dubbo Main
例子
public class Start {
public static void main(String[] args) throws Exception {
com.alibaba.dubbo.container.Main.main(args);
}
}
源码
public class Main {
//系统变量
public static final String CONTAINER_KEY = "dubbo.container";
public static final String SHUTDOWN_HOOK_KEY = "dubbo.shutdown.hook";
private static final Logger logger = LoggerFactory.getLogger(Main.class);
//SPI的container Loader容器
private static final ExtensionLoader<Container> loader = ExtensionLoader.getExtensionLoader(Container.class);
private static final ReentrantLock LOCK = new ReentrantLock();
private static final Condition STOP;
public Main() {
}
public static void main(String[] args) {
try {
//如果没有启动参数
if (args == null || args.length == 0) {
//获得系统变量 如jvm参数配置的-Ddubbo.container=spiKey 如果没有则使用loader.getDefaultExtensionName()的
String config = ConfigUtils.getProperty("dubbo.container", loader.getDefaultExtensionName());
//分割
args = Constants.COMMA_SPLIT_PATTERN.split(config);
}
//容器 可以多容器启动
final List<Container> containers = new ArrayList();
for(int i = 0; i < args.length; ++i) {
//spi获取对应容器实现
containers.add(loader.getExtension(args[i]));
}
logger.info("Use container type(" + Arrays.toString(args) + ") to run dubbo serivce.");
/**
* 埋点 jvm关闭时 关闭容器
*kill pid会优雅关闭 则有新的请求拒绝 等没有进行中的请求 才关闭
*kill -9并不会优雅关闭
*/
if ("true".equals(System.getProperty("dubbo.shutdown.hook"))) {
Runtime.getRuntime().addShutdownHook(new Thread() {
public void run() {
Iterator i$ = containers.iterator();
//遍历容器执行stop
while(i$.hasNext()) {
Container container = (Container)i$.next();
try {
container.stop();
Main.logger.info("Dubbo " + container.getClass().getSimpleName() + " stopped!");
} catch (Throwable var8) {
Main.logger.error(var8.getMessage(), var8);
}
try {
Main.LOCK.lock();
//类型Object的notify
Main.STOP.signal();
} finally {
Main.LOCK.unlock();
}
}
}
});
}
Iterator i$ = containers.iterator();
//循环启动容器
while(i$.hasNext()) {
Container container = (Container)i$.next();
container.start();
logger.info("Dubbo " + container.getClass().getSimpleName() + " started!");
}
System.out.println((new SimpleDateFormat("[yyyy-MM-dd HH:mm:ss]")).format(new Date()) + " Dubbo service server started!");
} catch (RuntimeException var10) {
var10.printStackTrace();
logger.error(var10.getMessage(), var10);
System.exit(1);
}
try {
LOCK.lock();
/**
* 阻塞 防止应用程序结束
* 类似object的wait()
*/
STOP.await();
} catch (InterruptedException var8) {
logger.warn("Dubbo service server stopped, interrupted by other thread!", var8);
} finally {
LOCK.unlock();
}
}
static {
//condition可参考资料https://blog.csdn.net/andyzhaojianhui/article/details/79361454
STOP = LOCK.newCondition();
}
}
loader.getDefaultExtensionName(public class ExtensionLoader<T> {
private final Holder<Map<String, Class<?>>> cachedClasses = new Holder();
public String getDefaultExtensionName() {
this.getExtensionClasses();
return this.cachedDefaultName;
}
private Map<String, Class<?>> getExtensionClasses() {
//默认Holder容器是空的
Map<String, Class<?>> classes = (Map)this.cachedClasses.get();
if (classes == null) {
Holder var2 = this.cachedClasses;
synchronized(this.cachedClasses) {
//防止缓存穿透 重复加载 加了一层判断
classes = (Map)this.cachedClasses.get();
if (classes == null) {
//真正加载的地方
classes = this.loadExtensionClasses();
this.cachedClasses.set(classes);
}
}
}
return classes;
}
private Map<String, Class<?>> loadExtensionClasses() {
/**
* 获得Container上的SPI注解 private static final ExtensionLoader<Container> loader = ExtensionLoader.getExtensionLoader(Container.class);
* type为Container
*/
SPI defaultAnnotation = (SPI)this.type.getAnnotation(SPI.class);
if (defaultAnnotation != null) {
//获取SPI上面的名字
String value = defaultAnnotation.value();
if ((value = value.trim()).length() > 0) {
String[] names = NAME_SEPARATOR.split(value);
if (names.length > 1) {
throw new IllegalStateException("more than 1 default extension name on extension " + this.type.getName() + ": " + Arrays.toString(names));
}
if (names.length == 1) {
this.cachedDefaultName = names[0];
}
}
}
Map<String, Class<?>> extensionClasses = new HashMap();
//加载这个目录下的spi文件配置 META-INF/dubbo/internal/com.alibaba.dubbo.container.Container
this.loadDirectory(extensionClasses, "META-INF/dubbo/internal/");
//加载这个目录下的spi文件配置 META-INF/dubbo/com.alibaba.dubbo.container.Container
this.loadDirectory(extensionClasses, "META-INF/dubbo/");
//加载这个目录下的spi文件配置META-INF/dubbo/services/com.alibaba.dubbo.container.Container
this.loadDirectory(extensionClasses, "META-INF/services/");
return extensionClasses;
}
private void loadDirectory(Map<String, Class<?>> extensionClasses, String dir) {
//加载这个目录下的spi文件配置 META-INF/dubbo/internal/com.alibaba.dubbo.container.Container
String fileName = dir + this.type.getName();
try {
ClassLoader classLoader = findClassLoader();
Enumeration urls;
if (classLoader != null) {
urls = classLoader.getResources(fileName);
} else {
urls = ClassLoader.getSystemResources(fileName);
}
if (urls != null) {
while(urls.hasMoreElements()) {
java.net.URL resourceURL = (java.net.URL)urls.nextElement();
this.loadResource(extensionClasses, classLoader, resourceURL);
}
}
} catch (Throwable var7) {
logger.error("Exception when load extension class(interface: " + this.type + ", description file: " + fileName + ").", var7);
}
}
}
SPI defaultAnnotation = (SPI)this.type.getAnnotation(SPI.class);
@SPI("spring")
public interface Container {
void start();
void stop();
}
所以默认加载的是SpringContainer