Android上使用grpc的方法教程
作者：林嘉伟
这篇文章主要给大家介绍了在Android上使用grpc的方法教程，文中通过示例代码给大家详细介绍了在android上使用grpc的方法以及可能遇到的种种问题的解决方法，对大家具有一定的参考学习价值，需要的朋友们下面来一起看看吧。
前言
最近的一个项目使用到了grpc实现跨平台的远程调用，在安卓端使用的时候遇到了一些坑，这里记录一下。
首先根据grpc android的官方Demo配置grpc依赖，测试它的hello world工程。
编译谷歌官方的helloworld工程
添加rotobuf-gradle-plugin插件
首先添加rotobuf-gradle-plugin插件，他是用来从proto文件自动生成java代码的:
//Project的build.gradle中添加rotobuf-gradle-plugin插件
buildscript {
...
dependencies {
...
classpath "com.google.protobuf:protobuf-gradle-plugin:0.8.0"
...
}
...
}
//App的build.gradle中添加下面配置
apply plugin: 'com.google.protobuf'
protobuf {
protoc {
artifact = 'com.google.protobuf:protoc:3.0.0'
}
plugins {
javalite {
artifact = "com.google.protobuf:protoc-gen-javalite:3.0.0"
}
grpc {
artifact = 'io.grpc:protoc-gen-grpc-java:1.0.0' // CURRENT_GRPC_VERSION
}
}
generateProtoTasks {
all().each { task ->
task.plugins {
javalite {}
grpc {
// Options added to --grpc_out
option 'lite'
}
}
}
}
}
添加proto文件并自动生成java代码
在src/main/目录下创建一个proto目录，并将官方的helloworld.proto放到proto目录下
之后只需要rebuild一下就能看到build/generated/source/proto/目录下根据helloworld.proto生成了几个Java类
添加安卓端grpc的依赖
//App的build.gradle中添加下面配置
dependencies {
...
compile 'io.grpc:grpc-okhttp:1.1.2'
compile 'io.grpc:grpc-protobuf-lite:1.1.2'
compile 'io.grpc:grpc-stub:1.1.2'
compile 'javax.annotation:javax.annotation-api:1.2'
...
}
configurations.all {
resolutionStrategy.force 'com.google.code.findbugs:jsr305:3.0.1'
}
我这个时候报了这个错误
Warning:Conflict with dependency ‘com.google.code.findbugs:jsr305'. Resolved versions for app (3.0.0) and test app (2.0.1) differ. See http://g.co/androidstudio/app-test-app-conflict for details.
这是因为com.google.code.findbugs:jsr305的版本不一致导致的
可以在App的build.gradle的android标签中配置一下解决
android {
...
configurations.all {
resolutionStrategy.force 'com.google.code.findbugs:jsr305:3.0.1'
}
...
}
编写demo代码
public class MainActivity extends AppCompatActivity {
private static final String TAG = "GrpcDemo";
private static final int PROT = 55055;
private static final String NAME = "linjw";
private static final String HOST = "localhost";
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
startServer(PROT);
startClient(HOST, PROT, NAME);
}
private void startServer(int port){
try {
Server server = ServerBuilder.forPort(port)
.addService(new GreeterImpl())
.build()
.start();
} catch (IOException e) {
e.printStackTrace();
Log.d(TAG, e.getMessage());
}
}
private void startClient(String host, int port, String name){
new GrpcTask(host, port, name).execute();
}
private class GreeterImpl extends GreeterGrpc.GreeterImplBase {
public void sayHello(HelloRequest request, StreamObserver<HelloReply> responseObserver) {
responseObserver.onNext(sayHello(request));
responseObserver.onCompleted();
}
private HelloReply sayHello(HelloRequest request) {
return HelloReply.newBuilder()
.setMessage("hello "+ request.getName())
.build();
}
}
private class GrpcTask extends AsyncTask<Void, Void, String> {
private String mHost;
private String mName;
private int mPort;
private ManagedChannel mChannel;
public GrpcTask(String host, int port, String name) {
this.mHost = host;
this.mName = name;
this.mPort = port;
}
@Override
protected void onPreExecute() {
}
@Override
protected String doInBackground(Void... nothing) {
try {
mChannel = ManagedChannelBuilder.forAddress(mHost, mPort)
.usePlaintext(true)
.build();
GreeterGrpc.GreeterBlockingStub stub = GreeterGrpc.newBlockingStub(mChannel);
HelloRequest message = HelloRequest.newBuilder().setName(mName).build();
HelloReply reply = stub.sayHello(message);
return reply.getMessage();
} catch (Exception e) {
StringWriter sw = new StringWriter();
PrintWriter pw = new PrintWriter(sw);
e.printStackTrace(pw);
pw.flush();
return "Failed... : " + System.lineSeparator() + sw;
}
}
@Override
protected void onPostExecute(String result) {
try {
mChannel.shutdown().awaitTermination(1, TimeUnit.SECONDS);
} catch (InterruptedException e) {
Thread.currentThread().interrupt();
}
Log.d(TAG, result);
}
}
}
这段代码运行会崩溃:
Caused by: io.grpc.ManagedChannelProvider$ProviderNotFoundException: No functional server found. Try adding a dependency on the grpc-netty artifact
猜测google使用netty替代了okhttp，尝试换成grpc-netty的依赖:
dependencies {
...
compile 'io.grpc:grpc-netty:1.1.2'
compile 'io.grpc:grpc-protobuf-lite:1.1.2'
compile 'io.grpc:grpc-stub:1.1.2'
compile 'javax.annotation:javax.annotation-api:1.2'
...
}
这么编译会报错
com.android.build.api.transform.TransformException: com.android.builder.packaging.DuplicateFileException: Duplicate files copied in APK META-INF/INDEX.LIST
需要加上下面的配置解决
android {
...
packagingOptions {
pickFirst 'META-INF/INDEX.LIST'
pickFirst 'META-INF/LICENSE'
pickFirst 'META-INF/io.netty.versions.properties'
}
...
}
当然，还需要加上INTERNET权限，要不然运行的时候还是会崩溃。
最终就能看的下面的打印，这样安卓grpc的helloworld就成功了。
03-03 00:04:20.000 6137-6137/linjw.com.grpcdemo D/GrpcDemo: hello linjw
使用com.google.protobuf.Any
Any可以携带任意类型的数据，用法相当于c语言的void指针。在项目中是很常用的，但是谷歌在javalite的版本不支持Any。
如果在proto文件中使用了Any的话生成java代码就会有报错，例如将helloworld的proto文件改成下面的样子:
// Copyright 2015, Google Inc.
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
// * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
syntax = "proto3";
option java_multiple_files = true;
option java_package = "io.grpc.examples.helloworld";
option java_outer_classname = "HelloWorldProto";
option objc_class_prefix = "HLW";
package helloworld;
import "google/protobuf/any.proto";
// The greeting service definition.
service Greeter {
// Sends a greeting
rpc SayHello (google.protobuf.Any) returns (HelloReply) {}
}
// The request message containing the user's name.
message HelloRequest {
string name = 1;
}
// The response message containing the greetings
message HelloReply {
string message = 1;
}
报错如下
google/protobuf/any.proto: File not found. helloworld.proto: Import “google/protobuf/any.proto” was not found or had errors. helloworld.proto:44:17: “google.protobuf.Any” is not defined.
使用grpc-jave代替grpc-javalite
但是现在做的这个项目的linux端实现已经用了Any，要改的话需要耗费比较大的精力。幸好尝试了下，发现安卓上也能跑支持Any的grpc-java。
首先我们要使用grpc-protobuf依赖替换grpc-protobuf-lite依赖
dependencies {
...
compile 'io.grpc:grpc-netty:1.1.2'
compile 'io.grpc:grpc-protobuf:1.1.2'
compile 'io.grpc:grpc-stub:1.1.2'
compile 'javax.annotation:javax.annotation-api:1.2'
...
}
接着修改protobuf-gradle-plugin配置使得自动生成java的代码而不是javalite的代码
protobuf {
protoc {
artifact = 'com.google.protobuf:protoc:3.0.0'
}
plugins {
grpc {
artifact = 'io.grpc:protoc-gen-grpc-java:1.0.0' // CURRENT_GRPC_VERSION
}
}
generateProtoTasks {
all().each { task ->
task.builtins {
java {}
}
task.plugins {
grpc {}
}
}
}
}
对应的修改helloworld的代码就能运行了
public class MainActivity extends AppCompatActivity {
private static final String TAG = "GrpcDemo";
private static final int PROT = 55055;
private static final String NAME = "linjw";
private static final String HOST = "localhost";
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
startServer(PROT);
startClient(HOST, PROT, NAME);
}
private void startServer(int port){
try {
Server server = ServerBuilder.forPort(port)
.addService(new GreeterImpl())
.build()
.start();
} catch (IOException e) {
e.printStackTrace();
Log.d(TAG, e.getMessage());
}
}
private void startClient(String host, int port, String name){
new GrpcTask(host, port, name).execute();
}
private class GreeterImpl extends GreeterGrpc.GreeterImplBase {
public void sayHello(Any request, StreamObserver<HelloReply> responseObserver) {
try {
responseObserver.onNext(sayHello(request.unpack(HelloRequest.class)));
responseObserver.onCompleted();
} catch (InvalidProtocolBufferException e) {
e.printStackTrace();
}
}
private HelloReply sayHello(HelloRequest request) {
return HelloReply.newBuilder()
.setMessage("hello "+ request.getName())
.build();
}
}
private class GrpcTask extends AsyncTask<Void, Void, String> {
private String mHost;
private String mName;
private int mPort;
private ManagedChannel mChannel;
public GrpcTask(String host, int port, String name) {
this.mHost = host;
this.mName = name;
this.mPort = port;
}
@Override
protected void onPreExecute() {
}
@Override
protected String doInBackground(Void... nothing) {
try {
mChannel = ManagedChannelBuilder.forAddress(mHost, mPort)
.usePlaintext(true)
.build();
GreeterGrpc.GreeterBlockingStub stub = GreeterGrpc.newBlockingStub(mChannel);
HelloRequest message = HelloRequest.newBuilder().setName(mName).build();
HelloReply reply = stub.sayHello(Any.pack(message));
return reply.getMessage();
} catch (Exception e) {
StringWriter sw = new StringWriter();
PrintWriter pw = new PrintWriter(sw);
e.printStackTrace(pw);
pw.flush();
return "Failed... : " + System.lineSeparator() + sw;
}
}
@Override
protected void onPostExecute(String result) {
try {
mChannel.shutdown().awaitTermination(1, TimeUnit.SECONDS);
} catch (InterruptedException e) {
Thread.currentThread().interrupt();
}
Log.d(TAG, result);
}
}
}
完整的demo代码可以点这里在我的github中查看（也可以通过本地下载）
Android方法数不能超过65535的问题
最后使用grpc，方法数会超过65535，可以使用com.android.support:multidex去解决
总结
以上就是这篇文章的全部内容了，希望本文的内容对大家的学习或者工作能带来一定的帮助，如有疑问大家可以留言交流，谢谢大家对脚本之家的支持。