Tomcat的server启动

1.server的启动

前面我们说过了，server的启动过程主要是通过catalina进行一个启动，而在启动过程中他又经历了哪些过程呢？

从代码中看，server的启动过程中，他继承了lifecycleMbeanBase这个类并且实现了接口server，

而在这lifecycleMbeanBase类中又继承了LifecycleBase这个类，并且LifecycleBase复写了他父接口其中的initInternal和startInter这两个方法，这两个方法是一个模板方法。

server的启动过程中还有一个重要的方法叫做await方法，就是catalina就是调用他进入到了等待状态，进入到了等待状态，其中

// Negative values - don't wait on port - tomcat is embedded or we just don't like ports
if( port == -2 ) {
// undocumented yet - for embedding apps that are around, alive.
return;
}
if( port==-1 ) {
try {
awaitThread = Thread.currentThread();
while(!stopAwait) {
try {
Thread.sleep( 10000 );
} catch( InterruptedException ex ) {
// continue and check the flag
}
}
} finally {
awaitThread = null;
}
return;
}

// Set up a server socket to wait on
try {
awaitSocket = new ServerSocket(port, 1,
InetAddress.getByName(address));
} catch (IOException e) {
log.error("StandardServer.await: create[" + address
+ ":" + port
+ "]: ", e);
return;
}

try {
awaitThread = Thread.currentThread();

// Loop waiting for a connection and a valid command
while (!stopAwait) {
ServerSocket serverSocket = awaitSocket;
if (serverSocket == null) {
break;
}

// Wait for the next connection
Socket socket = null;
StringBuilder command = new StringBuilder();
try {
InputStream stream;
long acceptStartTime = System.currentTimeMillis();
try {
socket = serverSocket.accept();
socket.setSoTimeout(10 * 1000); // Ten seconds
stream = socket.getInputStream();
} catch (SocketTimeoutException ste) {
// This should never happen but bug 56684 suggests that
// it does.
log.warn(sm.getString("standardServer.accept.timeout",
Long.valueOf(System.currentTimeMillis() - acceptStartTime)), ste);
continue;
} catch (AccessControlException ace) {
log.warn("StandardServer.accept security exception: "
+ ace.getMessage(), ace);
continue;
} catch (IOException e) {
if (stopAwait) {
// Wait was aborted with socket.close()
break;
}
log.error("StandardServer.await: accept: ", e);
break;
}

// Read a set of characters from the socket
int expected = 1024; // Cut off to avoid DoS attack
while (expected < shutdown.length()) {
if (random == null)
random = new Random();
expected += (random.nextInt() % 1024);
}
while (expected > 0) {
int ch = -1;
try {
ch = stream.read();
} catch (IOException e) {
log.warn("StandardServer.await: read: ", e);
ch = -1;
}
// Control character or EOF (-1) terminates loop
if (ch < 32 || ch == 127) {
break;
}
command.append((char) ch);
expected--;
}
} finally {
// Close the socket now that we are done with it
try {
if (socket != null) {
socket.close();
}
} catch (IOException e) {
// Ignore
}
}

// Match against our command string
boolean match = command.toString().equals(shutdown);
if (match) {
log.info(sm.getString("standardServer.shutdownViaPort"));
break;
} else
log.warn("StandardServer.await: Invalid command '"
+ command.toString() + "' received");
}
} finally {
ServerSocket serverSocket = awaitSocket;
awaitThread = null;
awaitSocket = null;

// Close the server socket and return
if (serverSocket != null) {
try {
serverSocket.close();
} catch (IOException e) {
// Ignore
}
}
}
这个方法中写着，当Tomcat的端口为-2时则直接退出等待状态，关闭Tomcat，如果为-1时则会一直循环，当stopAwait为图二时才会停止，而当为其他端口时，也会进入一个循环，这个循环可以跳出，有break，当指定的端口监听到shutdown一样的命令时，Tomcat就会关闭。

2.service的启动过程。

service也实现了LifecycleMBeanBase这个方法，从里面

protected void startInternal() throws LifecycleException {

if(log.isInfoEnabled())
log.info(sm.getString("standardService.start.name", this.name));
setState(LifecycleState.STARTING);

// Start our defined Container first
if (container != null) {
synchronized (container) {
container.start();
}
}

synchronized (executors) {
for (Executor executor: executors) {
executor.start();
}
}

// Start our defined Connectors second
synchronized (connectorsLock) {
for (Connector connector: connectors) {
try {
// If it has already failed, don't try and start it
if (connector.getState() != LifecycleState.FAILED) {
connector.start();
}
} catch (Exception e) {
log.error(sm.getString(
"standardService.connector.startFailed",
connector), e);
}
}
}
}

protected void startInternal() throws LifecycleException {

if(log.isInfoEnabled())
log.info(sm.getString("standardService.start.name", this.name));
setState(LifecycleState.STARTING);

// Start our defined Container first
if (container != null) {
synchronized (container) {
container.start();
}
}

synchronized (executors) {
for (Executor executor: executors) {
executor.start();
}
}

从他的初始化方法和start方法中可以看出来，他调用用了container，executors，connector等组件。其中container也就是我们说的container容器，executors是是executor的线程池，

这个线程池最多能够启用150个，最少四个线程。这样整个Tomcat就启动了。下面这个图片是转载的。大概就是这么个过程、

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