dubbo源码分析-dubbo-serialization

dubbo-serialization

dubbo-serialization是dubbo中实现序列化相关的代码。

共5种序列化方式，可从名字直接看出含义，这里不再赘述。

• dubbo-serialization-fastjson
• dubbo-serialization-fst
• dubbo-serialization-hessian2
• dubbo-serialization-jdk
• dubbo-serialization-kryo

dubbo-serialization-api

dubbo-serialization-api是底层实现，上述5种序列化方式均封装dubbo-serialization-api。

其中SerializableClassRegistry和SerializationOptimizer两个接口，未在源码中找到实现和引用。

• Cleanable

Cleanable是供Kryo序列化方式使用，源码如下：

package org.apache.dubbo.common.serialize;

public interface Cleanable {

    void cleanup();
}

在KryoObjectInput中实现如下：

    @Override
    public void cleanup() {
        KryoUtils.release(kryo);
        kryo = null;
    }

• DataInput
  DataInput实现了基本类型的读取。

package org.apache.dubbo.common.serialize;

import java.io.IOException;

/**
 * Data input.
 */
public interface DataInput {

    /**
     * Read boolean.
     *
     * @return boolean.
     * @throws IOException
     */
    boolean readBool() throws IOException;

    /**
     * Read byte.
     *
     * @return byte value.
     * @throws IOException
     */
    byte readByte() throws IOException;

    /**
     * Read short integer.
     *
     * @return short.
     * @throws IOException
     */
    short readShort() throws IOException;

    /**
     * Read integer.
     *
     * @return integer.
     * @throws IOException
     */
    int readInt() throws IOException;

    /**
     * Read long.
     *
     * @return long.
     * @throws IOException
     */
    long readLong() throws IOException;

    /**
     * Read float.
     *
     * @return float.
     * @throws IOException
     */
    float readFloat() throws IOException;

    /**
     * Read double.
     *
     * @return double.
     * @throws IOException
     */
    double readDouble() throws IOException;

    /**
     * Read UTF-8 string.
     *
     * @return string.
     * @throws IOException
     */
    String readUTF() throws IOException;

    /**
     * Read byte array.
     *
     * @return byte array.
     * @throws IOException
     */
    byte[] readBytes() throws IOException;
}

• DataOutput
  DataOutput实现了基本类型的写入。

package org.apache.dubbo.common.serialize;

import java.io.IOException;

/**
 * Data output.
 */
public interface DataOutput {

    /**
     * Write boolean.
     *
     * @param v value.
     * @throws IOException
     */
    void writeBool(boolean v) throws IOException;

    /**
     * Write byte.
     *
     * @param v value.
     * @throws IOException
     */
    void writeByte(byte v) throws IOException;

    /**
     * Write short.
     *
     * @param v value.
     * @throws IOException
     */
    void writeShort(short v) throws IOException;

    /**
     * Write integer.
     *
     * @param v value.
     * @throws IOException
     */
    void writeInt(int v) throws IOException;

    /**
     * Write long.
     *
     * @param v value.
     * @throws IOException
     */
    void writeLong(long v) throws IOException;

    /**
     * Write float.
     *
     * @param v value.
     * @throws IOException
     */
    void writeFloat(float v) throws IOException;

    /**
     * Write double.
     *
     * @param v value.
     * @throws IOException
     */
    void writeDouble(double v) throws IOException;

    /**
     * Write string.
     *
     * @param v value.
     * @throws IOException
     */
    void writeUTF(String v) throws IOException;

    /**
     * Write byte array.
     *
     * @param v value.
     * @throws IOException
     */
    void writeBytes(byte[] v) throws IOException;

    /**
     * Write byte array.
     *
     * @param v   value.
     * @param off offset.
     * @param len length.
     * @throws IOException
     */
    void writeBytes(byte[] v, int off, int len) throws IOException;

    /**
     * Flush buffer.
     *
     * @throws IOException
     */
    void flushBuffer() throws IOException;
}

• ObjectInput
  ObjectInput实现了对象的读取，继承DataInput。

package org.apache.dubbo.common.serialize;

import java.io.IOException;
import java.lang.reflect.Type;

/**
 * Object input.
 */
public interface ObjectInput extends DataInput {

    /**
     * read object.
     *
     * @return object.
     */
    Object readObject() throws IOException, ClassNotFoundException;

    /**
     * read object.
     *
     * @param cls object type.
     * @return object.
     */
     T readObject(Class cls) throws IOException, ClassNotFoundException;

    /**
     * read object.
     *
     * @param cls object type.
     * @return object.
     */
     T readObject(Class cls, Type type) throws IOException, ClassNotFoundException;

}

• ObjectOutput
  ObjectOutput实现了对象的写入，继承DataOutput。

package org.apache.dubbo.common.serialize;

import java.io.IOException;

/**
 * Object output.
 */
public interface ObjectOutput extends DataOutput {

    /**
     * write object.
     *
     * @param obj object.
     */
    void writeObject(Object obj) throws IOException;

}

• Serialization
  Serialization序列化接口。

package org.apache.dubbo.common.serialize;

import org.apache.dubbo.common.URL;
import org.apache.dubbo.common.extension.Adaptive;
import org.apache.dubbo.common.extension.SPI;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;

/**
 * Serialization. (SPI, Singleton, ThreadSafe)
 */
@SPI("hessian2")
public interface Serialization {

    /**
     * get content type id
     *
     * @return content type id
     */
    byte getContentTypeId();

    /**
     * get content type
     *
     * @return content type
     */
    String getContentType();

    /**
     * create serializer
     *
     * @param url
     * @param output
     * @return serializer
     * @throws IOException
     */
    @Adaptive
    ObjectOutput serialize(URL url, OutputStream output) throws IOException;

    /**
     * create deserializer
     *
     * @param url
     * @param input
     * @return deserializer
     * @throws IOException
     */
    @Adaptive
    ObjectInput deserialize(URL url, InputStream input) throws IOException;

}

dubbo-serialization-fastjson

用最简单的dubbo-serialization-fastjson来实例分析。

• FastJsonSerialization

package org.apache.dubbo.common.serialize.fastjson;

import org.apache.dubbo.common.URL;
import org.apache.dubbo.common.serialize.ObjectInput;
import org.apache.dubbo.common.serialize.ObjectOutput;
import org.apache.dubbo.common.serialize.Serialization;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;

public class FastJsonSerialization implements Serialization {

    @Override
    public byte getContentTypeId() {
        return 6;
    }

    @Override
    public String getContentType() {
        return "text/json";
    }

    // 序列化
    @Override
    public ObjectOutput serialize(URL url, OutputStream output) throws IOException {
        // 返回FastJsonObjectOutput实例
        return new FastJsonObjectOutput(output);
    }

    // 反序列化
    @Override
    public ObjectInput deserialize(URL url, InputStream input) throws IOException {
        // 返回FastJsonObjectInput实例
        return new FastJsonObjectInput(input);
    }

}

• FastJsonObjectInput
  FastJsonObjectInput，文件读取，主要方法如下：

   @Override
    public Object readObject() throws IOException, ClassNotFoundException {
        String json = readLine();
        return JSON.parse(json);
    }

    @Override
    @SuppressWarnings("unchecked")
    public  T readObject(Class cls, Type type) throws IOException, ClassNotFoundException {
        Object value = readObject(cls);
        return (T) PojoUtils.realize(value, cls, type);
    }

    private  T read(Class cls) throws IOException {
        String json = readLine();
        return JSON.parseObject(json, cls);
    }

• FastJsonObjectOutput
  FastJsonObjectOutput，文件写入，主要方法如下：

    @Override
    public void writeObject(Object obj) throws IOException {
        SerializeWriter out = new SerializeWriter();
        JSONSerializer serializer = new JSONSerializer(out);
        serializer.config(SerializerFeature.WriteEnumUsingToString, true);
        serializer.write(obj);
        out.writeTo(writer);
        out.close(); // for reuse SerializeWriter buf
        writer.println();
        writer.flush();
    }