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)