Check Web Accessibility in Java

Check Website Accessibility in Java

Checking website accessibility helps identify HTML and CSS issues that may prevent people with disabilities from using web content. Aspose.HTML for Java can evaluate an HTMLDocument against selected accessibility rules based on WCAG 2.0 and return structured validation results.

Use WebAccessibility to create an AccessibilityValidator, load a local file or webpage into an HTMLDocument, and call validate(). Inspect the returned ValidationResult to find failed rules, errors, warnings, and affected HTML or CSS objects.

The following Java example checks a remote webpage using all rules selected by ValidationBuilder.getAll() and prints the code, description, and status of each unsuccessful rule:

1. Create a WebAccessibility instance and call createValidator() with the required validation rules.
2. Load the page to check into an HTMLDocument.
3. Pass the document to AccessibilityValidator.validate().
4. Check ValidationResult.getSuccess() and iterate through getDetails() when the result is unsuccessful.
5. Read each failed rule’s code, description, and validation status.

// Check website for WCAG compliance in Java

// Create a WebAccessibility instance
WebAccessibility webAccessibility = new WebAccessibility();

// Create an accessibility validator with static instance
// for all rules from repository that match the builder settings
AccessibilityValidator validator = webAccessibility.createValidator(ValidationBuilder.getAll());

// Initialize an HTMLDocument object
final HTMLDocument document = new HTMLDocument("https://products.aspose.com/html/net/generators/video/");
ValidationResult validationResult = validator.validate(document);

// Checking for success
if (!validationResult.getSuccess()) {
    // Get a list of Details
    for (RuleValidationResult detail : validationResult.getDetails()) {
        System.out.println(String.format("%s: %s = %s",
                detail.getRule().getCode(),
                detail.getRule().getDescription(),
                detail.getSuccess()
        ));
    }
}

Understand Accessibility Errors and Warnings

Errors identify failed accessibility checks, while warnings provide information that can help improve the document without making the corresponding result unsuccessful. Both types include diagnostic data that developers can use to locate and review the reported issue.

IError

The IError interface describes a problem reported during validation. Its methods provide the message, status, type, and source of the issue:

Method	Returned information
getErrorMessage()	Human-readable description of the issue.
getSuccess()	Whether the associated check succeeded.
getErrorType()	Numeric issue type.
getErrorTypeName()	Type name, such as Error or Warning.
getTarget()	HTML or CSS object associated with the issue, when available.

Aspose.HTML uses the following result combinations:

• ErrorType = 1 and Success = false indicates an Error and an unsuccessful check.
• ErrorType = 2 and Success = true indicates a Warning with informational guidance.

Target

The Target class contains the HTML or CSS object associated with an error or warning. Use getItem() to retrieve the object and getTargetType() to determine its type before casting it. A validation issue does not always have a target, so check the returned Target for null.

TargetTypes

The TargetTypes enumeration identifies the type of object stored in a Target:

Name	Value	Stored object
HTMLElement	0	An HTML element, such as <img> or <button>.
CSSStyleRule	1	A CSS style rule.
CSSStyleSheet	2	A CSS stylesheet.

Generate a Detailed Accessibility Report

The next example validates a local HTML document and traverses unsuccessful rule results, technique errors, diagnostic messages, and target objects:

1. Load the HTML source into an HTMLDocument and validate it with an AccessibilityValidator.
2. Iterate through the RuleValidationResult objects returned by validationResult.getDetails().
3. Select unsuccessful rules and iterate through the ITechniqueResult objects returned by ruleResult.getErrors().
4. Read each IError type and message, then obtain its target with getTarget().
5. Check the target with getTargetType() before reading the affected HTML element, CSS rule, or stylesheet.

// Check HTML for WCAG compliance and output failed rule codes and error messages

// Create a WebAccessibility instance
WebAccessibility webAccessibility = new WebAccessibility();

// Create an accessibility validator with static instance
// for all rules from repository that match the builder settings
AccessibilityValidator validator = webAccessibility.createValidator(ValidationBuilder.getAll());

String documentPath = "input.html";

// Initialize an object of the HTMLDocument class
final HTMLDocument document = new HTMLDocument(documentPath);
ValidationResult validationResult = validator.validate(document);

for (RuleValidationResult ruleResult : validationResult.getDetails()) {
    //  list only unsuccessful rule
    if (!ruleResult.getSuccess()) {
        // print the code and description of the rule
        System.out.println(String.format("%s: %s = %s",
                ruleResult.getRule().getCode(),
                ruleResult.getRule().getDescription(),
                ruleResult.getSuccess()
        ));

        // print the results of methods with errors
        for (ITechniqueResult ruleDetail : ruleResult.getErrors()) {
            // print the code and description of the method
            StringBuilder str = new StringBuilder(String.format("\n%s: %s - %s",
                    ruleDetail.getRule().getCode(),
                    ruleDetail.getSuccess(),
                    ruleDetail.getRule().getDescription()
            ));
            // get an error object
            IError error = ruleDetail.getError();
            // get a target object
            Target target = error.getTarget();
            // get error type and message
            str.append(String.format("\n\n\t%s : %s",
                    error.getErrorTypeName(),
                    error.getErrorMessage()
            ));

            if (target != null) {
                // Checking the type of the contained object for casting and working with it
                if (target.getTargetType() == TargetTypes.CSSStyleRule) {
                    ICSSStyleRule cssRule = (ICSSStyleRule) target.getItem();
                    str.append(String.format("\n\n\t%s",
                            cssRule.getCSSText()
                    ));
                }
                if (ruleDetail.getError().getTarget().getTargetType() == TargetTypes.CSSStyleSheet) {
                    str.append(String.format("\n\n\t%s",
                            ((ICSSStyleSheet) target.getItem()).getTitle()
                    ));
                }
                if (ruleDetail.getError().getTarget().getTargetType() == TargetTypes.HTMLElement) {
                    str.append(String.format("\n\n\t%s",
                            ((HTMLElement) target.getItem()).getOuterHTML()
                    ));
                }
            }
            System.out.println(str);
        }
    }
}

For each unsuccessful rule, the example accesses its description, technique results, error messages, and available HTML or CSS targets. This diagnostic context can be used to build a developer-facing accessibility report. Automated results identify issues covered by the selected rules, but they do not replace manual accessibility testing.

Related Articles

• Web Accessibility Rules – select WCAG 2.0 requirements, criteria, and techniques for validation.
• Validation Results – inspect the result hierarchy returned by the accessibility validator.
• Color Contrast Accessibility – evaluate text and background color contrast.
• Screen Reader Accessibility – check alternative text and markup relevant to assistive technologies.

Try an Online Accessibility Check

Use the free online Web Accessibility Checker for a quick page scan, or the Color Contrast Checker to evaluate a foreground and background color pair.