java发送原生的http请求

发送get请求

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;

public class HttpGetUtil {
    public static void main(String[] args) {
        HttpURLConnection conn = null;
        InputStream inputStream = null;
        BufferedReader bufferedReader = null;

        try {
            URL url = new URL("http://www.xxx.com/xxx/check?orgCode=321300&waybillNo=773011197999686");
            conn = (HttpURLConnection)url.openConnection();
            conn.setRequestMethod("GET");
            conn.setConnectTimeout(5000);
            conn.setReadTimeout(5000);

            //设置请求头（如果没有请求头信息，则不需要写这一项）
            conn.setRequestProperty("appId", "app_service");

            conn.connect();

            inputStream = conn.getInputStream();
            bufferedReader = new BufferedReader(new InputStreamReader(inputStream, "UTF-8"));

            //拼接返回参数
            StringBuilder sb = new StringBuilder();
            String responseMsg = null;
            while ((responseMsg = bufferedReader.readLine()) != null){
                sb.append(responseMsg);
            }

            System.out.println(sb.toString());

        } catch (MalformedURLException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        } catch (Exception e){
            e.printStackTrace();
        } finally {
            if(bufferedReader != null){
                try {
                    bufferedReader.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if(inputStream != null){
                try {
                    inputStream.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if(conn != null){
                conn.disconnect();
            }
        }
    }
}

• connect() 方法
  1.这段代码已经使用url.openConnection()创建了连接，connect()方法可有可无。
  2.如果使用HttpURLConnection conn=new HttpURLConnection(new URL(“路径”))，则需要使用connect()方法进行连接。

发送post请求

import com.alibaba.fastjson.JSON;
import com.mr.zhang.thread.dto.ParamDto;
import java.io.*;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;

public class HttpPostUtil {
    public static void main(String[] args) {
        HttpURLConnection conn = null;
        InputStream inputStream = null;
        BufferedReader bufferedReader = null;

        try {
            URL url = new URL("http://www.xxx.com/xxx/xxxxxx/xxxxxxxxxxxxx");
            conn = (HttpURLConnection) url.openConnection();//通过openConnection创建对象
            conn.setRequestMethod("POST");
            //设置请求体格式，这里设置的是json格式
            conn.setRequestProperty("Content-Type", "application/json; charset=utf-8;");
            //连接服务器超时时间ms
            conn.setConnectTimeout(5000);
            //读取服务器返回超时时间ms
            conn.setReadTimeout(5000);

            //设置请求头
            conn.setRequestProperty("appId", "app_service");

            //设置请求体
            ParamDto paramDto = new ParamDto();
            paramDto.setOrgCode("222001");
            paramDto.setDataType("INTERCEPT");
            paramDto.setPdaCode("JSYG22200110001");
            paramDto.setVersionNo("1573360821238");
            String body = JSON.toJSONString(paramDto);

            //设置成true，向远程服务器写数据
            conn.setDoOutput(true);//默认是false，无法写入body
            OutputStream outputStream = conn.getOutputStream();
            outputStream.write(body.getBytes());
            outputStream.flush();
            outputStream.close();

            inputStream = conn.getInputStream();
            bufferedReader = new BufferedReader(new InputStreamReader(inputStream, "UTF-8"));
            StringBuilder sb = new StringBuilder();
            String responseMsg = null;
            while ((responseMsg = bufferedReader.readLine()) != null){
                sb.append(responseMsg);
            }

            System.out.println(sb.toString());

        } catch (MalformedURLException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        } catch (Exception e){
            e.printStackTrace();
        } finally {
            if(bufferedReader != null){
                try {
                    bufferedReader.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if(inputStream != null){
                try {
                    inputStream.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if(conn != null){
                conn.disconnect();
            }
        }
    }
}

• conn.setDoOutput(true);
  默认值是false，向远程服务器写数据时，需要设置成true

• conn.setDoInput(true);
  默认值是true，从远程服务器读数据时使用。因为默认是true，该参数可以不设置。