在 yar 中規(guī)定的傳輸協(xié)議如下圖所示，請求體為82個(gè)字節(jié)的yar_header_t和8字節(jié)的打包名稱和請求實(shí)體yar_request_t，在yar_header_t里面用body_len記錄8字節(jié)的打包名稱+請求實(shí)體的長度；返回體類似，只是實(shí)體內(nèi)容的結(jié)構(gòu)體稍微不同，在reval里面才是實(shí)際最后客戶端需要的結(jié)果。

整個(gè)傳輸以二進(jìn)制流的形式傳送。

在認(rèn)識 Yar 協(xié)議之后，就是在 Java 中實(shí)現(xiàn)類似的數(shù)據(jù)結(jié)構(gòu)和數(shù)據(jù)的二進(jìn)制裝包和解包，以及數(shù)據(jù)的傳輸了。為了記錄自己一步步封裝的過程，先使用比較過程的方式來實(shí)現(xiàn)這一個(gè)功能。

主要涉及到了三個(gè)類：YarClient類，傳輸和接受數(shù)據(jù)的實(shí)現(xiàn)；

YarProtocol類，按照上圖的傳輸協(xié)議來把yar_header_t和packager_name還有yar_request_t(yar_response_t)寫入二進(jìn)制流，也就是拼裝和解析傳輸數(shù)據(jù)；

JsonPackager類，實(shí)現(xiàn)對yar_request_t和yar_response_t的裝包和拆包。

下面的代碼只能提供整體的大概思路，如果要運(yùn)行需要下載完整版的代碼，在 Jdk 1.8 的環(huán)境下編譯運(yùn)行。package?yar;

import?yar.packager.YarPackager;

import?yar.protocol.YarRequest;

import?yar.protocol.YarResponse;

import?java.io.*;

import?java.lang.reflect.Proxy;

import?java.net.URL;

import?java.net.URLConnection;

import?java.util.HashMap;

/**

*?Created?by?zhoumengkang?on?2/12/15.

*/

public?class?YarClient?{

private?String?uri;

private?String?packager;

public?YarClient(String?uri){

this.uri?=?uri;

this.packager?=?YarConfig.getString("yar.packager");

}

public?final?Object?useService(Class?type)?{

YarClientInvocationHandler?handler?=?new?YarClientInvocationHandler(this);

if?(type.isInterface())?{

return?Proxy.newProxyInstance(type.getClassLoader(),?new?Class[]{type},?handler);

}?else?{

return?Proxy.newProxyInstance(type.getClassLoader(),?type.getInterfaces(),?handler);

}

}

public?Object?invoke(String?method,Object[]?args){

YarRequest?yarRequest?=?new?YarRequest();

yarRequest.setId(123456789);

yarRequest.setMethod(method);

yarRequest.setParameters(args);

yarRequest.setPackagerName(this.packager);

byte[]?res?=?null;

try?{

res?=?sendPost(this.uri,?YarProtocol.requestCreate(yarRequest));

}?catch?(IOException?e)?{

e.printStackTrace();

}

YarResponse?yarResponse?=?YarProtocol.responseFetch(res);

assert?yarResponse?!=?null;

return?yarResponse.getRetVal();

}

public?static?byte[]?sendPost(String?url,?byte[]?content)?{

OutputStream?out?=?null;

InputStream?in?=?null;

byte[]?b?=?null;

try?{

URL?realUrl?=?new?URL(url);

URLConnection?conn?=?realUrl.openConnection();

conn.setRequestProperty("accept",?"*/*");

conn.setRequestProperty("connection",?"Keep-Alive");

conn.setDoOutput(true);

conn.setDoInput(true);

out?=?conn.getOutputStream();

out.write(content);

out.flush();

out.close();

in?=?conn.getInputStream();

b?=?new?byte[in.available()];

in.read(b);

in.close();

}?catch?(Exception?e)?{

e.printStackTrace();

}?finally?{

try?{

if?(out?!=?null)?{

out.close();

}

if?(in?!=?null)?{

in.close();

}

}?catch?(IOException?ex)?{

ex.printStackTrace();

}

}

return?b;

}

}package?yar;

import?yar.packager.YarPackager;

import?yar.protocol.*;

import?java.io.*;

import?java.util.Arrays;

/**

*?Created?by?zhoumengkang?on?5/12/15.

*/

public?class?YarProtocol?{

public?static?final?int?YAR_PROTOCOL_MAGIC_NUM?=?0x80DFEC60;

public?static?final?int?YAR_HEADER_LENGTH?=?82;

public?static?final?int?YAR_PACKAGER_NAME_LENGTH?=?8;

public?static?YarHeader?render(YarRequest?yarRequest,int?length){

YarHeader?yarHeader?=?new?YarHeader();

yarHeader.setId((int)?yarRequest.getId());

yarHeader.setMagicNum(YAR_PROTOCOL_MAGIC_NUM);

yarHeader.setBodyLen(length);

yarHeader.setProvider(YarConfig.getString("yar.provider"));

yarHeader.setToken(YarConfig.getString("yar.token"));

return?yarHeader;

}

public?static?YarHeader?parse(byte[]?content){

YarHeader?yarHeader?=?new?YarHeader();

DataInputStream?in?=?new?DataInputStream(new?ByteArrayInputStream(content));

try?{

yarHeader.setId(in.readInt());

yarHeader.setVersion(in.readShort());

if?(in.readInt()?!=?YAR_PROTOCOL_MAGIC_NUM)?{

return?null;

}

yarHeader.setReserved(in.readInt());

byte[]?provider?=?new?byte[32];

in.read(provider,0,32);

yarHeader.setProvider(new?String(provider));

byte[]?token?=?new?byte[32];

in.read(token,0,32);

yarHeader.setToken(new?String(token));

yarHeader.setBodyLen(in.readInt());

}?catch?(IOException?e)?{

e.printStackTrace();

}?finally?{

try?{

in.close();

}?catch?(IOException?e)?{

e.printStackTrace();

}

}

return?yarHeader;

}

public?static?YarResponse?responseFetch(byte[]?responseByte){

YarResponse?yarResponse?=?new?YarResponse();

byte[]?header?=?new?byte[YAR_HEADER_LENGTH];

for?(int?i?=?0;?i?

header[i]?=?responseByte[i];

}

YarHeader?yarHeader?=?YarProtocol.parse(header);

byte[]?packager?=?new?byte[YAR_PACKAGER_NAME_LENGTH];

int?packagerLength?=?0;

for?(int?i?=?0;?i?

packager[i]?=?responseByte[YAR_HEADER_LENGTH?+?i];

//?在這個(gè)8字節(jié)中，當(dāng)是?php?或者是?json?的時(shí)候，后面的三個(gè)或者四個(gè)字節(jié)可能之前已經(jīng)被占用，需要截取下

if?(packager[i]?==?0){

packagerLength?=?i;

break;

}

}

String?packagerName?=?new?String(packager);

YarClient.debug(packagerName);

yarResponse.setPackagerName(packagerName.substring(0,?packagerLength));

int?off?=?YAR_HEADER_LENGTH?+?YAR_PACKAGER_NAME_LENGTH;

int?len?=?responseByte.length;

byte[]?yarResponseBody?=?new?byte[len];

for?(int?i?=?off;?i?

yarResponseBody[i?-?off]?=?responseByte[i];

}

try?{

return?YarPackager.get(yarResponse.getPackagerName()).unpack(yarResponseBody);

}?catch?(Exception?e)?{

e.printStackTrace();

}

return?null;

}

public?static?byte[]?requestCreate(YarRequest?yarRequest)?throws?IOException?{

byte[]?body;

ByteArrayOutputStream?bodyOut?=?new?ByteArrayOutputStream();

try?{

bodyOut.write(Arrays.copyOf(yarRequest.getPackagerName().toUpperCase().getBytes(),?8));

bodyOut.write(YarPackager.get(yarRequest.getPackagerName()).pack(yarRequest));

body?=?bodyOut.toByteArray();

}?catch?(Exception?e)?{

e.printStackTrace();

return?null;

}?finally?{

bodyOut.close();

}

YarHeader?yarHeader?=?render(yarRequest,body.length);

ByteArrayOutputStream?byteArrayOutputStream?=?new?ByteArrayOutputStream();

DataOutputStream?out?=?new?DataOutputStream(byteArrayOutputStream);

try?{

out.writeInt(yarHeader.getId());

out.writeShort(yarHeader.getVersion());

out.writeInt(yarHeader.getMagicNum());

out.writeInt(yarHeader.getReserved());

out.write(Arrays.copyOf(yarHeader.getProvider().getBytes(),32));

out.write(Arrays.copyOf(yarHeader.getToken().getBytes(),32));

out.writeInt(yarHeader.getBodyLen());

out.write(body);

return?byteArrayOutputStream.toByteArray();

}?finally?{

byteArrayOutputStream.close();

out.close();

}

}

}package?yar.packager;

import?org.json.JSONObject;

import?yar.YarClient;

import?yar.protocol.YarRequest;

import?yar.protocol.YarResponse;

import?java.util.Map;

/**

*?Created?by?zhoumengkang?on?4/12/15.

*/

public?class?JsonPackager?extends?YarPackager?{

@Override

public?byte[]?pack(YarRequest?yarRequest)?{

Map?request?=?requestFormat(yarRequest);

JSONObject?jsonObject?=?new?JSONObject(request);

String?string?=?jsonObject.toString();

return?string.getBytes();

}

@Override

public?YarResponse?unpack(byte[]?content)?{

JSONObject?jsonObject?=?new?JSONObject(new?String(content));

YarClient.debug(jsonObject);

YarResponse?yarResponse?=?new?YarResponse();

yarResponse.setId(jsonObject.getLong("i"));

yarResponse.setStatus(jsonObject.getInt("s"));

yarResponse.setOut(jsonObject.getString("o"));

yarResponse.setRetVal(jsonObject.get("r"));

return?yarResponse;

}

}

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