#Java tutorial how to#
#Java tutorial code#

Even if you do provide a java_package, you should still define a normal package as well to avoid name collisions in the Protocol Buffers name space as well as in non-Java languages.Īfter the package declaration, you can see three options that are Java-specific: java_multiple_files, java_package, and java_outer_classname. In Java, the package name is used as the Java package unless you have explicitly specified a java_package, as we have here. proto file starts with a package declaration, which helps to prevent naming conflicts between different projects. Let's go through each part of the file and see what it does.

Optional PhoneType type = 2 Īs you can see, the syntax is similar to C++ or Java. Option java_outer_classname = 'AddressBookProtos' proto file that defines your messages, addressbook.proto. proto file are simple: you add a message for each data structure you want to serialize, then specify a name and a type for each field in the message.

To create your address book application, you'll need to start with a.

#Java tutorial code#

The example code is included in the source code package, under the 'examples' directory. Importantly, the protocol buffer format supports the idea of extending the format over time in such a way that the code can still read data encoded with the old format. The generated class provides getters and setters for the fields that make up a protocol buffer and takes care of the details of reading and writing the protocol buffer as a unit. From that, the protocol buffer compiler creates a class that implements automatic encoding and parsing of the protocol buffer data with an efficient binary format. proto description of the data structure you wish to store. Protocol buffers are the flexible, efficient, automated solution to solve exactly this problem. Instead of these options, you can use protocol buffers. Also, navigating an XML DOM tree is considerably more complicated than navigating simple fields in a class normally would be. However, XML is notoriously space intensive, and encoding/decoding it can impose a huge performance penalty on applications. This can be a good choice if you want to share data with other applications/projects. This approach can be very attractive since XML is (sort of) human readable and there are binding libraries for lots of languages. This works best for encoding very simple data. This is a simple and flexible approach, although it does require writing one-off encoding and parsing code, and the parsing imposes a small run-time cost.

You can invent an ad-hoc way to encode the data items into a single string – such as encoding 4 ints as '12:3:-23:67'.

213), and also doesn't work very well if you need to share data with applications written in C++ or Python. This is the default approach since it's built into the language, but it has a host of well-known problems (see Effective Java, by Josh Bloch pp. How do you serialize and retrieve structured data like this? There are a few ways to solve this problem: Each person in the address book has a name, an ID, an email address, and a contact phone number. The example we're going to use is a very simple 'address book' application that can read and write people's contact details to and from a file. For more detailed reference information, see the Protocol Buffer Language Guide (proto2), the Protocol Buffer Language Guide (proto3), the Java API Reference, the Java Generated Code Guide, and the Encoding Reference. This isn't a comprehensive guide to using protocol buffers in Java.

Use the Java protocol buffer API to write and read messages.

#Java tutorial how to#

By walking through creating a simple example application, it shows you how to This tutorial provides a basic Java programmer's introduction to working with protocol buffers.