protobuf-java中的一些小技巧

本是古典何须时尚 2021-06-24 15:58 468阅读 0赞

**1、json字符串和pb对象之间的转换：**

1）pom.xml

<dependency>
    			<groupId>com.google.protobuf</groupId>
    			<artifactId>protobuf-java</artifactId>
    			<version>2.5.0</version>
    </dependency>
    <dependency>  
    			<groupId>com.googlecode.protobuf-java-format</groupId>  
    			<artifactId>protobuf-java-format</artifactId>  
    			<version>1.2</version>  
    </dependency>

2）pb消息定义：

option java_package = "com.abc.proto";
    option java_outer_classname="HelloWordPB";
    
    message HelloWord {
        optional int64 id = 1;
        optional string name = 2;
        repeated string recId = 3;
    }

3）java代码：

public class PBTest {
    	public static void main(String[] args) {
    		JSONObject jo = new JSONObject();
    		JSONArray ja = new JSONArray();
    		ja.add("1");
    		ja.add("2");
    		
    		jo.put("id", 123456);//这里不能是字符串类型，否则pb会报错
    		jo.put("name", "test");
    		jo.put("recId", ja);
    		
    		String jsonStr = jo.toJSONString();
    		System.out.println(jsonStr);
    		
    		//json > pb
    		Builder newBuilder = HelloWordPB.HelloWord.newBuilder();
    		try {
    			JsonFormat.merge(jsonStr, newBuilder);
    			System.out.println(newBuilder.build().toString());
    		} catch (ParseException e) {
    			// TODO Auto-generated catch block
    			e.printStackTrace();
    		}
    		
    		//pb > json
    		String printToString = JsonFormat.printToString(newBuilder.build());
    		System.out.println(printToString);
    	}
    }

输出：

{"name":"test","id":123456,"recId":["1","2"]}
    id: 123456
    name: "test"
    recId: "1"
    recId: "2"
    {"id": 123456,"name": "test","recId": ["1","2"]}

2、toString于pb对象之间转换：

public static void main(String...strings) {
    		
    		Builder newBuilder = ApiLogPB.ApiLog.newBuilder();
    		newBuilder.setCost(10);
    		newBuilder.setChId("default");
    		newBuilder.setReqId("reqid");
    		newBuilder.setFNum(12);
    		newBuilder.setPuid("puid");
    		newBuilder.setUId("uid");
    		
    		ApiLog apiLog = newBuilder.build();
    		String string = apiLog.toString();
    		System.out.println(string);
    		
    		System.out.println("--------------------------");
    		Builder newBuilder2 = ApiLogPB.ApiLog.newBuilder();
    		try {
    			TextFormat.merge(string, newBuilder2);
    		} catch (ParseException e) {
    			e.printStackTrace();
    		}
    		String chId = newBuilder2.getChId();
    		System.out.println(chId);
    	}

输出：

puid: "puid"
    uId: "uid"
    reqId: "reqid"
    fNum: 12
    cost: 10
    chId: "default"
    
    --------------------------
    default

3、从文件中构建pb对象：

1）pb结构

option java_package="com.lanjingling.cinema";
     
     enum MovieType{
         CHILDREN=1;
         ADULT=2;
         NORMAL=3;
         OHTER=4;
     }
     
     message Movie{
         required string name=1;
         required MovieType type=2;
         optional int32 releaseTimeStamp=3;
         optional string description=4;
     }
     
     message Ticket{
         required int32 id=1;
         repeated Movie movie=2;
         optional Customer customer=3;
     }

2）构建pb对象，tostring输出到文件：

public class Test {
    
    	public static void main(String[] args) throws Exception {
    		Cinema.Movie.Builder movieBuilder = Cinema.Movie.newBuilder();
            movieBuilder.setName("The Shining");
            movieBuilder.setType(Cinema.MovieType.ADULT);
            movieBuilder.setReleaseTimeStamp(327859200);
            Movie movie = movieBuilder.build();
            
            Cinema.Movie.Builder movieBuilder1 = Cinema.Movie.newBuilder();
            movieBuilder1.setName("The Shining1");
            movieBuilder1.setType(Cinema.MovieType.CHILDREN);
            movieBuilder1.setReleaseTimeStamp(327859201);
            Movie movie1 = movieBuilder1.build();
            
            Cinema.Ticket.Builder ticketBuilder = Cinema.Ticket.newBuilder();
            ticketBuilder.setId(1);
            ticketBuilder.addMovie(movie);
            ticketBuilder.addMovie(movie1);
            Ticket ticket = ticketBuilder.build();
            System.out.println(ticket.toString());
        }
    }

将输出保存到cineme.txt文件。内容如下：

id: 1
    movie {
      name: "The Shining"
      type: ADULT
      releaseTimeStamp: 327859200
    }
    movie {
      name: "The Shining1"
      type: CHILDREN
      releaseTimeStamp: 327859201
    }

3）从文件中读取数据，反序列化：

public class Test2 {
    
    	public static void main(String[] args) throws Exception {
            Cinema.Ticket.Builder ticketBuilder = Cinema.Ticket.newBuilder();
            InputStream inputStream = new FileInputStream("D://cinema.txt");
            TextFormat.merge(new InputStreamReader(inputStream), ticketBuilder);
            
            Ticket ticket = ticketBuilder.build();
            System.out.println(ticket);
    	}
    
    }

4、pb在构造Builder的时候可以传入一个pb对象：

1）假设我们从redis中读取了一个pb二进制数据，然后反序列化成pb对象：

com.abc.proto.UserRecHistoryPB.UserRecHistory userRecHistory = null;
    String KEY = MessageFormat.format(CacheConstants.CACHE_KEY_USER_HISTORY_PERF, deviceId);
    byte[] bs = couchbaseHistoryDao.get(KEY);
    if (bs != null) {
    	userRecHistory = UserRecHistoryPB.UserRecHistory.parseFrom(bs);
    }

2）接下来对userRecHistory进行修改，修改完毕后需要再保存到redis中：

Builder recHistoryBuilder = UserRecHistoryPB.UserRecHistory.newBuilder(userRecHistory);
    //修改
    UserRecHistory build = recHistoryBuilder.build();
    String KEY = MessageFormat.format(CacheConstants.CACHE_KEY_USER_HISTORY_PERF, deviceId);
    		int ttl = (int)(System.currentTimeMillis()/1000)+CacheConstants.CACHE_TIME_QUARTER;
    		couchbaseHistoryDao.set(KEY, 
    				ttl, 
    				build.toByteArray());

4、pb克隆：

pb的newBuilder就是一个深拷贝，类似于thrift的deepCopy();

Builder newBuilder = ApiLogPB.ApiLog.newBuilder();
    newBuilder.setCost(10);
    newBuilder.setChId("default");
    newBuilder.setReqId("reqid");
    newBuilder.setFNum(12);
    newBuilder.setPuid("puid");
    newBuilder.setUId("uid");
    
    ApiLog apiLog = newBuilder.build();
    //-----------
    Builder newBuilder22 = apiLog.newBuilder();//深拷贝
    
    类似于thtrift的：
    InnerRequest pbdReq = innerRequest.deepCopy();