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com.github.fartherp.framework.common.extension.ExtensionLoader Maven / Gradle / Ivy
/*
* Copyright (c) 2017. CK. All rights reserved.
*/
package com.github.fartherp.framework.common.extension;
import com.github.fartherp.framework.common.extension.io.UnsafeStringWriter;
import org.apache.commons.lang.StringUtils;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.Enumeration;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.TreeSet;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;
import java.util.regex.Pattern;
/**
* framework使用的扩展点获取。
*
* 自动注入关联扩展点。
* 自动Wrap上扩展点的Wrap类。
* 缺省获得的的扩展点是一个Adaptive Instance。
*
*
* @author CK
* @see JDK5.0的自动发现机制实现
*/
public class ExtensionLoader {
private static final Log logger = LogFactory.getLog(ExtensionLoader.class);
private static final String DEFAULT_DIRECTORY = "META-INF/";
private static final String FRAMEWORK_DIRECTORY = DEFAULT_DIRECTORY + "framework";
private static final Pattern NAME_SEPARATOR = Pattern.compile("\\s*[,]+\\s*");
private static final ConcurrentMap, ExtensionLoader> EXTENSION_LOADERS = new ConcurrentHashMap, ExtensionLoader>();
private static final ConcurrentMap, Object> EXTENSION_INSTANCES = new ConcurrentHashMap, Object>();
// ==============================
private final Class type;
private final ExtensionFactory objectFactory;
private final ConcurrentMap, String> cachedNames = new ConcurrentHashMap, String>();
private final Holder>> cachedClasses = new Holder>>();
private final Map cachedActivates = new ConcurrentHashMap();
private final ConcurrentMap> cachedInstances = new ConcurrentHashMap>();
private final Holder cachedAdaptiveInstance = new Holder();
private volatile Class cachedAdaptiveClass = null;
private String cachedDefaultName;
private volatile Throwable createAdaptiveInstanceError;
private Set> cachedWrapperClasses;
private Map exceptions = new ConcurrentHashMap();
private List paths;
private ExtensionLoader(Class type) {
this.type = type;
objectFactory = (type == ExtensionFactory.class ? null : ExtensionLoader.getExtensionLoader(ExtensionFactory.class).getAdaptiveExtension());
}
private ExtensionLoader(Class type, String path) {
this(type);
this.addPath(path);
}
/**
* 类上是否有{@link SPI}注解
* @param type Class
* @param 类型
* @return true of false
*/
private static boolean withExtensionAnnotation(Class type) {
return type.isAnnotationPresent(SPI.class);
}
/**
*
* 1: 类型不能为空
* 2: 类必须是接口
* 3: 必须有{@link @SPI}注解
*
* @param type Class
* @param path 扩展自定义目录
* @param 类型
* @return ExtensionLoader
*/
@SuppressWarnings("unchecked")
public static ExtensionLoader getExtensionLoader(Class type, String path) {
if (type == null) {
throw new IllegalArgumentException("Extension type == null");
}
if (!type.isInterface()) {
throw new IllegalArgumentException("Extension type(" + type + ") is not interface!");
}
if (!withExtensionAnnotation(type)) {
throw new IllegalArgumentException("Extension type(" + type +
") is not extension, because WITHOUT @" + SPI.class.getSimpleName() + " Annotation!");
}
ExtensionLoader loader = (ExtensionLoader) EXTENSION_LOADERS.get(type);
if (loader == null) {
ExtensionLoader extensionLoader = new ExtensionLoader(type, path);
EXTENSION_LOADERS.putIfAbsent(type, extensionLoader);
loader = extensionLoader;
}
return loader;
}
/**
* 默认目录 framework/
* @param type 类型
* @param Class
* @return ExtensionLoader
*/
public static ExtensionLoader getExtensionLoader(Class type) {
return getExtensionLoader(type, null);
}
private static ClassLoader findClassLoader() {
return ExtensionLoader.class.getClassLoader();
}
public String getExtensionName(T extensionInstance) {
return getExtensionName(extensionInstance.getClass());
}
public String getExtensionName(Class extensionClass) {
return cachedNames.get(extensionClass);
}
/**
* 返回扩展点实例，如果没有指定的扩展点或是还没加载（即实例化）则返回null。注意：此方法不会触发扩展点的加载。
*
* 一般应该调用{@link #getExtension(String)}方法获得扩展，这个方法会触发扩展点加载。
*
* @see #getExtension(String)
*/
@SuppressWarnings("unchecked")
public T getLoadedExtension(String name) {
if (StringUtils.isBlank(name)) {
throw new IllegalArgumentException("Extension name == null");
}
Holder holder = cachedInstances.get(name);
if (holder == null) {
Holder objectHolder = new Holder();
cachedInstances.putIfAbsent(name, objectHolder);
holder = objectHolder;
}
return (T) holder.get();
}
/**
* 返回已经加载的扩展点的名字。
*
* 一般应该调用{@link #getSupportedExtensions()}方法获得扩展，这个方法会返回所有的扩展点。
*
* @see #getSupportedExtensions()
*/
public Set getLoadedExtensions() {
return Collections.unmodifiableSet(new TreeSet(cachedInstances.keySet()));
}
/**
* 返回指定名字的扩展。如果指定名字的扩展不存在，则抛异常 {@link IllegalStateException}.
*
* @param name
* @return
*/
@SuppressWarnings("unchecked")
public T getExtension(String name) {
if (StringUtils.isBlank(name)) {
throw new IllegalArgumentException("Extension name == null");
}
if ("true".equals(name)) {
return getDefaultExtension();
}
Holder holder = cachedInstances.get(name);
if (holder == null) {
Holder objectHolder = new Holder();
cachedInstances.putIfAbsent(name, objectHolder);
holder = objectHolder;
}
Object instance = holder.get();
if (instance == null) {
synchronized (holder) {
instance = holder.get();
if (instance == null) {
instance = createExtension(name);
holder.set(instance);
}
}
}
return (T) instance;
}
/**
* 返回缺省的扩展，如果没有设置则返回null。
*/
public T getDefaultExtension() {
getExtensionClasses();
if (StringUtils.isBlank(cachedDefaultName) || "true".equals(cachedDefaultName)) {
return null;
}
return getExtension(cachedDefaultName);
}
public boolean hasExtension(String name) {
if (StringUtils.isBlank(name)) {
throw new IllegalArgumentException("Extension name == null");
}
try {
return getExtensionClass(name) != null;
} catch (Throwable t) {
return false;
}
}
public Set getSupportedExtensions() {
Map> clazzes = getExtensionClasses();
return Collections.unmodifiableSet(new TreeSet(clazzes.keySet()));
}
/**
* 返回缺省的扩展点名，如果没有设置缺省则返回null。
*/
public String getDefaultExtensionName() {
getExtensionClasses();
return cachedDefaultName;
}
/**
* 编程方式添加新扩展点。
*
* @param name 扩展点名
* @param clazz 扩展点类
* @throws IllegalStateException 要添加扩展点名已经存在。
*/
public void addExtension(String name, Class clazz) {
getExtensionClasses(); // load classes
if (!type.isAssignableFrom(clazz)) {
throw new IllegalStateException("Input type " + clazz + "not implement Extension " + type);
}
if (clazz.isInterface()) {
throw new IllegalStateException("Input type " + clazz + "can not be interface!");
}
if (!clazz.isAnnotationPresent(Adaptive.class)) {
if (StringUtils.isBlank(name)) {
throw new IllegalStateException("Extension name is blank (Extension " + type + ")!");
}
if (cachedClasses.get().containsKey(name)) {
throw new IllegalStateException("Extension name " +
name + " already existed(Extension " + type + ")!");
}
cachedNames.put(clazz, name);
cachedClasses.get().put(name, clazz);
} else {
if (cachedAdaptiveClass != null) {
throw new IllegalStateException("Adaptive Extension already existed(Extension " + type + ")!");
}
cachedAdaptiveClass = clazz;
}
}
/**
* 编程方式添加替换已有扩展点。
*
* @param name 扩展点名
* @param clazz 扩展点类
* @throws IllegalStateException 要添加扩展点名已经存在。
* @deprecated 不推荐应用使用，一般只在测试时可以使用
*/
@Deprecated
public void replaceExtension(String name, Class clazz) {
getExtensionClasses(); // load classes
if (!type.isAssignableFrom(clazz)) {
throw new IllegalStateException("Input type " + clazz + "not implement Extension " + type);
}
if (clazz.isInterface()) {
throw new IllegalStateException("Input type " + clazz + "can not be interface!");
}
if (!clazz.isAnnotationPresent(Adaptive.class)) {
if (StringUtils.isBlank(name)) {
throw new IllegalStateException("Extension name is blank (Extension " + type + ")!");
}
if (!cachedClasses.get().containsKey(name)) {
throw new IllegalStateException("Extension name " + name + " not existed(Extension " + type + ")!");
}
cachedNames.put(clazz, name);
cachedClasses.get().put(name, clazz);
cachedInstances.remove(name);
} else {
if (cachedAdaptiveClass == null) {
throw new IllegalStateException("Adaptive Extension not existed(Extension " + type + ")!");
}
cachedAdaptiveClass = clazz;
cachedAdaptiveInstance.set(null);
}
}
@SuppressWarnings("unchecked")
public T getAdaptiveExtension() {
Object instance = cachedAdaptiveInstance.get();
if (instance == null) {
if (createAdaptiveInstanceError == null) {
synchronized (cachedAdaptiveInstance) {
instance = cachedAdaptiveInstance.get();
if (instance == null) {
try {
instance = createAdaptiveExtension();
cachedAdaptiveInstance.set(instance);
} catch (Throwable t) {
createAdaptiveInstanceError = t;
throw new IllegalStateException("fail to create adaptive instance: " + t.toString(), t);
}
}
}
} else {
throw new IllegalStateException("fail to create adaptive instance: " + createAdaptiveInstanceError.toString(), createAdaptiveInstanceError);
}
}
return (T) instance;
}
private IllegalStateException findException(String name) {
for (Map.Entry entry : exceptions.entrySet()) {
if (entry.getKey().toLowerCase().contains(name.toLowerCase())) {
return entry.getValue();
}
}
StringBuilder buf = new StringBuilder("No such extension " + type.getName() + " by name " + name);
int i = 1;
for (Map.Entry entry : exceptions.entrySet()) {
if (i == 1) {
buf.append(", possible causes: ");
}
buf.append("\r\n(");
buf.append(i++);
buf.append(") ");
buf.append(entry.getKey());
buf.append(":\r\n");
buf.append(toString(entry.getValue()));
}
return new IllegalStateException(buf.toString());
}
public static String toString(Throwable e) {
UnsafeStringWriter w = new UnsafeStringWriter();
PrintWriter p = new PrintWriter(w);
p.print(e.getClass().getName());
if (e.getMessage() != null) {
p.print(": " + e.getMessage());
}
p.println();
try {
e.printStackTrace(p);
return w.toString();
} finally {
p.close();
}
}
@SuppressWarnings("unchecked")
private T createExtension(String name) {
Class clazz = getExtensionClasses().get(name);
if (clazz == null) {
throw findException(name);
}
try {
T instance = (T) EXTENSION_INSTANCES.get(clazz);
if (instance == null) {
T t = (T) clazz.newInstance();
EXTENSION_INSTANCES.putIfAbsent(clazz, t);
instance = t;
}
injectExtension(instance);
Set> wrapperClasses = cachedWrapperClasses;
if (wrapperClasses != null && wrapperClasses.size() > 0) {
for (Class wrapperClass : wrapperClasses) {
instance = injectExtension((T) wrapperClass.getConstructor(type).newInstance(instance));
}
}
return instance;
} catch (Throwable t) {
throw new IllegalStateException("Extension instance(name: " + name + ", class: " +
type + ") could not be instantiated: " + t.getMessage(), t);
}
}
private T injectExtension(T instance) {
try {
if (objectFactory != null) {
for (Method method : instance.getClass().getMethods()) {
if (method.getName().startsWith("set")
&& method.getParameterTypes().length == 1
&& Modifier.isPublic(method.getModifiers())) {
Class pt = method.getParameterTypes()[0];
try {
String property = method.getName().length() > 3 ? method.getName().substring(3, 4).toLowerCase() + method.getName().substring(4) : "";
Object object = objectFactory.getExtension(pt, property);
if (object != null) {
method.invoke(instance, object);
}
} catch (Exception e) {
logger.error("fail to inject via method " + method.getName()
+ " of interface " + type.getName() + ": " + e.getMessage(), e);
}
}
}
}
} catch (Exception e) {
logger.error(e.getMessage(), e);
}
return instance;
}
private Class getExtensionClass(String name) {
if (type == null) {
throw new IllegalArgumentException("Extension type == null");
}
if (name == null) {
throw new IllegalArgumentException("Extension name == null");
}
Class clazz = getExtensionClasses().get(name);
if (clazz == null) {
throw new IllegalStateException("No such extension \"" + name + "\" for " + type.getName() + "!");
}
return clazz;
}
private Map> getExtensionClasses() {
Map> classes = cachedClasses.get();
if (classes == null) {
synchronized (cachedClasses) {
classes = cachedClasses.get();
if (classes == null) {
classes = loadExtensionClasses();
cachedClasses.set(classes);
}
}
}
return classes;
}
// 此方法已经getExtensionClasses方法同步过。
private Map> loadExtensionClasses() {
final SPI defaultAnnotation = type.getAnnotation(SPI.class);
if (defaultAnnotation != null) {
cachedDefaultName = defaultAnnotation.value();
}
Map> extensionClasses = new HashMap>();
loadFile(extensionClasses, FRAMEWORK_DIRECTORY);
for (String path : paths) {
loadFile(extensionClasses, DEFAULT_DIRECTORY + path);
}
return extensionClasses;
}
/**
* 加载文件
* @param extensionClasses 扩展类
* @param dir 目录
*/
private void loadFile(Map> extensionClasses, String dir) {
int diff = dir.length() - dir.lastIndexOf("/");
String fileName = diff == 1 ? dir + type.getName() : dir + "/" + type.getName();
try {
Enumeration urls;
ClassLoader classLoader = findClassLoader();
if (classLoader != null) {
urls = classLoader.getResources(fileName);
} else {
urls = ClassLoader.getSystemResources(fileName);
}
if (urls != null) {
while (urls.hasMoreElements()) {
java.net.URL url = urls.nextElement();
try {
BufferedReader reader = new BufferedReader(new InputStreamReader(url.openStream(), "utf-8"));
try {
String line = null;
while ((line = reader.readLine()) != null) {
// 内部类 line: javassist=com.github.fartherp.framework.common.compiler.support.JavassistCompiler#Test
final int ci = line.indexOf('#');
if (ci >= 0) {
// line: javassist=com.github.fartherp.framework.common.compiler.support.JavassistCompiler
line = line.substring(0, ci).trim();
}
if (line.length() > 0) {
try {
String name = null;
int i = line.indexOf('=');
if (i > 0) {
// name: javassist
name = line.substring(0, i).trim();
// line: com.github.fartherp.framework.common.compiler.support.JavassistCompiler
line = line.substring(i + 1).trim();
}
if (line.length() > 0) {
Class clazz = Class.forName(line, true, classLoader);
if (!type.isAssignableFrom(clazz)) {
throw new IllegalStateException("Error when load extension class(interface: " +
type + ", class: " + clazz.getName() + "), class is not subtype of interface.");
}
// 类有@Adaptive注解，只需有一个@Adaptive，适配
if (clazz.isAnnotationPresent(Adaptive.class)) {
if (cachedAdaptiveClass == null) {
cachedAdaptiveClass = clazz;
} else if (!cachedAdaptiveClass.equals(clazz)) {
throw new IllegalStateException("More than 1 adaptive class found: "
+ cachedAdaptiveClass.getClass().getName()
+ ", " + clazz.getClass().getName());
}
} else {
try {
clazz.getConstructor(type);
Set> wrappers = cachedWrapperClasses;
if (wrappers == null) {
cachedWrapperClasses = new ConcurrentHashSet>();
wrappers = cachedWrapperClasses;
}
wrappers.add(clazz);
} catch (NoSuchMethodException e) {
clazz.getConstructor();
// if (name == null || name.length() == 0) {
// name = findAnnotationName(clazz);
// if (name == null || name.length() == 0) {
// if (clazz.getSimpleName().length() > type.getSimpleName().length()
// && clazz.getSimpleName().endsWith(type.getSimpleName())) {
// name = clazz.getSimpleName().substring(0, clazz.getSimpleName().length() - type.getSimpleName().length()).toLowerCase();
// } else {
// throw new IllegalStateException("No such extension name for the class " + clazz.getName() + " in the config " + url);
// }
// }
// }
String[] names = NAME_SEPARATOR.split(name);
if (names != null && names.length > 0) {
Activate activate = clazz.getAnnotation(Activate.class);
if (activate != null) {
cachedActivates.put(names[0], activate);
}
for (String n : names) {
if (!cachedNames.containsKey(clazz)) {
cachedNames.put(clazz, n);
}
Class c = extensionClasses.get(n);
if (c == null) {
extensionClasses.put(n, clazz);
} else if (c != clazz) {
throw new IllegalStateException("Duplicate extension " + type.getName() + " name " + n + " on " + c.getName() + " and " + clazz.getName());
}
}
}
}
}
}
} catch (Throwable t) {
IllegalStateException e = new IllegalStateException("Failed to load extension class(interface: " + type + ", class line: " + line + ") in " + url + ", cause: " + t.getMessage(), t);
exceptions.put(line, e);
}
}
} // end of while read lines
} finally {
reader.close();
}
} catch (Throwable t) {
logger.error("Exception when load extension class(interface: " +
type + ", class file: " + url + ") in " + url, t);
}
} // end of while urls
}
} catch (Throwable t) {
logger.error("Exception when load extension class(interface: " +
type + ", description file: " + fileName + ").", t);
}
}
/**
* 创建适配的扩展对象
* @return obj
*/
@SuppressWarnings("unchecked")
private T createAdaptiveExtension() {
try {
return injectExtension((T) getAdaptiveExtensionClass().newInstance());
} catch (Exception e) {
throw new IllegalStateException("Can not create adaptive extenstion " + type + ", cause: " + e.getMessage(), e);
}
}
/**
* 获取适配扩展类型
* @return Class
*/
private Class getAdaptiveExtensionClass() {
getExtensionClasses();
return cachedAdaptiveClass;
}
@Override
public String toString() {
return this.getClass().getName() + "[" + type.getName() + "]";
}
public static boolean isNotEmpty(String value) {
return !isEmpty(value);
}
public static boolean isEmpty(String value) {
return StringUtils.isBlank(value)
|| "false".equalsIgnoreCase(value)
|| "0".equalsIgnoreCase(value)
|| "null".equalsIgnoreCase(value)
|| "N/A".equalsIgnoreCase(value);
}
public void addPath(String path) {
if (this.paths == null) {
this.paths = new ArrayList();
}
this.paths.add(path);
}
}
