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    java对象常用的跨语言序列化反序列化主要有三种：一是xml形式；二是json形式；三是protobuf字节流形式。本篇文章主要介绍这三种序列化反序列化方式的实现和其效率对比。

    首先介绍xml形式的序列化与反序列化，使用jaxb来实现。JAXB能够使用Jackson对JAXB注解的支持实现(jackson-module-jaxb-annotations)，既方便生成XML，也方便生成JSON，这样一来可以更好的标志可以转换为JSON对象的JAVA类。JAXB允许JAVA人员将JAVA类映射为XML表示方式，常用的注解包括：@XmlRootElement,@XmlElement等等。其maven依赖为：

<!-- http://mvnrepository.com/artifact/com.sun.xml.bind/jaxb-core --> <dependency> <groupId>com.sun.xml.bind</groupId> <artifactId>jaxb-core</artifactId> <version>2.2.11</version> </dependency> <!-- http://mvnrepository.com/artifact/javax.xml/jaxb-api --> <dependency> <groupId>javax.xml</groupId> <artifactId>jaxb-api</artifactId> <version>2.1</version> </dependency> <!-- http://mvnrepository.com/artifact/com.sun.xml.bind/jaxb-impl --> <dependency> <groupId>com.sun.xml.bind</groupId> <artifactId>jaxb-impl</artifactId> <version>2.2.11</version> </dependency>

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定义的pojo类有两个：第一个是Book.java，另一个为BookList.java，是Book的集合类。只需要在定义的类名上添加@XmlRootElement注解即可，对业务代码没有侵入性。其中两个类中的属性值上有@Protobuf注解，这是protobuf序列化需要的，对xml序列化无影响。

Book类代码：

讯享网package zhangq.pojo; import javax.xml.bind.annotation.XmlRootElement; import com.baidu.bjf.remoting.protobuf.FieldType; import com.baidu.bjf.remoting.protobuf.annotation.Protobuf; @XmlRootElement public class Book { @Protobuf(fieldType = FieldType.INT32, order=1) int id; @Protobuf(fieldType = FieldType.STRING, order=2) String name; @Protobuf(fieldType = FieldType.STRING, order=3) String address; @Protobuf(fieldType = FieldType.STRING, order=4) String buyer; public int getId() { return id; } public void setId(int id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } public String getAddress() { return address; } public void setAddress(String address) { this.address = address; } public String getBuyer() { return buyer; } public void setBuyer(String buyer) { this.buyer = buyer; } @Override public String toString() { return "Book [id=" + id + ", name=" + name + ", address=" + address + ", buyer=" + buyer + "]"; } } 

BookList类代码：

package zhangq.pojo; import java.util.List; import javax.xml.bind.annotation.XmlRootElement; import com.baidu.bjf.remoting.protobuf.annotation.Protobuf; @XmlRootElement public class BookList{ @Protobuf(order=1) private List<Book> books; public List<Book> getBooks() { return books; } public void setBooks(List<Book> books) { this.books = books; } @Override public String toString() { return "BookList [books=" + books + "]"; } }

定义完pojo后，就可以进行xml的序列化与反序列化实现了。

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首先定义一个测试辅助类，用来生成pojo实例：

讯享网package zhangq.test; import java.util.ArrayList; import java.util.List; import zhangq.pojo.Book; import zhangq.pojo.BookList; public class TestHelper { public static BookList buildBookList(int count){ BookList bookList = new BookList(); List<Book> books = new ArrayList<Book>(); for (int i=0; i<count; i++){ books.add(buildBook(i)); } bookList.setBooks(books); return bookList; } public static Book buildBook(int id){ Book book = new Book(); book.setAddress("Peking"); book.setBuyer("hello"); book.setId(id); book.setName("Netty"); return book; } }

然后，定义一个性能记录类，用来记录序列化与反序列化的耗时：

package zhangq.util; import org.apache.log4j.Logger; public class PerformanceRecord { private static Logger m_Logger = Logger.getLogger(PerformanceRecord.class); private String desp; private long iStart; private PerformanceRecord(String desp){ this.desp = desp; } public static PerformanceRecord getInstance(String desp){ return new PerformanceRecord(desp); } public long start(){ iStart = System.nanoTime(); return iStart; } public double endInSeconds(){ long iEnd = System.nanoTime(); double timeInSeconds = (iEnd - iStart) / (.0); m_Logger.info(desp + " 耗时为 [" + timeInSeconds + "] 秒"); return timeInSeconds; } public double endInMs(){ long iEnd = System.nanoTime(); double timeInMs = (iEnd - iStart) / (.0); m_Logger.info(desp + " 耗时为 [" + timeInMs + "] 毫秒"); return timeInMs; } public long endInNs(){ long iEnd = System.nanoTime(); long timeInNs = (iEnd - iStart); m_Logger.info(desp + " 耗时为 [" + timeInNs + "] 纳秒"); return timeInNs; } }

使用jaxb进行xml序列化的代码为：

讯享网 public static String testMarshallList(int count) throws Exception{ BookList books = TestHelper.buildBookList(count); JAXBContext jaxbContext = JAXBContext.newInstance(BookList.class); Marshaller marshaller = jaxbContext.createMarshaller(); marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true); OutputStream outputStream = new ByteArrayOutputStream(); PerformanceRecord performanceRecord = PerformanceRecord.getInstance("XmlMashall"); performanceRecord.start(); marshaller.marshal(books, outputStream); performanceRecord.endInMs(); String string = outputStream.toString(); outputStream.close(); //m_Logger.debug("ObjToXml:"); //m_Logger.debug(string); return string; }

使用jaxb进行xml反序列化的代码为：

public static BookList testUnMarshallList(String string) throws Exception{ JAXBContext jaxbContext = JAXBContext.newInstance(BookList.class); Unmarshaller unmarshaller = jaxbContext.createUnmarshaller(); InputStream inputStream = new ByteArrayInputStream(string.getBytes()); PerformanceRecord performanceRecord = PerformanceRecord.getInstance("XmlUnmashall"); performanceRecord.start(); BookList books = (BookList)unmarshaller.unmarshal(inputStream); performanceRecord.endInMs(); //m_Logger.debug("XmlToObj:"); //m_Logger.debug(books.toString()); return books; }

讯享网 <!-- https://mvnrepository.com/artifact/com.fasterxml.jackson.core/jackson-core --> <dependency> <groupId>com.fasterxml.jackson.core</groupId> <artifactId>jackson-core</artifactId> <version>2.9.5</version> </dependency> <!-- https://mvnrepository.com/artifact/com.fasterxml.jackson.core/jackson-databind --> <dependency> <groupId>com.fasterxml.jackson.core</groupId> <artifactId>jackson-databind</artifactId> <version>2.9.5</version> </dependency> <!-- https://mvnrepository.com/artifact/com.fasterxml.jackson.core/jackson-annotations --> <dependency> <groupId>com.fasterxml.jackson.core</groupId> <artifactId>jackson-annotations</artifactId> <version>2.9.5</version> </dependency>

jackson的json序列化代码为：

 public static String testObjToJsonList(int count) throws Exception{ String string = null; BookList books = TestHelper.buildBookList(count); ObjectMapper mapper = new ObjectMapper(); PerformanceRecord performanceRecord = PerformanceRecord.getInstance("Jsonmashall"); performanceRecord.start(); string = mapper.writeValueAsString(books); performanceRecord.endInMs(); // m_Logger.debug("ObjToJson:"); // m_Logger.debug(string); return string; }

jackson的json反序列化代码为：

讯享网 public static BookList testJsonToObjList(String string) throws Exception{ BookList books = null; ObjectMapper mapper = new ObjectMapper(); PerformanceRecord performanceRecord = PerformanceRecord.getInstance("JsonUnmashall"); performanceRecord.start(); books = mapper.readValue(string, BookList.class); performanceRecord.endInMs(); // m_Logger.debug("JsonToObj:"); // m_Logger.debug(books.toString()); return books; }

    最后是protobuf字节流的序列化与反序列化，使用jprotobuf库进行，jprotobuf库的优点是使用简单，只需要在pojo上添加@protobuf注解即可，关于jprotobuf的介绍请看其git：https://github.com/jhunters/jprotobuf/ 。其maven依赖为：