JSP Custom Tags

Tag extension mechanism

extend the SimpleTagSupport class

all attributes are populated by calling standard setter methods

public class CustomMyTag extends SimpleTagSupport{ private String exampleString; public void setExampleString(String exampleString) { this.exampleString = exampleString; } public void doTag() throws IOException { JspWriter out = getJspContext().getOut(); out.println(“Hello”); } }

Evaluating Expressions

String eValue = ""; ExpressionEvaluator ee; VariableResolver vr = context.getVariableResolver();
ee = context.getExpressionEvaluator(); try { eValue = (String) ee.evaluate(value, String.class, vr, null); } catch (Exception e) {
}

${bean.value} is called an EL expression (Expression Language Expression)

Andrew McDonough is a consultant CTO and software developer, currently based between Berlin and London.

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