Package org.apache.velocity.tools.generic

Class LinkTool

  • All Implemented Interfaces:
    Cloneable
    Direct Known Subclasses:
    LinkTool
    @DefaultKey("link")
@SkipSetters
@ValidScope("request")
public class LinkTool
extends SafeConfig
implements Cloneable

    The LinkTool provides many methods to work with URIs and can help you:

    • construct full URIs (opaque, absolute or relative)
    • encode and decode URLs (part or whole)
    • retrieve path info for the current request
    • and more..

    This GenericTools (i.e. non-servlet based) version of LinkTool is largely based upon the same API and behavior as the older VelocityView version, with a few differences, particularly in internal representation and query handling. You can expect that in the future work will be done to more closely align the APIs. It is likely that the VelocityView version will become a subclass of this version that adds on servlet-awareness and related features. For now, though, they are entirely separate but similar tools.

    The LinkTool is somewhat special in that nearly all public methods return a new instance of LinkTool. This facilitates greatly the repeated use of the LinkTool in Velocity and leads to an elegant syntax.

     Template example(s):
   #set( $base = $link.relative('MyPage.vm').anchor('view') )
   <a href="$base.param('select','this')">this</a>
   <a href="$base.param('select','that')">that</a>

 Toolbox configuration:
 <tools>
   <toolbox scope="request">
     <tool class="org.apache.velocity.tools.generic.LinkTool"
              uri="http://velocity.apache.org/tools/devel/"/>
   </toolbox>
 </tools>

    Since:
    VelocityTools 2.0
    Version:
    $Id: LinkTool.java 601976 2007-12-07 03:50:51Z nbubna $
    Author:
    Nathan Bubna

    • Constructor Detail

      • LinkTool

        public LinkTool()
        Default constructor. Tool typically is configured before use.

    • Method Detail

      • debug

        protected final void debug​(String msg,
                           Object... args)

      • configure

        protected void configure​(ValueParser props)
        Description copied from class: SafeConfig
        Does the actual configuration. This is protected, so subclasses may share the same ValueParser and call configure at any time, while preventing templates from doing so when configure(Map) is locked.
        Overrides:
        configure in class SafeConfig

      • duplicate

        protected LinkTool duplicate()
        Equivalent to clone, but with no checked exceptions. If for some unfathomable reason clone() doesn't work, this will throw a RuntimeException.

      • duplicate

        protected LinkTool duplicate​(boolean deep)
        Equivalent to clone, but with no checked exceptions. If for some unfathomable reason clone() doesn't work, this will throw a RuntimeException. If doing a deep clone, then the parameter Map will also be cloned.

      • setCharacterEncoding

        public void setCharacterEncoding​(String chrst)

      • setXHTML

        public void setXHTML​(boolean xhtml)

        Controls the delimiter used for separating query data pairs. By default, the standard '&' character is used.

        This is not exposed to templates as this decision is best not made at that level.

        Subclasses may easily override the init() method to set this appropriately and then call super.init()

        Parameters:
        xhtml - if true, the XHTML query data delimiter ('&amp;') will be used. if false, then '&' will be used.
        See Also:
        Using Ampersands in Attribute Values (and Elsewhere)

      • setAppendParams

        public void setAppendParams​(boolean addParams)
        Sets whether or not the setParam(java.lang.Object, java.lang.Object, boolean) method will override existing query values for the same key or simply append the new value to a list of existing values.

      • setForceRelative

        public void setForceRelative​(boolean forceRelative)
        Sets whether or not the createURI() method should ignore the scheme, user, port and host values for non-opaque URIs, thus making toString() print the link as a relative one, not an absolute one. NOTE: using absolute(), absolute(Object), relative(), or relative(Object) will alter this setting accordingly on the new instances they return.

      • setScheme

        public void setScheme​(Object obj)
        This will treat empty strings like null values and will trim any trailing ':' character.

      • setUserInfo

        public void setUserInfo​(Object obj)

      • setHost

        public void setHost​(Object obj)

      • setPort

        public void setPort​(Object obj)
        If the specified object is null, this will set the port value to -1 to indicate that. If it is non-null and cannot be converted to an integer, then it will be set to -2 to indicate an error.

      • setPath

        public void setPath​(Object obj)
        If this instance is not opaque and the specified value does not start with a '/' character, then that will be prepended automatically.

      • combinePath

        protected String combinePath​(String start,
                             String end)
        If end is null, this will return start and vice versa. If neither is null, this will append the end to the start, making sure that there is only one '/' character between the two values.

      • setQuery

        public void setQuery​(Object obj)
        If the specified value is null, it will set the query to null. If a Map, it will copy all those values into a new LinkedHashMap and replace any current query value with that. If it is a String, it will use parseQuery(String) to parse it into a map of keys to values.

      • normalizeQuery

        protected String normalizeQuery​(String qs)

      • toQuery

        public String toQuery​(Map parameters)
        Converts the map of keys to values into a query string.

      • setParam

        public void setParam​(Object key,
                     Object value,
                     boolean append)
        If there is no existing value for this key in the query, it will simply add it and its value to the query. If the key already is present in the query and append is true, this will add the specified value to those already under that key. If appendParams is false, this will override the existing values with the specified new value.

      • setParams

        public void setParams​(Object obj,
                      boolean append)
        If append is false, this simply delegates to setQuery(java.lang.Object). Otherwise, if the specified object is null, it does nothing. If the object is not a Map, it will turn it into a String and use parseQuery(java.lang.String) to parse it. Once it is a Map, it will iterate through the entries appending each key/value to the current query data.

      • removeParam

        public Object removeParam​(Object key)
        Removes the query pair(s) with the specified key from the query data and returns the remove value(s), if any.

      • handleParamsBoolean

        protected void handleParamsBoolean​(boolean keep)
        In this class, this method ignores true values. If passed a false value, it will call setQuery(java.lang.Object) with a null value to clear all query data.

      • combineQuery

        protected String combineQuery​(String current,
                              String add)
        If the second param is null or empty, this will simply return the first and vice versa. Otherwise, it will trim any '?' at the start of the second param and any '&' or '&amp;' at the end of the first one, then combine the two, making sure that they are separated by only one delimiter.

      • toQuery

        protected String toQuery​(Object key,
                         Object value)
        Turns the specified key and value into a properly encoded query pair string. If the value is an array or List, then this will create a delimited string of query pairs, reusing the same key for each of the values separately.

      • parseQuery

        protected Map<String,​Object> parseQuery​(String query,
                                              String queryDelim)
        This will use the specified query delimiter to parse the specified query string into a map of keys to values. If there are multiple query pairs in the string that have the same key, then the values will be combined into a single List value associated with that key.

      • setFragment

        public void setFragment​(Object obj)
        Sets the anchor for this instance and treats empty strings like null.

      • setFromURI

        protected boolean setFromURI​(Object obj)
        If the specified value is null, this will set the scheme, userInfo, host, port, path, query, and fragment all to their null-equivalent values. Otherwise, this will convert the specified object into a URI, then those same values from the URI object to this instance, when not null or empty. In other words, when given a URI this will only set values present in the URI.

      • toURI

        protected URI toURI​(Object obj)
        Turns the specified object into a string and thereby a URI.

      • createURI

        protected URI createURI()
        Tries to create a URI from the current port, opacity, scheme, userInfo, host, path, query and fragment set for this instance, using the URI constructor that is appropriate to the opacity.

      • isXHTML

        public boolean isXHTML()
        Returns true if the query delimiter used by this instance is using &amp; as the delimiter for query data pairs or just using &.

      • getAppendParams

        public boolean getAppendParams()
        Returns true if param(Object,Object) appends values; false if the method overwrites existing value(s) for the specified key.

      • scheme

        public LinkTool scheme​(Object scheme)
        Returns a new instance with the specified value set as its scheme.

      • secure

        public LinkTool secure()
        Returns a new instance with the scheme set to "https".

      • insecure

        public LinkTool insecure()
        Returns a new instance with the scheme set to "http".

      • getScheme

        public String getScheme()
        Return the scheme value for this instance.

      • isSecure

        public boolean isSecure()
        Returns true if this instance's scheme is "https".

      • isOpaque

        public boolean isOpaque()
        Returns true if this instance represents an opaque URI.
        See Also:
        URI

      • user

        public LinkTool user​(Object info)
        Returns a new instance with the specified value set as its user info.

      • host

        public LinkTool host​(Object host)
        Returns a new instance with the specified value set as its host. If no scheme has yet been set, the new instance will also have its scheme set to the DEFAULT_SCHEME (http).

      • getHost

        public String getHost()
        Return the host value for this instance.

      • port

        public LinkTool port​(Object port)
        Returns a new instance with the specified value set as its port number. If the value cannot be parsed into an integer, the returned instance will always return null for toString() and other createURI()-dependent methods to alert the user to the error.

      • getPort

        public Integer getPort()
        Returns the port value, if any.

      • path

        public LinkTool path​(Object pth)
        Returns a new instance with the specified value set as its path.

      • getPath

        public String getPath()
        Returns the current path value for this instance.

      • append

        public LinkTool append​(Object pth)
        Appends the given value to the end of the current path value.

      • getDirectory

        public String getDirectory()
        Returns the directory stack in the set getPath() value, by just trimming off all that follows the last "/".

      • getFile

        public String getFile()
        Returns the last section of the path, which is all that follows the final "/".

      • getRoot

        public String getRoot()
        Returns the "root" for this URI, if it has one. This does not stick close to URI dogma and will try to insert the default scheme if there is none, and will return null if there is no host or if there was an error when the port value was last set. It will return null for any opaque URLs as well, as those have no host or port.

      • root

        public LinkTool root()
        Returns a new LinkTool instance that represents the "root" of the current one, if it has one. This essentially calls absolute() and sets the path, query, and fragment to null on the returned instance.
        See Also:
        getRoot()

      • directory

        public LinkTool directory()
        Returns a new LinkTool instance with the path set to the result of getDirectory() and the query and fragment set to null.

      • isRelative

        public boolean isRelative()
        Returns true if this instance is being forced to return relative URIs or has a null scheme value.

      • relative

        public LinkTool relative​(Object obj)

        Returns a copy of the link with the specified directory-relative URI reference set as the end of the path and setForceRelative(boolean) set to true. If the specified relative path is null, that is treated the same as an empty path.

        Example:
        <a href='$link.relative("/login/index.vm")'>Login Page</a>
        produces something like
        <a href="/myapp/login/index.vm">Login Page</a>
        Parameters:
        obj - A directory-relative URI reference (e.g. file path in current directory)
        Returns:
        a new instance of LinkTool with the specified changes
        See Also:
        relative()

      • isAbsolute

        public boolean isAbsolute()
        Returns true if this instance has a scheme value and is not being forced to create relative URIs.

      • absolute

        public LinkTool absolute()
        Returns a copy of this LinkTool instance that has setForceRelative(boolean) set to false and sets the scheme to the "http" if no scheme has been set yet.

      • absolute

        public LinkTool absolute​(Object obj)

        Returns a copy of the link with the specified URI reference either used as or converted to an absolute (non-relative) URI reference. Unless the specified URI contains a query or anchor, those values will not be overwritten when using this method.

        Example:
        <a href='$link.absolute("login/index.vm")'>Login Page</a>
        produces something like
        <a href="http://myserver.net/myapp/login/index.vm">Login Page</a>;
        <a href='$link.absolute("/login/index.vm")'>Login Page</a>
        produces something like
        <a href="http://myserver.net/login/index.vm">Login Page</a>;
        and
        <a href='$link.absolute("http://theirserver.com/index.jsp")'>Their, Inc.</a>
        produces something like
        <a href="http://theirserver.net/index.jsp">Their, Inc.</a>
        Parameters:
        obj - A root-relative or context-relative path or an absolute URI.
        Returns:
        a new instance of LinkTool with the specified path or URI
        See Also:
        absolute()

      • uri

        public LinkTool uri​(Object uri)

        Returns a copy of the link with the given URI reference set. Few changes are applied to the given URI reference. The URI reference can be absolute, server-relative, relative and may contain query parameters. This method will overwrite all previous settings for scheme, host port, path, query and anchor.

        Parameters:
        uri - URI reference to set
        Returns:
        a new instance of LinkTool

      • getUri

        public URI getUri()
        If the tool is not in "safe mode"--which it is by default-- this will return the URI representation of this instance, if any.
        See Also:
        SafeConfig.isSafeMode()

      • getBaseRef

        public String getBaseRef()
        Returns the full URI of this template without any query data. e.g. http://myserver.net/myapp/stuff/View.vm Note! The returned String will not represent any URI reference or query data set for this LinkTool. A typical application of this method is with the HTML base tag. For example: <base href="$link.baseRef">

      • query

        public LinkTool query​(Object query)
        Sets the specified value as the current query data, after normalizing the pair delimiters. This overrides any existing query.

      • getQuery

        public String getQuery()
        Returns the current query as a string, if any.

      • param

        public LinkTool param​(Object key,
                      Object value)

        Adds a key=value pair to the query data. Whether this new query pair is appended to the current query or overwrites any previous pair(s) with the same key is controlled by the getAppendParams() value. The default behavior is to append.

        Parameters:
        key - key of new query parameter
        value - value of new query parameter
        Returns:
        a new instance of LinkTool

      • append

        public LinkTool append​(Object key,
                       Object value)
        Appends a new key=value pair to the existing query data.
        Parameters:
        key - key of new query parameter
        value - value of new query parameter
        Returns:
        a new instance of LinkTool

      • set

        public LinkTool set​(Object key,
                    Object value)
        Sets a new key=value pair to the existing query data, overwriting any previous pair(s) that have the same key.
        Parameters:
        key - key of new query parameter
        value - value of new query parameter
        Returns:
        a new instance of LinkTool

      • remove

        public LinkTool remove​(Object key)
        Returns a new LinkTool instance that has any value(s) under the specified key removed from the query data.
        Parameters:
        key - key of the query pair(s) to be removed
        Returns:
        a new instance of LinkTool

      • params

        public LinkTool params​(Object parameters)
        This method can do two different things. If you pass in a boolean, it will create a new LinkTool duplicate and call handleParamsBoolean(boolean) on it. In this class, true values do nothing (subclasses may have use for them), but false values will clear out all params in the query for that instance. If you pass in a query string or a Map of parameters, those values will be added to the new LinkTool, either overwriting previous value(s) with those keys or appending to them, depending on the getAppendParams() value.
        Parameters:
        parameters - a boolean or new query data (either Map or query string)
        Returns:
        a new instance of LinkTool

      • getParams

        public Map getParams()

      • anchor

        public LinkTool anchor​(Object anchor)

        Returns a copy of the link with the specified anchor to be added to the end of the generated hyperlink.

        Example:
        <a href='$link.setAnchor("foo")'>Foo</a>
        produces something like
        <a href="#foo">Foo</a>
        Parameters:
        anchor - an internal document reference
        Returns:
        a new instance of LinkTool with the set anchor

      • getAnchor

        public String getAnchor()
        Returns the anchor (internal document reference) set for this link.

      • toString

        public String toString()
        Returns the full URI reference that's been built with this tool, including the query string and anchor, e.g. http://myserver.net/myapp/stuff/View.vm?id=42&type=blue#foo. Typically, it is not necessary to call this method explicitely. Velocity will call the toString() method automatically to obtain a representable version of an object.
        Overrides:
        toString in class Object

      • decodeQueryPercents

        protected String decodeQueryPercents​(String url)
        This is an ugly (but fast) hack that's needed because URI encodes things that we don't need encoded while not encoding things that we do need encoded. So, we have to encode query data before creating the URI to ensure they are properly encoded, but then URI encodes all the % from that encoding. Here, we isolate the query data and manually decode the encoded %25 in that section back to %, without decoding anything else.

      • equals

        public boolean equals​(Object obj)
        This instance is considered equal to any LinkTool instance whose toString() method returns a String equal to that returned by this instance's toString()
        Overrides:
        equals in class Object
        See Also:
        toString()

      • hashCode

        public int hashCode()
        Returns the hash code for the result of toString(). If toString() returns null (yes, we do break that contract), this will return -1.
        Overrides:
        hashCode in class Object