apache thrift 入门（一）

1.简介

　　Apache Thrift软件框架，是用来开发可扩展的跨语言的软件服务。通过软件堆栈和代码生成引擎相结合的方式来构建服务，使C++, Java, Python, PHP, Ruby, Erlang, Perl, Haskell, C#, Cocoa, JavaScript, Node.js, Smalltalk, OCaml 、Delphi 等语言之间的工作变得高效且无缝。

　　以上是官网的简介，首先Thrift 是一种服务之间RPC（Remote Procedure Call）协议通信，也就是远程调用。其次，它提供一种代码生成引擎，可以根据模板来生成不同语言的接口代码，这个代码文件里面就包括包括和服务端之间通讯的所有代码，我们就可以不写这些底层的代码啦。

　 生成后的代码长这样：

 /**
  * Autogenerated by Thrift Compiler (0.11.0)
  *
  * DO NOT EDIT UNLESS YOU ARE SURE THAT YOU KNOW WHAT YOU ARE DOING
  *  @generated
  */
 package com.thrift.demo;

 @SuppressWarnings({"cast", "rawtypes", "serial", "unchecked", "unused"})
 @javax.annotation.Generated(value = "Autogenerated by Thrift Compiler (0.11.0)", date = "2019-06-13")
 public class HelloWorldService {

   public interface Iface {

     public java.lang.String sayHello(java.lang.String name) throws org.apache.thrift.TException;

   }

   public interface AsyncIface {

     public void sayHello(java.lang.String name, org.apache.thrift.async.AsyncMethodCallback<java.lang.String> resultHandler) throws org.apache.thrift.TException;

   }

   public static class Client extends org.apache.thrift.TServiceClient implements Iface {
     public static class Factory implements org.apache.thrift.TServiceClientFactory<Client> {
       public Factory() {}
       public Client getClient(org.apache.thrift.protocol.TProtocol prot) {
         return new Client(prot);
       }
       public Client getClient(org.apache.thrift.protocol.TProtocol iprot, org.apache.thrift.protocol.TProtocol oprot) {
         return new Client(iprot, oprot);
       }
     }

     public Client(org.apache.thrift.protocol.TProtocol prot)
     {
       super(prot, prot);
     }

     public Client(org.apache.thrift.protocol.TProtocol iprot, org.apache.thrift.protocol.TProtocol oprot) {
       super(iprot, oprot);
     }

     public java.lang.String sayHello(java.lang.String name) throws org.apache.thrift.TException
     {
       send_sayHello(name);
       return recv_sayHello();
     }

     public void send_sayHello(java.lang.String name) throws org.apache.thrift.TException
     {
       sayHello_args args = new sayHello_args();
       args.setName(name);
       sendBase("sayHello", args);
     }

     public java.lang.String recv_sayHello() throws org.apache.thrift.TException
     {
       sayHello_result result = new sayHello_result();
       receiveBase(result, "sayHello");
       if (result.isSetSuccess()) {
         return result.success;
       }
       throw new org.apache.thrift.TApplicationException(org.apache.thrift.TApplicationException.MISSING_RESULT, "sayHello failed: unknown result");
     }

   }
   public static class AsyncClient extends org.apache.thrift.async.TAsyncClient implements AsyncIface {
     public static class Factory implements org.apache.thrift.async.TAsyncClientFactory<AsyncClient> {
       private org.apache.thrift.async.TAsyncClientManager clientManager;
       private org.apache.thrift.protocol.TProtocolFactory protocolFactory;
       public Factory(org.apache.thrift.async.TAsyncClientManager clientManager, org.apache.thrift.protocol.TProtocolFactory protocolFactory) {
         this.clientManager = clientManager;
         this.protocolFactory = protocolFactory;
       }
       public AsyncClient getAsyncClient(org.apache.thrift.transport.TNonblockingTransport transport) {
         return new AsyncClient(protocolFactory, clientManager, transport);
       }
     }

     public AsyncClient(org.apache.thrift.protocol.TProtocolFactory protocolFactory, org.apache.thrift.async.TAsyncClientManager clientManager, org.apache.thrift.transport.TNonblockingTransport transport) {
       super(protocolFactory, clientManager, transport);
     }

     public void sayHello(java.lang.String name, org.apache.thrift.async.AsyncMethodCallback<java.lang.String> resultHandler) throws org.apache.thrift.TException {
       checkReady();
       sayHello_call method_call = new sayHello_call(name, resultHandler, this, ___protocolFactory, ___transport);
       this.___currentMethod = method_call;
       ___manager.call(method_call);
     }

     public static class sayHello_call extends org.apache.thrift.async.TAsyncMethodCall<java.lang.String> {
       private java.lang.String name;
       public sayHello_call(java.lang.String name, org.apache.thrift.async.AsyncMethodCallback<java.lang.String> resultHandler, org.apache.thrift.async.TAsyncClient client, org.apache.thrift.protocol.TProtocolFactory protocolFactory, org.apache.thrift.transport.TNonblockingTransport transport) throws org.apache.thrift.TException {
         super(client, protocolFactory, transport, resultHandler, false);
         this.name = name;
       }

       public void write_args(org.apache.thrift.protocol.TProtocol prot) throws org.apache.thrift.TException {
         prot.writeMessageBegin(new org.apache.thrift.protocol.TMessage("sayHello", org.apache.thrift.protocol.TMessageType.CALL, 0));
         sayHello_args args = new sayHello_args();
         args.setName(name);
         args.write(prot);
         prot.writeMessageEnd();
       }

       public java.lang.String getResult() throws org.apache.thrift.TException {
         if (getState() != org.apache.thrift.async.TAsyncMethodCall.State.RESPONSE_READ) {
           throw new java.lang.IllegalStateException("Method call not finished!");
         }
         org.apache.thrift.transport.TMemoryInputTransport memoryTransport = new org.apache.thrift.transport.TMemoryInputTransport(getFrameBuffer().array());
         org.apache.thrift.protocol.TProtocol prot = client.getProtocolFactory().getProtocol(memoryTransport);
         return (new Client(prot)).recv_sayHello();
       }
     }

   }

   public static class Processor<I extends Iface> extends org.apache.thrift.TBaseProcessor<I> implements org.apache.thrift.TProcessor {
     private static final org.slf4j.Logger _LOGGER = org.slf4j.LoggerFactory.getLogger(Processor.class.getName());
     public Processor(I iface) {
       super(iface, getProcessMap(new java.util.HashMap<java.lang.String, org.apache.thrift.ProcessFunction<I, ? extends org.apache.thrift.TBase>>()));
     }

     protected Processor(I iface, java.util.Map<java.lang.String, org.apache.thrift.ProcessFunction<I, ? extends org.apache.thrift.TBase>> processMap) {
       super(iface, getProcessMap(processMap));
     }

     private static <I extends Iface> java.util.Map<java.lang.String,  org.apache.thrift.ProcessFunction<I, ? extends org.apache.thrift.TBase>> getProcessMap(java.util.Map<java.lang.String, org.apache.thrift.ProcessFunction<I, ? extends  org.apache.thrift.TBase>> processMap) {
       processMap.put("sayHello", new sayHello());
       return processMap;
     }

     public static class sayHello<I extends Iface> extends org.apache.thrift.ProcessFunction<I, sayHello_args> {
       public sayHello() {
         super("sayHello");
       }

       public sayHello_args getEmptyArgsInstance() {
         return new sayHello_args();
       }

       protected boolean isOneway() {
         return false;
       }

       @Override
       protected boolean handleRuntimeExceptions() {
         return false;
       }

       public sayHello_result getResult(I iface, sayHello_args args) throws org.apache.thrift.TException {
         sayHello_result result = new sayHello_result();
         result.success = iface.sayHello(args.name);
         return result;
       }
     }

   }

   public static class AsyncProcessor<I extends AsyncIface> extends org.apache.thrift.TBaseAsyncProcessor<I> {
     private static final org.slf4j.Logger _LOGGER = org.slf4j.LoggerFactory.getLogger(AsyncProcessor.class.getName());
     public AsyncProcessor(I iface) {
       super(iface, getProcessMap(new java.util.HashMap<java.lang.String, org.apache.thrift.AsyncProcessFunction<I, ? extends org.apache.thrift.TBase, ?>>()));
     }

     protected AsyncProcessor(I iface, java.util.Map<java.lang.String,  org.apache.thrift.AsyncProcessFunction<I, ? extends  org.apache.thrift.TBase, ?>> processMap) {
       super(iface, getProcessMap(processMap));
     }

     private static <I extends AsyncIface> java.util.Map<java.lang.String,  org.apache.thrift.AsyncProcessFunction<I, ? extends  org.apache.thrift.TBase,?>> getProcessMap(java.util.Map<java.lang.String,  org.apache.thrift.AsyncProcessFunction<I, ? extends  org.apache.thrift.TBase, ?>> processMap) {
       processMap.put("sayHello", new sayHello());
       return processMap;
     }

     public static class sayHello<I extends AsyncIface> extends org.apache.thrift.AsyncProcessFunction<I, sayHello_args, java.lang.String> {
       public sayHello() {
         super("sayHello");
       }

       public sayHello_args getEmptyArgsInstance() {
         return new sayHello_args();
       }

       public org.apache.thrift.async.AsyncMethodCallback<java.lang.String> getResultHandler(final org.apache.thrift.server.AbstractNonblockingServer.AsyncFrameBuffer fb, final int seqid) {
         final org.apache.thrift.AsyncProcessFunction fcall = this;
         return new org.apache.thrift.async.AsyncMethodCallback<java.lang.String>() {
           public void onComplete(java.lang.String o) {
             sayHello_result result = new sayHello_result();
             result.success = o;
             try {
               fcall.sendResponse(fb, result, org.apache.thrift.protocol.TMessageType.REPLY,seqid);
             } catch (org.apache.thrift.transport.TTransportException e) {
               _LOGGER.error("TTransportException writing to internal frame buffer", e);
               fb.close();
             } catch (java.lang.Exception e) {
               _LOGGER.error("Exception writing to internal frame buffer", e);
               onError(e);
             }
           }
           public void onError(java.lang.Exception e) {
             byte msgType = org.apache.thrift.protocol.TMessageType.REPLY;
             org.apache.thrift.TSerializable msg;
             sayHello_result result = new sayHello_result();
             if (e instanceof org.apache.thrift.transport.TTransportException) {
               _LOGGER.error("TTransportException inside handler", e);
               fb.close();
               return;
             } else if (e instanceof org.apache.thrift.TApplicationException) {
               _LOGGER.error("TApplicationException inside handler", e);
               msgType = org.apache.thrift.protocol.TMessageType.EXCEPTION;
               msg = (org.apache.thrift.TApplicationException)e;
             } else {
               _LOGGER.error("Exception inside handler", e);
               msgType = org.apache.thrift.protocol.TMessageType.EXCEPTION;
               msg = new org.apache.thrift.TApplicationException(org.apache.thrift.TApplicationException.INTERNAL_ERROR, e.getMessage());
             }
             try {
               fcall.sendResponse(fb,msg,msgType,seqid);
             } catch (java.lang.Exception ex) {
               _LOGGER.error("Exception writing to internal frame buffer", ex);
               fb.close();
             }
           }
         };
       }

       protected boolean isOneway() {
         return false;
       }

       public void start(I iface, sayHello_args args, org.apache.thrift.async.AsyncMethodCallback<java.lang.String> resultHandler) throws org.apache.thrift.TException {
         iface.sayHello(args.name,resultHandler);
       }
     }

   }

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

     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)1);

     private static final org.apache.thrift.scheme.SchemeFactory STANDARD_SCHEME_FACTORY = new sayHello_argsStandardSchemeFactory();
     private static final org.apache.thrift.scheme.SchemeFactory TUPLE_SCHEME_FACTORY = new sayHello_argsTupleSchemeFactory();

     public java.lang.String name; // 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 {
       NAME((short)1, "name");

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

       static {
         for (_Fields field : java.util.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: // NAME
             return NAME;
           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 java.lang.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(java.lang.String name) {
         return byName.get(name);
       }

       private final short _thriftId;
       private final java.lang.String _fieldName;

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

       public short getThriftFieldId() {
         return _thriftId;
       }

       public java.lang.String getFieldName() {
         return _fieldName;
       }
     }

     // isset id assignments
     public static final java.util.Map<_Fields, org.apache.thrift.meta_data.FieldMetaData> metaDataMap;
     static {
       java.util.Map<_Fields, org.apache.thrift.meta_data.FieldMetaData> tmpMap = new java.util.EnumMap<_Fields, org.apache.thrift.meta_data.FieldMetaData>(_Fields.class);
       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)));
       metaDataMap = java.util.Collections.unmodifiableMap(tmpMap);
       org.apache.thrift.meta_data.FieldMetaData.addStructMetaDataMap(sayHello_args.class, metaDataMap);
     }

     public sayHello_args() {
     }

     public sayHello_args(
       java.lang.String name)
     {
       this();
       this.name = name;
     }

     /**
      * Performs a deep copy on <i>other</i>.
      */
     public sayHello_args(sayHello_args other) {
       if (other.isSetName()) {
         this.name = other.name;
       }
     }

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

     @Override
     public void clear() {
       this.name = null;
     }

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

     public sayHello_args setName(java.lang.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 void setFieldValue(_Fields field, java.lang.Object value) {
       switch (field) {
       case NAME:
         if (value == null) {
           unsetName();
         } else {
           setName((java.lang.String)value);
         }
         break;

       }
     }

     public java.lang.Object getFieldValue(_Fields field) {
       switch (field) {
       case NAME:
         return getName();

       }
       throw new java.lang.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 java.lang.IllegalArgumentException();
       }

       switch (field) {
       case NAME:
         return isSetName();
       }
       throw new java.lang.IllegalStateException();
     }

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

     public boolean equals(sayHello_args that) {
       if (that == null)
         return false;
       if (this == that)
         return true;

       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;
       }

       return true;
     }

     @Override
     public int hashCode() {
       int hashCode = 1;

       hashCode = hashCode * 8191 + ((isSetName()) ? 131071 : 524287);
       if (isSetName())
         hashCode = hashCode * 8191 + name.hashCode();

       return hashCode;
     }

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

       int lastComparison = 0;

       lastComparison = java.lang.Boolean.valueOf(isSetName()).compareTo(other.isSetName());
       if (lastComparison != 0) {
         return lastComparison;
       }
       if (isSetName()) {
         lastComparison = org.apache.thrift.TBaseHelper.compareTo(this.name, other.name);
         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 {
       scheme(iprot).read(iprot, this);
     }

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

     @Override
     public java.lang.String toString() {
       java.lang.StringBuilder sb = new java.lang.StringBuilder("sayHello_args(");
       boolean first = true;

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

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

     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, java.lang.ClassNotFoundException {
       try {
         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 sayHello_argsStandardSchemeFactory implements org.apache.thrift.scheme.SchemeFactory {
       public sayHello_argsStandardScheme getScheme() {
         return new sayHello_argsStandardScheme();
       }
     }

     private static class sayHello_argsStandardScheme extends org.apache.thrift.scheme.StandardScheme<sayHello_args> {

       public void read(org.apache.thrift.protocol.TProtocol iprot, sayHello_args 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: // 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;
             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, sayHello_args struct) throws org.apache.thrift.TException {
         struct.validate();

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

     }

     private static class sayHello_argsTupleSchemeFactory implements org.apache.thrift.scheme.SchemeFactory {
       public sayHello_argsTupleScheme getScheme() {
         return new sayHello_argsTupleScheme();
       }
     }

     private static class sayHello_argsTupleScheme extends org.apache.thrift.scheme.TupleScheme<sayHello_args> {

       @Override
       public void write(org.apache.thrift.protocol.TProtocol prot, sayHello_args struct) throws org.apache.thrift.TException {
         org.apache.thrift.protocol.TTupleProtocol oprot = (org.apache.thrift.protocol.TTupleProtocol) prot;
         java.util.BitSet optionals = new java.util.BitSet();
         if (struct.isSetName()) {
           optionals.set(0);
         }
         oprot.writeBitSet(optionals, 1);
         if (struct.isSetName()) {
           oprot.writeString(struct.name);
         }
       }

       @Override
       public void read(org.apache.thrift.protocol.TProtocol prot, sayHello_args struct) throws org.apache.thrift.TException {
         org.apache.thrift.protocol.TTupleProtocol iprot = (org.apache.thrift.protocol.TTupleProtocol) prot;
         java.util.BitSet incoming = iprot.readBitSet(1);
         if (incoming.get(0)) {
           struct.name = iprot.readString();
           struct.setNameIsSet(true);
         }
       }
     }

     private static <S extends org.apache.thrift.scheme.IScheme> S scheme(org.apache.thrift.protocol.TProtocol proto) {
       return (org.apache.thrift.scheme.StandardScheme.class.equals(proto.getScheme()) ? STANDARD_SCHEME_FACTORY : TUPLE_SCHEME_FACTORY).getScheme();
     }
   }

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

     private static final org.apache.thrift.protocol.TField SUCCESS_FIELD_DESC = new org.apache.thrift.protocol.TField("success", org.apache.thrift.protocol.TType.STRING, (short)0);

     private static final org.apache.thrift.scheme.SchemeFactory STANDARD_SCHEME_FACTORY = new sayHello_resultStandardSchemeFactory();
     private static final org.apache.thrift.scheme.SchemeFactory TUPLE_SCHEME_FACTORY = new sayHello_resultTupleSchemeFactory();

     public java.lang.String success; // 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 {
       SUCCESS((short)0, "success");

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

       static {
         for (_Fields field : java.util.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 0: // SUCCESS
             return SUCCESS;
           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 java.lang.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(java.lang.String name) {
         return byName.get(name);
       }

       private final short _thriftId;
       private final java.lang.String _fieldName;

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

       public short getThriftFieldId() {
         return _thriftId;
       }

       public java.lang.String getFieldName() {
         return _fieldName;
       }
     }

     // isset id assignments
     public static final java.util.Map<_Fields, org.apache.thrift.meta_data.FieldMetaData> metaDataMap;
     static {
       java.util.Map<_Fields, org.apache.thrift.meta_data.FieldMetaData> tmpMap = new java.util.EnumMap<_Fields, org.apache.thrift.meta_data.FieldMetaData>(_Fields.class);
       tmpMap.put(_Fields.SUCCESS, new org.apache.thrift.meta_data.FieldMetaData("success", org.apache.thrift.TFieldRequirementType.DEFAULT,
           new org.apache.thrift.meta_data.FieldValueMetaData(org.apache.thrift.protocol.TType.STRING)));
       metaDataMap = java.util.Collections.unmodifiableMap(tmpMap);
       org.apache.thrift.meta_data.FieldMetaData.addStructMetaDataMap(sayHello_result.class, metaDataMap);
     }

     public sayHello_result() {
     }

     public sayHello_result(
       java.lang.String success)
     {
       this();
       this.success = success;
     }

     /**
      * Performs a deep copy on <i>other</i>.
      */
     public sayHello_result(sayHello_result other) {
       if (other.isSetSuccess()) {
         this.success = other.success;
       }
     }

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

     @Override
     public void clear() {
       this.success = null;
     }

     public java.lang.String getSuccess() {
       return this.success;
     }

     public sayHello_result setSuccess(java.lang.String success) {
       this.success = success;
       return this;
     }

     public void unsetSuccess() {
       this.success = null;
     }

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

     public void setSuccessIsSet(boolean value) {
       if (!value) {
         this.success = null;
       }
     }

     public void setFieldValue(_Fields field, java.lang.Object value) {
       switch (field) {
       case SUCCESS:
         if (value == null) {
           unsetSuccess();
         } else {
           setSuccess((java.lang.String)value);
         }
         break;

       }
     }

     public java.lang.Object getFieldValue(_Fields field) {
       switch (field) {
       case SUCCESS:
         return getSuccess();

       }
       throw new java.lang.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 java.lang.IllegalArgumentException();
       }

       switch (field) {
       case SUCCESS:
         return isSetSuccess();
       }
       throw new java.lang.IllegalStateException();
     }

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

     public boolean equals(sayHello_result that) {
       if (that == null)
         return false;
       if (this == that)
         return true;

       boolean this_present_success = true && this.isSetSuccess();
       boolean that_present_success = true && that.isSetSuccess();
       if (this_present_success || that_present_success) {
         if (!(this_present_success && that_present_success))
           return false;
         if (!this.success.equals(that.success))
           return false;
       }

       return true;
     }

     @Override
     public int hashCode() {
       int hashCode = 1;

       hashCode = hashCode * 8191 + ((isSetSuccess()) ? 131071 : 524287);
       if (isSetSuccess())
         hashCode = hashCode * 8191 + success.hashCode();

       return hashCode;
     }

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

       int lastComparison = 0;

       lastComparison = java.lang.Boolean.valueOf(isSetSuccess()).compareTo(other.isSetSuccess());
       if (lastComparison != 0) {
         return lastComparison;
       }
       if (isSetSuccess()) {
         lastComparison = org.apache.thrift.TBaseHelper.compareTo(this.success, other.success);
         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 {
       scheme(iprot).read(iprot, this);
     }

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

     @Override
     public java.lang.String toString() {
       java.lang.StringBuilder sb = new java.lang.StringBuilder("sayHello_result(");
       boolean first = true;

       sb.append("success:");
       if (this.success == null) {
         sb.append("null");
       } else {
         sb.append(this.success);
       }
       first = false;
       sb.append(")");
       return sb.toString();
     }

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

     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, java.lang.ClassNotFoundException {
       try {
         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 sayHello_resultStandardSchemeFactory implements org.apache.thrift.scheme.SchemeFactory {
       public sayHello_resultStandardScheme getScheme() {
         return new sayHello_resultStandardScheme();
       }
     }

     private static class sayHello_resultStandardScheme extends org.apache.thrift.scheme.StandardScheme<sayHello_result> {

       public void read(org.apache.thrift.protocol.TProtocol iprot, sayHello_result 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 0: // SUCCESS
               if (schemeField.type == org.apache.thrift.protocol.TType.STRING) {
                 struct.success = iprot.readString();
                 struct.setSuccessIsSet(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, sayHello_result struct) throws org.apache.thrift.TException {
         struct.validate();

         oprot.writeStructBegin(STRUCT_DESC);
         if (struct.success != null) {
           oprot.writeFieldBegin(SUCCESS_FIELD_DESC);
           oprot.writeString(struct.success);
           oprot.writeFieldEnd();
         }
         oprot.writeFieldStop();
         oprot.writeStructEnd();
       }

     }

     private static class sayHello_resultTupleSchemeFactory implements org.apache.thrift.scheme.SchemeFactory {
       public sayHello_resultTupleScheme getScheme() {
         return new sayHello_resultTupleScheme();
       }
     }

     private static class sayHello_resultTupleScheme extends org.apache.thrift.scheme.TupleScheme<sayHello_result> {

       @Override
       public void write(org.apache.thrift.protocol.TProtocol prot, sayHello_result struct) throws org.apache.thrift.TException {
         org.apache.thrift.protocol.TTupleProtocol oprot = (org.apache.thrift.protocol.TTupleProtocol) prot;
         java.util.BitSet optionals = new java.util.BitSet();
         if (struct.isSetSuccess()) {
           optionals.set(0);
         }
         oprot.writeBitSet(optionals, 1);
         if (struct.isSetSuccess()) {
           oprot.writeString(struct.success);
         }
       }

       @Override
       public void read(org.apache.thrift.protocol.TProtocol prot, sayHello_result struct) throws org.apache.thrift.TException {
         org.apache.thrift.protocol.TTupleProtocol iprot = (org.apache.thrift.protocol.TTupleProtocol) prot;
         java.util.BitSet incoming = iprot.readBitSet(1);
         if (incoming.get(0)) {
           struct.success = iprot.readString();
           struct.setSuccessIsSet(true);
         }
       }
     }

     private static <S extends org.apache.thrift.scheme.IScheme> S scheme(org.apache.thrift.protocol.TProtocol proto) {
       return (org.apache.thrift.scheme.StandardScheme.class.equals(proto.getScheme()) ? STANDARD_SCHEME_FACTORY : TUPLE_SCHEME_FACTORY).getScheme();
     }
   }

 }

HelloWorldService.java

这里面只要我们重写face  就可以了。

2.IDL（Interface Description Language）

　　Apache Thrift 需要一个定义数据类型和服务接口的简单定义文件作为模板提供给代码生成引擎用来生成生成客户端代码和服务端代码，并以此实现客户端与服务端之间的跨语言的无缝通讯。我们就不用编写大量重复的模块化代码来序列化和传输对象，实现远程接口调用了，我们可以直接专注于业务逻辑。

　　Thrift生成引擎需要定义文件，这个文件的语法，我们称之为 IDL（Interface Description Language）接口描述语言。我也不知道为啥叫这个 = 。=

　　官网文件：

 /*
  * Licensed to the Apache Software Foundation (ASF) under one
  * or more contributor license agreements. See the NOTICE file
  * distributed with this work for additional information
  * regarding copyright ownership. The ASF licenses this file
  * to you under the Apache License, Version 2.0 (the
  * "License"); you may not use this file except in compliance
  * with the License. You may obtain a copy of the License at
  *
  *   http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing,
  * software distributed under the License is distributed on an
  * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
  * KIND, either express or implied. See the License for the
  * specific language governing permissions and limitations
  * under the License.
  */

 # Thrift Tutorial
 # Mark Slee (mcslee@facebook.com)
 #
 # This file aims to teach you how to use Thrift, in a .thrift file. Neato. The
 # first thing to notice is that .thrift files support standard shell comments.
 # This lets you make your thrift file executable and include your Thrift build
 # step on the top line. And you can place comments like this anywhere you like.
 #
 # Before running this file, you will need to have installed the thrift compiler
 # into /usr/local/bin.

 /**
  * The first thing to know about are types. The available types in Thrift are:
  *
  *  bool        Boolean, one byte
  *  i8 (byte)   Signed 8-bit integer
  *  i16         Signed 16-bit integer
  *  i32         Signed 32-bit integer
  *  i64         Signed 64-bit integer
  *  double      64-bit floating point value
  *  string      String
  *  binary      Blob (byte array)
  *  map<t1,t2>  Map from one type to another
  *  list<t1>    Ordered list of one type
  *  set<t1>     Set of unique elements of one type
  *
  * Did you also notice that Thrift supports C style comments?
  */

 // Just in case you were wondering... yes. We support simple C comments too.

 /**
  * Thrift files can reference other Thrift files to include common struct
  * and service definitions. These are found using the current path, or by
  * searching relative to any paths specified with the -I compiler flag.
  *
  * Included objects are accessed using the name of the .thrift file as a
  * prefix. i.e. shared.SharedObject
  */
 include "shared.thrift"

 /**
  * Thrift files can namespace, package, or prefix their output in various
  * target languages.
  */

 namespace cl tutorial
 namespace cpp tutorial
 namespace d tutorial
 namespace dart tutorial
 namespace java tutorial
 namespace php tutorial
 namespace perl tutorial
 namespace haxe tutorial
 namespace netcore tutorial
 namespace netstd tutorial

 /**
  * Thrift lets you do typedefs to get pretty names for your types. Standard
  * C style here.
  */
 typedef i32 MyInteger

 /**
  * Thrift also lets you define constants for use across languages. Complex
  * types and structs are specified using JSON notation.
  */
 const i32 INT32CONSTANT = 9853
 const map<string,string> MAPCONSTANT = {'hello':'world', 'goodnight':'moon'}

 /**
  * You can define enums, which are just 32 bit integers. Values are optional
  * and start at 1 if not supplied, C style again.
  */
 enum Operation {
   ADD = 1,
   SUBTRACT = 2,
   MULTIPLY = 3,
   DIVIDE = 4
 }

 /**
  * Structs are the basic complex data structures. They are comprised of fields
  * which each have an integer identifier, a type, a symbolic name, and an
  * optional default value.
  *
  * Fields can be declared "optional", which ensures they will not be included
  * in the serialized output if they aren't set.  Note that this requires some
  * manual management in some languages.
  */
 struct Work {
   1: i32 num1 = 0,
   2: i32 num2,
   3: Operation op,
   4: optional string comment,
 }

 /**
  * Structs can also be exceptions, if they are nasty.
  */
 exception InvalidOperation {
   1: i32 whatOp,
   2: string why
 }

 /**
  * Ahh, now onto the cool part, defining a service. Services just need a name
  * and can optionally inherit from another service using the extends keyword.
  */
 service Calculator extends shared.SharedService {

   /**
    * A method definition looks like C code. It has a return type, arguments,
    * and optionally a list of exceptions that it may throw. Note that argument
    * lists and exception lists are specified using the exact same syntax as
    * field lists in struct or exception definitions.
    */

    void ping(),

    i32 add(1:i32 num1, 2:i32 num2),

    i32 calculate(1:i32 logid, 2:Work w) throws (1:InvalidOperation ouch),

    /**
     * This method has a oneway modifier. That means the client only makes
     * a request and does not listen for any response at all. Oneway methods
     * must be void.
     */
    oneway void zip()

 }

 /**
  * That just about covers the basics. Take a look in the test/ folder for more
  * detailed examples. After you run this file, your generated code shows up
  * in folders with names gen-<language>. The generated code isn't too scary
  * to look at. It even has pretty indentation.
  */

Thrift Tutorial

　　首先我们来注意一下数据类型：

  *  bool        Boolean, one byte
  *  i8 (byte)   Signed 8-bit integer
  *  i16         Signed 16-bit integer
  *  i32         Signed 32-bit integer
  *  i64         Signed 64-bit integer
  *  double      64-bit floating point value
  *  string      String
  *  binary      Blob (byte array)
  *  map<t1,t2>  Map from one type to another
  *  list<t1>    Ordered list of one type
  *  set<t1>     Set of unique elements of one type

　　

bool: 布尔值，true 或 false，对应 Java 的 Boolean

i8(byte): 8 位有符号整数，对应 Java 的 byte

i16：16 位有符号整数，对应 Java 的 short

i32：32 位有符号整数，对应 Java 的 int

i64：64 位有符号整数，对应 Java 的 long

double：64 位浮点数，对应 Java 的 double

string：utf-8编码的字符串，对应 Java 的 String

binary:字节数组，对应Java的Array[byte]

map、list、set不用多说。

这种定义方式和C语言很相似，同时thrift定义文件还支持C语言的注释方式

以上是基本的类型。

thrift的枚举类型类似于java

enum Operation {
  ADD = ,
  SUBTRACT = ,
  MULTIPLY = ,
  DIVIDE =
}

thrift自定义结构体和C语言一样是struct，也就是java中定义的DTO

struct Work {
  : i32 num1 = ,
  : i32 num2,
  : Operation op,
  : optional string comment,
}

thrift定义的方法可能会抛出异常，异常也是struct。这很合理 = ^_^=

exception InvalidOperation {
  : i32 whatOp,
  : string why
}

thrift 还支持 C语言的typedef 关键字进行类型定义，这个是用来自定义类型，你可以这样

typedef i32 MyInteger

这样你就可以用MyInteger 来代替 int类型了，好像是个没用的例子=。=

简单说了一下基本类型，接下来是限定修饰符：

常量修饰符：const

需要注意的是当声明的常量是复杂类型时，需要使用json格式

const i32 INT32CONSTANT =
const map<string,string> MAPCONSTANT = {'hello':'world', 'goodnight':'moon'}

啊哈，接下来到了最酷的环节，定义服务。定义服务需要一个名字，也可以选择继承某个服务。继承服务的话，需要 include "shared.thrift"。类似于导包

service Calculator extends shared.SharedService {

  /**
   * A method definition looks like C code. It has a return type, arguments,
   * and optionally a list of exceptions that it may throw. Note that argument
   * lists and exception lists are specified using the exact same syntax as
   * field lists in struct or exception definitions.
   */

   void ping(),

   i32 add(:i32 num1, :i32 num2),

   i32 calculate(:i32 logid, :Work w) throws (:InvalidOperation ouch),

   /**
    * This method has a oneway modifier. That means the client only makes
    * a request and does not listen for any response at all. Oneway methods
    * must be void.
    */
   oneway void zip()

}

以上就是所谓的 Interface Description Language 接口定义语言，这个名词到底哪来的 =_= !