JAVA RPC (四) 之thrift序列化普通对象

先简单写一个thrift文件

本地通过thrift编译之后会生成一个java源文件。------编译口令 ：thrift -gen java mytestrequest.thrift

编译后的源代码如下:

 /**
  * Autogenerated by Thrift Compiler (0.8.0)
  *
  * DO NOT EDIT UNLESS YOU ARE SURE THAT YOU KNOW WHAT YOU ARE DOING
  *  @generated
  */
 package com.thrift;

 import org.apache.thrift.scheme.IScheme;
 import org.apache.thrift.scheme.SchemeFactory;
 import org.apache.thrift.scheme.StandardScheme;

 import org.apache.thrift.scheme.TupleScheme;
 import org.apache.thrift.protocol.TTupleProtocol;
 import java.util.List;
 import java.util.ArrayList;
 import java.util.Map;
 import java.util.HashMap;
 import java.util.EnumMap;
 import java.util.Set;
 import java.util.HashSet;
 import java.util.EnumSet;
 import java.util.Collections;
 import java.util.BitSet;
 import java.nio.ByteBuffer;
 import java.util.Arrays;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;

 /**
  * 测试类
  *
  */
 public class koalasRequest implements org.apache.thrift.TBase<koalasRequest, koalasRequest._Fields>, java.io.Serializable, Cloneable {
   private static final org.apache.thrift.protocol.TStruct STRUCT_DESC = new org.apache.thrift.protocol.TStruct("koalasRequest");

   private static final org.apache.thrift.protocol.TField AGE_FIELD_DESC = new org.apache.thrift.protocol.TField("age", org.apache.thrift.protocol.TType.I32, (short)1);
   private static final org.apache.thrift.protocol.TField NAME_FIELD_DESC = new org.apache.thrift.protocol.TField("name", org.apache.thrift.protocol.TType.STRING, (short)2);
   private static final org.apache.thrift.protocol.TField ADDRESS_FIELD_DESC = new org.apache.thrift.protocol.TField("address", org.apache.thrift.protocol.TType.STRING, (short)3);

   private static final Map<Class<? extends IScheme>, SchemeFactory> schemes = new HashMap<Class<? extends IScheme>, SchemeFactory>();
   static {
     schemes.put(StandardScheme.class, new koalasRequestStandardSchemeFactory());
     schemes.put(TupleScheme.class, new koalasRequestTupleSchemeFactory());
   }

   public int age; // required
   public String name; // required
   public String address; // required

   /** The set of fields this struct contains, along with convenience methods for finding and manipulating them. */
   public enum _Fields implements org.apache.thrift.TFieldIdEnum {
     AGE((short)1, "age"),
     NAME((short)2, "name"),
     ADDRESS((short)3, "address");

     private static final Map<String, _Fields> byName = new HashMap<String, _Fields>();

     static {
       for (_Fields field : EnumSet.allOf(_Fields.class)) {
         byName.put(field.getFieldName(), field);
       }
     }

     /**
      * Find the _Fields constant that matches fieldId, or null if its not found.
      */
     public static _Fields findByThriftId(int fieldId) {
       switch(fieldId) {
         case 1: // AGE
           return AGE;
         case 2: // NAME
           return NAME;
         case 3: // ADDRESS
           return ADDRESS;
         default:
           return null;
       }
     }

     /**
      * Find the _Fields constant that matches fieldId, throwing an exception
      * if it is not found.
      */
     public static _Fields findByThriftIdOrThrow(int fieldId) {
       _Fields fields = findByThriftId(fieldId);
       if (fields == null) throw new IllegalArgumentException("Field " + fieldId + " doesn't exist!");
       return fields;
     }

     /**
      * Find the _Fields constant that matches name, or null if its not found.
      */
     public static _Fields findByName(String name) {
       return byName.get(name);
     }

     private final short _thriftId;
     private final String _fieldName;

     _Fields(short thriftId, String fieldName) {
       _thriftId = thriftId;
       _fieldName = fieldName;
     }

     public short getThriftFieldId() {
       return _thriftId;
     }

     public String getFieldName() {
       return _fieldName;
     }
   }

   // isset id assignments
   private static final int __AGE_ISSET_ID = 0;
   private BitSet __isset_bit_vector = new BitSet(1);
   public static final Map<_Fields, org.apache.thrift.meta_data.FieldMetaData> metaDataMap;
   static {
     Map<_Fields, org.apache.thrift.meta_data.FieldMetaData> tmpMap = new EnumMap<_Fields, org.apache.thrift.meta_data.FieldMetaData>(_Fields.class);
     tmpMap.put(_Fields.AGE, new org.apache.thrift.meta_data.FieldMetaData("age", org.apache.thrift.TFieldRequirementType.DEFAULT,
         new org.apache.thrift.meta_data.FieldValueMetaData(org.apache.thrift.protocol.TType.I32)));
     tmpMap.put(_Fields.NAME, new org.apache.thrift.meta_data.FieldMetaData("name", org.apache.thrift.TFieldRequirementType.DEFAULT,
         new org.apache.thrift.meta_data.FieldValueMetaData(org.apache.thrift.protocol.TType.STRING)));
     tmpMap.put(_Fields.ADDRESS, new org.apache.thrift.meta_data.FieldMetaData("address", org.apache.thrift.TFieldRequirementType.DEFAULT,
         new org.apache.thrift.meta_data.FieldValueMetaData(org.apache.thrift.protocol.TType.STRING)));
     metaDataMap = Collections.unmodifiableMap(tmpMap);
     org.apache.thrift.meta_data.FieldMetaData.addStructMetaDataMap(koalasRequest.class, metaDataMap);
   }

   public koalasRequest() {
   }

   public koalasRequest(
     int age,
     String name,
     String address)
   {
     this();
     this.age = age;
     setAgeIsSet(true);
     this.name = name;
     this.address = address;
   }

   /**
    * Performs a deep copy on <i>other</i>.
    */
   public koalasRequest(koalasRequest other) {
     __isset_bit_vector.clear();
     __isset_bit_vector.or(other.__isset_bit_vector);
     this.age = other.age;
     if (other.isSetName()) {
       this.name = other.name;
     }
     if (other.isSetAddress()) {
       this.address = other.address;
     }
   }

   public koalasRequest deepCopy() {
     return new koalasRequest(this);
   }

   @Override
   public void clear() {
     setAgeIsSet(false);
     this.age = 0;
     this.name = null;
     this.address = null;
   }

   public int getAge() {
     return this.age;
   }

   public koalasRequest setAge(int age) {
     this.age = age;
     setAgeIsSet(true);
     return this;
   }

   public void unsetAge() {
     __isset_bit_vector.clear(__AGE_ISSET_ID);
   }

   /** Returns true if field age is set (has been assigned a value) and false otherwise */
   public boolean isSetAge() {
     return __isset_bit_vector.get(__AGE_ISSET_ID);
   }

   public void setAgeIsSet(boolean value) {
     __isset_bit_vector.set(__AGE_ISSET_ID, value);
   }

   public String getName() {
     return this.name;
   }

   public koalasRequest setName(String name) {
     this.name = name;
     return this;
   }

   public void unsetName() {
     this.name = null;
   }

   /** Returns true if field name is set (has been assigned a value) and false otherwise */
   public boolean isSetName() {
     return this.name != null;
   }

   public void setNameIsSet(boolean value) {
     if (!value) {
       this.name = null;
     }
   }

   public String getAddress() {
     return this.address;
   }

   public koalasRequest setAddress(String address) {
     this.address = address;
     return this;
   }

   public void unsetAddress() {
     this.address = null;
   }

   /** Returns true if field address is set (has been assigned a value) and false otherwise */
   public boolean isSetAddress() {
     return this.address != null;
   }

   public void setAddressIsSet(boolean value) {
     if (!value) {
       this.address = null;
     }
   }

   public void setFieldValue(_Fields field, Object value) {
     switch (field) {
     case AGE:
       if (value == null) {
         unsetAge();
       } else {
         setAge((Integer)value);
       }
       break;

     case NAME:
       if (value == null) {
         unsetName();
       } else {
         setName((String)value);
       }
       break;

     case ADDRESS:
       if (value == null) {
         unsetAddress();
       } else {
         setAddress((String)value);
       }
       break;

     }
   }

   public Object getFieldValue(_Fields field) {
     switch (field) {
     case AGE:
       return Integer.valueOf(getAge());

     case NAME:
       return getName();

     case ADDRESS:
       return getAddress();

     }
     throw new IllegalStateException();
   }

   /** Returns true if field corresponding to fieldID is set (has been assigned a value) and false otherwise */
   public boolean isSet(_Fields field) {
     if (field == null) {
       throw new IllegalArgumentException();
     }

     switch (field) {
     case AGE:
       return isSetAge();
     case NAME:
       return isSetName();
     case ADDRESS:
       return isSetAddress();
     }
     throw new IllegalStateException();
   }

   @Override
   public boolean equals(Object that) {
     if (that == null)
       return false;
     if (that instanceof koalasRequest)
       return this.equals((koalasRequest)that);
     return false;
   }

   public boolean equals(koalasRequest that) {
     if (that == null)
       return false;

     boolean this_present_age = true;
     boolean that_present_age = true;
     if (this_present_age || that_present_age) {
       if (!(this_present_age && that_present_age))
         return false;
       if (this.age != that.age)
         return false;
     }

     boolean this_present_name = true && this.isSetName();
     boolean that_present_name = true && that.isSetName();
     if (this_present_name || that_present_name) {
       if (!(this_present_name && that_present_name))
         return false;
       if (!this.name.equals(that.name))
         return false;
     }

     boolean this_present_address = true && this.isSetAddress();
     boolean that_present_address = true && that.isSetAddress();
     if (this_present_address || that_present_address) {
       if (!(this_present_address && that_present_address))
         return false;
       if (!this.address.equals(that.address))
         return false;
     }

     return true;
   }

   @Override
   public int hashCode() {
     return 0;
   }

   public int compareTo(koalasRequest other) {
     if (!getClass().equals(other.getClass())) {
       return getClass().getName().compareTo(other.getClass().getName());
     }

     int lastComparison = 0;
     koalasRequest typedOther = (koalasRequest)other;

     lastComparison = Boolean.valueOf(isSetAge()).compareTo(typedOther.isSetAge());
     if (lastComparison != 0) {
       return lastComparison;
     }
     if (isSetAge()) {
       lastComparison = org.apache.thrift.TBaseHelper.compareTo(this.age, typedOther.age);
       if (lastComparison != 0) {
         return lastComparison;
       }
     }
     lastComparison = Boolean.valueOf(isSetName()).compareTo(typedOther.isSetName());
     if (lastComparison != 0) {
       return lastComparison;
     }
     if (isSetName()) {
       lastComparison = org.apache.thrift.TBaseHelper.compareTo(this.name, typedOther.name);
       if (lastComparison != 0) {
         return lastComparison;
       }
     }
     lastComparison = Boolean.valueOf(isSetAddress()).compareTo(typedOther.isSetAddress());
     if (lastComparison != 0) {
       return lastComparison;
     }
     if (isSetAddress()) {
       lastComparison = org.apache.thrift.TBaseHelper.compareTo(this.address, typedOther.address);
       if (lastComparison != 0) {
         return lastComparison;
       }
     }
     return 0;
   }

   public _Fields fieldForId(int fieldId) {
     return _Fields.findByThriftId(fieldId);
   }

   public void read(org.apache.thrift.protocol.TProtocol iprot) throws org.apache.thrift.TException {
     schemes.get(iprot.getScheme()).getScheme().read(iprot, this);
   }

   public void write(org.apache.thrift.protocol.TProtocol oprot) throws org.apache.thrift.TException {
     schemes.get(oprot.getScheme()).getScheme().write(oprot, this);
   }

   @Override
   public String toString() {
     StringBuilder sb = new StringBuilder("koalasRequest(");
     boolean first = true;

     sb.append("age:");
     sb.append(this.age);
     first = false;
     if (!first) sb.append(", ");
     sb.append("name:");
     if (this.name == null) {
       sb.append("null");
     } else {
       sb.append(this.name);
     }
     first = false;
     if (!first) sb.append(", ");
     sb.append("address:");
     if (this.address == null) {
       sb.append("null");
     } else {
       sb.append(this.address);
     }
     first = false;
     sb.append(")");
     return sb.toString();
   }

   public void validate() throws org.apache.thrift.TException {
     // check for required fields
   }

   private void writeObject(java.io.ObjectOutputStream out) throws java.io.IOException {
     try {
       write(new org.apache.thrift.protocol.TCompactProtocol(new org.apache.thrift.transport.TIOStreamTransport(out)));
     } catch (org.apache.thrift.TException te) {
       throw new java.io.IOException(te);
     }
   }

   private void readObject(java.io.ObjectInputStream in) throws java.io.IOException, ClassNotFoundException {
     try {
       // it doesn't seem like you should have to do this, but java serialization is wacky, and doesn't call the default constructor.
       __isset_bit_vector = new BitSet(1);
       read(new org.apache.thrift.protocol.TCompactProtocol(new org.apache.thrift.transport.TIOStreamTransport(in)));
     } catch (org.apache.thrift.TException te) {
       throw new java.io.IOException(te);
     }
   }

   private static class koalasRequestStandardSchemeFactory implements SchemeFactory {
     public koalasRequestStandardScheme getScheme() {
       return new koalasRequestStandardScheme();
     }
   }

   private static class koalasRequestStandardScheme extends StandardScheme<koalasRequest> {

     public void read(org.apache.thrift.protocol.TProtocol iprot, koalasRequest struct) throws org.apache.thrift.TException {
       org.apache.thrift.protocol.TField schemeField;
       iprot.readStructBegin();
       while (true)
       {
         schemeField = iprot.readFieldBegin();
         if (schemeField.type == org.apache.thrift.protocol.TType.STOP) {
           break;
         }
         switch (schemeField.id) {
           case 1: // AGE
             if (schemeField.type == org.apache.thrift.protocol.TType.I32) {
               struct.age = iprot.readI32();
               struct.setAgeIsSet(true);
             } else {
               org.apache.thrift.protocol.TProtocolUtil.skip(iprot, schemeField.type);
             }
             break;
           case 2: // NAME
             if (schemeField.type == org.apache.thrift.protocol.TType.STRING) {
               struct.name = iprot.readString();
               struct.setNameIsSet(true);
             } else {
               org.apache.thrift.protocol.TProtocolUtil.skip(iprot, schemeField.type);
             }
             break;
           case 3: // ADDRESS
             if (schemeField.type == org.apache.thrift.protocol.TType.STRING) {
               struct.address = iprot.readString();
               struct.setAddressIsSet(true);
             } else {
               org.apache.thrift.protocol.TProtocolUtil.skip(iprot, schemeField.type);
             }
             break;
           default:
             org.apache.thrift.protocol.TProtocolUtil.skip(iprot, schemeField.type);
         }
         iprot.readFieldEnd();
       }
       iprot.readStructEnd();

       // check for required fields of primitive type, which can't be checked in the validate method
       struct.validate();
     }

     public void write(org.apache.thrift.protocol.TProtocol oprot, koalasRequest struct) throws org.apache.thrift.TException {
       struct.validate();

       oprot.writeStructBegin(STRUCT_DESC);
       oprot.writeFieldBegin(AGE_FIELD_DESC);
       oprot.writeI32(struct.age);
       oprot.writeFieldEnd();
       if (struct.name != null) {
         oprot.writeFieldBegin(NAME_FIELD_DESC);
         oprot.writeString(struct.name);
         oprot.writeFieldEnd();
       }
       if (struct.address != null) {
         oprot.writeFieldBegin(ADDRESS_FIELD_DESC);
         oprot.writeString(struct.address);
         oprot.writeFieldEnd();
       }
       oprot.writeFieldStop();
       oprot.writeStructEnd();
     }

   }

   private static class koalasRequestTupleSchemeFactory implements SchemeFactory {
     public koalasRequestTupleScheme getScheme() {
       return new koalasRequestTupleScheme();
     }
   }

   private static class koalasRequestTupleScheme extends TupleScheme<koalasRequest> {

     @Override
     public void write(org.apache.thrift.protocol.TProtocol prot, koalasRequest struct) throws org.apache.thrift.TException {
       TTupleProtocol oprot = (TTupleProtocol) prot;
       BitSet optionals = new BitSet();
       if (struct.isSetAge()) {
         optionals.set(0);
       }
       if (struct.isSetName()) {
         optionals.set(1);
       }
       if (struct.isSetAddress()) {
         optionals.set(2);
       }
       oprot.writeBitSet(optionals, 3);
       if (struct.isSetAge()) {
         oprot.writeI32(struct.age);
       }
       if (struct.isSetName()) {
         oprot.writeString(struct.name);
       }
       if (struct.isSetAddress()) {
         oprot.writeString(struct.address);
       }
     }

     @Override
     public void read(org.apache.thrift.protocol.TProtocol prot, koalasRequest struct) throws org.apache.thrift.TException {
       TTupleProtocol iprot = (TTupleProtocol) prot;
       BitSet incoming = iprot.readBitSet(3);
       if (incoming.get(0)) {
         struct.age = iprot.readI32();
         struct.setAgeIsSet(true);
       }
       if (incoming.get(1)) {
         struct.name = iprot.readString();
         struct.setNameIsSet(true);
       }
       if (incoming.get(2)) {
         struct.address = iprot.readString();
         struct.setAddressIsSet(true);
       }
     }
   }

 }

生成了一个500多行的代码，那么我们现在对这个请求对象进行序列化，看看序列化结果。

import org.apache.thrift.TException;
import org.apache.thrift.protocol.TBinaryProtocol;
import org.apache.thrift.protocol.TProtocol;
import org.apache.thrift.transport.TIOStreamTransport;

import java.io.ByteArrayOutputStream;
import java.util.Arrays;

public class KoalaThriftSerialization {

    public static void main(String[] args) throws TException {

        koalasRequest request = new koalasRequest (  );
        request.setName ( "小明" );
        request.setAge ( 20 );
        request.setAddress ( "北京" );

        ByteArrayOutputStream out = new ByteArrayOutputStream();
        TIOStreamTransport tioStreamTransport = new TIOStreamTransport (out);
        TProtocol protocol = new TBinaryProtocol (tioStreamTransport);
        request.write ( protocol );
        System.out.println (Arrays.toString ( out.toByteArray () ) );

    }

}

看一看对于这么个简单的request对象,thrift到底序列化成什么了

实际生产中的传输方式一般采用TFramedTransport,序列化采用二进制序列化协议TBinaryProtocol，当然也有json和压缩协议等等，二进制确实最高效的。

我们来看看thrift的序列化方法。

  public void write(org.apache.thrift.protocol.TProtocol oprot) throws org.apache.thrift.TException {
     schemes.get(oprot.getScheme()).getScheme().write(oprot, this);
   }

 public void write(org.apache.thrift.protocol.TProtocol oprot, koalasRequest struct) throws org.apache.thrift.TException {
       struct.validate();

       oprot.writeStructBegin(STRUCT_DESC);
       oprot.writeFieldBegin(AGE_FIELD_DESC);
       oprot.writeI32(struct.age);
       oprot.writeFieldEnd();
       if (struct.name != null) {
         oprot.writeFieldBegin(NAME_FIELD_DESC);
         oprot.writeString(struct.name);
         oprot.writeFieldEnd();
       }
       if (struct.address != null) {
         oprot.writeFieldBegin(ADDRESS_FIELD_DESC);
         oprot.writeString(struct.address);
         oprot.writeFieldEnd();
       }
       oprot.writeFieldStop();
       oprot.writeStructEnd();
     }

1：validate 验证一下request中是否合法，主要是验证在thrift文件里属性为required的，但是实际传输中为空的字段。required字段为空则会报错。

2：writeStructBegin 开始序列化request，TBinaryProtocol什么也不做，当然用户可以自己自定义Protocol。

3:  writeFieldBegin 写入age字段开始，下面来看看writeFieldBegin到底写了什么

  private static final org.apache.thrift.protocol.TField AGE_FIELD_DESC = new org.apache.thrift.protocol.TField("age", org.apache.thrift.protocol.TType.I32, (short)1);

//
// Source code recreated from a .class file by IntelliJ IDEA
// (powered by Fernflower decompiler)
//

package org.apache.thrift.protocol;

public final class TType {
    public static final byte STOP = 0;
    public static final byte VOID = 1;
    public static final byte BOOL = 2;
    public static final byte BYTE = 3;
    public static final byte DOUBLE = 4;
    public static final byte I16 = 6;
    public static final byte I32 = 8;
    public static final byte I64 = 10;
    public static final byte STRING = 11;
    public static final byte STRUCT = 12;
    public static final byte MAP = 13;
    public static final byte SET = 14;
    public static final byte LIST = 15;
    public static final byte ENUM = 16;

    public TType() {
    }
}

public void writeFieldBegin(TField field) throws TException {
        this.writeByte(field.type);
        this.writeI16(field.id);
    }

public void writeByte(byte b) throws TException {
        this.bout[0] = b;
        this.trans_.write(this.bout, 0, 1);
    }

public void writeI16(short i16) throws TException {
        this.i16out[0] = (byte)(255 & i16 >> 8);
        this.i16out[1] = (byte)(255 & i16);
        this.trans_.write(this.i16out, 0, 2);
    }

（1）首先先写入age的类型和序号,age为int类型，int类型在thrift里面设置是byte类型的【8】，在写入age的位置，因为thrift的定义的age的位置序号是1，thrift会写入一下short类型的1，也就说thrift的请求体的成员最大数量不能超过short的最大值32767,一般来说够了，哪有变态的请求体需要几万个成员变量啊，不得把程序员搞死！写入short占用两个字节那么继续写入【0 1】

4: writeI32

public void writeI32(int i32) throws TException {
        this.i32out[0] = (byte)(255 & i32 >> 24);
        this.i32out[1] = (byte)(255 & i32 >> 16);
        this.i32out[2] = (byte)(255 & i32 >> 8);
        this.i32out[3] = (byte)(255 & i32);
        this.trans_.write(this.i32out, 0, 4);
    }

直接将age的值写入,也就是 0 0 0 20 占4个字节

5:writeFieldEnd 写入age字段结束，什么也不做。

以上写入一个int类型的字段就写完了，接下来写入String类型的name和String类型的address同理,需要注意的是

public void writeString(String str) throws TException {
        try {
            byte[] dat = str.getBytes("UTF-8");
            this.writeI32(dat.length);
            this.trans_.write(dat, 0, dat.length);
        } catch (UnsupportedEncodingException var3) {
            throw new TException("JVM DOES NOT SUPPORT UTF-8");
        }
    }

在写入String的时候需要先write字符串的长度,int类型占4个字节，因为string类型占用的字节不固定，反序列化时需要知道字符串类型到底是几个字节。

重复这个过程一直到写完所有的字段，这个过程都是由thrift给java语言自动生成的，很方便吧。

所以对于thrift来说,他的序列化就是对各个字段进行写入 1 字段类型 （1 byte）、2字段位置(2 byte)、3字段内容 ，TBinaryProtocol中对java所有的类型的写入都有封装,小伙伴们可以自行下载代码查看！

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koalas rpc源码地址https://gitee.com/a1234567891/koalas-rpc