spring mvc 4.1支持protobuf converters

最近公司有个项目需要和c++做信息交换，现在流行比较流行http+protobuf方式，一是比较简单学习成本低，二是信息的压缩比例比较好，节省带宽。

经过调研spring 4.1以后开始支持protobuf HttpMessageConverter 详细的配置如下：

• pom.xml配置：

<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>还有要引入spring核心包及spring mvc包 版本4.1.6.RELEASE，如果不知道怎么引入，百度一下

配置portoc插件，也可以不用这个插件，得需要自己用protoc.exe生产java文件

<plugin>    <groupId>com.google.protobuf.tools</groupId>    <artifactId>maven-protoc-plugin</artifactId>    <version>0.1.10</version>    <executions>        <execution>            <id>generate-sources</id>            <goals>                <goal>compile</goal>            </goals>            <phase>generate-sources</phase>            <configuration>                <protoSourceRoot>${basedir}/src/main/proto/</protoSourceRoot>                <includes>                    <param>**/*.proto</param>                </includes>            </configuration>        </execution>    </executions>    <configuration>        <protocExecutable>D:/dev/protoc.exe</protocExecutable><!--protoc.exe文件地址,使用2.5版本-->    </configuration></plugin>

• springmvc-servlet.xml配置

<mvc:annotation-driven>    <mvc:message-converters>　　　　<!--看了一下源码，客户端请求类型必须设置成application/x-protobuf采用用这个类来解析实体

        <bean class="org.springframework.http.converter.protobuf.ProtobufHttpMessageConverter">

        </bean>    </mvc:message-converters></mvc:annotation-driven>

• user.proto文件，目录/src/main/proto/和protoc插件配置路径保持一致，如果不想用插件可以自己用protoc.exe生成java文件，可以参见protobuf使用

package com.my.pb;

 option java_package = "com.my.pb";

 option java_outer_classname = "UserProto";

 message User {   optional int64 id = 1;   optional string name = 2;   message PhoneNumber {       required string number = 1;     }     repeated PhoneNumber phone = 4; }

• controller类

@Controllerpublic class ProtobufController{

    @RequestMapping(value = "/proto/write1",method= RequestMethod.POST)    public ResponseEntity<UserProto.User> protoWrite1(RequestEntity<UserProto.User> requestEntity) {        //System.out.println("server===\n");        UserProto.User user =  requestEntity.getBody();        System.out.println("server===\n" + user);        return ResponseEntity.ok(user);    }}

• 客户端测试代码，使用Apache的httpclient进行测试

@Test    public void testWrite() throws IOException {        CloseableHttpClient httpclient = HttpClients.createDefault();        HttpPost httpPost = new HttpPost(baseUri+"/proto/write1");

        UserProto.User user =   UserProto.User.newBuilder().setId(1).setName("zhangsan").addPhone(UserProto.User.PhoneNumber.newBuilder().setNumber("18611163408")).build();//构造

        ByteArrayInputStream inputStream = new ByteArrayInputStream(user.toByteArray());        InputStreamEntity inputStreamEntity = new InputStreamEntity(inputStream);

　　　　//这两行很重要的，是告诉springmvc客户端请求和响应的类型，指定application/x-protobuf类型,spring会用ProtobufHttpMessageConverter类来解析请求和响应的实体

        httpPost.addHeader("Content-Type","application/x-protobuf");        httpPost.addHeader("Accept", "application/x-protobuf");

　　　　　httpPost.setEntity(inputStreamEntity);        CloseableHttpResponse response2 = httpclient.execute(httpPost);

        try {            System.out.println(response2.getStatusLine());            HttpEntity entity2 = response2.getEntity();

            ByteArrayOutputStream buf = new ByteArrayOutputStream();            entity2.writeTo(buf);            System.out.println(new String(buf.toByteArray())+"#################");            UserProto.User user2 = UserProto.User.parseFrom(buf.toByteArray());            System.out.println(user2);        } finally {            response2.close();        }    }

• 总结：

当时调试的时候试了很多次，响应总是被转成xml类型，最后看了源码才发现客户端要设置httpPost.addHeader("Accept", "application/x-protobuf");其实也可以自己实现HttpMessageConverter，也不是很麻烦，本人比较懒，有现成的东西不太爱闭门造车轮。

参考文献：http://jinnianshilongnian.iteye.com/blog/2107205http://docs.spring.io/spring/docs/current/spring-framework-reference/htmlsingle/