基本概念
RPC（Remote Procedure Call）远程过程调用，简单的理解是一个节点请求另一个节点提供的服务
本地过程调用：如果需要将本地student对象的age+1，可以实现一个addAge()方法，将student对象传入，对年龄进行更新之后返回即可，本地方法调用的函数体通过函数指针来指定。
远程过程调用：上述操作的过程中，如果addAge()这个方法在服务端，执行函数的函数体在远程机器上，如何告诉机器需要调用这个方法呢？
总结一下上述过程：
// Client端
// Student student = Call(ServerAddr, addAge, student)
1. 将这个调用映射为Call ID。
2. 将Call ID，student（params）序列化，以二进制形式打包
3. 把2中得到的数据包发送给ServerAddr，这需要使用网络传输层
4. 等待服务器返回结果
5. 如果服务器调用成功，那么就将结果反序列化，并赋给student，年龄更新
// Server端
1. 在本地维护一个Call ID到函数指针的映射call_id_map，可以用Map<String, Method> callIdMap
2. 等待服务端请求
3. 得到一个请求后，将其数据包反序列化，得到Call ID
4. 通过在callIdMap中查找，得到相应的函数指针
5. 将student（params）反序列化后，在本地调用addAge()函数，得到结果
6. 将student结果序列化后通过网络返回给Client
服务者
消费者
API
让服务者和消费者都依赖API
使用代理对象
具体代码在ProxyUtils中
public class ConsumerApp {
public static void main(String[] args) {
//while死循环是为了测试调用提供者是否为随机
while (true) {
try {
Thread.sleep(2000);
// 获得代理对象
AddService addService = ProxyUtils.getProxy(AddService.class);
// 只要调用方法就会进入代理对象invoke方法
int result = addService.add(15, 684);
System.out.println(result);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
}
API中创建Request，AddService，ProxyUtils，ZkUtils
创建Request(该类为传输对象，必须实现序列化)
public class Request implements Serializable{
/**
*
*/
private static final long serialVersionUID = 1L;
private String interfaceName;
private String methodName;
private Object[] args;
public String getInterfaceName() {
return interfaceName;
}
public void setInterfaceName(String interfaceName) {
this.interfaceName = interfaceName;
}
public String getMethodName() {
return methodName;
}
public void setMethodName(String methodName) {
this.methodName = methodName;
}
public Object[] getArgs() {
return args;
}
public void setArgs(Object[] args) {
this.args = args;
}
@Override
public String toString() {
return "Request [interfaceName=" + interfaceName + ", methodName=" + methodName + ", args="
+ Arrays.toString(args) + "]";
}
}
创建AddService
package com.chenlei.service;
public interface AddService {
public int add(Integer a, Integer b);
}
创建ProxyUtils(重点)
public class ProxyUtils {
private static Random RDM = new Random();
@SuppressWarnings("unchecked")
public static <T> T getProxy(Class<T> interfaces) {
T proxy = (T) Proxy.newProxyInstance(ProxyUtils.class.getClassLoader(), new Class<?>[] { interfaces },
new InvocationHandler() {
@Override
public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
String methodName = method.getName();
if ("toString".equals(methodName)) {
return interfaces.getClass().getName() + "$Proxy";
}
if ("hashCode".equals(methodName)) {
return Object.class.hashCode();
}
if ("equals".equals(methodName)) {
return Object.class.equals(this);
}
// 消费者发送过去
Request request = new Request();
request.setInterfaceName(interfaces.getName());
request.setMethodName(methodName);
request.setArgs(args);
// 找到interfaces下的所有节点
List<String> serverList = ZkUtils.discover(interfaces.getName());
String one = randomOne(serverList);// 拿到的结果为ip:port 如127.0.0.1:8888
String[] split = one.split(":");
String address = split[0];
Integer port = Integer.valueOf(split[1]);
Socket socket = null;
// 打开书出管道，发送请求
Object result = null;
OutputStream outputStream = null;
ObjectOutputStream objectOutputStream = null;
InputStream inputStream = null;
ObjectInputStream objectInputStream = null;
try {
socket = new Socket(address, port);
outputStream = socket.getOutputStream();
objectOutputStream = new ObjectOutputStream(outputStream);
objectOutputStream.writeObject(request);
inputStream = socket.getInputStream();
objectInputStream = new ObjectInputStream(inputStream);
result = objectInputStream.readObject();
System.out.println("本次调用的是======" + port);
} catch (Exception e) {
e.printStackTrace();
} finally {
closeResources(objectInputStream, inputStream, objectOutputStream, outputStream, socket);
}
return result;
}
});
return proxy;
}
/**
* 从节点中随机找出一个
*
* @param serverList
* @return
*/
private static String randomOne(List<String> serverList) {
if (null == serverList || 0 == serverList.size()) {
return null;
}
int index = RDM.nextInt(serverList.size());
return serverList.get(index);
}
/**
* 关闭资源的方法
*/
public static void closeResources(Closeable... resources) {
for (Closeable resource : resources) {
if (null != resource) {
try {
resource.close();
} catch (IOException e) {
e.printStackTrace();
} finally {
resource = null;
}
}
}
}
}
在API项目中导入zkclient的依赖
public class ZkUtils {
private static final String ZK_URL = "自己的域名:2181";
private static ZkClient zkClient = null;
//创建zookeeper缓存
private static Map<String, List<String>> cache = new HashMap<String, List<String>>();
static {
zkClient = new ZkClient(ZK_URL, 10000, 10000);
}
/**
* 服务节点向zookeeper的注册
*
* @param serverName
* @param serverPort
*/
public static void register(String serverName, String serverPort) {
if (null == serverName || "".equals(serverName)) {
throw new RuntimeException("服务名不能为空");
}
if (null == serverPort || "".equals(serverPort)) {
throw new RuntimeException("服务ip和端口不能为空");
}
if (!zkClient.exists("/" + serverName)) {
zkClient.createPersistent("/" + serverName);
}
if (!zkClient.exists("/" + serverName + "/" + serverPort)) {
zkClient.createEphemeral("/" + serverName + "/" + serverPort);
}
System.out.println("注册一个服务节点为" + "/" + serverName + "/" + serverPort);
}
/**
* 向zookeeper发现服务节点
*
* @param serverName
* @return
*/
public static List<String> discover(String serverName) {
if (null == serverName || "".equals(serverName)) {
throw new RuntimeException("服务名不能为空");
}
// 先从缓存里找
if (cache.containsKey(serverName)) {
System.out.println("在缓存中找到" + serverName + "节点");
}
// 如果该节点在zookeeper中不存在，直接返回空
if (!zkClient.exists("/" + serverName)) {
return null;
}
zkClient.subscribeChildChanges("/" + serverName, new IZkChildListener() {
@Override
public void handleChildChange(String parentPath, List<String> currentChilds) throws Exception {
// 一旦进入此方法，证明有节点改变
cache.put(serverName, currentChilds);
System.out.println(serverName + "节点有变化-----" + "缓存完成更新");
}
});
return zkClient.getChildren("/" + serverName);
}
}
创建AddServiceImpl
注意类名最好是AddService+Impl，并且类全路径也要对应com.chenlei.service.impl.AddServiceImpl,否则代码需要调整
package com.chenlei.service.impl;
import com.chenlei.service.AddService;
public class AddServiceImpl implements AddService {
@Override
public int add(Integer a, Integer b) {
return a + b;
}
}
创建ProviderApp(重点)
public class ProviderApp {
public static void main(String[] args) {
Integer port = 7777;
ServerSocket serverSocket = bind(port);
// 向zookeeper注册
ZkUtils.register(AddService.class.getName(), "127.0.0.1" + ":" + port);
// 监听+处理请求
listener(serverSocket);
}
/**
* 监听和处理请求
*
* @param serverSocket
*/
private static void listener(ServerSocket serverSocket) {
//此处死循环是为了让次提供者一直处于工作状态
while (true) {
Socket socket = null;
InputStream inputStream = null;
ObjectInputStream objectInputStream = null;
OutputStream outputStream = null;
ObjectOutputStream objectOutputStream = null;
try {
socket = serverSocket.accept();
inputStream = socket.getInputStream();
objectInputStream = new ObjectInputStream(inputStream);
Request request = (Request) objectInputStream.readObject();
Object answer = invoker(request);
outputStream = socket.getOutputStream();
objectOutputStream = new ObjectOutputStream(outputStream);
objectOutputStream.writeObject(answer);
} catch (Exception e) {
e.printStackTrace();
} finally {
ProxyUtils.closeResources(objectOutputStream, outputStream, objectInputStream, inputStream, socket);
}
}
}
/**
* 处理请求返回结果
*
* @param request
* @return
*/
private static Object invoker(Request request) {
// 获得从消费者传过来的信息
String interfaceName = request.getInterfaceName();
String methodName = request.getMethodName();
Object[] args = request.getArgs();
// 获得对应实现类全名
String className = getClassNameByInterfaceName(interfaceName);
Object answer = null;
try {
// 找到该类
Class<?> clazz = Class.forName(className);
// 创建一个对象
Object object = clazz.newInstance();
Class<?>[] argsType = new Class<?>[args.length];
if (null != args || 0 != args.length) {
for (int i = 0; i < args.length; i++) {
argsType[i] = args[i].getClass();
}
}
Method method = clazz.getMethod(methodName, argsType);
answer = method.invoke(object, args);
} catch (Exception e) {
e.printStackTrace();
}
return answer;
}
/**
* 通过请求者传来的类信息，获得对应实现类的所有信息,并返回实现类的全名
*
* @param interfaceName
* @return
*/
private static String getClassNameByInterfaceName(String interfaceName) {
// 传过来的接口名为com.chenlei.service.AddService
int index = interfaceName.lastIndexOf(".");
StringBuilder sb = new StringBuilder();
// com.chenlei.service
sb.append(interfaceName.subSequence(0, index));
// com.chenlei.service.impl.
sb.append(".impl.");
// com.chenlei.service.impl.AddService
sb.append(interfaceName.substring(index + 1)).append("Impl");
return sb.toString();
}
/**
* 绑定一个端口
*
* @param port
* @return
*/
private static ServerSocket bind(Integer port) {
ServerSocket serverSocket = null;
try {
serverSocket = new ServerSocket(port);
} catch (IOException e) {
e.printStackTrace();
}
return serverSocket;
}
/**
* 测试代码
*/
//public static void main(String[] args) {
// String interfaceName = "com.chenlei.service.AddService";
// int index = interfaceName.lastIndexOf(".");
// StringBuilder sb = new StringBuilder();
// // com.chenlei.service
// sb.append(interfaceName.subSequence(0, index));
// // com.chenlei.service.impl.
// sb.append(".impl.");
// // com.chenlei.service.impl.AddService
// sb.append(interfaceName.substring(index + 1)).append("Impl");
// System.out.println(sb.toString());
//}
}
写代码思路
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