Package org.apache.openjpa.lib.util

Class Options

  • All Implemented Interfaces:
    Serializable, Cloneable, Map<Object,​Object>
    public class Options
extends TypedProperties
    A specialization of the Properties map type with the added abilities to read application options from the command line and to use bean patterns to set an object's properties via command-line the stored mappings. A typical use pattern for this class is to construct a new instance in the main method, then call setFromCmdLine(java.lang.String[]) with the given args. Next, an instanceof the class being invoked is created, and setInto(java.lang.Object) is called with that instance as a parameter. With this pattern, the user can configure any bean properties of the class, or even properties of classes reachable from the class, through the command line.
    Author:
    Abe White
    See Also:
    Serialized Form

    • Field Detail

      • EMPTY

        public static Options EMPTY
        Immutable empty instance.

    • Constructor Detail

      • Options

        public Options()
        Default constructor.

    • Method Detail

      • setFromCmdLine

        public String[] setFromCmdLine​(String[] args)
        Parses the given argument list into flag/value pairs, which are stored as properties. Flags that are present without values are given the value "true". If any flag is found for which there is already a mapping present, the existing mapping will be overwritten. Flags should be of the form:
        java Foo -flag1 value1 -flag2 value2 ... arg1 arg2 ...
        Parameters:
        args - the command-line arguments
        Returns:
        all arguments in the original array beyond the flag/value pair list

      • setInto

        public Options setInto​(Object obj)
        This method uses reflection to set all the properties in the given object that are named by the keys in this map. For a given key 'foo', the algorithm will look for a 'setFoo' method in the given instance. For a given key 'foo.bar', the algorithm will first look for a 'getFoo' method in the given instance, then will recurse on the return value of that method, now looking for the 'bar' property. This allows the setting of nested object properties. If in the above example the 'getFoo' method is not present or returns null, the algorithm will look for a 'setFoo' method; if found it will constrct a new instance of the correct type, set it using the 'setFoo' method, then recurse on it as above. Property names can be nested in this way to an arbitrary depth. For setter methods that take multiple parameters, the value mapped to the key can use the ',' as an argument separator character. If not enough values are present for a given method after splitting the string on ',', the remaining arguments will receive default values. All arguments are converted from string form to the correct type if possible(i.e. if the type is primitive, java.lang.Clas, or has a constructor that takes a single string argument). Examples:
        • Map Entry: "age"->"12"
          Resultant method call: obj.setAge(12)
        • Map Entry: "range"->"1,20"
          Resultant method call: obj.setRange(1, 20)
        • Map Entry: "range"->"10"
          Resultant method call: obj.setRange(10, 10)
        • Map Entry: "brother.name"->"Bob"
          Resultant method call: obj.getBrother().setName("Bob")
        Any keys present in the map for which there is no corresponding property in the given object will be ignored, and will be returned in the Map returned by this method.
        Returns:
        an Options of key-value pairs in this object for which no setters could be found.
        Throws:
        RuntimeException - on parse error

      • findOptionsFor

        public static Collection<String> findOptionsFor​(Class<?> type)
        Finds all the options that can be set on the provided class. This does not look for path-traversal expressions.
        Parameters:
        type - The class for which available options should be listed.
        Returns:
        The available option names in type. The names will have initial caps. They will be ordered alphabetically.

      • removeProperty

        public String removeProperty​(String key,
                             String key2,
                             String def)
        Specialization of Properties.remove(Object) to allow a value to appear under either of two keys; useful for short and long versions of command-line flags.