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package org.apache.taglibs.standard.tag.common.core;
import java.beans.IntrospectionException;
import java.beans.Introspector;
import java.beans.PropertyDescriptor;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.Map;
import javax.el.ExpressionFactory;
import javax.el.ValueExpression;
import javax.el.VariableMapper;
import javax.el.ELException;
import javax.servlet.jsp.JspApplicationContext;
import javax.servlet.jsp.JspFactory;
import javax.servlet.jsp.JspException;
import javax.servlet.jsp.JspTagException;
import javax.servlet.jsp.PageContext;
import javax.servlet.jsp.tagext.BodyTagSupport;
import org.apache.taglibs.standard.resources.Resources;
/**
* <p>Support for handlers of the <set> tag.</p>
*
* @author Shawn Bayern
*/
public class SetSupport extends BodyTagSupport {
//*********************************************************************
// Internal state
protected Object value; // tag attribute
protected boolean valueSpecified; // status
protected Object target; // tag attribute
protected String property; // tag attribute
private String var; // tag attribute
private int scope; // tag attribute
private boolean scopeSpecified; // status
//*********************************************************************
// Construction and initialization
/**
* Constructs a new handler. As with TagSupport, subclasses should
* not provide other constructors and are expected to call the
* superclass constructor.
*/
public SetSupport() {
super();
init();
}
// resets local state
private void init() {
value = var = null;
scopeSpecified = valueSpecified = false;
scope = PageContext.PAGE_SCOPE;
}
// Releases any resources we may have (or inherit)
public void release() {
super.release();
init();
}
//*********************************************************************
// Tag logic
public int doEndTag() throws JspException {
Object result; // what we'll store in scope:var
// determine the value by...
if (value != null) {
// ... reading our attribute
result = value;
} else if (valueSpecified) {
// ... accepting an explicit null
result = null;
} else {
// ... retrieving and trimming our body
if (bodyContent == null || bodyContent.getString() == null)
result = "";
else
result = bodyContent.getString().trim();
}
// decide what to do with the result
if (var != null) {
/*
* Store the result, letting an IllegalArgumentException
* propagate back if the scope is invalid (e.g., if an attempt
* is made to store something in the session without any
* HttpSession existing).
*/
if (result != null) {
if (result instanceof ValueExpression) {
if (scope != PageContext.PAGE_SCOPE) {
throw new JspException(
Resources.getMessage("SET_BAD_SCOPE_DEFERRED"));
}
VariableMapper vm =
pageContext.getELContext().getVariableMapper();
if (vm != null) {
vm.setVariable(var, (ValueExpression)result);
}
} else {
// Make sure to clear any previous mapping for this
// variable in the variable mapper.
if (scope == PageContext.PAGE_SCOPE) {
VariableMapper vm =
pageContext.getELContext().getVariableMapper();
if (vm != null) {
vm.setVariable(var, null);
}
}
pageContext.setAttribute(var, result, scope);
}
} else {
if (scopeSpecified)
pageContext.removeAttribute(var, scope);
else
pageContext.removeAttribute(var);
if (scope == PageContext.PAGE_SCOPE) {
VariableMapper vm =
pageContext.getELContext().getVariableMapper();
if (vm != null) {
vm.setVariable(var, null);
}
}
}
} else if (target != null) {
// save the result to target.property
if (target instanceof Map) {
// ... treating it as a Map entry
if (result == null)
((Map) target).remove(property);
else
((Map) target).put(property, result);
} else {
// ... treating it as a bean property
try {
PropertyDescriptor pd[] =
Introspector.getBeanInfo(target.getClass())
.getPropertyDescriptors();
boolean succeeded = false;
for (int i = 0; i < pd.length; i++) {
if (pd[i].getName().equals(property)) {
Method m = pd[i].getWriteMethod();
if (m == null) {
throw new JspException(
Resources.getMessage("SET_NO_SETTER_METHOD",
property));
}
if (result != null) {
try {
m.invoke(target,
new Object[] {
convertToExpectedType(result, m.getParameterTypes()[0])});
} catch (javax.el.ELException ex) {
throw new JspTagException(ex);
}
} else {
m.invoke(target, new Object[] { null });
}
succeeded = true;
}
}
if (!succeeded) {
throw new JspTagException(
Resources.getMessage("SET_INVALID_PROPERTY",
property));
}
} catch (IllegalAccessException ex) {
throw new JspException(ex);
} catch (IntrospectionException ex) {
throw new JspException(ex);
} catch (InvocationTargetException ex) {
throw new JspException(ex);
}
}
} else {
// should't ever occur because of validation in TLV and setters
throw new JspTagException();
}
return EVAL_PAGE;
}
/**
* Convert an object to an expected type according to the conversion
* rules of the Expression Language.
*/
private Object convertToExpectedType( final Object value,
Class expectedType ) {
JspFactory jspFactory = JspFactory.getDefaultFactory();
JspApplicationContext jspAppContext =
jspFactory.getJspApplicationContext(pageContext.getServletContext());
ExpressionFactory exprFactory = jspAppContext.getExpressionFactory();
return exprFactory.coerceToType(value, expectedType);
}
//*********************************************************************
// Accessor methods
// for tag attribute
public void setVar(String var) {
this.var = var;
}
// for tag attribute
public void setScope(String scope) {
this.scope = Util.getScope(scope);
this.scopeSpecified = true;
}
}
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