摘要：今天我瞎翻的源代碼，發(fā)現(xiàn)可以用包下提供的很快速的創(chuàng)建服務(wù)，它的創(chuàng)建方式和極其的類似。創(chuàng)建服務(wù)創(chuàng)建服務(wù)并注冊前面創(chuàng)建的，使用來處理請求。使用默認的只要運行這個方法，一個服務(wù)就啟動了，監(jiān)聽端口是，下面是我寫了兩個完整的例子。

我最開始學(xué)習(xí) Java web 編程是要去寫一個 servlet， 重寫里面的 service 方法，然后去配置 web.xml 文件，最后就是部署到 tomcat 或者 jetty 容器中并啟動。后來就是使用一些框架，struts2 SpringMvc。今天我瞎翻 JDK 的源代碼，發(fā)現(xiàn)可以用 com.sun.net.httpserver 包下提供的 API 很快速的創(chuàng)建 web 服務(wù)，它的創(chuàng)建方式和 golang 極其的類似。

首先要實現(xiàn) HttpHandler， 重寫 handle 方法。

public class MyHandler implements HttpHandler {
    @Override
    public void handle(HttpExchange httpExchange) throws IOException {
    
    }
}

創(chuàng)建 web 服務(wù)并注冊前面創(chuàng)建的 handler，使用 handler 來處理請求。

public class Main {

    public static void main(String[] args) {
        try {
            HttpServer server = HttpServer.create(new InetSocketAddress(8000), 0);
            server.createContext("/web", new MyHandler());
            // 使用默認的 excutor
            server.setExecutor(null);
            server.start();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

只要運行這個 main 方法，一個 web 服務(wù)就啟動了，監(jiān)聽端口是 8000， 下面是我寫了兩個完整的例子。

package me.deweixu.handler;

import com.sun.net.httpserver.HttpExchange;
import com.sun.net.httpserver.HttpHandler;
import netscape.javascript.JSObject;

import java.io.IOException;
import java.io.OutputStream;
import java.util.Map;

/**
 * Created by simeone
 *
 * @author: simeone
 * @Date: 2018/5/19
 */
public class GetHandler implements HttpHandler {
    @Override
    public void handle(HttpExchange httpExchange) throws IOException {
        System.out.println("Method: " + httpExchange.getRequestMethod());
        String param = httpExchange.getRequestURI().getQuery();
        System.out.println("Param:" + param);
        httpExchange.sendResponseHeaders(200, 0);

        OutputStream os = httpExchange.getResponseBody();
        os.write(param.getBytes());
        os.close();
    }

}

package me.deweixu.handler;

import com.sun.net.httpserver.Headers;
import com.sun.net.httpserver.HttpExchange;
import com.sun.net.httpserver.HttpHandler;

import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.Reader;
import java.io.UnsupportedEncodingException;

/**
 * Created by simeone
 *
 * @author: simeone
 * @Date: 2018/5/19
 */
public class PostHandler implements HttpHandler {
    @Override
    public void handle(HttpExchange httpExchange) throws IOException {
        System.out.println("Method: " + httpExchange.getRequestMethod());

        InputStream is = httpExchange.getRequestBody();
        String response = is2string(is);
        System.out.println("response: " + response);
        is.close();
        httpExchange.sendResponseHeaders(200, response.length());

        Headers headers = httpExchange.getResponseHeaders();
        headers.set("Content-Type", "application/json; charset=utf8");

        OutputStream os = httpExchange.getResponseBody();
        os.write(response.getBytes());
        os.close();
    }

    private String is2string(InputStream is) throws IOException {
        final int bufferSize = 1024;
        final char[] buffer = new char[bufferSize];
        final StringBuilder out = new StringBuilder();
        Reader in = new InputStreamReader(is, "UTF-8");
        for (; ; ) {
            int rsz = in.read(buffer, 0, buffer.length);
            if (rsz < 0)
                break;
            out.append(buffer, 0, rsz);
        }
        return out.toString();
    }
}

package me.deweixu;

import com.sun.net.httpserver.HttpServer;
import me.deweixu.handler.GetHandler;
import me.deweixu.handler.PostHandler;

import java.io.IOException;
import java.net.InetSocketAddress;

public class Main {

    public static void main(String[] args) {
        try {
            HttpServer server = HttpServer.create(new InetSocketAddress(8000), 0);
            server.createContext("/post", new PostHandler());
            server.createContext("/get", new GetHandler());
            server.setExecutor(null);
            server.start();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

# get
$ curl http://127.0.0.1:8000/get?name=simeone&address=beijing
name=simeone&address=beijing

# post
$ curl -H "Content-Type: application/json" -d "{"username":"simeone", "address":"beijing"}" http://127.0.0.1:8000/post
{"username":"simeone", "address":"beijing"}