# 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:

description
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:

description
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

## Constructor Summary

Constructors
Modifier
Constructor
Description
`protected`
`HttpServer()`
Constructor for subclasses to call.

## Method Summary

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).
`static HttpServer`
`create(InetSocketAddress addr, int backlog, String path, HttpHandler handler, Filter... filters)`
Creates an `HttpServer` instance with an initial context.
`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`

## Constructor Details

### HttpServer

protected HttpServer()
Constructor for subclasses to call.

## Method Details

### 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.

Returns:
  an instance of `HttpServer`
Throws:
  `IOException` - if an I/O error occurs

### 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(InetSocketAddress, int)` 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
Returns:
  an instance of `HttpServer`
Throws:
  `IOException` - if an I/O error occurs
  `BindException` - if the server cannot bind to the requested address, or if the server is already bound

### create

public static HttpServer create(InetSocketAddress addr, int backlog, String path, HttpHandler handler, Filter... filters) throws IOException
Creates an `HttpServer` instance with an initial context.

The server is created with an initial context that maps the URI `path` to the exchange `handler`. The initial context is created as if by an invocation of `createContext(path)`. The `filters`, if any, are added to the initial context, in the order they are given. The returned server is not started so can be configured further if required.

The server instance will bind to the given `InetSocketAddress`.

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
  `path` - the root URI path of the context, must be absolute
  `handler` - the HttpHandler for the context
  `filters` - the Filters for the context, optional
Returns:
  the HttpServer
Throws:
  `BindException` - if the server cannot bind to the address
  `IOException` - if an I/O error occurs
  `IllegalArgumentException` - if path is invalid
  `NullPointerException` - if any of: `path`, `handler`, `filters`, or any element of `filters`, are `null`
Since:
  18

### 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.

API Note:
  The path should generally, but is not required to, end with '/'. If the path does not end with '/', eg such as with `"/foo"` then this would match requests with a path of `"/foobar"` or `"/foo/bar"`.
Parameters:
  `path` - the root URI path to associate the context with
  `handler` - the handler to invoke for incoming requests
Returns:
  an instance of `HttpContext`
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.

API Note:
  The path should generally, but is not required to, end with '/'. If the path does not end with '/', eg such as with `"/foo"` then this would match requests with a path of `"/foobar"` or `"/foo/bar"`.
Parameters:
  `path` - the root URI path to associate the context with
Returns:
  an instance of `HttpContext`
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 `InetSocketAddress` the server is listening on