Advanced Components in Java Generating Universal Product Code version A in Java Advanced Components

How to generate, print barcode using .NET, Java sdk library control with example project source code free download:
5. using none tocompose none with web,windows application PLANET Now add a new cele none for none brity and a brief biography for him or her as I did above for John Lennon. Format the biography using different styles and colors to your heart"s content and then click on the Save button. You will see the ShowAll page and the newly added celebrity will be somewhere at the end of collection, perhaps on page four.

Find the new celebrity and click on the last name to see the details. Depending on how you formatted the biography, you should see something similar to this:. As you can see, al l the formatting is displayed properly, and this is the reason why we used a new component, OutputRaw in the last example. In fact, this component is quite similar to an ordinary Output component, or even to a basic extension it simply outputs whatever is given to it as a value. The difference is that both regular output and extension encode the content that they insert into the page while OutputRaw just inserts into the resulting HTML its value, no matter what it contains.

For instance, if the value provided by the component"s binding is <b>bold text</b>, then regular output will encode angle brackets and produce the following result: <b>bold text</b>. As a result, instead of formatted text, the page will display the tags verbatim: <b> bold text</b>. The OutputRaw however will insert into the page what was given to it, and as a result, we"ll see bold text.

. [ 155 ]. Advanced Components Security Note: Please use the OutputRaw component with caution. If you will use it to freely display any content entered by a random user, someone might enter a hostile script and achieve sinister results that you cannot even imagine.. All right, we had none none enough of work and study in this chapter. Now we can relax and review what was done..

Summary. We have learned to none none use four powerful and useful components Grid, BeanEditForm, DateField and FCKEditor. They can save us a lot of work since with minimal configuration, they produce a rather sophisticated, functionally rich piece of interface. We have also found out that: We can change the way an object is displayed by Grid and BeanEditForm components, in terms of which properties are displayed and how they are ordered.

We can override the default rendering of a property by Grid or the default editor selected for it by BeanEditForm, using the <t:parameter> element. We can modify the titles of the columns in the Grid or the labels of the fields in the BeanEditForm by providing appropriate messages in the application"s message catalog..

We can change the appearance of the components by overriding the default CSS styles in the stylesheet that we provide ourselves. We already have several controls that accept user input in the application, but nowhere have we checked what kind of input is submitted so far. This is acceptable at the initial stage of development, when we are the only users of the application, and we know for sure which kind of information should be entered in each field.

However, every real life application must validate user input, and if there are errors, it should inform the user about them in a friendly and clear way. The next chapter will discuss the powerful validation system of Tapestry 5..

[ 156 ]. User Input Validation One of the benefit none none s of having a web application is that it can be very easily accessed by everyone around the world. One of the downsides of this is that when so many people use your application, they are going to have errors in their input. Some people are not attentive, others are tired and, finally, everyone in this world has his or her individual style of thinking, so something that seems obvious to the developers of the application might puzzle someone else.

A well-designed web application should immediately be able to define that the input is wrong and stop otherwise all kinds of errors can happen inside of the application. If this application is user-friendly, it should: Clearly and unambiguously inform the user that some part of the input is erroneous, and should be corrected. Identify the field that is erroneous and mark it in some way.

If possible, display the erroneous value, and maybe even explain why exactly it is wrong.. Let"s see how Tape stry 5, being a highly efficient and user-friendly framework, handles these issues..
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