HttpClient / Http客户端
HttpClient / Http客户端:
-
- HttpClient的定义
- HttpClient的作用
- HttpClient的常用核心API
- HttpClient要导入的依赖
- HttpClient发送请求的步骤
- HttpClient入门案例：
-
- HttpClient(Http客户端)发送get请求
- HttpClient(Http客户端)发送post请求
- HttpClient工具类 (代码)
HttpClient的定义
- HttpClient (Http客户端) 是Apache Jakarta Common 下的子项目，可以用来提供高效率、最新的、功能丰富的支持HTTP协议的 客户端编程工具包，其支持HTTP协议最新的版本和建议。
- 说的直白点就是：
我们可在 java 程序中可通过HttpClient(Http客户端) 这个工具包来构造http请求、发送http请求、接收响应结果、解析(请求)返回的结果。
（在Java中通过编码的方式来发送http请求）
HttpClient的作用
- 可在 java程序中可通过HttpClient(Http客户端) 这个工具包来构造http请求、发送http请求、接收响应结果、解析(请求)返回的结果。
HttpClient的常用核心API
- HttpClient
- HttpClients
- CloseableHttpClient
- HttpGet
- HttpPost
HttpClient要导入的依赖
<dependency>
<groupId>org.apache.httpcomponentsgroupId>
<artifactId>httpclientartifactId>
<version>4.5.13version>
dependency>
HttpClient发送请求的步骤
第一步、创建HttpClient对象 (Http客户端对象)。使用该对象可进行“发送请求”。
（HttpClient (Http客户端类)是一个接口，最后创建是其的实现类）第二步、创建http请求对象。比如说我们要发送一个get请求，我们就要创建一个HttpGet对象；如果要发送post请求，我们就就要构建一个HttpPost对象。
第三步、发送请求,接收响应结果。调用HttpClient对象的execute方法发送请求（发送请求），且接收响应结果。
第四步、解析返回结果。
- 获取服务端返回的状态码。
- 获取客户端返回的数据 (获得响应体，且解析响应体)。
第五步、关闭资源。
(ps : 例子在下面的入门案例中。)
HttpClient入门案例：
HttpClient(Http客户端)发送get请求
@SpringBootTest
public class HttpClientTest { //Http客户端测试类
/**
测试通过httpclient(Http客户端)发送GET请求
*/
@Test
public void testGet() throws Exception {
//创建HttpClient对象 --HttpClien为接口,最后创建出来的为: 与其相关的实现类
CloseableHttpClient httpClient = HttpClients.createDefault();
//创建Http请求对象 (get请求)
HttpGet httpGet = new HttpGet("http://localhost:8080/user/shop/status");
//发送请求,接收响应结果
CloseableHttpResponse response = httpClient.execute(httpGet);
//解析返回结果
//获取服务端返回的状态码
int statusCode = response.getStatusLine().getStatusCode();
System.out.println("服务端返回的状态码为: " +statusCode);
//获取服务端(响应)返回的数据 --- 获得响应体
HttpEntity entity = response.getEntity();
//通过EntityUtils工具类解析“响应体” --- 解析响应体
String body = EntityUtils.toString(entity);
System.out.println("服务端返回的数据为: "+body);
//关闭资源
response.close();
httpClient.close();
}
}
HttpClient(Http客户端)发送post请求
@SpringBootTest
public class HttpClientTest { //Http客户端测试类
/**
* 测试类通过HttpClient(Http客户端)发送Post请求
*/
@Test
public void testPost() throws Exception {
//创建HttpClient对象 --- HttpClient为接口，最后创建出来的为: 与其相关的实现类。
CloseableHttpClient httpClient = HttpClients.createDefault();
//创建Http请求对象 (Post请求)
HttpPost httpPost = new HttpPost("http://localhost:8080/admin/employee/login");
//设置post请求的参数 (设置Http请求对象的“参数”)
JSONObject jsonObject = new JSONObject();
jsonObject.put("username", "admin");
jsonObject.put("password", 123456);
StringEntity entity = new StringEntity(jsonObject.toString()); //参数为:json字符串
entity.setContentEncoding("utf-8"); //设置请求的“编码方式”
//请求提交过来的是json格式的数据，这样后端才能正确解析数据
entity.setContentType("application/json"); //设置请求的“数据格式”
//设置post请求的参数
httpPost.setEntity(entity);
//发送请求,接收响应结果
CloseableHttpResponse reponse = httpClient.execute(httpPost);
//解析返回结果
int statusCode = reponse.getStatusLine().getStatusCode(); //获取服务端返回的状态码
System.out.println("响应码为: "+statusCode);
HttpEntity entity1 = reponse.getEntity();
String body = EntityUtils.toString(entity1); //使用EntityUtils解析响应体
System.out.println("响应数据为: "+body);
//关闭资源
reponse.close();
httpClient.close();
}
}
HttpClient工具类 (代码)
package com.sky.utils;
import com.alibaba.fastjson.JSONObject;
import org.apache.http.NameValuePair;
import org.apache.http.client.config.RequestConfig;
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.client.utils.URIBuilder;
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.util.EntityUtils;
import java.io.IOException;
import java.net.URI;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
/**
* Http工具类
*/
public class HttpClientUtil {
static final int TIMEOUT_MSEC = 5 * 1000;
/**
* 发送GET方式请求
* @param url
* @param paramMap
* @return
*/
public static String doGet(String url,Map<String,String> paramMap){
// 创建Httpclient对象
CloseableHttpClient httpClient = HttpClients.createDefault();
String result = "";
CloseableHttpResponse response = null;
try{
URIBuilder builder = new URIBuilder(url);
if(paramMap != null){
for (String key : paramMap.keySet()) {
builder.addParameter(key,paramMap.get(key));
}
}
URI uri = builder.build();
//创建GET请求
HttpGet httpGet = new HttpGet(uri);
//发送请求
response = httpClient.execute(httpGet);
//判断响应状态
if(response.getStatusLine().getStatusCode() == 200){
result = EntityUtils.toString(response.getEntity(),"UTF-8");
}
}catch (Exception e){
e.printStackTrace();
}finally {
try {
response.close();
httpClient.close();
} catch (IOException e) {
e.printStackTrace();
}
}
return result;
}
/**
* 发送POST方式请求
* @param url
* @param paramMap
* @return
* @throws IOException
*/
public static String doPost(String url, Map<String, String> paramMap) throws IOException {
// 创建Httpclient对象
CloseableHttpClient httpClient = HttpClients.createDefault();
CloseableHttpResponse response = null;
String resultString = "";
try {
// 创建Http Post请求
HttpPost httpPost = new HttpPost(url);
// 创建参数列表
if (paramMap != null) {
List<NameValuePair> paramList = new ArrayList();
for (Map.Entry<String, String> param : paramMap.entrySet()) {
paramList.add(new BasicNameValuePair(param.getKey(), param.getValue()));
}
// 模拟表单
UrlEncodedFormEntity entity = new UrlEncodedFormEntity(paramList);
httpPost.setEntity(entity);
}
httpPost.setConfig(builderRequestConfig());
// 执行http请求
response = httpClient.execute(httpPost);
resultString = EntityUtils.toString(response.getEntity(), "UTF-8");
} catch (Exception e) {
throw e;
} finally {
try {
response.close();
} catch (IOException e) {
e.printStackTrace();
}
}
return resultString;
}
/**
* 发送POST方式请求
* @param url
* @param paramMap
* @return
* @throws IOException
*/
public static String doPost4Json(String url, Map<String, String> paramMap) throws IOException {
// 创建Httpclient对象
CloseableHttpClient httpClient = HttpClients.createDefault();
CloseableHttpResponse response = null;
String resultString = "";
try {
// 创建Http Post请求
HttpPost httpPost = new HttpPost(url);
if (paramMap != null) {
//构造json格式数据
JSONObject jsonObject = new JSONObject();
for (Map.Entry<String, String> param : paramMap.entrySet()) {
jsonObject.put(param.getKey(),param.getValue());
}
StringEntity entity = new StringEntity(jsonObject.toString(),"utf-8");
//设置请求编码
entity.setContentEncoding("utf-8");
//设置数据类型
entity.setContentType("application/json");
httpPost.setEntity(entity);
}
httpPost.setConfig(builderRequestConfig());
// 执行http请求
response = httpClient.execute(httpPost);
resultString = EntityUtils.toString(response.getEntity(), "UTF-8");
} catch (Exception e) {
throw e;
} finally {
try {
response.close();
} catch (IOException e) {
e.printStackTrace();
}
}
return resultString;
}
private static RequestConfig builderRequestConfig() {
return RequestConfig.custom()
.setConnectTimeout(TIMEOUT_MSEC)
.setConnectionRequestTimeout(TIMEOUT_MSEC)
.setSocketTimeout(TIMEOUT_MSEC).build();
}
}