[dubbo-website] branch master updated: add Protobuf-json serialization demo. (#486)

[kirito]

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The following commit(s) were added to refs/heads/master by this push:
     new 7877c75  add Protobuf-json serialization demo. (#486)
7877c75 is described below

commit 7877c75f07390d543693b51c120ccb3795da81d9
Author: violin <guo....@ctrip.com>
AuthorDate: Fri Nov 8 13:10:48 2019 +0800

    add Protobuf-json serialization demo. (#486)
---
 .../zh-cn/user/demos/GooglePb-generic-reference.md | 80 ++++++++++++++++++++++
 1 file changed, 80 insertions(+)

diff --git a/docs/zh-cn/user/demos/GooglePb-generic-reference.md 
b/docs/zh-cn/user/demos/GooglePb-generic-reference.md
new file mode 100644
index 0000000..b327c3f
--- /dev/null
+++ b/docs/zh-cn/user/demos/GooglePb-generic-reference.md
@@ -0,0 +1,80 @@
+# GoogleProtobuf对象泛化调用
+泛化接口调用方式主要用于客户端没有 API 接口及模型类元的情况，参考 
[泛化调用](http://dubbo.apache.org/zh-cn/docs/user/demos/group-merger.html)。
+一般泛化调用只能用于生成的服务参数为POJO的情况，而GoogleProtobuf的对象是基于Builder生成的非正常POJO，可以通过protobuf-json泛化调用。
  
+GoogleProtobuf序列化相关的Demo可以参考[protobuf-demo](https://github.com/vio-lin/dubbo-samples/tree/protobuf-demo)
+# 通过Spring对Goolgle Protobuf对象泛化调用
+在Spring中配置声明generic = "protobuf-json"
+```
+<dubbo:reference id="barService" interface="com.foo.BarService" 
generic="protobuf-json" />
+```
+在 Java 代码获取 barService 并开始泛化调用：
+```
+GenericService barService = (GenericService) 
applicationContext.getBean("barService");
+Object result = barService.$invoke("sayHello",new 
String[]{"org.apache.dubbo.protobuf.GooglePbBasic$CDubboGooglePBRequestType"}, 
new 
Object[]{"{\"double\":0.0,\"float\":0.0,\"bytesType\":\"Base64String\",\"int32\":0}"});
+```
+# 通过 API 方式对Goolgle Protobuf对象泛化调用
+```
+ReferenceConfig<GenericService> reference = new 
ReferenceConfig<GenericService>();
+// 弱类型接口名
+reference.setInterface(GenericService.class.getName());
+reference.setInterface("com.xxx.XxxService");
+// 声明为Protobuf-json
+reference.setGeneric(Constants.GENERIC_SERIALIZATION_PROTOBUF);
+
+GenericService genericService = reference.get();
+Map<String, Object> person = new HashMap<String, Object>();
+person.put("fixed64", "0");
+person.put("int64", "0");
+// 参考google官方的protobuf 3 的语法，服务的每个方法中只传输一个POJO对象
+// protobuf的泛化调用只允许传递一个类型为String的json对象来代表请求参数
+String requestString = new Gson().toJson(person);
+// 返回对象是GoolgeProtobuf响应对象的json字符串。
+Object result = genericService.$invoke("sayHello", new String[] {
+    "com.xxx.XxxService.GooglePbBasic$CDubboGooglePBRequestType"},
+    new Object[] {requestString});
+```
+# 有关GoogleProtobuf对象的处理
+GoogleProtobuf对象是由Protocol契约生成,相关知识请参考[ProtocolBuffers文档](https://developers.google.com/protocol-buffers/?hl=zh-CN)。
+假如有如下Protobuf 契约
+```
+syntax = "proto3";
+package com.xxx.XxxService.GooglePbBasic.basic;
+message CDubboGooglePBRequestType {
+    double double = 1;
+    float float = 2;
+    int32 int32 = 3;
+    bool bool = 13;
+    string string = 14;
+    bytes bytesType = 15;
+}
+
+message CDubboGooglePBResponseType {
+    string msg = 1;
+}
+
+service CDubboGooglePBService {
+    rpc sayHello (CDubboGooglePBRequestType) returns 
(CDubboGooglePBResponseType);
+}
+```
+则对应请求按照如下方法构造
+```
+Map<String, Object> person = new HashMap<>();
+person.put("double", "1.000");
+person.put("float", "1.00");
+person.put("int32","1" );
+person.put("bool","false" );
+//String 的对象需要经过base64编码
+person.put("string","someBaseString");
+person.put("bytesType","150");
+```
+# GoogleProtobuf服务元数据解析
+Google Protobuf对象缺少标准的JSON格式，生成的服务元数据信息存在错误。
+请添加如下依赖元数据解析的依赖。
+```
+<dependency>
+    <groupId>org.apache.dubbo</groupId>
+    <artifactId>dubbo-metadata-definition-protobuf</artifactId>
+    <version>${dubbo.version}</version>
+</dependency>
+```
+从服务元数据中也可以比较容易构建泛化调用对象。