Java如何发送Http请求呢?

Java发送Http请求的实现思路

方式1:
   使用Apache中的HttpClient发送请求

方式2:
   使用JDK中原生态的方法URLConnection

使用apache中httpclient发送http请求

import java.util.Arraylist;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import org.apache.http.HttpEntity;
import org.apache.http.client.entity.UrlEncodedFormEntity;
import org.apache.http.client.methods.CloseableHttpResponse;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.entity.ContentType;
import org.apache.http.entity.StringEntity;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.message.BasicNameValuePair;
import org.apache.http.protocol.HTTP;
import org.apache.http.util.EntityUtils;
import org.junit.Test;

import com.fasterxml.jackson.databind.ObjectMapper;

public class HttpTest {
    String uri = "http://127.0.0.1:8080/test";

    /**
     * Get方法
     */
    @Test
    public void test1() {
        try {
            CloseableHttpClient client = null;
            CloseableHttpResponse response = null;
            try {
                HttpGet httpGet = new HttpGet(uri + "/test1?id=8888&name=java265");

                client = HttpClients.createDefault();
                response = client.execute(httpGet);
                HttpEntity entity = response.getEntity();
                String result = EntityUtils.toString(entity);
                System.out.println(result);
            } finally {
                if (response != null) {
                    response.close();
                }
                if (client != null) {
                    client.close();
                }
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    /**
     * Post发送form表单数据
     */
    @Test
    public void test2() {
        try {
            CloseableHttpClient client = null;
            CloseableHttpResponse response = null;
            try {
                // 创建一个提交数据的容器
                List<BasicNameValuePair> parames = new ArrayList<>();
                parames.add(new BasicNameValuePair("id", "888"));
                parames.add(new BasicNameValuePair("name", "java265"));

                HttpPost httpPost = new HttpPost(uri + "/test1");
                httpPost.setEntity(new UrlEncodedFormEntity(parames, "UTF-8"));

                client = HttpClients.createDefault();
                response = client.execute(httpPost);
                HttpEntity entity = response.getEntity();
                String result = EntityUtils.toString(entity);
                System.out.println(result);
            } finally {
                if (response != null) {
                    response.close();
                }
                if (client != null) {
                    client.close();
                }
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    /**
     * Post发送json数据
     */
    @Test
    public void test3() {
        try {
            CloseableHttpClient client = null;
            CloseableHttpResponse response = null;
            try {
                ObjectMapper objectMapper = new ObjectMapper();
                Map<String, Object> data = new HashMap<String, Object>();
                data.put("code", "888");
                data.put("name", "java265");

                HttpPost httpPost = new HttpPost(uri + "/test2");
                httpPost.setHeader(HTTP.CONTENT_TYPE, "application/json");
                httpPost.setEntity(new StringEntity(objectMapper.writeValueAsString(data),
                        ContentType.create("text/json", "UTF-8")));

                client = HttpClients.createDefault();
                response = client.execute(httpPost);
                HttpEntity entity = response.getEntity();
                String result = EntityUtils.toString(entity);
                System.out.println(result);
            } finally {
                if (response != null) {
                    response.close();
                }
                if (client != null) {
                    client.close();
                }
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

使用JDK自带HttpURLConnection

import java.io.BufferedOutputStream;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.HttpURLConnection;
import java.net.URL;
import java.util.HashMap;
import java.util.Map;

import org.junit.Test;

import com.fasterxml.jackson.databind.ObjectMapper;

public class HttpApi {
    String uri = "http://127.0.0.1:8080/test";

    /**
     * Get方法
     */
    @Test
    public void test1() {
        try {
            URL url = new URL(uri + "/test1?id=8888&name=java265");
            HttpURLConnection connection = (HttpURLConnection) url.openConnection();

            connection.setDoOutput(true); // 设置该连接是可以输出的
            connection.setRequestMethod("GET"); // 设置请求方式
            connection.setRequestProperty("Content-Type", "application/x-www-form-urlencoded; charset=UTF-8");

            BufferedReader br = new BufferedReader(new InputStreamReader(connection.getInputStream(), "utf-8"));
            String line = null;
            StringBuilder result = new StringBuilder();
            while ((line = br.readLine()) != null) { // 读取数据
                result.append(line + "\n");
            }
            connection.disconnect();

            System.out.println(result.toString());
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    /**
     * Post方法发送form表单
     */
    @Test
    public void test2() {
        try {
            URL url = new URL(uri + "/test1");
            HttpURLConnection connection = (HttpURLConnection) url.openConnection();

            connection.setDoInput(true); // 设置可输入
            connection.setDoOutput(true); // 设置该连接是可以输出的
            connection.setRequestMethod("POST"); // 设置请求方式
            connection.setRequestProperty("Content-Type", "application/x-www-form-urlencoded; charset=UTF-8");

            PrintWriter pw = new PrintWriter(new BufferedOutputStream(connection.getOutputStream()));
            pw.write("id=888&name=java265");
            pw.flush();
            pw.close();

            BufferedReader br = new BufferedReader(new InputStreamReader(connection.getInputStream(), "utf-8"));
            String line = null;
            StringBuilder result = new StringBuilder();
            while ((line = br.readLine()) != null) { // 读取数据
                result.append(line + "\n");
            }
            connection.disconnect();

            System.out.println(result.toString());
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    /**
     * Post方法发送json数据
     */
    @Test
    public void test3() {
        try {
            URL url = new URL(uri + "/test2");
            HttpURLConnection connection = (HttpURLConnection) url.openConnection();

            connection.setDoInput(true); // 设置可输入
            connection.setDoOutput(true); // 设置该连接是可以输出的
            connection.setRequestMethod("POST"); // 设置请求方式
            connection.setRequestProperty("Content-Type", "application/json;charset=UTF-8");

            ObjectMapper objectMapper = new ObjectMapper();
            Map<String, Object> data = new HashMap<String, Object>();
            data.put("id", "888");
            data.put("name", "java265");
            PrintWriter pw = new PrintWriter(new BufferedOutputStream(connection.getOutputStream()));
            pw.write(objectMapper.writeValueAsString(data));
            pw.flush();
            pw.close();

            BufferedReader br = new BufferedReader(new InputStreamReader(connection.getInputStream(), "utf-8"));
            String line = null;
            StringBuilder result = new StringBuilder();
            while ((line = br.readLine()) != null) { // 读取数据
                result.append(line + "\n");
            }
            connection.disconnect();

            System.out.println(result.toString());
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}