Class HttpServer

java.lang.Object
- com.sun.net.httpserver.HttpServer

Direct Known Subclasses:: HttpsServer

public abstract class HttpServer
extends Object

This class implements a simple HTTP server. A HttpServer is bound to an IP address and port number and listens for incoming TCP connections from clients on this address. The sub-class HttpsServer implements a server which handles HTTPS requests.

One or more HttpHandler objects must be associated with a server in order to process requests. Each such HttpHandler is registered with a root URI path which represents the location of the application or service on this server. The mapping of a handler to a HttpServer is encapsulated by a HttpContext object. HttpContexts are created by calling createContext(String,HttpHandler). Any request for which no handler can be found is rejected with a 404 response. Management of threads can be done external to this object by providing a Executor object. If none is provided a default implementation is used.

Mapping request URIs to HttpContext paths

When a HTTP request is received, the appropriate HttpContext (and handler) is located by finding the context whose path is the longest matching prefix of the request URI's path. Paths are matched literally, which means that the strings are compared case sensitively, and with no conversion to or from any encoded forms. For example. Given a HttpServer with the following HttpContexts configured.

Context	Context path
ctx1	"/"
ctx2	"/apps/"
ctx3	"/apps/foo/"

the following table shows some request URIs and which, if any context they would match with.

Request URI	Matches context
"http://foo.com/apps/foo/bar"	ctx3
"http://foo.com/apps/Foo/bar"	no match, wrong case
"http://foo.com/apps/app1"	ctx2
"http://foo.com/foo"	ctx1

Note about socket backlogs

When binding to an address and port number, the application can also specify an integer backlog parameter. This represents the maximum number of incoming TCP connections which the system will queue internally. Connections are queued while they are waiting to be accepted by the HttpServer. When the limit is reached, further connections may be rejected (or possibly ignored) by the underlying TCP implementation. Setting the right backlog value is a compromise between efficient resource usage in the TCP layer (not setting it too high) and allowing adequate throughput of incoming requests (not setting it too low).

Since:: 1.6

Constructors

Modifier	Constructor	Description
`protected`	`HttpServer()`

Methods

Modifier and Type	Method	Description
`abstract void`	`bind(InetSocketAddress addr, int backlog)`	Binds a currently unbound HttpServer to the given address and port number.
`static HttpServer`	`create()`	creates a HttpServer instance which is initially not bound to any local address/port.
`static HttpServer`	`create(InetSocketAddress addr, int backlog)`	Create a `HttpServer` instance which will bind to the specified `InetSocketAddress` (IP address and port number) A maximum backlog can also be specified.
`abstract HttpContext`	`createContext(String path)`	Creates a HttpContext without initially specifying a handler.
`abstract HttpContext`	`createContext(String path, HttpHandler handler)`	Creates a HttpContext.
`abstract InetSocketAddress`	`getAddress()`	returns the address this server is listening on
`abstract Executor`	`getExecutor()`	returns this server's Executor object if one was specified with `setExecutor(Executor)`, or `null` if none was specified.
`abstract void`	`removeContext(HttpContext context)`	Removes the given context from the server.
`abstract void`	`removeContext(String path)`	Removes the context identified by the given path from the server.
`abstract void`	`setExecutor(Executor executor)`	sets this server's `Executor` object.
`abstract void`	`start()`	Starts this server in a new background thread.
`abstract void`	`stop(int delay)`	stops this server by closing the listening socket and disallowing any new exchanges from being processed.

Methods declared in class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructors

HttpServer

protected HttpServer()

Methods

create

public static HttpServer create()
                         throws IOException

creates a HttpServer instance which is initially not bound to any local address/port. The HttpServer is acquired from the currently installed HttpServerProvider The server must be bound using bind(InetSocketAddress,int) before it can be used.

Throws:: IOException

create

public static HttpServer create(InetSocketAddress addr,
                                int backlog)
                         throws IOException

Create a HttpServer instance which will bind to the specified InetSocketAddress (IP address and port number) A maximum backlog can also be specified. This is the maximum number of queued incoming connections to allow on the listening socket. Queued TCP connections exceeding this limit may be rejected by the TCP implementation. The HttpServer is acquired from the currently installed HttpServerProvider

Parameters:: addr - the address to listen on, if null then bind() must be called to set the address; backlog - the socket backlog. If this value is less than or equal to zero, then a system default value is used.
Throws:: BindException - if the server cannot bind to the requested address, or if the server is already bound.; IOException

bind

public abstract void bind(InetSocketAddress addr,
                          int backlog)
                   throws IOException

Binds a currently unbound HttpServer to the given address and port number. A maximum backlog can also be specified. This is the maximum number of queued incoming connections to allow on the listening socket. Queued TCP connections exceeding this limit may be rejected by the TCP implementation.

Parameters:: addr - the address to listen on; backlog - the socket backlog. If this value is less than or equal to zero, then a system default value is used.
Throws:: BindException - if the server cannot bind to the requested address or if the server is already bound.; NullPointerException - if addr is null; IOException

start

public abstract void start()

Starts this server in a new background thread. The background thread inherits the priority, thread group and context class loader of the caller.

setExecutor

public abstract void setExecutor(Executor executor)

sets this server's Executor object. An Executor must be established before start() is called. All HTTP requests are handled in tasks given to the executor. If this method is not called (before start()) or if it is called with a null Executor, then a default implementation is used, which uses the thread which was created by the start() method.

Parameters:: executor - the Executor to set, or null for default implementation
Throws:: IllegalStateException - if the server is already started

getExecutor

public abstract Executor getExecutor()

returns this server's Executor object if one was specified with setExecutor(Executor), or null if none was specified.

Returns:: the Executor established for this server or null if not set.

stop

public abstract void stop(int delay)

stops this server by closing the listening socket and disallowing any new exchanges from being processed. The method will then block until all current exchange handlers have completed or else when approximately delay seconds have elapsed (whichever happens sooner). Then, all open TCP connections are closed, the background thread created by start() exits, and the method returns. Once stopped, a HttpServer cannot be re-used.

Parameters:: delay - the maximum time in seconds to wait until exchanges have finished.
Throws:: IllegalArgumentException - if delay is less than zero.

createContext

public abstract HttpContext createContext(String path,
                                          HttpHandler handler)

Creates a HttpContext. A HttpContext represents a mapping from a URI path to a exchange handler on this HttpServer. Once created, all requests received by the server for the path will be handled by calling the given handler object. The context is identified by the path, and can later be removed from the server using this with the removeContext(String) method.

The path specifies the root URI path for this context. The first character of path must be '/'.

The class overview describes how incoming request URIs are mapped to HttpContext instances.

Parameters:: path - the root URI path to associate the context with; handler - the handler to invoke for incoming requests.
Throws:: IllegalArgumentException - if path is invalid, or if a context already exists for this path; NullPointerException - if either path, or handler are null

createContext

public abstract HttpContext createContext(String path)

Creates a HttpContext without initially specifying a handler. The handler must later be specified using HttpContext.setHandler(HttpHandler). A HttpContext represents a mapping from a URI path to an exchange handler on this HttpServer. Once created, and when the handler has been set, all requests received by the server for the path will be handled by calling the handler object. The context is identified by the path, and can later be removed from the server using this with the removeContext(String) method.

The path specifies the root URI path for this context. The first character of path must be '/'.

The class overview describes how incoming request URIs are mapped to HttpContext instances.

Parameters:: path - the root URI path to associate the context with
Throws:: IllegalArgumentException - if path is invalid, or if a context already exists for this path; NullPointerException - if path is null

removeContext

public abstract void removeContext(String path)
                            throws IllegalArgumentException

Removes the context identified by the given path from the server. Removing a context does not affect exchanges currently being processed but prevents new ones from being accepted.

Parameters:: path - the path of the handler to remove
Throws:: IllegalArgumentException - if no handler corresponding to this path exists.; NullPointerException - if path is null

removeContext

public abstract void removeContext(HttpContext context)

Removes the given context from the server. Removing a context does not affect exchanges currently being processed but prevents new ones from being accepted.

Parameters:: context - the context to remove
Throws:: NullPointerException - if context is null

getAddress

public abstract InetSocketAddress getAddress()

returns the address this server is listening on

Returns:: the address/port number the server is listening on

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https://docs.oracle.com/en/java/javase/11/docs/api/jdk.httpserver/com/sun/net/httpserver/HttpServer.html