Java 实现Http协议
HTTP协议属于应用层协议,它构建于TCP和IP协议之上,处于TCP/IP协议架构层的顶端,所以,它不用处理下层协议间诸如丢包补发、握手及数据的分段及重新组装等繁琐的细节,使开发人员可以专注于应用业务。
协议是通信的规范,为了更好的理解HTTP协议,我们可以基于Java的Socket API接口,通过设计一个简单的应用层通信协议,来简单分析下协议实现的过程和细节。
在我们今天的示例程序中,客户端会向服务端发送一条命令,服务端在接收到命令后,会判断命令是否是“HELLO”,如果是“HELLO”, 则服务端返回给客户端的响应为“hello”,否则,服务端返回给客户端的响应为“bye bye”。
我们接下来用Java实现这个简单的应用层通信协议,
一、协议请求的定义
协议的请求主要包括:编码、命令和命令长度三个字段。
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package com.binghe.params; /** * 协议请求的定义 * @author binghe * */ public class Request { /** * 协议编码 */ private byte encode; /** * 命令 */ private String command; /** * 命令长度 */ private int commandLength; public Request() { super (); } public Request( byte encode, String command, int commandLength) { super (); this .encode = encode; this .command = command; this .commandLength = commandLength; } public byte getEncode() { return encode; } public void setEncode( byte encode) { this .encode = encode; } public String getCommand() { return command; } public void setCommand(String command) { this .command = command; } public int getCommandLength() { return commandLength; } public void setCommandLength( int commandLength) { this .commandLength = commandLength; } @Override public String toString() { return "Request [encode=" + encode + ", command=" + command + ", commandLength=" + commandLength + "]" ; } } |
二、响应协议的定义
协议的响应主要包括:编码、响应内容和响应长度三个字段。
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package com.binghe.params; /** * 协议响应的定义 * @author binghe * */ public class Response { /** * 编码 */ private byte encode; /** * 响应内容 */ private String response; /** * 响应长度 */ private int responseLength; public Response() { super (); } public Response( byte encode, String response, int responseLength) { super (); this .encode = encode; this .response = response; this .responseLength = responseLength; } public byte getEncode() { return encode; } public void setEncode( byte encode) { this .encode = encode; } public String getResponse() { return response; } public void setResponse(String response) { this .response = response; } public int getResponseLength() { return responseLength; } public void setResponseLength( int responseLength) { this .responseLength = responseLength; } @Override public String toString() { return "Response [encode=" + encode + ", response=" + response + ", responseLength=" + responseLength + "]" ; } } |
三、编码常量定义
编码常量的定义主要包括UTF-8和GBK两种编码。
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package com.binghe.constant; /** * 常量类 * @author binghe * */ public final class Encode { //UTF-8编码 public static final byte UTF8 = 1 ; //GBK编码 public static final byte GBK = 2 ; } |
四、客户端的实现
客户端先构造一个request请求,通过Socket接口将其发送到远端,并接收远端的响应信息,并构造成一个Response对象。
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package com.binghe.protocol.client; import java.io.IOException; import java.io.InputStream; import java.io.OutputStream; import java.net.Socket; import com.binghe.constant.Encode; import com.binghe.params.Request; import com.binghe.params.Response; import com.binghe.utils.ProtocolUtils; /** * 客户端代码 * @author binghe * */ public final class Client { public static void main(String[] args) throws IOException{ //请求 Request request = new Request(); request.setCommand( "HELLO" ); request.setCommandLength(request.getCommand().length()); request.setEncode(Encode.UTF8); Socket client = new Socket( "127.0.0.1" , 4567 ); OutputStream out = client.getOutputStream(); //发送请求 ProtocolUtils.writeRequest(out, request); //读取响应数据 InputStream in = client.getInputStream(); Response response = ProtocolUtils.readResponse(in); System.out.println( "获取的响应结果信息为: " + response.toString()); } } |
五、服务端的实现
服务端接收客户端的请求,根据接收命令的不同,响应不同的消息信息,如果是“HELLO”命令,则响应“hello”信息,否则响应“bye bye”信息。
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package com.binghe.protocol.server; import java.io.IOException; import java.io.InputStream; import java.io.OutputStream; import java.net.ServerSocket; import java.net.Socket; import com.binghe.constant.Encode; import com.binghe.params.Request; import com.binghe.params.Response; import com.binghe.utils.ProtocolUtils; /** * Server端代码 * @author binghe * */ public final class Server { public static void main(String[] args) throws IOException{ ServerSocket server = new ServerSocket( 4567 ); while ( true ) { Socket client = server.accept(); //读取请求数据 InputStream input = client.getInputStream(); Request request = ProtocolUtils.readRequest(input); System.out.println( "收到的请求参数为: " + request.toString()); OutputStream out = client.getOutputStream(); //组装响应数据 Response response = new Response(); response.setEncode(Encode.UTF8); if ( "HELLO" .equals(request.getCommand())){ response.setResponse( "hello" ); } else { response.setResponse( "bye bye" ); } response.setResponseLength(response.getResponse().length()); ProtocolUtils.writeResponse(out, response); } } } |
六、ProtocolUtils工具类的实现
ProtocolUtils
的readRequest
方法将从传递进来的输入流中读取请求的encode
、command
和commandLength
三个参数,进行相应的编码转化,构造成Request
对象返回。而writeResponse
方法则是将response
对象的字段根据对应的编码写入到响应的输出流中。
有一个细节需要重点注意:OutputStream
中直接写入一个int类型,会截取其低8位,丢弃其高24位,所以,在传递和接收数据时,需要进行相应的转化操作。
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package com.binghe.utils; import java.io.IOException; import java.io.InputStream; import java.io.OutputStream; import com.binghe.constant.Encode; import com.binghe.params.Request; import com.binghe.params.Response; /** * 协议工具类 * @author binghe * */ public final class ProtocolUtils { /** * 从输入流中反序列化Request对象 * @param input * @return * @throws IOException */ public static Request readRequest(InputStream input) throws IOException{ //读取编码 byte [] encodeByte = new byte [ 1 ]; input.read(encodeByte); byte encode = encodeByte[ 0 ]; //读取命令长度 byte [] commandLengthBytes = new byte [ 4 ]; input.read(commandLengthBytes); int commandLength = ByteUtils.byte2Int(commandLengthBytes); //读取命令 byte [] commandBytes = new byte [commandLength]; input.read(commandBytes); String command = "" ; if (Encode.UTF8 == encode){ command = new String(commandBytes, "UTF-8" ); } else if (Encode.GBK == encode){ command = new String(commandBytes, "GBK" ); } //组装请求返回 Request request = new Request(encode, command, commandLength); return request; } /** * 从输入流中反序列化Response对象 * @param input * @return * @throws IOException */ public static Response readResponse(InputStream input) throws IOException{ //读取编码 byte [] encodeByte = new byte [ 1 ]; input.read(encodeByte); byte encode = encodeByte[ 0 ]; //读取响应长度 byte [] responseLengthBytes = new byte [ 4 ]; input.read(responseLengthBytes); int responseLength = ByteUtils.byte2Int(responseLengthBytes); //读取命令 byte [] responseBytes = new byte [responseLength]; input.read(responseBytes); String response = "" ; if (Encode.UTF8 == encode){ response = new String(responseBytes, "UTF-8" ); } else if (Encode.GBK == encode){ response = new String(responseBytes, "GBK" ); } //组装请求返回 Response resp = new Response(encode, response, responseLength); return resp; } /** * 序列化请求信息 * @param output * @param response */ public static void writeRequest(OutputStream output, Request request) throws IOException{ //将response响应返回给客户端 output.write(request.getEncode()); //output.write(response.getResponseLength());直接write一个int类型会截取低8位传输丢弃高24位 output.write(ByteUtils.int2ByteArray(request.getCommandLength())); if (Encode.UTF8 == request.getEncode()){ output.write(request.getCommand().getBytes( "UTF-8" )); } else if (Encode.GBK == request.getEncode()){ output.write(request.getCommand().getBytes( "GBK" )); } output.flush(); } /** * 序列化响应信息 * @param output * @param response */ public static void writeResponse(OutputStream output, Response response) throws IOException{ //将response响应返回给客户端 output.write(response.getEncode()); //output.write(response.getResponseLength());直接write一个int类型会截取低8位传输丢弃高24位 output.write(ByteUtils.int2ByteArray(response.getResponseLength())); if (Encode.UTF8 == response.getEncode()){ output.write(response.getResponse().getBytes( "UTF-8" )); } else if (Encode.GBK == response.getEncode()){ output.write(response.getResponse().getBytes( "GBK" )); } output.flush(); } } |
七、ByteUtils类的实现
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package com.binghe.utils; /** * 字节转化工具类 * @author binghe * */ public final class ByteUtils { /** * 将byte数组转化为int数字 * @param bytes * @return */ public static int byte2Int( byte [] bytes){ int num = bytes[ 3 ] & 0xFF ; num |= ((bytes[ 2 ] << 8 ) & 0xFF00 ); num |= ((bytes[ 1 ] << 16 ) & 0xFF0000 ); num |= ((bytes[ 0 ] << 24 ) & 0xFF000000 ); return num; } /** * 将int类型数字转化为byte数组 * @param num * @return */ public static byte [] int2ByteArray( int i){ byte [] result = new byte [ 4 ]; result[ 0 ] = ( byte )(( i >> 24 ) & 0xFF ); result[ 1 ] = ( byte )(( i >> 16 ) & 0xFF ); result[ 2 ] = ( byte )(( i >> 8 ) & 0xFF ); result[ 3 ] = ( byte )(i & 0xFF ); return result; } } |
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原文链接:https://blog.csdn.net/l1028386804/article/details/117154518