gRPC Java代码生成

编译器调用

option java_outer_classname = "Foo";

protoc --proto_path=src --java_out=build/gen src/foo.proto

$ protoc.exe -h
Usage: D:\DEV\grpc\protoc-3.0.0-win32\bin\protoc.exe [OPTION] PROTO_FILES
Parse PROTO_FILES and generate output based on the options given:
-IPATH, --proto_path=PATH   Specify the directory in which to search for
imports.  May be specified multiple times;
directories will be searched in order.  If not
given, the current working directory is used.
--version                   Show version info and exit.
-h, --help                  Show this text and exit.
--encode=MESSAGE_TYPE       Read a text-format message of the given type
from standard input and write it in binary
to standard output.  The message type must
be defined in PROTO_FILES or their imports.
--decode=MESSAGE_TYPE       Read a binary message of the given type from
standard input and write it in text format
to standard output.  The message type must
be defined in PROTO_FILES or their imports.
--decode_raw                Read an arbitrary protocol message from
standard input and write the raw tag/value
pairs in text format to standard output.  No
PROTO_FILES should be given when using this
flag.
-oFILE,                     Writes a FileDescriptorSet (a protocol buffer,
--descriptor_set_out=FILE defined in descriptor.proto) containing all of
the input files to FILE.
--include_imports           When using --descriptor_set_out, also include
all dependencies of the input files in the
set, so that the set is self-contained.
--include_source_info       When using --descriptor_set_out, do not strip
SourceCodeInfo from the FileDescriptorProto.
This results in vastly larger descriptors that
include information about the original
location of each decl in the source file as
well as surrounding comments.
--dependency_out=FILE       Write a dependency output file in the format
expected by make. This writes the transitive
set of input file paths to FILE
--error_format=FORMAT       Set the format in which to print errors.
FORMAT may be 'gcc' (the default) or 'msvs'
(Microsoft Visual Studio format).
--print_free_field_numbers  Print the free field numbers of the messages
defined in the given proto files. Groups share
the same field number space with the parent
message. Extension ranges are counted as
occupied fields numbers.

--plugin=EXECUTABLE         Specifies a plugin executable to use.
Normally, protoc searches the PATH for
plugins, but you may specify additional
executables not in the path using this flag.
Additionally, EXECUTABLE may be of the form
NAME=PATH, in which case the given plugin name
is mapped to the given executable even if
the executable's own name differs.
--cpp_out=OUT_DIR           Generate C++ header and source.
--csharp_out=OUT_DIR        Generate C# source file.
--java_out=OUT_DIR          Generate Java source file.
--javanano_out=OUT_DIR      Generate Java Nano source file.
--js_out=OUT_DIR            Generate JavaScript source.
--objc_out=OUT_DIR          Generate Objective C header and source.
--python_out=OUT_DIR        Generate Python source file.
--ruby_out=OUT_DIR          Generate Ruby source file.

包——Packages

package foo.bar;

package foo.bar;
option java_package = "com.example.foo.bar";

消息——Messages

message Foo {}

option optimize_for = CODE_SIZE;

option optimize_for = LITE_RUNTIME;

static Foo getDefaultInstance()

Foo.newBuilder().build()

static Descriptor getDescriptor():

static Foo Foo parseFrom(...)

Foo.newBuilder().mergeFrom(...).build()

static Parser parser()

Foo.Builder newBuilder()

Foo.Builder newBuilder(Foo prototype)

构造器——Builders

builder.mergeFrom(obj).setFoo(1).setBar("abc").clearBaz();

子构造器——Sub Builders

message Foo {
optional int32 val = 1;
// some other fields.
}

message Bar {
optional Foo foo = 1;
// some other fields.
}

message Baz {
optional Bar bar = 1;
// some other fields.
}

baz = baz.toBuilder().setBar(
baz.getBar().toBuilder().setFoo(
baz.getBar().getFoo().toBuilder().setVal(10).build()
).build()).build();

Baz.Builder builder = baz.toBuilder();
builder.getBarBuilder().getFooBuilder().setVal(10);
baz = builder.build();

内嵌类型——Nested Types

message Foo { message Bar { } }

字段——Fields

int32 foo_bar = 5;

public static final int FOO_BAR_FIELD_NUMBER = 5;.

单个字段——Singular Fields (proto3)

int32 foo = 1;

int getFoo():  返回字段的当前值。如果字段未设值，返回这个字段类型的默认值。

Builder setFoo(int value)

hasFoo()

true

getFoo()

value

Builder clearFoo()

getFoo()

内嵌消息字段——Embedded Message Fields

setFoo()

.build()

getFoo()

Foo.getDefaultInstance()返回

FooOrBuilder getFooOrBuilder()

Builder getFooBuilder()

枚举字段——Enum Fields

int getFooValue()

getFoo()

UNRECOGNIZED

重复字段——Repeated Fields

repeated int32 foo = 1;

Builder setFoo(int index, int value):

Builder addFoo(int value):

Builder addAllFoo(Iterable<? extends Integer> value): 使用

Builder clearFoo():

重复内嵌字段——Repeated Embedded Message Fields

.build()

FooOrBuilder getFooOrBuilder(int index)

List<FooOrBuilder> getFooOrBuilderList()

Builder getFooBuilder(int index)

Builder addFooBuilder(int index)

Builder addFooBuilder()

Builder removeFoo(int index)

List<Builder> getFooBuilderList()

重复枚举类型——Repeated Enum Fields (仅proto3 )

int getFooValue(int index):

List getFooValueList():

Builder setFooValue(int index, int value)

Oneof 字段

oneof oneof_name {
int32 foo = 1;
...
}

ONEOF_NAME_NOT_SET

ONEOF_NAME_NOT_SET

Map 字段

map<int32, int32> weight = 1;

Map<Integer, Integer> getWeightMap()

int getWeightOrDefault(int key, int default)

int getWeightOrThrow(int key)

IllegalArgumentException

boolean containsWeight(int key)

int getWeightCount()

Builder putWeight(int key, int value)

Builder putAllWeight(Map<Integer, Integer> value)

Builder removeWeight(int key)

Builder clearWeight()

@Deprecated Map<Integer, Integer> getMutableWeight()

Any

import "google/protobuf/any.proto";

message ErrorStatus {
string message = 1;
google.protobuf.Any details = 2;
}

class Any {
// Packs the given message into an Any using the default type URL
// prefix “type.googleapis.com”.
public static Any pack(Message message);
// Packs the given message into an Any using the given type URL
// prefix.
public static Any pack(Message message,
String typeUrlPrefix);

// Checks whether this Any message’s payload is the given type.
public <T extends Message> boolean is(class<T> clazz);

// Unpacks Any into the given message type. Throws exception if
// the type doesn’t match or parsing the payload has failed.
public <T extends Message> T unpack(class<T> clazz)
throws InvalidProtocolBufferException;
}

Oneofs

oneof oneof_name {
int32 foo_int = 4;
string foo_string = 9;
...
}

public enum OneofNameCase
implements com.google.protobuf.Internal.EnumLite {
FOO_INT(4),
FOO_STRING(9),
...
ONEOF_NAME_NOT_SET(0);
...
};

int getNumber()

static OneofNameCase forNumber(int value)

OneofNameCase getOneofNameCase()

Builder clearOneofName()

枚举

enum Foo {
VALUE_A = 0;
VALUE_B = 5;
VALUE_C = 1234;
}

服务——Services

option java_generic_services = true;

option java_generic_services = false;

接口——Interface

service Foo {
rpc Bar(FooRequest) returns(FooResponse);
}

abstract void bar(RpcController controller, FooRequest                request, RpcCallback<FooResponse> done);

request

done

getDescriptorForType

ServiceDescriptor

callMethod

getRequestPrototype and getRequestPrototype

static ServiceDescriptor getDescriptor()

Foo.Interface

object impl

Foo.Interface

Foo.newReflectiveService(impl)

Foo.newReflectiveService(Foo.Interface)

Service wrapping

wrapper

存根——Stub

Foo service

Foo.Stub

Foo.Stub

Foo.Stub(RpcChannel channel)

RpcChannel getChannel()

channel.callMethod()

RpcChannel

RpcController

阻塞接口——Blocking Interfaces

Foo.BlockingInterface

Foo.Interface

abstract FooResponse bar(RpcController controller, FooRequest request) throws ServiceException;

Foo.BlockingInterface

Foo.BlockingInterface的

BlockingRpcChannel

插件插入点——Plugin Insertion Points

outer_class_scope

class_scope:TYPENAME

包名.消息类型——package.MessageType

builder_scope:TYPENAME

包名.消息类型——package.MessageType

enum_scope:TYPENAME:

包名.枚举类型——package.EnumType

注意：对于Java代码生成器，决定输出文件名称的逻辑非常复杂。你可能需要查看protoc的源码，特别是java_headers.cc，确保你考虑到了所有的情形。

注意：不要依赖标准代码生成器声明的私有类属性来生成代码，因为这些实现细节可能在未来的Protocol Buffers的版本中会有改动。