Map with the keys root and context set appropriately

    • getTypeConverter

      public static TypeConverter getTypeConverter(OgnlContext context)
      Gets the currently configured TypeConverter for the given context - if any.
      Parameters:
      context - The context to get the converter from.
      Returns:
      The converter - or null if none found.

    • setRoot

      public static void setRoot(OgnlContext context, Object root)
      Sets the root object to use for all expressions in the given context - doesn't necessarily replace root object instances explicitly passed in to other expression resolving methods on this class.
      Parameters:
      context - The context to store the root object in.
      root - The root object.

    • getRoot

      public static Object getRoot(OgnlContext context)
      Gets the stored root object for the given context - if any.
      Parameters:
      context - The context to get the root object from.
      Returns:
      The root object - or null if none found.

    • getLastEvaluation

      public static Evaluation getLastEvaluation(OgnlContext context)
      Gets the last Evaluation executed on the given context.
      Parameters:
      context - The context to get the evaluation from.
      Returns:
      The Evaluation - or null if none was found.

    • getValue

      public static Object getValue(Object tree, OgnlContext context, Object root) throws OgnlException
      Evaluates the given OGNL expression tree to extract a value from the given root object. The default context is set for the given context and root via addDefaultContext().
      Parameters:
      tree - the OGNL expression tree to evaluate, as returned by parseExpression()
      context - the naming context for the evaluation
      root - the root object for the OGNL expression
      Returns:
      the result of evaluating the expression
      Throws:
      MethodFailedException - if the expression called a method which failed
      NoSuchPropertyException - if the expression referred to a nonexistent property
      InappropriateExpressionException - if the expression can't be used in this context
      OgnlException - if there is a pathological environmental problem

    • getValue

      public static Object getValue(Object tree, OgnlContext context, Object root, Class<?> resultType) throws OgnlException
      Evaluates the given OGNL expression tree to extract a value from the given root object. The default context is set for the given context and root via addDefaultContext().
      Parameters:
      tree - the OGNL expression tree to evaluate, as returned by parseExpression()
      context - the naming context for the evaluation
      root - the root object for the OGNL expression
      resultType - the converted type of the resultant object, using the context's type converter
      Returns:
      the result of evaluating the expression
      Throws:
      MethodFailedException - if the expression called a method which failed
      NoSuchPropertyException - if the expression referred to a nonexistent property
      InappropriateExpressionException - if the expression can't be used in this context
      OgnlException - if there is a pathological environmental problem

    • getValue

      public static Object getValue(ExpressionAccessor expression, OgnlContext context, Object root)
      Gets the value represented by the given pre-compiled expression on the specified root object.
      Parameters:
      expression - The pre-compiled expression, as found in Node.getAccessor().
      context - The ognl context.
      root - The object to retrieve the expression value from.
      Returns:
      The value.

    • getValue

      public static Object getValue(ExpressionAccessor expression, OgnlContext context, Object root, Class<?> resultType)
      Gets the value represented by the given pre-compiled expression on the specified root object.
      Parameters:
      expression - The pre-compiled expression, as found in Node.getAccessor().
      context - The ognl context.
      root - The object to retrieve the expression value from.
      resultType - The desired object type that the return value should be converted to using the getTypeConverter(OgnlContext) }.
      Returns:
      The value.

    • getValue

      public static Object getValue(String expression, OgnlContext context, Object root) throws OgnlException
      Evaluates the given OGNL expression to extract a value from the given root object in a given context
      Parameters:
      expression - the OGNL expression to be parsed
      context - the naming context for the evaluation
      root - the root object for the OGNL expression
      Returns:
      the result of evaluating the expression
      Throws:
      MethodFailedException - if the expression called a method which failed
      NoSuchPropertyException - if the expression referred to a nonexistent property
      InappropriateExpressionException - if the expression can't be used in this context
      OgnlException - if there is a pathological environmental problem
      See Also:

    • getValue

      public static Object getValue(String expression, OgnlContext context, Object root, Class<?> resultType) throws OgnlException
      Evaluates the given OGNL expression to extract a value from the given root object in a given context
      Parameters:
      expression - the OGNL expression to be parsed
      context - the naming context for the evaluation
      root - the root object for the OGNL expression
      resultType - the converted type of the resultant object, using the context's type converter
      Returns:
      the result of evaluating the expression
      Throws:
      MethodFailedException - if the expression called a method which failed
      NoSuchPropertyException - if the expression referred to a nonexistent property
      InappropriateExpressionException - if the expression can't be used in this context
      OgnlException - if there is a pathological environmental problem
      See Also:

    • getValue

      public static Object getValue(Object tree, Object root) throws OgnlException
      Evaluates the given OGNL expression tree to extract a value from the given root object.
      Parameters:
      tree - the OGNL expression tree to evaluate, as returned by parseExpression()
      root - the root object for the OGNL expression
      Returns:
      the result of evaluating the expression
      Throws:
      MethodFailedException - if the expression called a method which failed
      NoSuchPropertyException - if the expression referred to a nonexistent property
      InappropriateExpressionException - if the expression can't be used in this context
      OgnlException - if there is a pathological environmental problem

    • getValue

      public static Object getValue(Object tree, Object root, Class<?> resultType) throws OgnlException
      Evaluates the given OGNL expression tree to extract a value from the given root object.
      Parameters:
      tree - the OGNL expression tree to evaluate, as returned by parseExpression()
      root - the root object for the OGNL expression
      resultType - the converted type of the resultant object, using the context's type converter
      Returns:
      the result of evaluating the expression
      Throws:
      MethodFailedException - if the expression called a method which failed
      NoSuchPropertyException - if the expression referred to a nonexistent property
      InappropriateExpressionException - if the expression can't be used in this context
      OgnlException - if there is a pathological environmental problem

    • getValue

      public static Object getValue(String expression, Object root) throws OgnlException
      Convenience method that combines calls to parseExpression and getValue.
      Parameters:
      expression - the OGNL expression to be parsed
      root - the root object for the OGNL expression
      Returns:
      the result of evaluating the expression
      Throws:
      ExpressionSyntaxException - if the expression is malformed
      MethodFailedException - if the expression called a method which failed
      NoSuchPropertyException - if the expression referred to a nonexistent property
      InappropriateExpressionException - if the expression can't be used in this context
      OgnlException - if there is a pathological environmental problem
      See Also:

    • getValue

      public static Object getValue(String expression, Object root, Class<?> resultType) throws OgnlException
      Convenience method that combines calls to parseExpression and getValue.
      Parameters:
      expression - the OGNL expression to be parsed
      root - the root object for the OGNL expression
      resultType - the converted type of the resultant object, using the context's type converter
      Returns:
      the result of evaluating the expression
      Throws:
      ExpressionSyntaxException - if the expression is malformed
      MethodFailedException - if the expression called a method which failed
      NoSuchPropertyException - if the expression referred to a nonexistent property
      InappropriateExpressionException - if the expression can't be used in this context
      OgnlException - if there is a pathological environmental problem
      See Also:

    • setValue

      public static void setValue(Object tree, OgnlContext context, Object root, Object value) throws OgnlException
      Evaluates the given OGNL expression tree to insert a value into the object graph rooted at the given root object. The default context is set for the given context and root via addDefaultContext().
      Parameters:
      tree - the OGNL expression tree to evaluate, as returned by parseExpression()
      context - the naming context for the evaluation
      root - the root object for the OGNL expression
      value - the value to insert into the object graph
      Throws:
      MethodFailedException - if the expression called a method which failed
      NoSuchPropertyException - if the expression referred to a nonexistent property
      InappropriateExpressionException - if the expression can't be used in this context
      OgnlException - if there is a pathological environmental problem

    • setValue

      public static void setValue(ExpressionAccessor expression, OgnlContext context, Object root, Object value)
      Sets the value given using the pre-compiled expression on the specified root object.
      Parameters:
      expression - The pre-compiled expression, as found in Node.getAccessor().
      context - The ognl context.
      root - The object to set the expression value on.
      value - The value to set.

    • setValue

      public static void setValue(String expression, OgnlContext context, Object root, Object value) throws OgnlException
      Evaluates the given OGNL expression to insert a value into the object graph rooted at the given root object given the context.
      Parameters:
      expression - the OGNL expression to be parsed
      context - the naming context for the evaluation
      root - the root object for the OGNL expression
      value - the value to insert into the object graph
      Throws:
      MethodFailedException - if the expression called a method which failed
      NoSuchPropertyException - if the expression referred to a nonexistent property
      InappropriateExpressionException - if the expression can't be used in this context
      OgnlException - if there is a pathological environmental problem

    • setValue

      public static void setValue(Object tree, Object root, Object value) throws OgnlException
      Evaluates the given OGNL expression tree to insert a value into the object graph rooted at the given root object.
      Parameters:
      tree - the OGNL expression tree to evaluate, as returned by parseExpression()
      root - the root object for the OGNL expression
      value - the value to insert into the object graph
      Throws:
      MethodFailedException - if the expression called a method which failed
      NoSuchPropertyException - if the expression referred to a nonexistent property
      InappropriateExpressionException - if the expression can't be used in this context
      OgnlException - if there is a pathological environmental problem

    • setValue

      public static void setValue(String expression, Object root, Object value) throws OgnlException
      Convenience method that combines calls to parseExpression and setValue.
      Parameters:
      expression - the OGNL expression to be parsed
      root - the root object for the OGNL expression
      value - the value to insert into the object graph
      Throws:
      ExpressionSyntaxException - if the expression is malformed
      MethodFailedException - if the expression called a method which failed
      NoSuchPropertyException - if the expression referred to a nonexistent property
      InappropriateExpressionException - if the expression can't be used in this context
      OgnlException - if there is a pathological environmental problem
      See Also:

    • isConstant

      public static boolean isConstant(Object tree, OgnlContext context) throws OgnlException
      Checks if the specified Node instance represents a constant expression.
      Parameters:
      tree - The Node to check.
      context - The context to use.
      Returns:
      True if the node is a constant - false otherwise.
      Throws:
      OgnlException - If an error occurs checking the expression.

    • isConstant

      public static boolean isConstant(String expression, OgnlContext context) throws OgnlException
      Checks if the specified expression represents a constant expression.
      Parameters:
      expression - The expression to check.
      context - The context to use.
      Returns:
      True if the node is a constant - false otherwise.
      Throws:
      OgnlException - If an error occurs checking the expression.

    • isConstant

      public static boolean isConstant(Object tree) throws OgnlException
      Same as isConstant(String, OgnlContext) - only the Map context is created for you.
      Parameters:
      tree - The Node to check.
      Returns:
      True if the node represents a constant expression - false otherwise.
      Throws:
      OgnlException - If an exception occurs.

    • isConstant

      public static boolean isConstant(String expression) throws OgnlException
      Same as isConstant(String, OgnlContext) - only the Map instance is created for you.
      Parameters:
      expression - The expression to check.
      Returns:
      True if the expression represents a constant - false otherwise.
      Throws:
      OgnlException - If an exception occurs.

    • isSimpleProperty

      public static boolean isSimpleProperty(Object tree, OgnlContext context) throws OgnlException
      Throws:
      OgnlException

    • isSimpleProperty

      public static boolean isSimpleProperty(String expression, OgnlContext context) throws OgnlException
      Throws:
      OgnlException

    • isSimpleProperty

      public static boolean isSimpleProperty(Object tree) throws OgnlException
      Throws:
      OgnlException

    • isSimpleProperty

      public static boolean isSimpleProperty(String expression) throws OgnlException
      Throws:
      OgnlException

    • isSimpleNavigationChain

      public static boolean isSimpleNavigationChain(Object tree, OgnlContext context) throws OgnlException
      Throws:
      OgnlException

    • isSimpleNavigationChain

      public static boolean isSimpleNavigationChain(String expression, OgnlContext context) throws OgnlException
      Throws:
      OgnlException

    • isSimpleNavigationChain

      public static boolean isSimpleNavigationChain(Object tree) throws OgnlException
      Throws:
      OgnlException

    • isSimpleNavigationChain

      public static boolean isSimpleNavigationChain(String expression) throws OgnlException
      Throws:
      OgnlException