com.btr.proxy.selector.pac.JavaxPacScriptParser Maven / Gradle / Ivy
package com.btr.proxy.selector.pac;
import java.lang.reflect.Method;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.script.ScriptEngine;
import javax.script.ScriptEngineManager;
import javax.script.ScriptException;
/*****************************************************************************
* PAC parser using the Rhino JavaScript engine bundled with Java 1.6
* If you need PAC support with Java 1.5 then you should have a look at
* RhinoPacScriptParser.
*
* More information about PAC can be found there:
* Proxy_auto-config
* web-browser-auto-proxy-configuration
*
* @author Bernd Rosstauscher ([email protected]) Copyright 2009
****************************************************************************/
public class JavaxPacScriptParser implements PacScriptParser {
static final String SCRIPT_METHODS_OBJECT = "__pacutil";
static final Logger log = Logger.getLogger(JavaxPacScriptParser.class
.getCanonicalName());
private final PacScriptSource source;
private final ScriptEngine engine;
/*************************************************************************
* Constructor
*
* @param source
* the source for the PAC script.
* @throws ProxyEvaluationException
* on error.
************************************************************************/
public JavaxPacScriptParser(PacScriptSource source)
throws ProxyEvaluationException {
this.source = source;
this.engine = setupEngine();
}
/*************************************************************************
* Initializes the JavaScript engine and adds aliases for the functions
* defined in ScriptMethods.
*
* @throws ProxyEvaluationException
* on error.
************************************************************************/
private ScriptEngine setupEngine() throws ProxyEvaluationException {
ScriptEngineManager mng = new ScriptEngineManager();
ScriptEngine newEngine = mng.getEngineByMimeType("text/javascript");
assert newEngine != null : "Javascript engine not available";
newEngine.put(SCRIPT_METHODS_OBJECT, new PacScriptMethods());
Class scriptMethodsClazz = ScriptMethods.class;
Method[] scriptMethods = scriptMethodsClazz.getMethods();
for (Method method : scriptMethods) {
String name = method.getName();
int args = method.getParameterTypes().length;
StringBuilder toEval = new StringBuilder(name).append(" = function(");
for (int i = 0; i < args; i++) {
if (i > 0) {
toEval.append(",");
}
toEval.append("arg").append(i);
}
toEval.append(") {return ");
String functionCall = buildFunctionCallCode(name, args);
// If return type is java.lang.String convert it to a JS string
if (String.class.isAssignableFrom(method.getReturnType())) {
functionCall = "String(" + functionCall + ")";
}
toEval.append(functionCall).append("; }");
try {
newEngine.eval(toEval.toString());
} catch (ScriptException e) {
log.log(Level.INFO, "JS evaluation error when creating alias for "
+ name + ".", e);
throw new ProxyEvaluationException("Error setting up script engine", e);
}
}
return newEngine;
}
/*************************************************************************
* Builds a JavaScript code snippet to call a function that we bind.
*
* @param functionName
* of the bound function
* @param args
* of the bound function
* @return the JS code to invoke the method.
************************************************************************/
private String buildFunctionCallCode(String functionName, int args) {
StringBuilder functionCall = new StringBuilder();
functionCall.append(SCRIPT_METHODS_OBJECT).append(".").append(functionName)
.append("(");
for (int i = 0; i < args; i++) {
if (i > 0) {
functionCall.append(",");
}
functionCall.append("arg").append(i);
}
functionCall.append(")");
return functionCall.toString();
}
/***************************************************************************
* Gets the source of the PAC script used by this parser.
*
* @return a PacScriptSource.
**************************************************************************/
@Override
public PacScriptSource getScriptSource() {
return this.source;
}
/*************************************************************************
* Evaluates the given URL and host against the PAC script.
*
* @param url
* the URL to evaluate.
* @param host
* the host name part of the URL.
* @return the script result.
* @throws ProxyEvaluationException
* on execution error.
************************************************************************/
@Override
public String evaluate(String url, String host)
throws ProxyEvaluationException {
try {
StringBuilder script = new StringBuilder(this.source.getScriptContent());
String evalMethod = " ;FindProxyForURL (\"" + url + "\",\"" + host
+ "\")";
script.append(evalMethod);
Object result = this.engine.eval(script.toString());
return (String) result;
} catch (Exception e) {
log.log(Level.INFO, "JS evaluation error.", e);
throw new ProxyEvaluationException("Error while executing PAC script: "
+ e.getMessage(), e);
}
}
}