HttpClient

使用HttpClient模拟浏览器访问

HttpClient 是Apache HttpComponents 下的子项目，是支持 HTTP 协议的客户端编程工具包。它被用来发送和接受 HTTP 消息，并不能处理http响应内容。

依赖

xml

 <dependency>
            <groupId>org.apache.httpcomponents</groupId>
            <artifactId>httpclient</artifactId>
       <version>4.5.6</version>
</dependency>

基本使用

Get

java

//httpClient的创建
CloseableHttpClient httpClient = HttpClients.createDefault();
//创建一个GET对象
HttpGet get = new HttpGet("http://shirtiny.cn");
//发送请求，得到一个response对象
CloseableHttpResponse response = httpClient.execute(get);
//取响应实体，转换成字符串打印
HttpEntity entity = response.getEntity();
String string = EntityUtils.toString(entity, "utf-8");
//响应状态码
int statusCode = response.getStatusLine().getStatusCode();

当需要传递参数时，可以直接在url改，也可以使用URIBuilder构建url

参数

java

//基础url
URIBuilder uriBuilder = new URIBuilder("https://api.kaaass.net/biliapi/video/resolve");
//加入参数
uriBuilder.addParameter("id","53175612");
uriBuilder.addParameter("quality","80");
//构建出url
URI uri = uriBuilder.build();
//放入get请求对象中即可
HttpGet get=new HttpGet(uri);
//然后执行...
httpClient.execute(get);

POST

与Get类似。当需要提交表格数据时：

java

//创建一个post对象
HttpPost post = new HttpPost("http://localhost:8082/httpclient/post.html");
//创建一个Entity。模拟一个表单
List<NameValuePair> kvList = new ArrayList<>();
kvList.add(new BasicNameValuePair("username", "zhangsan"));
kvList.add(new BasicNameValuePair("password", "123"));
//包装成一个Entity对象
StringEntity entity = new UrlEncodedFormEntity(kvList, "utf-8");
//设置请求的内容
post.setEntity(entity);
//执行post请求
CloseableHttpResponse response = httpClient.execute(post);

工具类

一个方便其他服务调用的httpClient的工具类。

java

package Http_Utils;

import ...

public class HttpClientUtil {

 public static String doGet(String url, Map<String, String> param) {

  // 创建Httpclient对象
  CloseableHttpClient httpclient = HttpClients.createDefault();

  String resultString = "";
  CloseableHttpResponse response = null;
  try {
   // 创建uri
   URIBuilder builder = new URIBuilder(url);
   if (param != null) {
    for (String key : param.keySet()) {
     builder.addParameter(key, param.get(key));
    }
   }
   URI uri = builder.build();

   // 创建http GET请求
   HttpGet httpGet = new HttpGet(uri);

   // 执行请求
   response = httpclient.execute(httpGet);
   // 判断返回状态是否为200
   if (response.getStatusLine().getStatusCode() == 200) {
    resultString = EntityUtils.toString(response.getEntity(), "UTF-8");
   }
  } catch (Exception e) {
   e.printStackTrace();
  } finally {
   try {
    if (response != null) {
     response.close();
    }
    httpclient.close();
   } catch (IOException e) {
    e.printStackTrace();
   }
  }
  return resultString;
 }

 public static String doGet(String url) {
  return doGet(url, null);
 }

 public static String doPost(String url, Map<String, String> param) {
  // 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 (param != null) {
    List<NameValuePair> paramList = new ArrayList<>();
    for (String key : param.keySet()) {
     paramList.add(new BasicNameValuePair(key, param.get(key)));
    }
    // 模拟表单
    UrlEncodedFormEntity entity = new UrlEncodedFormEntity(paramList);
    httpPost.setEntity(entity);
   }
   // 执行http请求
   response = httpClient.execute(httpPost);
   resultString = EntityUtils.toString(response.getEntity(), "utf-8");
  } catch (Exception e) {
   e.printStackTrace();
  } finally {
   try {
    response.close();
   } catch (IOException e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
   }
  }

  return resultString;
 }

 public static String doPost(String url) {
  return doPost(url, null);
 }

 public static String doPostJson(String url, String json) {
  // 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);
   // 创建请求内容
   StringEntity entity = new StringEntity(json, ContentType.APPLICATION_JSON);
   httpPost.setEntity(entity);
   // 执行http请求
   response = httpClient.execute(httpPost);
   resultString = EntityUtils.toString(response.getEntity(), "utf-8");
  } catch (Exception e) {
   e.printStackTrace();
  } finally {
   try {
    response.close();
   } catch (IOException e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
   }
  }

  return resultString;
 }
}