/*
* $Id$
*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*/
package org.apache.struts2.components;
import com.opensymphony.xwork2.inject.Inject;
import com.opensymphony.xwork2.util.TextParseUtil;
import com.opensymphony.xwork2.util.ValueStack;
import org.apache.struts2.StrutsConstants;
import org.apache.struts2.StrutsException;
import org.apache.struts2.dispatcher.mapper.ActionMapper;
import org.apache.struts2.dispatcher.mapper.ActionMapping;
import org.apache.struts2.util.ComponentUtils;
import org.apache.struts2.util.FastByteArrayOutputStream;
import org.apache.struts2.views.jsp.TagUtils;
import org.apache.struts2.views.util.UrlHelper;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.PrintWriter;
import java.io.Writer;
import java.util.LinkedHashMap;
import java.util.Map;
import java.util.Stack;
/**
* Base class to extend for UI components.
* <p/>
* This class is a good extension point when building reuseable UI components.
*
*/
public class Component {
public static final String COMPONENT_STACK = "__component_stack";
protected ValueStack stack;
protected Map parameters;
protected ActionMapper actionMapper;
protected boolean throwExceptionOnELFailure;
private UrlHelper urlHelper;
/**
* Constructor.
*
* @param stack OGNL value stack.
*/
public Component(ValueStack stack) {
this.stack = stack;
this.parameters = new LinkedHashMap<String, Object>();
getComponentStack().push(this);
}
/**
* Gets the name of this component.
* @return the name of this component.
*/
private String getComponentName() {
Class c = getClass();
String name = c.getName();
int dot = name.lastIndexOf('.');
return name.substring(dot + 1).toLowerCase();
}
@Inject
public void setActionMapper(ActionMapper mapper) {
this.actionMapper = mapper;
}
@Inject(StrutsConstants.STRUTS_EL_THROW_EXCEPTION)
public void setThrowExceptionsOnELFailure(String throwException) {
this.throwExceptionOnELFailure = "true".equals(throwException);
}
@Inject
public void setUrlHelper(UrlHelper urlHelper) {
this.urlHelper = urlHelper;
}
/**
* Gets the OGNL value stack assoicated with this component.
* @return the OGNL value stack assoicated with this component.
*/
public ValueStack getStack() {
return stack;
}
/**
* Gets the component stack of this component.
* @return the component stack of this component, never <tt>null</tt>.
*/
public Stack<Component> getComponentStack() {
Stack<Component> componentStack = (Stack<Component>) stack.getContext().get(COMPONENT_STACK);
if (componentStack == null) {
componentStack = new Stack<Component>();
stack.getContext().put(COMPONENT_STACK, componentStack);
}
return componentStack;
}
/**
* Callback for the start tag of this component.
* Should the body be evaluated?
*
* @param writer the output writer.
* @return true if the body should be evaluated
*/
public boolean start(Writer writer) {
return true;
}
/**
* Callback for the end tag of this component.
* Should the body be evaluated again?
* <p/>
* <b>NOTE:</b> will pop component stack.
* @param writer the output writer.
* @param body the rendered body.
* @return true if the body should be evaluated again
*/
public boolean end(Writer writer, String body) {
return end(writer, body, true);
}
/**
* Callback for the start tag of this component.
* Should the body be evaluated again?
* <p/>
* <b>NOTE:</b> has a parameter to determine to pop the component stack.
* @param writer the output writer.
* @param body the rendered body.
* @param popComponentStack should the component stack be popped?
* @return true if the body should be evaluated again
*/
protected boolean end(Writer writer, String body, boolean popComponentStack) {
assert(body != null);
try {
writer.write(body);
} catch (IOException e) {
throw new StrutsException("IOError while writing the body: " + e.getMessage(), e);
}
if (popComponentStack) {
popComponentStack();
}
return false;
}
/**
* Pops the component stack.
*/
protected void popComponentStack() {
getComponentStack().pop();
}
/**
* Finds the nearest ancestor of this component stack.
* @param clazz the class to look for, or if assignable from.
* @return the component if found, <tt>null</tt> if not.
*/
protected Component findAncestor(Class clazz) {
Stack componentStack = getComponentStack();
int currPosition = componentStack.search(this);
if (currPosition >= 0) {
int start = componentStack.size() - currPosition - 1;
//for (int i = componentStack.size() - 2; i >= 0; i--) {
for (int i = start; i >=0; i--) {
Component component = (Component) componentStack.get(i);
if (clazz.isAssignableFrom(component.getClass()) && component != this) {
return component;
}
}
}
return null;
}
/**
* Evaluates the OGNL stack to find a String value.
* @param expr OGNL expression.
* @return the String value found.
*/
protected String findString(String expr) {
return (String) findValue(expr, String.class);
}
/**
* Evaluates the OGNL stack to find a String value.
* <p/>
* If the given expression is <tt>null</tt/> a error is logged and a <code>RuntimeException</code> is thrown
* constructed with a messaged based on the given field and errorMsg paramter.
*
* @param expr OGNL expression.
* @param field field name used when throwing <code>RuntimeException</code>.
* @param errorMsg error message used when throwing <code>RuntimeException</code>.
* @return the String value found.
* @throws StrutsException is thrown in case of expression is <tt>null</tt>.
*/
protected String findString(String expr, String field, String errorMsg) {
if (expr == null) {
throw fieldError(field, errorMsg, null);
} else {
return findString(expr);
}
}
/**
* Constructs a <code>RuntimeException</code> based on the given information.
* <p/>
* A message is constructed and logged at ERROR level before being returned
* as a <code>RuntimeException</code>.
* @param field field name used when throwing <code>RuntimeException</code>.
* @param errorMsg error message used when throwing <code>RuntimeException</code>.
* @param e the caused exception, can be <tt>null</tt>.
* @return the constructed <code>StrutsException</code>.
*/
protected StrutsException fieldError(String field, String errorMsg, Exception e) {
String msg = "tag '" + getComponentName() + "', field '" + field +
( parameters != null && parameters.containsKey("name")?"', name '" + parameters.get("name"):"") +
"': " + errorMsg;
throw new StrutsException(msg, e);
}
/**
* Finds a value from the OGNL stack based on the given expression.
* Will always evaluate <code>expr</code> against stack except when <code>expr</code>
* is null. If altsyntax (%{...}) is applied, simply strip it off.
*
* @param expr the expression. Returns <tt>null</tt> if expr is null.
* @return the value, <tt>null</tt> if not found.
*/
protected Object findValue(String expr) {
if (expr == null) {
return null;
}
expr = stripExpressionIfAltSyntax(expr);
return getStack().findValue(expr, throwExceptionOnELFailure);
}
/**
* If altsyntax (%{...}) is applied, simply strip the "%{" and "}" off.
* @param expr the expression (must be not null)
* @return the stripped expression if altSyntax is enabled. Otherwise
* the parameter expression is returned as is.
*/
protected String stripExpressionIfAltSyntax(String expr) {
return ComponentUtils.stripExpressionIfAltSyntax(stack, expr);
}
/**
* Is the altSyntax enabled? [TRUE]
* <p/>
* See <code>struts.properties</code> where the altSyntax flag is defined.
*/
public boolean altSyntax() {
return ComponentUtils.altSyntax(stack);
}
/**
* Adds the sorrounding %{ } to the expression for proper processing.
* @param expr the expression.
* @return the modified expression if altSyntax is enabled, or the parameter
* expression otherwise.
*/
protected String completeExpressionIfAltSyntax(String expr) {
if (altSyntax()) {
return "%{" + expr + "}";
}
return expr;
}
/**
* This check is needed for backwards compatibility with 2.1.x
* @param expr the expression.
* @return the found string if altSyntax is enabled. The parameter
* expression otherwise.
*/
protected String findStringIfAltSyntax(String expr) {
if (altSyntax()) {
return findString(expr);
}
return expr;
}
/**
* Evaluates the OGNL stack to find an Object value.
* <p/>
* Function just like <code>findValue(String)</code> except that if the
* given expression is <tt>null</tt/> a error is logged and
* a <code>RuntimeException</code> is thrown constructed with a
* messaged based on the given field and errorMsg paramter.
*
* @param expr OGNL expression.
* @param field field name used when throwing <code>RuntimeException</code>.
* @param errorMsg error message used when throwing <code>RuntimeException</code>.
* @return the Object found, is never <tt>null</tt>.
* @throws StrutsException is thrown in case of not found in the OGNL stack, or expression is <tt>null</tt>.
*/
protected Object findValue(String expr, String field, String errorMsg) {
if (expr == null) {
throw fieldError(field, errorMsg, null);
} else {
Object value = null;
Exception problem = null;
try {
value = findValue(expr);
} catch (Exception e) {
problem = e;
}
if (value == null) {
throw fieldError(field, errorMsg, problem);
}
return value;
}
}
/**
* Evaluates the OGNL stack to find an Object of the given type. Will evaluate
* <code>expr</code> the portion wrapped with altSyntax (%{...})
* against stack when altSyntax is on, else the whole <code>expr</code>
* is evaluated against the stack.
* <p/>
* This method only supports the altSyntax. So this should be set to true.
* @param expr OGNL expression.
* @param toType the type expected to find.
* @return the Object found, or <tt>null</tt> if not found.
*/
protected Object findValue(String expr, Class toType) {
if (altSyntax() && toType == String.class) {
return TextParseUtil.translateVariables('%', expr, stack);
} else {
expr = stripExpressionIfAltSyntax(expr);
return getStack().findValue(expr, toType, throwExceptionOnELFailure);
}
}
/**
* Renders an action URL by consulting the {@link org.apache.struts2.dispatcher.mapper.ActionMapper}.
* @param action the action
* @param namespace the namespace
* @param method the method
* @param req HTTP request
* @param res HTTP response
* @param parameters parameters
* @param scheme http or https
* @param includeContext should the context path be included or not
* @param encodeResult should the url be encoded
* @param forceAddSchemeHostAndPort should the scheme host and port be forced
* @param escapeAmp should ampersand (&) be escaped to &
* @return the action url.
*/
protected String determineActionURL(String action, String namespace, String method,
HttpServletRequest req, HttpServletResponse res, Map parameters, String scheme,
boolean includeContext, boolean encodeResult, boolean forceAddSchemeHostAndPort,
boolean escapeAmp) {
String finalAction = findString(action);
String finalMethod = method != null ? findString(method) : null;
String finalNamespace = determineNamespace(namespace, getStack(), req);
ActionMapping mapping = new ActionMapping(finalAction, finalNamespace, finalMethod, parameters);
String uri = actionMapper.getUriFromActionMapping(mapping);
return urlHelper.buildUrl(uri, req, res, parameters, scheme, includeContext, encodeResult, forceAddSchemeHostAndPort, escapeAmp);
}
/**
* Determines the namespace of the current page being renderdd. Useful for Form, URL, and href generations.
* @param namespace the namespace
* @param stack OGNL value stack
* @param req HTTP request
* @return the namepsace of the current page being rendered, is never <tt>null</tt>.
*/
protected String determineNamespace(String namespace, ValueStack stack, HttpServletRequest req) {
String result;
if (namespace == null) {
result = TagUtils.buildNamespace(actionMapper, stack, req);
} else {
result = findString(namespace);
}
if (result == null) {
result = "";
}
return result;
}
/**
* Pushes this component's parameter Map as well as the component itself on to the stack
* and then copies the supplied parameters over. Because the component's parameter Map is
* pushed before the component itself, any key-value pair that can't be assigned to componet
* will be set in the parameters Map.
*
* @param params the parameters to copy.
*/
public void copyParams(Map params) {
stack.push(parameters);
stack.push(this);
try {
for (Object o : params.entrySet()) {
Map.Entry entry = (Map.Entry) o;
String key = (String) entry.getKey();
stack.setValue(key, entry.getValue());
}
} finally {
stack.pop();
stack.pop();
}
}
/**
* Constructs a string representation of the given exception.
* @param t the exception
* @return the exception as a string.
*/
protected String toString(Throwable t) {
FastByteArrayOutputStream bout = new FastByteArrayOutputStream();
PrintWriter wrt = new PrintWriter(bout);
t.printStackTrace(wrt);
wrt.close();
return bout.toString();
}
/**
* Gets the parameters.
* @return the parameters. Is never <tt>null</tt>.
*/
public Map getParameters() {
return parameters;
}
/**
* Adds all the given parameters to this component's own parameters.
* @param params the parameters to add.
*/
public void addAllParameters(Map params) {
parameters.putAll(params);
}
/**
* Adds the given key and value to this component's own parameter.
* <p/>
* If the provided key is <tt>null</tt> nothing happens.
* If the provided value is <tt>null</tt> any existing parameter with
* the given key name is removed.
* @param key the key of the new parameter to add.
* @param value the value assoicated with the key.
*/
public void addParameter(String key, Object value) {
if (key != null) {
Map params = getParameters();
if (value == null) {
params.remove(key);
} else {
params.put(key, value);
}
}
}
/**
* Overwrite to set if body should be used.
* @return always false for this component.
*/
public boolean usesBody() {
return false;
}
}