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因?yàn)樽罱悬c(diǎn)時(shí)間，所以就想讀一些技術(shù)的源碼，最近選擇hessian。廢話不多說(shuō)，進(jìn)入正題：
hessian客戶(hù)端時(shí)序圖：
hessian服務(wù)端時(shí)序圖：
因?yàn)閔essian源碼相對(duì)于spring算很簡(jiǎn)單了。所以不浪費(fèi)大家寶貴的時(shí)間來(lái)分析源碼。想說(shuō)說(shuō)怎么實(shí)現(xiàn)遠(yuǎn)程調(diào)用(rpc)。
遠(yuǎn)程調(diào)用，顧名思義就是通過(guò)遠(yuǎn)程調(diào)用別的機(jī)器(JVM or ...)中的方法。要想實(shí)現(xiàn)遠(yuǎn)程調(diào)用，思路是怎樣呢?
常用的模式代理，工廠。為啥怎么說(shuō)呢?
遠(yuǎn)程調(diào)用通過(guò)網(wǎng)絡(luò)，肯定需要工廠產(chǎn)出不同的類(lèi)，不然一個(gè)類(lèi)寫(xiě)，會(huì)死人的。
2、
代理模式，因?yàn)檎{(diào)用前你是不知道實(shí)際的調(diào)用，肯定是通過(guò)代理調(diào)用到遠(yuǎn)程方法。
下面給大家說(shuō)說(shuō)遠(yuǎn)程調(diào)用的原理(PS:不懂代理的同學(xué)，先上百度搜索：java代理)。
實(shí)現(xiàn)自定義的遠(yuǎn)程調(diào)用，就是序列化成字節(jié)流后，發(fā)送到服務(wù)端，服務(wù)端根據(jù)調(diào)用的api、方法、參數(shù)去具體調(diào)用一個(gè)方法，調(diào)用方法后把結(jié)果輸入到輸出流里面，最后結(jié)果展示在代理的return中。
ok，開(kāi)始貼代碼：
客戶(hù)端(HttpRpcClient)：
1
String url =?"http://localhost:8080/hessian-study-server/helloworld1";
2
??
3、??????HttpProxyFactory factory =?new?HttpProxyFactory();
3
????????Class clazz = Class.forName("com.jzx.hessian.server.SayHelloService");
4
????????SayHelloService sayHelloService = (SayHelloService) factory.create(clazz, url);
5
????????System.out.println(sayHelloService.sayHello("小明
4、",?"男"));
6
????????UserVo vo = sayHelloService.sayHello1("小明",?"男");
7
????????System.out.println("姓名："?+ vo.getName() +?" 性別："?+ vo.getSex());
從代碼中分析，首先創(chuàng)建了一個(gè)工廠類(lèi)HttpProxyFactory，其次創(chuàng)建了一個(gè)類(lèi)的描述。
HttpProxyFactory代碼(主要目的是得到一個(gè)代理)：
1
if?(api ==?null) {
2
????????????throw?new?NullPointe
5、rException("api must not be null for HttpProxyFactory.create()");
3
????????}
4
????????InvocationHandler handler =?null;
5
?
6
????????handler =?new?HttpProxy(url,?this, api);
7
?
8
????????return?Proxy.newProxyInstance(Thread.currentThread().getContextClassLoader(),?new?Cla
6、ss[] { api }, handler);
HttpProxy代理干了啥 (得到調(diào)用接口類(lèi)、方法名、參數(shù)值)：
1
HttpTransportation transportation =?new?HttpTransportation();
2
????????transportation.setClazz(api);
3
????????transportation.setMethod(method.getName());
4
????????transportation.setParams(args);
5
????????byte[] byte
7、s = ObjectUtils.objectToByte(transportation);
6
????????Object result = sendPost(url, bytes);
7
????????return?result;
序列化對(duì)象發(fā)送POST請(qǐng)求：
01
PrintWriter out =?null;
02
????????BufferedReader in =?null;
03
????????Object result =?null;
04
????????try?{
05
????????????URL real
8、Url =?new?URL(url);
06
????????????// 打開(kāi)和URL之間的連接
07
????????????URLConnection conn = realUrl.openConnection();
08
????????????// 設(shè)置通用的請(qǐng)求屬性
09
????????????conn.setRequestProperty("accept",?"*/*");
10
????????????conn.setRequestProperty("connection",?"Keep-Alive");
11
????????
9、????conn.setRequestProperty("user-agent",?"Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1;SV1)");
12
????????????// 發(fā)送POST請(qǐng)求必須設(shè)置如下兩行
13
????????????conn.setDoOutput(true);
14
????????????conn.setDoInput(true);
15
????????????// 獲取URLConnection對(duì)象對(duì)應(yīng)的輸出流
16
????????????OutputStre
10、am outputStream = conn.getOutputStream();
17
????????????outputStream.write(param);
18
????????????outputStream.close();
19
????????????// 定義BufferedReader輸入流來(lái)讀取URL的響應(yīng)
20
????????????// in = new BufferedReader(new InputStreamReader(conn.getInputStream()));
21
????????????byte[] b
11、ytes = toByteArray(conn.getInputStream());
22
????????????Object object = ObjectUtils.byteToObject(bytes);
23
????????????if?(object?instanceof?String) {
24
????????????????byte[] dest =?new?byte[bytes.length -?7];
25
????????????????System.arraycopy(bytes,?7, dest,?0, dest.length);
12、
26
????????????????result =?new?String(dest,?"UTF-8");
27
//????????????? result = new String(bytes, "UTF-8");
28
????????????}
29
????????????if?(object?instanceof?UserVo) {
30
????????????????result = object;
31
????????????}
32
????????}?catch?(Exception e) {
33
??
13、??????????System.out.println("發(fā)送 POST 請(qǐng)求出現(xiàn)異常！"?+ e);
34
????????????e.printStackTrace();
35
????????}
36
????????// 使用finally塊來(lái)關(guān)閉輸出流、輸入流
37
????????finally?{
38
????????????try?{
39
????????????????if?(out !=?null) {
40
????????????????????out.close();
41
????????????
14、????}
42
????????????????if?(in !=?null) {
43
????????????????????in.close();
44
????????????????}
45
????????????}?catch?(IOException ex) {
46
????????????????ex.printStackTrace();
47
????????????}
48
????????}
49
????????return?result;
以上是客戶(hù)端的分割線-----------------
15、-------服務(wù)端：
配置一個(gè)sevlet，初始化配置文件：
01
@Override
02
????public?void?init(ServletConfig config)?throws?ServletException {
03
????????super.init(config);
04
????????if?(getInitParameter("home-api") !=?null) {
05
????????????String className = getInitParameter("home-api");
06
?????
16、???????try?{
07
????????????????_homeAPI = Class.forName(className);
08
????????????}?catch?(Exception e) {
09
?
10
????????????}
11
????????}
12
????????if?(getInitParameter("service-class") !=?null) {
13
????????????String className = getInitParameter("service-class");
17、
14
????????????Class clazz;
15
????????????try?{
16
????????????????clazz = Class.forName(className);
17
????????????????_homeImpl = clazz.newInstance();
18
????????????}?catch?(Exception e) {
19
?
20
????????????}
21
????????}
22
????????httpRpcSkeleton =?new?
18、HttpRpcSkeleton(_homeAPI, _homeImpl);
23
????}
01
@Override
02
????public?void?service(ServletRequest request, ServletResponse response)?throws?ServletException, IOException {
03
????????HttpServletRequest req = (HttpServletRequest) request;
04
????????HttpServletResponse res = (
19、HttpServletResponse) response;
05
?
06
????????if?(!req.getMethod().equals("POST")) {
07
????????????res.setStatus(500);?// , "Hessian Requires POST");
08
????????????PrintWriter out = res.getWriter();
09
?
10
????????????res.setContentType("text/html");
11
????????????ou
20、t.println("
httrpc Requires POST
");
12
????????????return;
13
????????}
14
????????OutputStream out = res.getOutputStream();
15
????????try?{
16
????????????httpRpcSkeleton.invoke(req, out);
17
????????}?catch?(Exception e) {
18
????????????e.printStackTrace();
21、
19
????????}?finally?{
20
????????????out.flush();
21
????????????out.close();
22
????????}
23
????}
看到請(qǐng)求最終被HttpRpcSkeleton的invoke調(diào)用，相關(guān)代碼：
01
public?void?invoke(HttpServletRequest request, OutputStream out)?throws?Exception {
02
????????int?len = request.getContentLength()
22、;
03
????????ServletInputStream input = request.getInputStream();
04
????????byte[] buffer =?new?byte[len];
05
????????input.read(buffer,?0, len);
06
????????HttpTransportation transportation = (HttpTransportation) ObjectUtils.byteToObject(buffer);
07
????????Method method = meth
23、odMap.get(transportation.getMethod());
08
????????Object result = method.invoke(_homeImpl, transportation.getParams());
09
????????out.write(ObjectUtils.objectToByte(result));
10
????????// out.write(result.getBytes());
11
????}
以上就是實(shí)現(xiàn)遠(yuǎn)程，調(diào)用的原理。
另外對(duì)項(xiàng)目的說(shuō)明,有興趣的童鞋，可以試下不用java本身的序列化，試試protobuf。
另外有一個(gè)疑問(wèn)困擾了一個(gè)晚上，當(dāng)返回為字符串的時(shí)候，ObjectInputStream會(huì)多7個(gè)字節(jié)，不解，本人的java io很low，求解。
源碼為maven結(jié)構(gòu)：
運(yùn)行時(shí)截圖：
18 / 18
hessian源碼相對(duì)于spring操作事例演示
