Add an HTTP library that wraps dart:io.

pkg/http/lib/src/base_client.dart

+// Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+library base_client;
+
+import 'dart:io';
+import 'dart:scalarlist';
+import 'dart:uri';
+
+import 'base_request.dart';
+import 'request.dart';
+import 'response.dart';
+import 'streamed_response.dart';
+import 'utils.dart';
+
+/// The abstract base class for an HTTP client. This is a mixin-style class;
+/// subclasses only need to implement [send] and maybe [close], and then they
+/// get various convenience methods for free.
+abstract class BaseClient {
+  /// Sends an HTTP HEAD request with the given headers to the given URL, which
+  /// can be a [Uri] or a [String].
+  ///
+  /// For more fine-grained control over the request, use [send] instead.
+  Future<Response> head(url, {Map<String, String> headers}) =>
+    _sendUnstreamed("HEAD", url, headers);
+
+  /// Sends an HTTP GET request with the given headers to the given URL, which
+  /// can be a [Uri] or a [String].
+  ///
+  /// For more fine-grained control over the request, use [send] instead.
+  Future<Response> get(url, {Map<String, String> headers}) =>
+    _sendUnstreamed("GET", url, headers);
+
+  /// Sends an HTTP POST request with the given headers and fields to the given
+  /// URL, which can be a [Uri] or a [String]. If any fields are specified, the
+  /// content-type is automatically set to
+  /// `"application/x-www-form-urlencoded"`.
+  ///
+  /// For more fine-grained control over the request, use [send] instead.
+  Future<Response> post(url,
+      {Map<String, String> headers,
+       Map<String, String> fields}) =>
+    _sendUnstreamed("POST", url, headers, fields);
+
+  /// Sends an HTTP PUT request with the given headers and fields to the given
+  /// URL, which can be a [Uri] or a [String]. If any fields are specified, the
+  /// content-type is automatically set to
+  /// `"application/x-www-form-urlencoded"`.
+  ///
+  /// For more fine-grained control over the request, use [send] instead.
+  Future<Response> put(url,
+      {Map<String, String> headers,
+       Map<String, String> fields}) =>
+    _sendUnstreamed("PUT", url, headers, fields);
+
+  /// Sends an HTTP DELETE request with the given headers to the given URL,
+  /// which can be a [Uri] or a [String].
+  ///
+  /// For more fine-grained control over the request, use [send] instead.
+  Future<Response> delete(url, {Map<String, String> headers}) =>
+    _sendUnstreamed("DELETE", url, headers);
+
+  /// Sends an HTTP GET request with the given headers to the given URL, which
+  /// can be a [Uri] or a [String], and returns a Future that completes to the
+  /// body of the response as a String.
+  ///
+  /// The Future will emit an [HttpException] if the response doesn't have a
+  /// success status code.
+  ///
+  /// For more fine-grained control over the request and response, use [send] or
+  /// [get] instead.
+  Future<String> read(url, {Map<String, String> headers}) {
+    return get(url, headers: headers).transform((response) {
+      _checkResponseSuccess(url, response);
+      return response.body;
+    });
+  }
+
+  /// Sends an HTTP GET request with the given headers to the given URL, which
+  /// can be a [Uri] or a [String], and returns a Future that completes to the
+  /// body of the response as a list of bytes.
+  ///
+  /// The Future will emit an [HttpException] if the response doesn't have a
+  /// success status code.
+  ///
+  /// For more fine-grained control over the request and response, use [send] or
+  /// [get] instead.
+  Future<Uint8List> readBytes(url, {Map<String, String> headers}) {
+    return get(url, headers: headers).transform((response) {
+      _checkResponseSuccess(url, response);
+      return response.bodyBytes;
+    });
+  }
+
+  /// Sends an HTTP request and asynchronously returns the response.
+  ///
+  /// Implementers should call [BaseRequest.finalize] to get the body of the
+  /// request as an [InputStream]. They shouldn't make any assumptions about the
+  /// state of the stream; it could have data written to it asynchronously at a
+  /// later point, or it could already be closed when it's returned.
+  Future<StreamedResponse> send(BaseRequest request);
+
+  /// Sends a non-streaming [Request] and returns a non-streaming [Response].
+  Future<Response> _sendUnstreamed(
+      String method, url, Map<String, String> headers,
+      [Map<String, String> fields]) {
+    // Wrap everything in a Future block so that synchronous validation errors
+    // are passed asynchronously through the Future chain.
+    return async.chain((_) {
+      if (url is String) url = new Uri.fromString(url);
+      var request = new Request(method, url);
+
+      if (headers != null) mapAddAll(request.headers, headers);
+      if (fields != null && !fields.isEmpty) request.bodyFields = fields;
+
+      return send(request);
+    }).chain(Response.fromStream);
+  }
+
+  /// Throws an error if [response] is not successful.
+  void _checkResponseSuccess(url, Response response) {
+    if (response.statusCode < 400) return;
+    var message = "Request to $url failed with status ${response.statusCode}";
+    if (response.reasonPhrase != null) {
+      message = "$message: ${response.reasonPhrase}";
+    }
+    throw new HttpException("$message.");
+  }
+
+  /// Closes the client and cleans up any resources associated with it. It's
+  /// important to close each client when it's done being used; failing to do so
+  /// can cause the Dart process to hang.
+  void close() {}
+}