com.avaje.ebean.config.ClassLoadConfig Maven / Gradle / Ivy
package com.avaje.ebean.config;
import java.io.IOException;
import java.net.URL;
import java.util.Enumeration;
/**
* Helper to find classes taking into account the context class loader.
*/
public class ClassLoadConfig {
protected final ClassLoaderContext context;
/**
* Construct with the default classLoader search with context classLoader first.
*/
public ClassLoadConfig() {
this(null);
}
/**
* Specify the classLoader to use for class detection and new instance creation.
*/
public ClassLoadConfig(ClassLoader classLoader) {
this.context = new ClassLoaderContext(classLoader);
}
/**
* Return true if the Java.time types are available and should be supported.
*/
public boolean isJavaTimePresent() {
return isPresent("java.time.LocalDate");
}
/**
* Return true if Java7 is present.
*/
public boolean isJava7Present() {
return isPresent("java.nio.file.Path");
}
/**
* Return true if the Joda types are available and should be supported.
*/
public boolean isJodaTimePresent() {
return isPresent("org.joda.time.LocalDateTime");
}
/**
* Return true if javax validation annotations like Size and NotNull are present.
*/
public boolean isJavaxValidationAnnotationsPresent() {
return isPresent("javax.validation.constraints.NotNull");
}
/**
* Return true if Jackson annotations like JsonIgnore are present.
*/
public boolean isJacksonAnnotationsPresent() {
return isPresent("com.fasterxml.jackson.annotation.JsonIgnore");
}
/**
* Return true if Jackson ObjectMapper is present.
*/
public boolean isJacksonObjectMapperPresent() {
return isPresent("com.fasterxml.jackson.databind.ObjectMapper");
}
/**
* Return a new instance of the class using the default constructor.
*/
public Object newInstance(String className) {
try {
Class cls = forName(className);
return cls.newInstance();
} catch (Exception e) {
throw new IllegalArgumentException("Error constructing " + className, e);
}
}
/**
* Return the resources for the given name.
*/
public Enumeration getResources(String name) throws IOException {
return context.getResources(name);
}
/**
* Return true if the given class is present.
*/
protected boolean isPresent(String className) {
try {
forName(className);
return true;
} catch (Throwable ex) {
// Class or one of its dependencies is not present...
return false;
}
}
/**
* Load a class taking into account a context class loader (if present).
*/
protected Class forName(String name) throws ClassNotFoundException {
return context.forName(name);
}
/**
* Return the classLoader to use for service loading etc.
*/
public ClassLoader getClassLoader() {
return context.getClassLoader();
}
/**
* Wraps the preferred, caller and context class loaders.
*/
protected class ClassLoaderContext {
/**
* Optional - if set only use this classLoader (no fallback).
*/
protected final ClassLoader preferredLoader;
protected final ClassLoader contextLoader;
protected final ClassLoader callerLoader;
ClassLoaderContext(ClassLoader preferredLoader) {
this.preferredLoader = preferredLoader;
this.callerLoader = ServerConfig.class.getClassLoader();
this.contextLoader = contextLoader();
}
ClassLoader contextLoader() {
ClassLoader loader = Thread.currentThread().getContextClassLoader();
return (loader != null) ? loader: callerLoader;
}
Enumeration getResources(String name) throws IOException {
if (preferredLoader != null) {
return preferredLoader.getResources(name);
}
return contextLoader().getResources(name);
}
Class forName(String name) throws ClassNotFoundException {
if (preferredLoader != null) {
// only use the explicitly set classLoader
return classForName(name, preferredLoader);
}
try {
// try the context loader first
return classForName(name, contextLoader);
} catch (ClassNotFoundException e) {
if (callerLoader == contextLoader) {
throw e;
} else {
// fallback to the caller classLoader
return classForName(name, callerLoader);
}
}
}
Class classForName(String name, ClassLoader classLoader) throws ClassNotFoundException {
return Class.forName(name, true, classLoader);
}
ClassLoader getClassLoader() {
return preferredLoader != null ? preferredLoader : contextLoader;
}
}
}