Protocol Buffers学习笔记 - Windows上搭建开发环境，开发Java序列化应用

Google Protocol Buffers (ProtoBuf)是Google开源的数据序列化工具/框架/方法，比使用XML更小、更快、也更简单高效。目前Hadoop, HBase等很多开源软件使用ProtoBuf作为序列化工具。官方网站： https://developers.google.com/protocol-buffers/

在Windows上搭建Protobuf Java实验环境需要如下软件：

1. MS Visual Studio C++ (编译protoc, optional)

2. JDK (编译Java源码)

3. Maven (build protobuf jar包）

第一步：下载源码及Windows下编译好的protoc.exe, 下载地址：https://developers.google.com/protocol-buffers/docs/downloads

如果你的Windows上安装了Visual Studio,就可以不用下载protoc.exe，可以用源码编译出protoc。博主的电脑上没有Visual Studio, 因此直接下载了protoc.exe

第二步：下载及安装Maven,  Maven官网：http://maven.apache.org/

安装后将maven的bin目录设置到Window path环境变量下

第三步：编译protobuf jar包

将下载的protoc.exe放到src目录，然后进入java目录运行：

mvn package

在target目录下产生protobuf-java-2.6.0.jar

mvn install

将jar包安装到maven repository.

至此我们得到了开发protobuf Java应用需要的protoc.exe和protobuf-java-2.6.0.jar, 这是我们开发protobuf Java应用仅需要的2个文件。下面就可以开发应用了。

Protobuf Java应用开发

1. 创建项目

mvn archetype:generate -DgroupId=proto -DartifactId=ProtobufTest

并生成eclipse项目：

mvn eclipse:eclipse

然后用eclipse打开项目， 进入Eclipse, Import -> Existing Maven Projects

2. 创建proto文件

在proto包中创建文件addressbook.proto,内容如下：

package proto.generated;

option java_package = "proto.generated";
option java_outer_classname = "AddressBookProtos";

message Person {
required string name = 1;
required int32 id = 2;
optional string email = 3;

enum PhoneType {
MOBILE = 0;
HOME = 1;
WORK = 2;
}

message PhoneNumber {
required string number = 1;
optional PhoneType type = 2 [default = HOME];
}

repeated PhoneNumber phone = 4;
}

message AddressBook {
repeated Person person = 1;
}

3. 编译proto文件
进入proto目录运行：
protoc --java_out=..\ addressbook.proto
在generated目录下生成了AddressBookProtos.java
添加依赖到pom.xml中：
   <dependency>

      <groupId>com.google.protobuf</groupId>

      <artifactId>protobuf-java</artifactId>

      <version>2.6.0</version>

    </dependency>

5. 测试写消息（序列化）
在proto包中创建如下Java类 AddPerson.java

package proto;
import proto.generated.AddressBookProtos.AddressBook;
import proto.generated.AddressBookProtos.Person;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;

class AddPerson {
static Person newPerson() {
Person.Builder person = Person.newBuilder();

person.setId(1);
person.setName("Mike");
person.setEmail("mike@abc.com");

Person.PhoneNumber.Builder phoneNumber =
Person.PhoneNumber.newBuilder().setNumber("12388888888");
phoneNumber.setType(Person.PhoneType.MOBILE);
person.addPhone(phoneNumber);

return person.build();
}

public static void main(String[] args) throws Exception {
AddressBook.Builder addressBook = AddressBook.newBuilder();

// Read the existing address book.
try {
addressBook.mergeFrom(new FileInputStream(args[0]));
} catch (FileNotFoundException e) {
System.out.println(args[0] + ": File not found.  Creating a new file.");
}

// Add an address.
addressBook.addPerson(AddPerson.newPerson());

// Write the new address book back to disk.
FileOutputStream output = new FileOutputStream(args[0]);
addressBook.build().writeTo(output);
output.close();
}
}

添加一个命令行参数运行，运行后产生序列化文件。
6. 测试读消息（反序列化）
在proto包中创建如下Java类ListPeople.java

package proto;
import proto.generated.AddressBookProtos.AddressBook;
import proto.generated.AddressBookProtos.Person;
import java.io.FileInputStream;

class ListPeople {
// Iterates though all people in the AddressBook and prints info about them.
static void Print(AddressBook addressBook) {
for (Person person: addressBook.getPersonList()) {
System.out.println("Person ID: " + person.getId());
System.out.println("  Name: " + person.getName());
if (person.hasEmail()) {
System.out.println("  E-mail address: " + person.getEmail());
}

for (Person.PhoneNumber phoneNumber : person.getPhoneList()) {
switch (phoneNumber.getType()) {
case MOBILE:
System.out.print("  Mobile phone #: ");
break;
case HOME:
System.out.print("  Home phone #: ");
break;
case WORK:
System.out.print("  Work phone #: ");
break;
}
System.out.println(phoneNumber.getNumber());
}
}
}

// Main function:  Reads the entire address book from a file and prints all
//   the information inside.
public static void main(String[] args) throws Exception {
if (args.length != 1) {
System.err.println("Usage:  ListPeople ADDRESS_BOOK_FILE");
System.exit(-1);
}

// Read the existing address book.
AddressBook addressBook =
AddressBook.parseFrom(new FileInputStream(args[0]));

Print(addressBook);
}
}

添加与写消息时相同的命令行参数，运行后显示刚刚写入的消息。