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DART Cookbook

By : Ivo Balbaert
Book Image

DART Cookbook

By: Ivo Balbaert

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DART Cookbook
Ivo Balbaert
Oct, 2014 | 346 pages
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Table of Contents (18 chapters)
Dart Cookbook
Dart Cookbook
Credits
Credits
About the Author
About the Author
About the Reviewers
About the Reviewers
www.PacktPub.com
www.PacktPub.com
Preface
Preface
Free Chapter
1
Working with Dart Tools
Working with Dart Tools
Introduction
Configuring the Dart environment
Setting up the checked and production modes
Rapid Dart Editor troubleshooting
Hosting your own private pub mirror
Using Sublime Text 2 as an IDE
Compiling your app to JavaScript
Debugging your app in JavaScript for Chrome
Using the command-line tools
Solving problems when pub get fails
Shrinking the size of your app
Making a system call
Using snapshotting
Getting information from the operating system
2
Structuring, Testing, and Deploying an Application
Structuring, Testing, and Deploying an Application
Introduction
Exiting from an app
Parsing command-line arguments
Structuring an application
Using a library from within your app
Microtesting your code with assert
Unit testing a Polymer web app
Adding logging to your app
Documenting your app
Profiling and benchmarking your app
Publishing and deploying your app
Using different settings in the checked and production modes
3
Working with Data Types
Working with Data Types
Introduction
Concatenating strings
Using regular expressions
Strings and Unicode
Using complex numbers
Creating an enum
Flattening a list
Generating a random number within a range
Getting a random element from a list
Working with dates and times
Improving performance in numerical computations
Using SIMD for enhanced performance
4
Object Orientation
Object Orientation
Introduction
Testing and converting types
Comparing two objects
Using a factory constructor
Building a singleton
Using reflection
Using mixins
Using annotations
Using the call method
Using noSuchMethod
Making toJSON and fromJSON methods in your class
Creating common classes for client and server apps
5
Handling Web Applications
Handling Web Applications
Introduction
Responsive design
Sanitizing HTML
Using a browser's local storage
Using application cache to work offline
Preventing an onSubmit event from reloading the page
Dynamically inserting rows in an HTML table
Using CORS headers
Using keyboard events
Enabling drag-and-drop
Enabling touch events
Creating a Chrome app
Structuring a game project
Using WebGL in your app
Authorizing OAuth2 to Google services
Talking with JavaScript
Using JavaScript libraries
6
Working with Files and Streams
Working with Files and Streams
Introduction
Reading and processing a file line by line
Writing to a file
Searching in a file
Concatenating files
Downloading a file
Working with blobs
Transforming streams
7
Working with Web Servers
Working with Web Servers
Introduction
Creating a web server
Posting JSON-formatted data
Receiving data on the web server
Serving files with http_server
Using sockets
Using WebSockets
Using secure sockets and servers
Using a JSON web service
8
Working with Futures, Tasks, and Isolates
Working with Futures, Tasks, and Isolates
Introduction
Writing a game loop
Error handling with Futures
Scheduling tasks using Futures
Running a recurring function
Using isolates in the Dart VM
Using isolates in web apps
Using multiple cores with isolates
Using the Worker Task framework
9
Working with Databases
Working with Databases
Introduction
Storing data locally with IndexedDB
Using Lawndart to write offline web apps
Storing data in MySQL
Storing data in PostgreSQL
Storing data in Oracle
Storing data in MongoDB
Storing data in RethinkDB
10
Polymer Dart Recipes
Polymer Dart Recipes
Introduction
Data binding with polymer.dart
Binding and repeating over a list
Binding to a map
Using custom attributes and template conditionals
Binding to an input text field or a text area
Binding to a checkbox
Binding to radio buttons
Binding to a selected field
Event handling
Polymer elements with JavaScript interop
Extending DOM elements
Working with custom elements
Automatic node finding
Internationalizing a Polymer app
11
Working with Angular Dart
Working with Angular Dart
Introduction
Setting up an Angular app
Using a controller
Using a component
Using formatters as filters
Creating a view
Using a service
Deploying your app
Index
Index

Downloading a file

This recipe shows you the simplest ways to download a file through code, first in a command-line application and then from a web application. As an example, we download the front page of the Learning Dart website from http://learningdart.org.

Getting ready

A client program (be it web or command-line) receives content, such as files or web pages, from a web server using the HTTP protocol. The dart:html and dart:io package provides us with the basic classes we need to do this, which are as follows:

  • The Uriclass class (from dart:core) has all we need to parse, encode, and decode web addresses; the method Uri.parse is often used

  • The HttpRequest class (from dart:html) has the getString method to fetch a file from a URL

  • The HttpClientclass class (from dart:io) has all kinds of methods, such as get and post, to send a request (class HttpClientRequest) to a web server and get a response (class HttpClientResponse) back

How to do it...

  1. For a web app, this is shown in download_string.dart...

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