http通信示例Httpclient和HttpServer

本示例源于为朋友解决一个小问题,数据库到服务器的数据传输,由于本人能力有限,暂时将它理解为从数据库中获取数取表数据,实际上有可能是文件或者其他形式的数据,不过原理都得用流传输,

首先httpclient

import com.alibaba.fastjson.JSON;
import com.alibaba.fastjson.JSONArray;
import netscape.javascript.JSObject;

import java.io.*;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
import java.sql.*;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

/**
 * Created by jisen on 2018/5/24.
 */
public class Httpclient {
    public static void main(String[] args) throws SQLException, ClassNotFoundException, IOException {
        String dataByJDBC = getDataByJDBC();
        //如果不从数据库取直接发送字符串
        //String dataByJDBC="hello httpserver";
        String backData = httpPost(dataByJDBC);

        System.out.println(backData);
    }

    //获取数据库的数据并封装成json字符串
    public static String getDataByJDBC() throws ClassNotFoundException, SQLException {

        String driver = "com.mysql.jdbc.Driver";
        String url = "jdbc:mysql://localhost:3306/admin?useSSL=false";
        String username = "root";
        String password = "root";
        Class.forName(driver);
        Connection connection = DriverManager.getConnection(url, username, password);

        //从数据库中获取数据
        String sql = "select * from menu";
        PreparedStatement preparedStatement = connection.prepareStatement(sql);//预处理说起来

        ResultSet resultSet = preparedStatement.executeQuery();
        int columnCount  = resultSet.getMetaData().getColumnCount();
        ResultSetMetaData metaData = resultSet.getMetaData();
        Map<String,Object> dataMap = new HashMap<String,Object>();
        List<Map<String,Object>> list = new ArrayList<>();
        while (resultSet.next()){
            for(int i=1 ; i<=columnCount;i++){
                String columnName = metaData.getColumnName(i);
                Object object = resultSet.getObject(i);
                dataMap.put(columnName,object);
            }
            list.add(dataMap);
        }

        String jsonString = JSON.toJSONString(list);
        System.out.println(jsonString);
        return jsonString;
    }

    public static String httpGet() throws IOException {
        URL url = new URL("http://localhost:8080/httpServer?param1=jisen&param2=jisen2");
        HttpURLConnection conn = (HttpURLConnection) url.openConnection();
        conn.setRequestMethod("GET");
        conn.connect();
        //接收反馈
        BufferedReader reader = new BufferedReader(new InputStreamReader(conn.getInputStream()));
        StringBuffer sBuffer = new StringBuffer();
        String line = "";
        while ((line = reader.readLine())!=null){
            sBuffer.append(line).append("\r\n");
        }
        reader.close();
        return sBuffer.toString();
    }

    public static String httpPost(String data) throws IOException {
        URL url = new URL("http://localhost:8080/httpServer");
        HttpURLConnection conn = (HttpURLConnection) url.openConnection();
        conn.setRequestMethod("POST");
        //HttpURLConnection中的doInput默认为true,而doOutput默认为false,所以如果需要些内容到流,需要设置为true
        conn.setDoOutput(true);
        conn.connect();
        //写入流,发送Http请求
        BufferedWriter writer = new BufferedWriter(new OutputStreamWriter(
                conn.getOutputStream()));
        writer.write(data);
        writer.flush();

        //接收反馈
        BufferedReader reader = new BufferedReader(new InputStreamReader(
                conn.getInputStream(),"utf8"));
        StringBuffer sBuffer = new StringBuffer();
        String line = "";
        while ((line = reader.readLine()) != null) {
            sBuffer.append(line).append("\r\n");
        }
        reader.close();
        return sBuffer.toString();
    }
}

其次httpserver

import com.sun.net.httpserver.HttpContext;
import com.sun.net.httpserver.HttpExchange;
import com.sun.net.httpserver.HttpHandler;
import com.sun.net.httpserver.HttpServer;
import java.io.*;
import java.net.InetSocketAddress;
import java.net.URI;
import java.util.HashMap;
import java.util.Map;

/**
 * Created by jisen on 2018/5/24.
 */
public class MyHttpServer  {

    public static void main(String[] args) throws IOException {
        HttpServer httpServer = HttpServer.create(new InetSocketAddress(8080),10);
        httpServer.createContext("/httpServer", new MyHandler());
        httpServer.setExecutor(null);
        httpServer.start();
    }
     static class MyHandler implements HttpHandler {
        public void handle(HttpExchange he) throws IOException {

            InputStream is = he.getRequestBody();
            //接收反馈
            BufferedReader reader = new BufferedReader(new InputStreamReader(
                    is,"utf8"));

            StringBuffer sBuffer = new StringBuffer();

            String line = "";
            while ((line = reader.readLine()) != null) {
                sBuffer.append(line).append("\r\n");
            }
            reader.close();
            is.close();
            System.out.println("接收到来自数据库的数据");
            System.out.println(sBuffer);
            //服务器收到
            String response = "the data is receive";
            he.sendResponseHeaders(200, response.length());
            OutputStream os = he.getResponseBody();
            os.write(response.getBytes());
            os.close();
        }
    }
}