Netty with protobuf

这是一篇关于netty和protobuf2的文章，先来介绍一下protobuf的简单使用。网上有很多基本的protobuf的介绍，这里就不在赘述了。

protobuf官网上提供了一个例子，我们就拿那个例子来改造：

proto文件描述了消息的结构，这个文件时这样的

package tutorial;option java_package = "com.example.tutorial";
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;
}

我们现在通过protobuf提供的源代码编译器生成我们的Java代码

E:\tools2\protobuf>protoc.exe -I=E:\test-protobuf --java_out=E:\test-protobuf E:\test-protobuf\addressbook.proto

-I表示指定proto文件的目录位置，--java-out表示输出Java源代码的目录位置，后跟的参数表示文件的路径

现在在你所指定的目录下有一个Java类文件，就是AddressBookProtos.java文件。

通过这个类可以把这个类序列化，看示例代码：

@Test
public void test() throws IOException {AddressBookProtos.AddressBook.Builder addressBookBuilder = AddressBookProtos.AddressBook.newBuilder();AddressBookProtos.Person.PhoneNumber.Builder phoneNumberBuilder = AddressBookProtos.Person.PhoneNumber.newBuilder();AddressBookProtos.Person.Builder personBuilder = AddressBookProtos.Person.newBuilder();personBuilder.setEmail("744858873@qq.com").setId(123456789).setName("hellolyx");personBuilder.addPhone(phoneNumberBuilder.setNumber("15840330465").setType(AddressBookProtos.Person.PhoneType.HOME).build());personBuilder.addPhone(phoneNumberBuilder.setNumber("15840330466").setType(AddressBookProtos.Person.PhoneType.WORK).build());personBuilder.addPhone(phoneNumberBuilder.setNumber("15840330467").setType(AddressBookProtos.Person.PhoneType.MOBILE).build());personBuilder.addPhone(phoneNumberBuilder.setNumber("15840330468").setType(AddressBookProtos.Person.PhoneType.MOBILE).build());personBuilder.addPhone(phoneNumberBuilder.setNumber("15840330469").setType(AddressBookProtos.Person.PhoneType.MOBILE).build());personBuilder.setPhone(0, phoneNumberBuilder.setNumber("110").setType(AddressBookProtos.Person.PhoneType.MOBILE).build());//向电话薄里添加一个联系人addressBookBuilder.addPerson(personBuilder.build());personBuilder.setEmail("78655676@qq.com").setId(123456789).setName("hellodog");personBuilder.addPhone(phoneNumberBuilder.setNumber("15840330465").setType(AddressBookProtos.Person.PhoneType.HOME).build());personBuilder.addPhone(phoneNumberBuilder.setNumber("15840330466").setType(AddressBookProtos.Person.PhoneType.WORK).build());personBuilder.addPhone(phoneNumberBuilder.setNumber("15840330467").setType(AddressBookProtos.Person.PhoneType.MOBILE).build());personBuilder.addPhone(phoneNumberBuilder.setNumber("15840330468").setType(AddressBookProtos.Person.PhoneType.MOBILE).build());personBuilder.addPhone(phoneNumberBuilder.setNumber("15840330469").setType(AddressBookProtos.Person.PhoneType.MOBILE).build());personBuilder.setPhone(0, phoneNumberBuilder.setNumber("119").setType(AddressBookProtos.Person.PhoneType.MOBILE).build());//再次向电话薄里添加一个联系人addressBookBuilder.addPerson(personBuilder.build());personBuilder.setEmail("78655676@qq.com").setId(123456789).setName("hellopig");personBuilder.addPhone(phoneNumberBuilder.setNumber("15840330465").setType(AddressBookProtos.Person.PhoneType.HOME).build());personBuilder.addPhone(phoneNumberBuilder.setNumber("15840330466").setType(AddressBookProtos.Person.PhoneType.WORK).build());personBuilder.addPhone(phoneNumberBuilder.setNumber("15840330467").setType(AddressBookProtos.Person.PhoneType.MOBILE).build());personBuilder.addPhone(phoneNumberBuilder.setNumber("15840330468").setType(AddressBookProtos.Person.PhoneType.MOBILE).build());personBuilder.addPhone(phoneNumberBuilder.setNumber("15840330469").setType(AddressBookProtos.Person.PhoneType.MOBILE).build());personBuilder.setPhone(0, phoneNumberBuilder.setNumber("124").setType(AddressBookProtos.Person.PhoneType.MOBILE).build());addressBookBuilder.addPerson(personBuilder.build());/*** 一个电话薄里添加了三个人*/byte[] book = addressBookBuilder.build().toByteArray();String path = "E:\\test-protobuf\\test.txt";FileOutputStream fileOutputStream = new FileOutputStream(path);fileOutputStream.write(book);fileOutputStream.close();//反序列化AddressBookProtos.AddressBook b = AddressBookProtos.AddressBook.parseFrom(book);System.out.println(b.toString());
}

这是通过proto.exe生成的Java类的基本用法，最后打印出来的信息略。

通过这种方式，你可以发现序列化一个类是不是很方便啊，并且序列化和反序列有很好的性能，同时序列后的数据量很小。

在上个例子中，我们吧序列化后的数据保存在了txt文件中，现在可以通过读取这个文本文件反序列化。

/*** 在运行时确定消息格式，动态生成消息*/
@Test
public void test8876() throws IOException {String messagePath = "E:\\test-protobuf\\test.txt";FileInputStream fileInputStream = new FileInputStream(messagePath);byte[] message = new byte[fileInputStream.available()];fileInputStream.read(message);Descriptors.FileDescriptor fileDescriptor = AddressBookProtos.getDescriptor();Descriptors.Descriptor addressBookDescriptor = fileDescriptor.findMessageTypeByName("AddressBook");DynamicMessage addressBook = DynamicMessage.parseFrom(addressBookDescriptor, message);System.out.println(addressBook.toString());
}

这就是基本的protobuf-java类库的基本使用方法。对于protobuf的自描述消息还没有研究的很透彻，等研究明白了，再把那个发上来。

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