/*
* Copyright 2002-2017 the original author or authors.
*
* Licensed 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.springframework.web.servlet.view.script;
import java.io.IOException;
import java.io.InputStreamReader;
import java.nio.charset.Charset;
import java.nio.charset.StandardCharsets;
import java.util.Arrays;
import java.util.HashMap;
import java.util.Locale;
import java.util.Map;
import java.util.function.Function;
import javax.script.Invocable;
import javax.script.ScriptEngine;
import javax.script.ScriptEngineManager;
import javax.script.ScriptException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.springframework.beans.BeansException;
import org.springframework.beans.factory.BeanFactoryUtils;
import org.springframework.beans.factory.NoSuchBeanDefinitionException;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextException;
import org.springframework.core.NamedThreadLocal;
import org.springframework.core.io.Resource;
import org.springframework.core.io.ResourceLoader;
import org.springframework.scripting.support.StandardScriptEvalException;
import org.springframework.scripting.support.StandardScriptUtils;
import org.springframework.util.Assert;
import org.springframework.util.FileCopyUtils;
import org.springframework.util.ObjectUtils;
import org.springframework.util.StringUtils;
import org.springframework.web.servlet.view.AbstractUrlBasedView;
/**
* An {@link AbstractUrlBasedView} subclass designed to run any template library
* based on a JSR-223 script engine.
*
* <p>If not set, each property is auto-detected by looking up a single
* {@link ScriptTemplateConfig} bean in the web application context and using
* it to obtain the configured properties.
*
* <p>Nashorn Javascript engine requires Java 8+, and may require setting the
* {@code sharedEngine} property to {@code false} in order to run properly. See
* {@link ScriptTemplateConfigurer#setSharedEngine(Boolean)} for more details.
*
* @author Sebastien Deleuze
* @author Juergen Hoeller
* @since 4.2
* @see ScriptTemplateConfigurer
* @see ScriptTemplateViewResolver
*/
public class ScriptTemplateView extends AbstractUrlBasedView {
public static final String DEFAULT_CONTENT_TYPE = "text/html";
private static final Charset DEFAULT_CHARSET = StandardCharsets.UTF_8;
private static final String DEFAULT_RESOURCE_LOADER_PATH = "classpath:";
private static final ThreadLocal<Map<Object, ScriptEngine>> enginesHolder =
new NamedThreadLocal<>("ScriptTemplateView engines");
private ScriptEngine engine;
private String engineName;
private Locale locale;
private Boolean sharedEngine;
private String[] scripts;
private String renderObject;
private String renderFunction;
private Charset charset;
private String[] resourceLoaderPaths;
private ResourceLoader resourceLoader;
private volatile ScriptEngineManager scriptEngineManager;
/**
* Constructor for use as a bean.
* @see #setUrl
*/
public ScriptTemplateView() {
setContentType(null);
}
/**
* Create a new ScriptTemplateView with the given URL.
* @since 4.2.1
*/
public ScriptTemplateView(String url) {
super(url);
setContentType(null);
}
/**
* See {@link ScriptTemplateConfigurer#setEngine(ScriptEngine)} documentation.
*/
public void setEngine(ScriptEngine engine) {
Assert.isInstanceOf(Invocable.class, engine, "ScriptEngine must implement Invocable");
this.engine = engine;
}
/**
* Set the {@link Locale} to pass to the render function.
* @since 5.0
*/
public void setLocale(Locale locale) {
this.locale = locale;
}
/**
* See {@link ScriptTemplateConfigurer#setEngineName(String)} documentation.
*/
public void setEngineName(String engineName) {
this.engineName = engineName;
}
/**
* See {@link ScriptTemplateConfigurer#setSharedEngine(Boolean)} documentation.
*/
public void setSharedEngine(Boolean sharedEngine) {
this.sharedEngine = sharedEngine;
}
/**
* See {@link ScriptTemplateConfigurer#setScripts(String...)} documentation.
*/
public void setScripts(String... scripts) {
this.scripts = scripts;
}
/**
* See {@link ScriptTemplateConfigurer#setRenderObject(String)} documentation.
*/
public void setRenderObject(String renderObject) {
this.renderObject = renderObject;
}
/**
* See {@link ScriptTemplateConfigurer#setRenderFunction(String)} documentation.
*/
public void setRenderFunction(String functionName) {
this.renderFunction = functionName;
}
/**
* See {@link ScriptTemplateConfigurer#setContentType(String)}} documentation.
* @since 4.2.1
*/
@Override
public void setContentType(String contentType) {
super.setContentType(contentType);
}
/**
* See {@link ScriptTemplateConfigurer#setCharset(Charset)} documentation.
*/
public void setCharset(Charset charset) {
this.charset = charset;
}
/**
* See {@link ScriptTemplateConfigurer#setResourceLoaderPath(String)} documentation.
*/
public void setResourceLoaderPath(String resourceLoaderPath) {
String[] paths = StringUtils.commaDelimitedListToStringArray(resourceLoaderPath);
this.resourceLoaderPaths = new String[paths.length + 1];
this.resourceLoaderPaths[0] = "";
for (int i = 0; i < paths.length; i++) {
String path = paths[i];
if (!path.endsWith("/") && !path.endsWith(":")) {
path = path + "/";
}
this.resourceLoaderPaths[i + 1] = path;
}
}
@Override
protected void initApplicationContext(ApplicationContext context) {
super.initApplicationContext(context);
ScriptTemplateConfig viewConfig = autodetectViewConfig();
if (this.engine == null && viewConfig.getEngine() != null) {
setEngine(viewConfig.getEngine());
}
if (this.engineName == null && viewConfig.getEngineName() != null) {
this.engineName = viewConfig.getEngineName();
}
if (this.scripts == null && viewConfig.getScripts() != null) {
this.scripts = viewConfig.getScripts();
}
if (this.renderObject == null && viewConfig.getRenderObject() != null) {
this.renderObject = viewConfig.getRenderObject();
}
if (this.renderFunction == null && viewConfig.getRenderFunction() != null) {
this.renderFunction = viewConfig.getRenderFunction();
}
if (this.getContentType() == null) {
setContentType(viewConfig.getContentType() != null ? viewConfig.getContentType() : DEFAULT_CONTENT_TYPE);
}
if (this.charset == null) {
this.charset = (viewConfig.getCharset() != null ? viewConfig.getCharset() : DEFAULT_CHARSET);
}
if (this.resourceLoaderPaths == null) {
String resourceLoaderPath = viewConfig.getResourceLoaderPath();
setResourceLoaderPath(resourceLoaderPath == null ? DEFAULT_RESOURCE_LOADER_PATH : resourceLoaderPath);
}
if (this.resourceLoader == null) {
this.resourceLoader = getApplicationContext();
}
if (this.sharedEngine == null && viewConfig.isSharedEngine() != null) {
this.sharedEngine = viewConfig.isSharedEngine();
}
Assert.isTrue(!(this.engine != null && this.engineName != null),
"You should define either 'engine' or 'engineName', not both.");
Assert.isTrue(!(this.engine == null && this.engineName == null),
"No script engine found, please specify either 'engine' or 'engineName'.");
if (Boolean.FALSE.equals(this.sharedEngine)) {
Assert.isTrue(this.engineName != null,
"When 'sharedEngine' is set to false, you should specify the " +
"script engine using the 'engineName' property, not the 'engine' one.");
}
else if (this.engine != null) {
loadScripts(this.engine);
}
else {
setEngine(createEngineFromName());
}
Assert.isTrue(this.renderFunction != null, "The 'renderFunction' property must be defined.");
}
protected ScriptEngine getEngine() {
if (Boolean.FALSE.equals(this.sharedEngine)) {
Map<Object, ScriptEngine> engines = enginesHolder.get();
if (engines == null) {
engines = new HashMap<>(4);
enginesHolder.set(engines);
}
Object engineKey = (!ObjectUtils.isEmpty(this.scripts) ?
new EngineKey(this.engineName, this.scripts) : this.engineName);
ScriptEngine engine = engines.get(engineKey);
if (engine == null) {
engine = createEngineFromName();
engines.put(engineKey, engine);
}
return engine;
}
else {
// Simply return the configured ScriptEngine...
return this.engine;
}
}
protected ScriptEngine createEngineFromName() {
if (this.scriptEngineManager == null) {
this.scriptEngineManager = new ScriptEngineManager(getApplicationContext().getClassLoader());
}
ScriptEngine engine = StandardScriptUtils.retrieveEngineByName(this.scriptEngineManager, this.engineName);
loadScripts(engine);
return engine;
}
protected void loadScripts(ScriptEngine engine) {
if (!ObjectUtils.isEmpty(this.scripts)) {
for (String script : this.scripts) {
Resource resource = getResource(script);
if (resource == null) {
throw new IllegalStateException("Script resource [" + script + "] not found");
}
try {
engine.eval(new InputStreamReader(resource.getInputStream()));
}
catch (Throwable ex) {
throw new IllegalStateException("Failed to evaluate script [" + script + "]", ex);
}
}
}
}
protected Resource getResource(String location) {
for (String path : this.resourceLoaderPaths) {
Resource resource = this.resourceLoader.getResource(path + location);
if (resource.exists()) {
return resource;
}
}
return null;
}
protected ScriptTemplateConfig autodetectViewConfig() throws BeansException {
try {
return BeanFactoryUtils.beanOfTypeIncludingAncestors(
getApplicationContext(), ScriptTemplateConfig.class, true, false);
}
catch (NoSuchBeanDefinitionException ex) {
throw new ApplicationContextException("Expected a single ScriptTemplateConfig bean in the current " +
"Servlet web application context or the parent root context: ScriptTemplateConfigurer is " +
"the usual implementation. This bean may have any name.", ex);
}
}
@Override
public boolean checkResource(Locale locale) throws Exception {
return (getResource(getUrl()) != null);
}
@Override
protected void prepareResponse(HttpServletRequest request, HttpServletResponse response) {
super.prepareResponse(request, response);
setResponseContentType(request, response);
response.setCharacterEncoding(this.charset.name());
}
@Override
protected void renderMergedOutputModel(Map<String, Object> model, HttpServletRequest request,
HttpServletResponse response) throws Exception {
try {
ScriptEngine engine = getEngine();
Invocable invocable = (Invocable) engine;
String url = getUrl();
String template = getTemplate(url);
Function<String, String> templateLoader = path -> {
try {
return getTemplate(path);
}
catch (IOException ex) {
throw new IllegalStateException(ex);
}
};
RenderingContext context = new RenderingContext(this.getApplicationContext(), this.locale, templateLoader, url);
Object html;
if (this.renderObject != null) {
Object thiz = engine.eval(this.renderObject);
html = invocable.invokeMethod(thiz, this.renderFunction, template, model, context);
}
else {
html = invocable.invokeFunction(this.renderFunction, template, model, context);
}
response.getWriter().write(String.valueOf(html));
}
catch (ScriptException ex) {
throw new ServletException("Failed to render script template", new StandardScriptEvalException(ex));
}
}
protected String getTemplate(String path) throws IOException {
Resource resource = getResource(path);
if (resource == null) {
throw new IllegalStateException("Template resource [" + path + "] not found");
}
InputStreamReader reader = new InputStreamReader(resource.getInputStream(), this.charset);
return FileCopyUtils.copyToString(reader);
}
/**
* Key class for the {@code enginesHolder ThreadLocal}.
* Only used if scripts have been specified; otherwise, the
* {@code engineName String} will be used as cache key directly.
*/
private static class EngineKey {
private final String engineName;
private final String[] scripts;
public EngineKey(String engineName, String[] scripts) {
this.engineName = engineName;
this.scripts = scripts;
}
@Override
public boolean equals(Object other) {
if (this == other) {
return true;
}
if (!(other instanceof EngineKey)) {
return false;
}
EngineKey otherKey = (EngineKey) other;
return (this.engineName.equals(otherKey.engineName) && Arrays.equals(this.scripts, otherKey.scripts));
}
@Override
public int hashCode() {
return (this.engineName.hashCode() * 29 + Arrays.hashCode(this.scripts));
}
}
}