接口 ValueStack：com.opensymphony.xwork2.util

相关阅读：

在 Struts 2 中自定义支持 OGNL 的标签：http://blog.csdn.net/ieayoio/article/details/49721587

API：http://www.boyunjian.com/javadoc/com.opensymphony/xwork-core/2.1.6/_/com/opensymphony/xwork2/util/ValueStack.html

com.opensymphony.xwork2.util

接口 ValueStack

• 所有已知实现类:

  OgnlValueStack

  ---

  
  

  public interface ValueStack

  ValueStack allows multiple beans to be pushed in and dynamic EL expressions to be evaluated against it. When evaluating an expression, the stack will be searched down the stack, from the latest objects pushed in to the earliest, looking for a bean with a getter or setter for the given property or a method of the given name (depending on the expression being evaluated).

• • 字段概要

    字段 限定符和类型字段和说明static java.lang.StringREPORT_ERRORS_ON_NO_PROP static java.lang.StringVALUE_STACK 

  • 方法概要

    方法 限定符和类型方法和说明java.lang.StringfindString(java.lang.String expr) java.lang.StringfindString(java.lang.String expr, boolean throwExceptionOnFailure) java.lang.ObjectfindValue(java.lang.String expr)
    Find a value by evaluating the given expression against the stack in the default search order.
    java.lang.ObjectfindValue(java.lang.String expr, boolean throwExceptionOnFailure) java.lang.ObjectfindValue(java.lang.String expr, java.lang.Class asType)
    Find a value by evaluating the given expression against the stack in the default search order.
    java.lang.ObjectfindValue(java.lang.String expr, java.lang.Class asType, boolean throwExceptionOnFailure) java.util.Map<java.lang.String,java.lang.Object>getContext()
    Gets the context for this value stack.
    java.util.Map<java.lang.Object,java.lang.Object>getExprOverrides()
    Gets the override map if anyone exists.
    CompoundRootgetRoot()
    Get the CompoundRoot which holds the objects pushed onto the stack
    java.lang.Objectpeek()
    Get the object on the top of the stack without changing the stack.
    java.lang.Objectpop()
    Get the object on the top of the stack and remove it from the stack.
    voidpush(java.lang.Object o)
    Put this object onto the top of the stack
    voidset(java.lang.String key, java.lang.Object o)
    Sets an object on the stack with the given key so it is retrievable by findValue(String),findValue(String, Class)
    voidsetDefaultType(java.lang.Class defaultType)
    Sets the default type to convert to if no type is provided when getting a value.
    voidsetExprOverrides(java.util.Map<java.lang.Object,java.lang.Object> overrides)
    Set a override map containing key -> values that takes precedent when doing find operations on the ValueStack.
    voidsetValue(java.lang.String expr, java.lang.Object value)
    Attempts to set a property on a bean in the stack with the given expression using the default search order.
    voidsetValue(java.lang.String expr, java.lang.Object value, boolean throwExceptionOnFailure)
    Attempts to set a property on a bean in the stack with the given expression using the default search order.
    intsize()
    Get the number of objects in the stack

• • 字段详细资料

    • VALUE_STACK

      static final java.lang.String VALUE_STACK

      另请参阅:

      常量字段值

    • REPORT_ERRORS_ON_NO_PROP

      static final java.lang.String REPORT_ERRORS_ON_NO_PROP

      另请参阅:

      常量字段值

  • 方法详细资料

    • getContext

      java.util.Map<java.lang.String,java.lang.Object> getContext()

      Gets the context for this value stack. The context holds all the information in the value stack and it's surroundings.

      返回:

      the context.

    • setDefaultType

      void setDefaultType(java.lang.Class defaultType)

      Sets the default type to convert to if no type is provided when getting a value.

      参数:

      defaultType - the new default type

    • setExprOverrides

      void setExprOverrides(java.util.Map<java.lang.Object,java.lang.Object> overrides)

      Set a override map containing key -> values that takes precedent when doing find operations on the ValueStack.

      See the unit test for ValueStackTest for examples.

      参数:

      overrides - overrides map.

    • getExprOverrides

      java.util.Map<java.lang.Object,java.lang.Object> getExprOverrides()

      Gets the override map if anyone exists.

      返回:

      the override map, null if not set.

    • getRoot

      CompoundRoot getRoot()

      Get the CompoundRoot which holds the objects pushed onto the stack

      返回:

      the root

    • setValue

      void setValue(java.lang.String expr,            java.lang.Object value)

      Attempts to set a property on a bean in the stack with the given expression using the default search order.

      参数:

      expr - the expression defining the path to the property to be set.

      value - the value to be set into the named property

    • setValue

      void setValue(java.lang.String expr,            java.lang.Object value,            boolean throwExceptionOnFailure)

      Attempts to set a property on a bean in the stack with the given expression using the default search order.

      参数:

      expr - the expression defining the path to the property to be set.

      value - the value to be set into the named property

      throwExceptionOnFailure - a flag to tell whether an exception should be thrown if there is no property with the given name.

    • findString

      java.lang.String findString(java.lang.String expr)

    • findString

      java.lang.String findString(java.lang.String expr,                          boolean throwExceptionOnFailure)

    • findValue

      java.lang.Object findValue(java.lang.String expr)

      Find a value by evaluating the given expression against the stack in the default search order.

      参数:

      expr - the expression giving the path of properties to navigate to find the property value to return

      返回:

      the result of evaluating the expression

    • findValue

      java.lang.Object findValue(java.lang.String expr,                         boolean throwExceptionOnFailure)

    • findValue

      java.lang.Object findValue(java.lang.String expr,                         java.lang.Class asType)

      Find a value by evaluating the given expression against the stack in the default search order.

      参数:

      expr - the expression giving the path of properties to navigate to find the property value to return

      asType - the type to convert the return value to

      返回:

      the result of evaluating the expression

    • findValue

      java.lang.Object findValue(java.lang.String expr,                         java.lang.Class asType,                         boolean throwExceptionOnFailure)

    • peek

      java.lang.Object peek()

      Get the object on the top of the stack without changing the stack.

      返回:

      the object on the top.

      另请参阅:

      CompoundRoot.peek()

    • pop

      java.lang.Object pop()

      Get the object on the top of the stack and remove it from the stack.

      返回:

      the object on the top of the stack

      另请参阅:

      CompoundRoot.pop()

    • push

      void push(java.lang.Object o)

      Put this object onto the top of the stack

      参数:

      o - the object to be pushed onto the stack

      另请参阅:

      CompoundRoot.push(Object)

    • set

      void set(java.lang.String key,       java.lang.Object o)

      Sets an object on the stack with the given key so it is retrievable by findValue(String), findValue(String, Class)

      参数:

      key - the key

      o - the object

    • size

      int size()

      Get the number of objects in the stack

      返回:

      the number of objects in the stack