Jodd JSP tag library

Jodd comes with powerful JSP tag and big JSP functions library. Here is the overview of most important tags.

To use Jodd JSP library, you need to define taglib directive at the top of your JSP page (use any prefix you like):

    <%@ taglib prefix="j" uri="/jodd" %>

Set & Unset

Sets or unsets variable value in some scope. Attributes are:

  • name - variable name
  • value - variable value
  • scope - one of:
    • page (default)
    • request
    • session
    • application

Example:

      <j:set name="foo" value="173" scope="request"/>

Display foo value with: ${foo}

      <j:unset name="foo" scope="request"/>

Debug

Outputs parameter values and attribute values from all scopes. Useful for quick debugging. Tip: wrap debug tag with the pre tag in HTML, to have more readable output:

Example:

    <j:debug/>

Url

This tag creates full URLs that are context independent and with parameters encoded. Url tag uses dynamic attributes that represents url parameters, so the base path is set by tag parameter '_'. Additionally, it is possible to set page variable value, instead to render url to the page. Example:

    <j:url _="index.html" foo="something" id="173" />

may render as: /app/index.html?foo=something&id=173. And:

    <j:url _="hello.html" _var="u" boo="3" />

Now ${u} may render as: /hello.html?boo=3

If

Renders the tag body if test condition is true. Example:

    <j:if test="${foo > 10}">
       greater then 10!
    </j:if>

IfElse, Then & Else

Similar as If tag, except this one offers complete then and else blocks, that will be rendered if condition is true or false, respectively. Example:

    <j:ifelse test="${foo == 'hello'}">
        <j:then>
          Hello to you, too!
       </j:then>
        <j:else>
            Please say hello:)
        </j:else>
    </j:ifelse>

Switch, Case & Default

Offers switch/case/default functionality. Example:

    <j:switch vale="${foo}">

        <j:case value="One">
          You are the first!
       </j:case>

        <j:case value="Two">
            Second place for you!
        </j:case>

        <j:case value="Three">
            And you are third,
        </j:case>

        <j:default>
            Sorry, try again.
        </j:default>
    </j:switch>

For

Generic loop, like in Java, iterates tag body multiple times. Supports looping in both directions. The attributes are:

  • start - first value
  • end - last value
  • step - looping step, default 1
  • status - optional name of status object
  • modulus - modulus value of current iteration count, default 2. May be used to e.g. detect odd/even rows (modulus = 2), or detect every 1st, 2nd and 3rd row (modulus = 3).

Like all Jodd looping tags, For tag has optional status attribute that defines status variable name. If specified, status object is available inside looping tag body and provide various information about the current iteration:

  • start and end - first and last value of the iteration;
  • step - looping step, default 1;
  • count - total count;
  • even, odd - flags for even and odd iterations;
  • modulus - the value of modulus;
  • index and value - 0-based and 1-based item of current iteration;
  • first and last - flag for first and/or last iteration;

Status object has custom toString() that gives complete status for iteration, what is useful for development. It prints the following:

value : count : 'F' for first : 'L' for last : modulus

For tag supports steps during looping. Moreover, setting step to 0 will notify For tag to choose the correct direction, based on start and end values.

Example:

    <j:for start="1" end="5" status="s" modulus="3">
        ${s} |
    </j:for>
    1:1:F:_:1 | 2:2:_:_:2 | 3:3:_:_:0 | 4:4:_:_:1 | 5:5:_:L:2 |

    <j:for start="1" end="5" step="2" status="s">
        ${s} |
    </j:for>
    1:1:F:_:1 | 3:2:_:_:0 | 5:3:_:L:1 |

    <j:for start="3" end="1" step="-1" status="s">
        ${s} |
    </j:for>
    3:1:F:_:1 | 2:2:_:_:0 | 1:3:_:L:1 |

    <j:for start="1" end="3" step="0" status="s">
        ${s} |
    </j:for>
    1:1:F:_:1 | 2:2:_:_:0 | 3:3:_:L:1 |

    <j:for start="3" end="1" step="0" status="s">
        ${s} |
    </j:for>
    3:1:F:_:1 | 2:2:_:_:0 | 1:3:_:L:1 |

Loop

Loop tag offers more enhanced looping then For tag. For example, it contains both end and to variables to define loop end value, inclusive and not-inclusive. Moreover, instead of setting the end value (using end or to), it is possible to specify just the count. Example:

    <j:loop start="1" end="5" status="s">
        ${s} |
    </j:loop>
    1:1:F:_:1 | 2:2:_:_:0 | 3:3:_:_:1 | 4:4:_:_:0 | 5:5:_:L:1 |

    <j:loop start="1" to="5" status="s">
        ${s} |
    </j:loop>
    1:1:F:_:1 | 2:2:_:_:0 | 3:3:_:_:1 | 4:4:_:L:0 |

    <j:loop start="1" to="-1" step="-1" status="s">
        ${s} |
    </j:loop>
    1:1:F:_:1 | 0:2:_:L:0 |

    <j:loop start="1" count="3" status="s">
        ${s} |
    </j:loop>
    1:1:F:_:1 | 2:2:_:_:0 | 3:3:_:L:1 |

    <j:loop start="1" end="5" autoDirection="true" step="3" status="s">
        ${s} |
    </j:loop>
    1:1:F:_:1 | 4:2:_:L:0 |

    <j:loop start="5" end="1" autoDirection="true" step="3" status="s">
        ${s} |
    </j:loop>
    5:1:F:_:1 | 2:2:_:L:0 |

Iterator

Iterator iterates some collection or an array. Iterator also can iterate a string that represents comma-separated array.

There are two optional attributes: from and count that determine starting index and total number of items to iterate. Example:

    <j:iter items="1,2,3" var="i" status="s">
        ${i} ${s} |
    </j:iter>
    1 1:F:_:1 | 2 2:_:_:0 | 3 3:_:L:1 |

    <j:iter items="1,2,3" var="i" from="2" status="s">
        ${i} ${s} |
    </j:iter>
    3 1:F:L:1 |

Form

Form tag populates HTML form automatically. Read more here.