Apache Mina -2

我们可以了解到 mina是个异步通信框架，一般使用场景是服务端开发，长连接、异步通信使用mina是及其方便的。不多说，看例子。

本次mina 使用的例子是使用maven构建的，过程中需要用到的jar包如下：

<dependency>
<groupId>org.apache.mina</groupId>
<artifactId>mina-integration-beans</artifactId>
<version>2.0.16</version>
</dependency>
<dependency>
<groupId>org.apache.mina</groupId>
<artifactId>mina-core</artifactId>
<version>2.0.16</version>
</dependency>

导入jar包，pom文件会报错，具体错误如下：

Missing artifact org.apache.mina:mina-core:bundle:2.0.16 pom.xml
1
原因是因为缺少maven-bundle-plugin导入即可

<build>
<plugins>
<plugin>
<groupId>org.apache.felix</groupId>
<artifactId>maven-bundle-plugin</artifactId>
<extensions>true</extensions>
</plugin>
</plugins>
</build>

本次mina机制的消息通讯接口规范主要为：
包头2个字节，包长2个字节，协议类型2个字节，数据包标识码8个字节，报文正文内容，校验码4个字节,包尾2个字节
mina 与spring 结合后，使用更加方便。
spring配置文件如下：

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:p="http://www.springframework.org/schema/p"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd"
default-lazy-init="false">

<bean id="executorFilter" class="org.apache.mina.filter.executor.ExecutorFilter" />
<bean id="mdcInjectionFilter" class="org.apache.mina.filter.logging.MdcInjectionFilter">
<constructor-arg value="remoteAddress" />
</bean>

<bean id="loggingFilter" class="org.apache.mina.filter.logging.LoggingFilter" />

<bean id="codecFilter" class="org.apache.mina.filter.codec.ProtocolCodecFilter">
<constructor-arg>

<bean class="com.onion.mina.server.NSMinaCodeFactory"></bean>
</constructor-arg>
</bean>

<bean id="keepAliveFilter" class="org.apache.mina.filter.keepalive.KeepAliveFilter">

<constructor-arg>
<bean class="com.onion.mina.server.NSMinaKeepAliveMessageFactory"></bean>
</constructor-arg>

<constructor-arg type="org.apache.mina.core.session.IdleStatus"
value="BOTH_IDLE">
</constructor-arg>

<property name="requestInterval" value="1500" />

<property name="requestTimeout" value="30" />

<property name="forwardEvent" value="true" />
</bean>

<bean id="serverHandler" class="com.onion.mina.server.NSMinaHandler" />
</beans>

mina 核心包括 IOhandler处理器，编码工厂（包含编码器，解码器）等核心。

服务端代码如下：

编码工厂（NSMinaCodeFactory）如下所示：

public class NSMinaCodeFactory implements ProtocolCodecFactory {
private final NSProtocalEncoder encoder;
private final NSProtocalDecoder decoder;

public NSMinaCodeFactory() {
this(Charset.forName("utf-8"));
}

public NSMinaCodeFactory(Charset charset) {
encoder = new NSProtocalEncoder();
decoder = new NSProtocalDecoder();
}

public ProtocolDecoder getDecoder(IoSession arg0) throws Exception {
// TODO Auto-generated method stub
return decoder;
}

public ProtocolEncoder getEncoder(IoSession arg0) throws Exception {
// TODO Auto-generated method stub
return encoder;
}
}

编码器——负责将需要发送给客户端的数据进行编码，然后发送给客户端

public class NSProtocalEncoder extends ProtocolEncoderAdapter {
private static final Logger logger = Logger.getLogger(NSProtocalEncoder.class);

@SuppressWarnings("unused")
private final Charset charset = Charset.forName("GBK");

/**
* 在此处实现包的编码工作，并把它写入输出流中
*/
public void encode(IoSession session, Object message,
ProtocolEncoderOutput out) throws Exception {
// TODO Auto-generated method stub
if(message instanceof BaseMessageForClient){
BaseMessageForClient clientmessage = (BaseMessageForClient)message;
byte[] packhead_arr = clientmessage.getPackHead().getBytes(charset);//包头2个字节
byte[] length_arr = ByteTools.intToByteArray(clientmessage.getLength()+19, 2);//包长
byte[] funcid_arr = ByteTools.intToByteArray(clientmessage.getFuncid(), 1);//协议类型
byte[] packetIdCode_arr = ByteTools.longToByteArray(clientmessage.getPacketIdCode(), 8);//数据包标识码
byte[] content_arr = clientmessage.getContent().getBytes(charset);//内容
byte[] checkcode_arr = ByteTools.longToByteArray(clientmessage.getCheckCode(), 4);//校验码
byte[] packtail_arr = clientmessage.getPackTail().getBytes();//包尾
IoBuffer buffer = IoBuffer.allocate(packhead_arr.length + length_arr.length + funcid_arr.length + packetIdCode_arr.length+ content_arr.length + checkcode_arr.length + packtail_arr.length);
buffer.setAutoExpand(true);
buffer.put(packhead_arr);
buffer.put(length_arr);
buffer.put(funcid_arr);
buffer.put(packetIdCode_arr);
buffer.put(content_arr);
buffer.put(checkcode_arr);
buffer.put(packtail_arr);
buffer.flip();
out.write(buffer);
out.flush();

buffer.free();
}else{
String value = (String)message;
logger.warn("encode message:" + message);
IoBuffer buffer = IoBuffer.allocate(value.getBytes().length);
buffer.setAutoExpand(true);
if(value != null){
buffer.put(value.trim().getBytes());
}
buffer.flip();
out.write(buffer);
out.flush();

buffer.free();

}
}

}

解码器——负责将客户端发送过来的数据进行解码变换为对象，传输给IoHandler处理器进行处理。本解码器包含了断包问题解决。

public class NSProtocalDecoder implements ProtocolDecoder {

private static final Logger logger = Logger.getLogger(NSProtocalDecoder.class);
private final AttributeKey context = new AttributeKey(getClass(), "context");
private final Charset charset = Charset.forName("GBK");
private final String PACK_HEAD = "$$"; //包头
private final String PACK_TAIL = " "; //包尾

// 请求报文的最大长度 100k
private int maxPackLength = 102400;

public int getMaxPackLength() {
return maxPackLength;
}

public void setMaxPackLength(int maxPackLength) {
if (maxPackLength <= 0) {
throw new IllegalArgumentException("请求报文最大长度：" + maxPackLength);
}
this.maxPackLength = maxPackLength;
}

private Context getContext(IoSession session) {
Context ctx;
ctx = (Context) session.getAttribute(context);
if (ctx == null) {
ctx = new Context();
session.setAttribute(context, ctx);
}
return ctx;
}

public void decode(IoSession session, IoBuffer in, ProtocolDecoderOutput out)
throws Exception {
Long start = System.currentTimeMillis();
// 报文前缀长度包头2个字节，包长2个字节，协议类型2个字节，数据包标识码8个字节，校验码4个字节,包尾2个字节
final int packHeadLength = 19;
// 先获取上次的处理上下文，其中可能有未处理完的数据
Context ctx = getContext(session);
// 先把当前buffer中的数据追加到Context的buffer当中
ctx.append(in);
// 把position指向0位置，把limit指向原来的position位置
IoBuffer buf = ctx.getBuffer();
buf.flip();
// 然后按数据包的协议进行读取
while (buf.remaining() >= packHeadLength) {
logger.debug("test 长度1：" + buf.remaining());
buf.mark();
// 读取包头 2个字节
String packhead = new String(new byte[]{buf.get(),buf.get()});
logger.debug("包头：" + packhead);
if(PACK_HEAD.equals(packhead)){
//读取包的长度 2个字节报文的长度，不包含包头和包尾
byte[] length_byte = new byte[]{buf.get(),buf.get()};
byte[] length_byte_arr = new byte[]{0,0,0,0};
length_byte_arr[2] = length_byte[0];
length_byte_arr[3] = length_byte[1];
int length = ByteTools.byteArrayToInt(length_byte_arr);
logger.debug("长度：" + length);
logger.debug("test 长度1：" + buf.remaining());
// 检查读取是否正常，不正常的话清空buffer
if (length < 0 || length > maxPackLength) {
logger.debug("报文长度[" + length + "] 超过最大长度：" + maxPackLength
+ "或者小于0,清空buffer");
buf.clear();
break;
//packHeadLength - 2 :减去包尾的长度，
//length - 2 <= buf.remaining() ：代表length-本身长度占用的两个字节-包头长度
}else if(length >= packHeadLength && length - 4 <= buf.remaining()){
//读取协议类型2个字节
byte[] funcid_byte = new byte[]{buf.get()};
byte[] funcid_byte_arr = new byte[]{0,0,0,0};
//funcid_byte_arr[2] = funcid_byte[0];
funcid_byte_arr[3] = funcid_byte[0];
int funcid = ByteTools.byteArrayToInt(funcid_byte_arr);
logger.warn("协议类型：" + funcid);
//读取数据包标识码8个字节
byte[] packetIdCode_byte = new byte[]{buf.get(),buf.get(),buf.get(),buf.get(),buf.get(),buf.get(),buf.get(),buf.get()};
long packetIdCode = ByteTools.byteArrayToLong(packetIdCode_byte);
logger.debug("数据包标识码：" + packetIdCode);

//读取报文正文内容
int oldLimit = buf.limit();
logger.debug("limit:" + (buf.position() + length));
//当前读取的位置 + 总长度 - 前面读取的字节长度 - 校验码
buf.limit(buf.position() + length - 19);
String content = buf.getString(ctx.getDecoder());
buf.limit(oldLimit);
logger.debug("报文正文内容：" + content);
CRC32 crc = new CRC32();
crc.update(content.getBytes("GBK"));

//读取校验码 4个字节
byte[] checkcode_byte = new byte[]{buf.get(),buf.get(),buf.get(),buf.get()};
byte[] checkcode_byte_arr = new byte[]{0,0,0,0,0,0,0,0};
checkcode_byte_arr[4] = checkcode_byte[0];
checkcode_byte_arr[5] = checkcode_byte[1];
checkcode_byte_arr[6] = checkcode_byte[2];
checkcode_byte_arr[7] = checkcode_byte[3];
long checkcode = ByteTools.byteArrayToLong(checkcode_byte_arr);
logger.debug("校验码：" + checkcode);
//验证校验码
if(checkcode != crc.getValue()){
// 如果消息包不完整,将指针重新移动消息头的起始位置
buf.reset();
break;
}
//读取包尾 2个字节
String packtail = new String(new byte[]{buf.get(),buf.get()});
logger.debug("包尾：" + packtail);
if(!PACK_TAIL.equals(packtail)){
// 如果消息包不完整,将指针重新移动消息头的起始位置
buf.reset();
break;
}
BaseMessageForServer message = new BaseMessageForServer();
message.setLength(length);
message.setCheckCode(checkcode);
message.setFuncid(funcid);
message.setPacketIdCode(packetIdCode);
message.setContent(content);
out.write(message);
}else{
// 如果消息包不完整,将指针重新移动消息头的起始位置
buf.reset();
break;
}
}else{
// 如果消息包不完整,将指针重新移动消息头的起始位置
buf.reset();
break;
}
}
if (buf.hasRemaining()) {
// 将数据移到buffer的最前面
IoBuffer temp = IoBuffer.allocate(maxPackLength).setAutoExpand(true);
temp.put(buf);
temp.flip();
buf.clear();
buf.put(temp);
} else {// 如果数据已经处理完毕，进行清空
buf.clear();
}
}

public void finishDecode(IoSession session, ProtocolDecoderOutput out)
throws Exception {
// TODO Auto-generated method stub

}

public void dispose(IoSession session) throws Exception {
// TODO Auto-generated method stub

}

// 记录上下文，因为数据触发没有规模，很可能只收到数据包的一半
// 所以，需要上下文拼起来才能完整的处理
private class Context {
private final CharsetDecoder decoder;
private IoBuffer buf;
private int matchCount = 0;
private int overflowPosition = 0;

private Context() {
decoder = charset.newDecoder();
buf = IoBuffer.allocate(3000).setAutoExpand(true);
}

public CharsetDecoder getDecoder() {
return decoder;
}

public IoBuffer getBuffer() {
return buf;
}

@SuppressWarnings("unused")
public int getOverflowPosition() {
return overflowPosition;
}

@SuppressWarnings("unused")
public int getMatchCount() {
return matchCount;
}

@SuppressWarnings("unused")
public void setMatchCount(int matchCount) {
this.matchCount = matchCount;
}

@SuppressWarnings("unused")
public void reset() {
overflowPosition = 0;
matchCount = 0;
decoder.reset();
}

public void append(IoBuffer in) {
getBuffer().put(in);
}
}

}

NSMinaHandler——处理器，处理业务数据。继承IoHandlerAdapter 接口，主要重写messageReceived 方法

public class NSMinaHandler extends IoHandlerAdapter {

private final Logger logger = Logger.getLogger(NSMinaHandler.class);

public static ConcurrentHashMap<Long, IoSession> sessionHashMap = new ConcurrentHashMap<Long, IoSession>();

@Override
public void exceptionCaught(IoSession session, Throwable cause)
throws Exception {
session.closeOnFlush();
logger.error("session occured exception, so close it."
+ cause.getMessage());
}

@Override
public void messageReceived(IoSession session, Object message)
throws Exception {
BaseMessageForServer basemessage = (BaseMessageForServer) message;
logger.debug("客户端"
+ ((InetSocketAddress) session.getRemoteAddress()).getAddress()
.getHostAddress() + "连接成功！");
session.setAttribute("type", message);
String remoteAddress = ((InetSocketAddress) session.getRemoteAddress())
.getAddress().getHostAddress();
session.setAttribute("ip", remoteAddress);
// 组装消息内容，返回给客户端
BaseMessageForClient messageForClient = new BaseMessageForClient();
messageForClient.setFuncid(2);
if (basemessage.getContent().indexOf("hello") > 0) {
// 内容
messageForClient.setContent("hello,我收到您的消息了！ ");
} else {
// 内容
messageForClient.setContent("恭喜，您已经入门！ ");
}
// 校验码生成
CRC32 crc32 = new CRC32();
crc32.update(messageForClient.getContent().getBytes());
// crc校验码
messageForClient.setCheckCode(crc32.getValue());
// 长度
messageForClient
.setLength(messageForClient.getContent().getBytes().length);

// 数据包标识码
messageForClient.setPacketIdCode(basemessage.getPacketIdCode());
session.write(messageForClient);
}

@Override
public void messageSent(IoSession session, Object message) throws Exception {
logger.debug("messageSent:" + message);
}

@Override
public void sessionCreated(IoSession session) throws Exception {
logger.debug("remote client [" + session.getRemoteAddress().toString()
+ "] connected.");
Long time = System.currentTimeMillis();
session.setAttribute("id", time);
sessionHashMap.put(time, session);
}

@Override
public void sessionClosed(IoSession session) throws Exception {
logger.debug("sessionClosed");
session.closeOnFlush();
sessionHashMap.remove(session.getAttribute("id"));
}

@Override
public void sessionIdle(IoSession session, IdleStatus status)
throws Exception {
logger.debug("session idle, so disconnecting......");
session.closeOnFlush();
logger.warn("disconnected");
}

@Override
public void sessionOpened(IoSession session) throws Exception {
logger.debug("sessionOpened.");
}

}

还有个就是心跳工厂：

public class NSMinaKeepAliveMessageFactory implements KeepAliveMessageFactory {

private final Logger logger = Logger
.getLogger(NSMinaKeepAliveMessageFactory.class);

private BaseMessageForServer basemessage;
/** 心跳包内容 */

private static long packetIdCode = 0;

/**
* 判断是否心跳请求包是的话返回true
*/
public boolean isRequest(IoSession session, Object message) {
// TODO Auto-generated method stub
if (message instanceof BaseMessageForServer) {
basemessage = (BaseMessageForServer) message;
// 心跳包方法协议类型
if (basemessage.getFuncid() == 3) {
// 为3，代表是一个心跳包，
packetIdCode = basemessage.getPacketIdCode();

return true;
} else {
return false;
}
} else {
return false;
}
}

/**
* 由于被动型心跳机制，没有请求当然也就不关注反馈因此直接返回false
*/
public boolean isResponse(IoSession session, Object message) {
// TODO Auto-generated method stub
return false;
}

/**
* 被动型心跳机制无请求因此直接返回nul
*/
public Object getRequest(IoSession session) {
// TODO Auto-generated method stub
return null;
}

/**
* 根据心跳请求request 反回一个心跳反馈消息
*/
public Object getResponse(IoSession session, Object request) {
// 组装消息内容，返回给客户端
BaseMessageForClient messageForClient = new BaseMessageForClient();
messageForClient.setFuncid(4);
// 内容
messageForClient.setContent("2222");
// 校验码生成
CRC32 crc32 = new CRC32();
crc32.update(messageForClient.getContent().getBytes());
// crc校验码
messageForClient.setCheckCode(crc32.getValue());
// 长度
messageForClient
.setLength(messageForClient.getContent().getBytes().length);

// 数据包标识码
messageForClient.setPacketIdCode(packetIdCode);
return messageForClient;
}

}

到此服务端代码结束。其实服务端与客户端都存在相似之处。编码，解码器都是一样的。客户端启动程序如下：

public class ClientTest {

public static void main(String[] args) {
NioSocketConnector connector = new NioSocketConnector();
//添加过滤器
connector.getFilterChain().addLast("logger", new LoggingFilter());
//设置编码，解码过滤器
connector.getFilterChain().addLast("codec", new ProtocolCodecFilter(new ByteArrayCodecFactory()));
//connector.getFilterChain().addLast("codec", new ProtocolCodecFilter(new TextLineCodecFactory(Charset.forName("utf-8"))));//设置编码过滤器
connector.setHandler(new ClientHandler());//设置事件处理器
ConnectFuture cf = connector.connect(new InetSocketAddress("127.0.0.1",8888)); //建立连接
cf.awaitUninterruptibly(); //等待连接创建完成
BaseMessageForServer message = new BaseMessageForServer();
String content = "hello world!";
CRC32 crc = new CRC32();
try {
crc.update(content.getBytes("GBK"));
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
}
message.setFuncid(5);
message.setPacketIdCode(10000);
message.setContent(content);
message.setCheckCode(crc.getValue());
message.setLength(content.getBytes().length);
cf.getSession().write(message);
}
}

到此mina基本的已完成。
---------------------
原文：https://blog.csdn.net/u012151597/article/details/78847234

岁月无声无息的溜走，除了带走一个无聊者的时光，还会沉淀一个努力者的人生。