Netty-09-socket bio 例子
2017年11月16日大约 5 分钟
学习的步骤
学习 netty 有些心浮气躁，效果一点也不好。
这次就从最简单的开始，一步步学习，大概步骤如下：
socket bio 调用=>socket bio+threadPool=》socket nio=>socket aio
使用 netty
netty bio=>netty nio
rpc 雏形
本地调用=》rpc 反射
为了后期手写 rpc 做准备
socket bio 简单的字符串例子
client
package com.github.houbb.netty.calc.socket.bio;
import java.io.IOException;
import java.io.OutputStream;
import java.net.Socket;
/**
* @author binbin.hou
* @date 2019/4/22
* @since 0.0.1
*/
public class SocketBioClient {
/**
* 地址
*/
private final String address;
/**
* 端口号
*/
private final int port;
public SocketBioClient(String address, int port) {
this.address = address;
this.port = port;
}
public void start() {
try {
//1. 根据地址信息创建 socket
Socket socket = new Socket(this.address, this.port);
// 设置超时时间
socket.setSoTimeout(1000);
// 客户端输入
final String input = "hello socket client!";
// 获取 socket 输出流，用于输出到客户端
OutputStream outputStream = socket.getOutputStream();
outputStream.write(input.getBytes());
} catch (IOException e) {
e.printStackTrace();
}
}
public static void main(String[] args) {
new SocketBioClient("127.0.0.1", 8080).start();
}
}server
package com.github.houbb.netty.calc.socket.bio;
import java.io.IOException;
import java.io.InputStream;
import java.net.ServerSocket;
import java.net.Socket;
/**
* @author binbin.hou
* @date 2019/4/22
* @since 0.0.1
*/
public class SocketBioServer {
/**
* 端口号
*/
private final int port;
public SocketBioServer(int port) {
this.port = port;
}
public void start() {
try {
// 创建 server socket
ServerSocket serverSocket = new ServerSocket(port);
// 服务一直启动
while (true) {
// 获取连接的 socket
Socket socket = serverSocket.accept();
System.out.println("client 连接成功...");
// 声明 byte 数组，用于存放读取内容
byte[] chars = new byte[1024];
InputStream inputStream = socket.getInputStream();
inputStream.read(chars);
String string = new String(chars);
System.out.println("客户端内容： " + string);
}
} catch (IOException e) {
e.printStackTrace();
}
}
public static void main(String[] args) {
new SocketBioServer(8080).start();
}
}改进为循环调用
上面的例子非常的简单，无法进行交互。
下面我们添加一个可以进行客户端和服务器交互的例子。
客户端
package com.github.houbb.netty.calc.socket.bio.in;
import java.io.*;
import java.net.Socket;
/**
* bio read from sys.in client
*
* @author binbin.hou
* @date 2019/4/23
* @since 0.0.1
*/
public class SocketBioInClient {
private final String address;
private final int port;
public SocketBioInClient(String address, int port) {
this.address = address;
this.port = port;
}
/**
* 直接运行
* 1. 监听固定的端口
*/
public void start() {
try {
Socket socket = new Socket(address, port);
//timeout 1s
socket.setSoTimeout(1000);
// read form console input
BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(System.in));
//2. 用于输出到服务端
PrintWriter printWriter = new PrintWriter(socket.getOutputStream());
// 用于获取服务器的反馈
BufferedReader socketReader = new BufferedReader(new InputStreamReader(socket.getInputStream()));
boolean flag = true;
while (flag) {
final String line = bufferedReader.readLine();
System.out.println("Client input: " + line);
// 立刻刷新输出流
printWriter.println(line);
printWriter.flush();
if ("bye".equalsIgnoreCase(line)) {
flag = false;
System.out.println("------------------------");
}
final String serverEcho = socketReader.readLine();
System.out.println("Server: " + serverEcho);
}
} catch (IOException e) {
e.printStackTrace();
}
}
public static void main(String[] args) {
SocketBioInClient client = new SocketBioInClient("127.0.0.1", 8080);
client.start();
}
}服务器
package com.github.houbb.netty.calc.socket.bio.in;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.ServerSocket;
import java.net.Socket;
/**
* bio read from sys.in server
*
* @author binbin.hou
* @date 2019/4/23
* @since 0.0.1
*/
public class SocketBioInServer {
private final int port;
public SocketBioInServer(int port) {
this.port = port;
}
public void start() {
try {
ServerSocket serverSocket = new ServerSocket(port);
System.out.println("Server start listen on: " + port);
Socket socket = serverSocket.accept();
//1. 获取 socket 的输入内容
BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(socket.getInputStream()));
//2. 用于输出到客户端
PrintWriter printWriter = new PrintWriter(socket.getOutputStream());
while (true) {
String line = bufferedReader.readLine();
System.out.println("Received: " + line);
// 立刻刷新输出流
printWriter.println("Server echo " + line);
printWriter.flush();
}
} catch (IOException e) {
e.printStackTrace();
}
}
public static void main(String[] args) {
SocketBioInServer socketBioInServer = new SocketBioInServer(8080);
socketBioInServer.start();
}
}测试
- 启动
首先运行 server，然后启动 client。
- 测试
客户端输入 hello
hello
Client input: hello
Server: Server echo hello服务器信息
Server start listen on: 8080
Received: hello- 结束
客户端输入 bye
bye
Client input: bye
------------------------
Server: Server echo bye服务器信息
Received: bye
java.net.SocketException: Connection reset
....关闭资源修正版
之所以会有上面的异常，是因为写的时候，偷懒，没有吧响应的 socket 等资源释放掉。
下面给出完整的修订版本。
客户端
package com.github.houbb.netty.calc.socket.bio.close;
import java.io.*;
import java.net.Socket;
/**
* bio read from sys.in client
*
* @author binbin.hou
* @date 2019/4/23
* @since 0.0.1
*/
public class SocketBioCloseClient {
private final String address;
private final int port;
public SocketBioCloseClient(String address, int port) {
this.address = address;
this.port = port;
}
/**
* 直接运行
* 1. 监听固定的端口
*/
public void start() {
Socket socket = null;
BufferedReader bufferedReader = null;
PrintWriter printWriter = null;
BufferedReader socketReader = null;
try {
socket = new Socket(address, port);
//timeout 1s
socket.setSoTimeout(1000);
// read form console input
bufferedReader = new BufferedReader(new InputStreamReader(System.in));
//2. 用于输出到服务端
printWriter = new PrintWriter(socket.getOutputStream());
// 用于获取服务器的反馈
socketReader = new BufferedReader(new InputStreamReader(socket.getInputStream()));
boolean flag = true;
while (flag) {
final String line = bufferedReader.readLine();
System.out.println("Client input: " + line);
// 立刻刷新输出流
printWriter.println(line);
printWriter.flush();
if ("bye".equalsIgnoreCase(line)) {
flag = false;
System.out.println("------------------------");
}
final String serverEcho = socketReader.readLine();
System.out.println("Server: " + serverEcho);
}
} catch (IOException e) {
e.printStackTrace();
} finally {
close(socketReader);
close(printWriter);
close(bufferedReader);
close(socket);
}
}
/**
* 执行关闭
* 1. 这里可以替换为 TWR
* @param closeable 可关闭的
*/
private void close(final Closeable closeable) {
if(closeable != null) {
try {
closeable.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
public static void main(String[] args) {
SocketBioCloseClient client = new SocketBioCloseClient("127.0.0.1", 8080);
client.start();
}
}服务器
package com.github.houbb.netty.calc.socket.bio.close;
import java.io.*;
import java.net.ServerSocket;
import java.net.Socket;
/**
* bio read from sys.in server
*
* @author binbin.hou
* @date 2019/4/23
* @since 0.0.1
*/
public class SocketBioCloseServer {
private final int port;
public SocketBioCloseServer(int port) {
this.port = port;
}
public void start() {
ServerSocket serverSocket = null;
BufferedReader bufferedReader = null;
PrintWriter printWriter = null;
try {
serverSocket = new ServerSocket(port);
System.out.println("Server start listen on: " + port);
Socket socket = serverSocket.accept();
//1. 获取 socket 的输入内容
bufferedReader = new BufferedReader(new InputStreamReader(socket.getInputStream()));
//2. 用于输出到客户端
printWriter = new PrintWriter(socket.getOutputStream());
while (true) {
String line = bufferedReader.readLine();
System.out.println("Received: " + line);
// 立刻刷新输出流
printWriter.println("Server echo " + line);
printWriter.flush();
// 需要中断跳出，不然会一直循环
if("bye".equalsIgnoreCase(line)) {
break;
}
}
} catch (IOException e) {
e.printStackTrace();
} finally {
close(printWriter);
close(bufferedReader);
close(serverSocket);
}
}
/**
* 执行关闭
* 1. 这里可以替换为 TWR
* @param closeable 可关闭的
*/
private void close(final Closeable closeable) {
if(closeable != null) {
try {
closeable.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
public static void main(String[] args) {
SocketBioCloseServer socketBioInServer = new SocketBioCloseServer(8080);
socketBioInServer.start();
}
}测试
- 启动
启动服务端+客户端
- 客户端
输入
qq
Client input: qq
Server: Server echo qq
bye
Client input: bye
------------------------
Server: Server echo bye- 服务器对应输出
Server start listen on: 8080
Received: qq
Received: bye进一步思考
现象
如果我们打开多个客户端，后面打开的客户端并不会得到反馈。
只会得到一个超时的异常。
qq
Client input: qq
java.net.SocketTimeoutException: Read timed out
at java.net.SocketInputStream.socketRead0(Native Method)
at java.net.SocketInputStream.socketRead(SocketInputStream.java:116)
at java.net.SocketInputStream.read(SocketInputStream.java:171)
at java.net.SocketInputStream.read(SocketInputStream.java:141)
at sun.nio.cs.StreamDecoder.readBytes(StreamDecoder.java:284)
at sun.nio.cs.StreamDecoder.implRead(StreamDecoder.java:326)
at sun.nio.cs.StreamDecoder.read(StreamDecoder.java:178)
at java.io.InputStreamReader.read(InputStreamReader.java:184)
at java.io.BufferedReader.fill(BufferedReader.java:161)
at java.io.BufferedReader.readLine(BufferedReader.java:324)
at java.io.BufferedReader.readLine(BufferedReader.java:389)
at com.github.houbb.netty.calc.socket.bio.in.SocketBioInClient.start(SocketBioInClient.java:57)
at com.github.houbb.netty.calc.socket.bio.in.SocketBioInClient.main(SocketBioInClient.java:67)原因分析
因为前一个 client 占用了唯一的服务端，后面的 client 并不能获取 server 端的反馈。
问题的解决
一个最简单的方式就是，我们为每一个客户端，都创建一个对应的 server。
这样就解决了客户端被阻塞的问题。
我们参考下一节的内容。
拓展阅读
流的关闭顺序
Connection reset 异常
这里遇到了一个异常。按照常理，我们应该忽略这个内容，但是这里恰恰是我们可以学习到知识的地方。
参考资料
贡献者
binbin.hou