Google protobuf 与 Java POJO bean 相互转换

以你之姓@ 2022-09-05 14:56 303阅读 0赞

### 1 摘要 ###

Google 的 protocol buffers 协议(简称: protobuf) ，凭借文本体积小、支持多语言、序列化与反序列化优秀等特点在一些场景中应用广泛。本文将介绍如何实现 protobuf 中定义的 message 与 Java 的 POJO bean 的相互转换。

准备工作:

[Spring boot 2.5 集成 Google protocol buffer][Spring boot 2.5 _ Google protocol buffer]

[Protubuf 定义复杂格式的 message][Protubuf _ message]

### 2 核心 Maven 依赖 ###

./demo-mybatis-plus/pom.xml

<dependency>
                <groupId>com.google.protobuf</groupId>
                <artifactId>protobuf-java</artifactId>
                <version>${protobuf.version}</version>
            </dependency>
            <dependency>
                <groupId>io.grpc</groupId>
                <artifactId>grpc-all</artifactId>
                <version>${grpc.version}</version>
            </dependency>

其中 `${protobuf.version}` 的版本为 `3.17.3`，`${grpc.version}` 的版本为 `1.39.0`

### 3 核心代码 ###

#### 3.1 protobuf 文件 ####

./demo-mybatis-plus/src/main/java/com/ljq/demo/springboot/mybatisplus/model/protobuf/Student.proto

syntax = "proto3";
    
    option optimize_for = CODE_SIZE;
    option java_package = "com.ljq.demo.springboot.mybatisplus.model.entity";
    option java_outer_classname = "StudentPb";
    
    // 学生信息
    message Student {
    
      // id
      int64 id = 1;
      // 姓名
      string name = 2;
      // 出生日期(时间戳)
      int32 birth_date = 3;
    }
    
    // 班级信息
    message ClassInfo {
    
      // id
      int64 id = 1;
      // 年级
      int32 grade = 2;
      // 班级编号
      int32 number = 3;
    
    }
    
    // 学生选修课
    message ElectiveCourse {
    
      // 学生 id
      int64 stu_id = 1;
      // 课程名称
      repeated string course_names = 2;
    
    }
    
    // 学生班级信息
    message StudentClass {
    
      // id
      int64 id = 1;
      // 学生信息
      Student student = 2;
      // 班级信息
      ClassInfo class_info = 3;
    
    }
    
    // 性别
    message StudentSex {
      enum Sex{
        MAN = 0;
        WOMEN = 1;
      }
      Sex sex = 2;
    }
    
    // 教师信息
    message Teacher {
      // id
      uint64 id = 1;
      // 姓名
      string name = 2;
    }

./demo-mybatis-plus/src/main/java/com/ljq/demo/springboot/mybatisplus/model/protobuf/Tree.proto

syntax = "proto3";
    
    option optimize_for = CODE_SIZE;
    option java_package = "com.ljq.demo.springboot.mybatisplus.model.entity";
    option java_outer_classname = "TreePb";
    
    import "com/ljq/demo/springboot/mybatisplus/model/protobuf/Student.proto";
    
    // 学生植树
    message Tree {
        // 树木品种
        string tree_type = 2;
        // 植树时间
        uint32 plant_date = 3;
        // 种树学生信息
        Student student = 4;
        // 学生选修课
        ElectiveCourse elective_course = 5;
        // 教师
        repeated Teacher teachers = 6;
    }

其中 `Tree.proto` 文件引用了外部的 `Student.proto` 文件

#### 3.2 Java PoJo 类 ####

Tree 实体类中包含常用的复杂数据结构，其中包含了普通字段、对象属性、列表属性

./demo-mybatis-plus/src/main/java/com/ljq/demo/springboot/mybatisplus/model/entity/TreeEntity.java

package com.ljq.demo.springboot.mybatisplus.model.entity;
    
    import com.ljq.demo.springboot.mybatisplus.model.param.student.StudentReceiveParam;
    import lombok.AllArgsConstructor;
    import lombok.Builder;
    import lombok.Data;
    import lombok.NoArgsConstructor;
    
    import java.io.Serializable;
    import java.util.List;
    
    /** * @Description: 学生植树 * @Author: junqiang.lu * @Date: 2021/8/17 */
    @Data
    @Builder
    @NoArgsConstructor
    @AllArgsConstructor
    public class TreeEntity implements Serializable { 
    
        private static final long serialVersionUID = 3727053267859322959L;
    
        /** * 数目品种 */
        private String treeType;
        /** * 植树时间 */
        private Integer plantDate;
        /** * 学生信息 */
        private StudentReceiveParam student;
        /** * 选修课 */
        private ElectiveCourseEntity electiveCourse;
        /** * 教师列表 */
        private List<TeacherEntity> teachers;
    
    }

学生信息 java bean

./demo-mybatis-plus/src/main/java/com/ljq/demo/springboot/mybatisplus/model/param/student/StudentReceiveParam.java

package com.ljq.demo.springboot.mybatisplus.model.param.student;
    
    import io.swagger.annotations.ApiModel;
    import io.swagger.annotations.ApiModelProperty;
    import lombok.AllArgsConstructor;
    import lombok.Builder;
    import lombok.Data;
    import lombok.NoArgsConstructor;
    
    import java.io.Serializable;
    
    /** * @Description: 接收学生信息(pb) * @Author: junqiang.lu * @Date: 2021/8/7 */
    @Data
    @Builder
    @NoArgsConstructor
    @AllArgsConstructor
    @ApiModel(value = "接收学生信息(pb)", description = "查询学生信息")
    public class StudentReceiveParam implements Serializable { 
    
        private static final long serialVersionUID = -8856061586998092638L;
    
        /** * id */
        @ApiModelProperty(value = "id", required = true, example = "1")
        private Long id;
        /** * 姓名 */
        @ApiModelProperty(value = "姓名", required = true)
        private String name;
        /** * 出生日期(时间戳,精确到秒) */
        @ApiModelProperty(value = "出生日期(时间戳,精确到秒)", required = true, example = "1")
        private Integer birthDate;
    
    
    }

选修课实体类，选修课中包含列表

./demo-mybatis-plus/src/main/java/com/ljq/demo/springboot/mybatisplus/model/entity/ElectiveCourseEntity.java

package com.ljq.demo.springboot.mybatisplus.model.entity;
    
    import lombok.AllArgsConstructor;
    import lombok.Builder;
    import lombok.Data;
    import lombok.NoArgsConstructor;
    
    import java.io.Serializable;
    import java.util.List;
    
    /** * @Description: 选修课 * @Author: junqiang.lu * @Date: 2021/8/17 */
    @Data
    @Builder
    @NoArgsConstructor
    @AllArgsConstructor
    public class ElectiveCourseEntity implements Serializable { 
    
        private static final long serialVersionUID = -9214802138019634356L;
    
        /** * 学生 id */
        private Long stuId;
        /** * 课程名称 */
        private List<String> courseNames;
    
    }

教师信息

./demo-mybatis-plus/src/main/java/com/ljq/demo/springboot/mybatisplus/model/entity/TeacherEntity.java

package com.ljq.demo.springboot.mybatisplus.model.entity;
    
    import com.baomidou.mybatisplus.annotation.IdType;
    import com.baomidou.mybatisplus.annotation.TableField;
    import com.baomidou.mybatisplus.annotation.TableId;
    import com.baomidou.mybatisplus.annotation.TableName;
    import io.swagger.annotations.ApiModel;
    import io.swagger.annotations.ApiModelProperty;
    import lombok.Data;
    import java.io.Serializable;
    
    /** * 教师实体类 * * @author junqiang.lu * @date 2020-10-09 17:27:32 */
    @Data
    @TableName(value = "teacher", resultMap = "teacherMap")
    @ApiModel(value = "教师", description = "教师")
    public class TeacherEntity implements Serializable { 
    
    	private static final long serialVersionUID = 1L;
    
        /** * id **/
        @TableId(value = "ID", type = IdType.AUTO)
        @ApiModelProperty(value = "id", name = "id")
        private Long id;
        /** * 姓名 **/
        @TableField(value = "NAME")
        @ApiModelProperty(value = "姓名", name = "name")
        private String name;
    
    }

#### 3.3 protobuf bean 转换工具类 ####

./demo-mybatis-plus/src/main/java/com/ljq/demo/springboot/mybatisplus/common/util/ProtobufBeanUtil.java

package com.ljq.demo.springboot.mybatisplus.common.util;
    
    import com.google.gson.Gson;
    import com.google.protobuf.Message;
    import com.google.protobuf.util.JsonFormat;
    
    import javax.validation.constraints.NotNull;
    import java.io.IOException;
    
    /** * @Description: protobuf bean 转换工具类 * @Author: junqiang.lu * @Date: 2021/8/9 */
    public class ProtobufBeanUtil { 
    
        private ProtobufBeanUtil(){ 
        }
    
        /** * 将ProtoBean对象转化为POJO对象 * * @param destPojoClass 目标POJO对象的类类型 * @param sourceMessage 含有数据的ProtoBean对象实例 * @param <PojoType> 目标POJO对象的类类型范型 * @return * @throws IOException */
        public static <PojoType> PojoType toPojoBean(@NotNull Class<PojoType> destPojoClass, @NotNull Message sourceMessage)
                throws IOException { 
            String json = JsonFormat.printer().print(sourceMessage);
            return new Gson().fromJson(json, destPojoClass);
        }
    
        /** * 将POJO对象转化为ProtoBean对象 * * @param destBuilder 目标Message对象的Builder类 * @param sourcePojoBean 含有数据的POJO对象 * @return * @throws IOException */
        public static void toProtoBean(@NotNull Message.Builder destBuilder, @NotNull Object sourcePojoBean) throws IOException { 
            String json = new Gson().toJson(sourcePojoBean);
            JsonFormat.parser().merge(json, destBuilder);
        }
    
    
    }

#### 3.4 测试示例 ####

基本属性赋值与压力测试

./demo-mybatis-plus/src/test/java/com/ljq/demo/springboot/mybatisplus/common/util/ProtobufBeanUtilTest.java

package com.ljq.demo.springboot.mybatisplus.common.util;
    
    import com.ljq.demo.springboot.mybatisplus.model.entity.StudentPb;
    import com.ljq.demo.springboot.mybatisplus.model.param.student.StudentReceiveParam;
    import org.junit.Test;
    
    import java.io.IOException;
    
    
    public class ProtobufBeanUtilTest { 
    
        @Test
        public void toPojoBean() throws IOException { 
            // 赋值
            StudentPb.Student student = StudentPb.Student.newBuilder()
                    .setId(111L)
                    .setName("张三")
                    .setBirthDate(1628233076)
                    .build();
            // 属性拷贝
            StudentReceiveParam receiveParam = ProtobufBeanUtil.toPojoBean(StudentReceiveParam.class, student);
            System.out.println(receiveParam);
        }
    
        @Test
        public void toProtoBean() throws IOException { 
            StudentReceiveParam receiveParam = new StudentReceiveParam();
            receiveParam.setId(123L);
            receiveParam.setName("李四");
            receiveParam.setBirthDate(1628233076);
            // 属性拷贝
            StudentPb.Student.Builder studentBuilder = StudentPb.Student.newBuilder();
            ProtobufBeanUtil.toProtoBean(studentBuilder, receiveParam);
            // 打印
            System.out.println("id: " + studentBuilder.getId());
            System.out.println("name: " + studentBuilder.getName());
            System.out.println("birth_date: " + studentBuilder.getBirthDate());
        }
    
        /** * proto to pojo 压力测试 * * @throws IOException */
        @Test
        public void toPojoBeanPressure() throws IOException { 
            // 赋值
            StudentPb.Student student = StudentPb.Student.newBuilder()
                    .setId(111L)
                    .setName("张三")
                    .setBirthDate(1628233076)
                    .build();
            long start = System.currentTimeMillis();
            for (int i = 0; i < 100000; i++) { 
                StudentReceiveParam receiveParam = ProtobufBeanUtil.toPojoBean(StudentReceiveParam.class, student);
            }
            long stop = System.currentTimeMillis();
            System.out.println("耗时: " + (stop-start));
        }
    
        /** * pojo to proto 压力测试 */
        @Test
        public void toProtoBeanPressure() throws IOException { 
            StudentReceiveParam receiveParam = new StudentReceiveParam();
            receiveParam.setId(123L);
            receiveParam.setName("李四");
            receiveParam.setBirthDate(1628233076);
            // 属性拷贝
            long start = System.currentTimeMillis();
            for (int i = 0; i < 100000; i++) { 
                StudentPb.Student.Builder studentBuilder = StudentPb.Student.newBuilder();
                ProtobufBeanUtil.toProtoBean(studentBuilder, receiveParam);
            }
            long stop = System.currentTimeMillis();
            System.out.println("耗时: " + (stop-start));
    
        }
    }

复杂参数格式对象转换测试

./demo-mybatis-plus/src/test/java/com/ljq/demo/springboot/mybatisplus/model/entity/TreeVoTest.java

package com.ljq.demo.springboot.mybatisplus.model.entity;
    
    import com.ljq.demo.springboot.mybatisplus.common.util.ProtobufBeanUtil;
    import com.ljq.demo.springboot.mybatisplus.model.param.student.StudentReceiveParam;
    import org.junit.Test;
    
    import java.io.IOException;
    import java.util.ArrayList;
    import java.util.List;
    
    public class TreeVoTest { 
    
        /** * 测试-赋值 */
        @Test
        public void value() { 
            TreePb.Tree tree = TreePb.Tree.newBuilder()
                    .setTreeType("杨树")
                    .setPlantDate(1628233076)
                    .setStudent(StudentPb.Student.newBuilder()
                            .setId(123L)
                            .setName("王五")
                            .setBirthDate(1628233076))
                    .setElectiveCourse(StudentPb.ElectiveCourse.newBuilder()
                            .setStuId(123L)
                            .addCourseNames("语文")
                            .addCourseNames("数学")
                            .addCourseNames("物理"))
                    .addTeachers(StudentPb.Teacher.newBuilder()
                            .setId(666L)
                            .setName("化学王子秦老师"))
                    .addTeachers(StudentPb.Teacher.newBuilder()
                            .setId(888L)
                            .setName("马保国"))
                    .build();
            // 输出值
            System.out.println("tree type: " + tree.getTreeType());
            System.out.println("plant date: " + tree.getPlantDate());
            System.out.println("tree protobuf: " + tree);
    
        }
    
        @Test
        public void convertToPojo() throws IOException { 
            TreePb.Tree tree = TreePb.Tree.newBuilder()
                    .setTreeType("杨树")
                    .setPlantDate(1628233076)
                    .setStudent(StudentPb.Student.newBuilder()
                            .setId(123L)
                            .setName("王五")
                            .setBirthDate(1628233076))
                    .setElectiveCourse(StudentPb.ElectiveCourse.newBuilder()
                            .setStuId(123L)
                            .addCourseNames("语文")
                            .addCourseNames("数学")
                            .addCourseNames("物理"))
                    .addTeachers(StudentPb.Teacher.newBuilder()
                            .setId(666L)
                            .setName("化学王子秦老师"))
                    .addTeachers(StudentPb.Teacher.newBuilder()
                            .setId(888L)
                            .setName("马保国"))
                    .build();
            TreeEntity treeEntity = ProtobufBeanUtil.toPojoBean(TreeEntity.class, tree);
            System.out.println("tree entity: " + treeEntity);
    
        }
    
        @Test
        public void convertToProtobuf() throws IOException { 
            List<String> courseNameList = new ArrayList<>();
            for (int i = 0; i < 3; i++) { 
                courseNameList.add("科目" + (i+1));
            }
            List<TeacherEntity> teacherList = new ArrayList<>();
            TeacherEntity teacher;
            for (int i = 0; i < 3; i++) { 
                teacher = new TeacherEntity();
                teacher.setId((i+1L));
                teacher.setName("老师" + (i+1));
                teacherList.add(teacher);
            }
            TreeEntity treeEntity = TreeEntity.builder()
                    .treeType("梧桐树")
                    .plantDate(1628233076)
                    .student(StudentReceiveParam.builder()
                            .id(1234L)
                            .name("张三")
                            .birthDate(1628233076)
                            .build())
                    .electiveCourse(ElectiveCourseEntity.builder()
                            .stuId(1234L)
                            .courseNames(courseNameList)
                            .build())
                    .teachers(teacherList)
                    .build();
            // 树木信息
            System.out.println("TreeEntity: " + treeEntity);
            // pojoBean -> protobuf
            TreePb.Tree.Builder tree = TreePb.Tree.newBuilder();
            ProtobufBeanUtil.toProtoBean(tree, treeEntity);
            System.out.println("tree protobuf:" + tree.build());
    
    
        }
    
    }

测试结果:

复杂结构的对象也能够转换，使用工具类转换极大地提升了属性复制的效率。

### 4 推荐参考资料 ###

[protobuf 与 Java 对象互转][protobuf _ Java]

[Protobuf与POJO的相互转化 - 通过Json][Protobuf_POJO_ - _Json]

### 5 Github 源码 ###

**Gtihub 源码地址** : [https://github.com/Flying9001/springBootDemo][https_github.com_Flying9001_springBootDemo]

个人公众号:**404Code**,分享半个互联网人的技术与思考，感兴趣的可以关注.  
![404Code][]

[Spring boot 2.5 _ Google protocol buffer]: https://blog.csdn.net/Mrqiang9001/article/details/119678817
[Protubuf _ message]: https://blog.csdn.net/Mrqiang9001/article/details/119784992
[protobuf _ Java]: https://www.jianshu.com/p/85c511cc2bf7
[Protobuf_POJO_ - _Json]: https://segmentfault.com/a/1190000020288933
[https_github.com_Flying9001_springBootDemo]: https://github.com/Flying9001/springBootDemo
[404Code]: /images/20220829/f6cd6153f11b4523a3a162f5d3153b5e.png