java用httpclient如何实现http请求 java用httpclient实现http请求代码

java用httpclient如何实现http请求？本篇文章小编给大家分享一下java用httpclient实现http请求代码，小编觉得挺不错的，现在分享给大家供大家参考，有需要的小伙伴们可以来看看。

java实现http请求的方法常用有两种，一种则是通过java自带的标准类HttpURLConnection去实现，另一种是通过apache的httpclient去实现。

本文用httpclient去实现，需要导入httpclient和httpcore两个jar包，测试时用的httpclient-4.5.1和httpcore-4.4.3。

HttpMethod.java

package demo;
public enum HttpMethod {
  GET, POST;
}

HttpHeader.java

package demo;

import java.util.HashMap;
import java.util.Map;

/**
 * 请求头
 */
public class HttpHeader {
  private Map params = new HashMap();
    
  public HttpHeader addParam(String name, String value) {
    this.params.put(name, value);
    return this;
  }
  
  public Map getParams() {
    return this.params;
  }
}

HttpParamers.java

package demo;

import java.io.IOException;
import java.net.URLEncoder;
import java.util.HashMap;
import java.util.Map;
import java.util.Set;

import com.alibaba.fastjson.JSON;

/**
 * 请求参数
 */
public class HttpParamers {
  private Map params = new HashMap();
  private HttpMethod httpMethod;
  private String jsonParamer = "";

  public HttpParamers(HttpMethod httpMethod) {
    this.httpMethod = httpMethod;
  }

  public static HttpParamers httpPostParamers() {
    return new HttpParamers(HttpMethod.POST);
  }

  public static HttpParamers httpGetParamers() {
    return new HttpParamers(HttpMethod.GET);
  }
  
  public HttpParamers addParam(String name, String value) {
    this.params.put(name, value);
    return this;
  }

  public HttpMethod getHttpMethod() {
    return this.httpMethod;
  }

  public String getQueryString(String charset) throws IOException {
    if ((this.params == null) || (this.params.isEmpty())) {
      return null;
    }
    StringBuilder query = new StringBuilder();
    Set> entries = this.params.entrySet();

    for (Map.Entry entry : entries) {
      String name = entry.getKey();
      String value = entry.getValue();
      query.append("&").append(name).append("=").append(URLEncoder.encode(value, charset));
    }
    return query.substring(1);
  }

  public boolean isJson() {
    return !isEmpty(this.jsonParamer);
  }

  public Map getParams() {
    return this.params;
  }

  public String toString() {
    return "HttpParamers " + JSON.toJSONString(this);    
  }

  public String getJsonParamer() {
    return this.jsonParamer;
  }
  
  public void setJsonParamer() {
    this.jsonParamer = JSON.toJSONString(this.params);
  }
  
  private static boolean isEmpty(CharSequence cs) {
    return (cs == null) || (cs.length() == 0);
  }
}

HttpClient.java

package demo;

import java.io.IOException;
import java.util.Map;
import java.util.Set;

import org.apache.http.HttpEntity;
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.methods.HttpRequestBase;
import org.apache.http.entity.StringEntity;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.protocol.HTTP;
import org.apache.http.util.EntityUtils;

public class HttpClient {
  public static final String DEFAULT_CHARSET = "UTF-8";
  public static final String JSON_CONTENT_FORM = "application/json;charset=UTF-8";
  public static final String CONTENT_FORM = "application/x-www-form-urlencoded;charset=UTF-8";
  
  public static String doService(String url, HttpParamers paramers, HttpHeader header, int connectTimeout, int readTimeout) throws Exception {
    HttpMethod httpMethod = paramers.getHttpMethod();
    switch (httpMethod) {
      case GET:
        return doGet(url, paramers, header, connectTimeout, readTimeout);
      case POST:
        return doPost(url, paramers, header, connectTimeout, readTimeout);
    }
    return null;
  }
  
  /**
   * post方法
   * @param url
   * @param paramers
   * @param header
   * @param connectTimeout
   * @param readTimeout
   * @return
   * @throws IOException
   */
  public static String doPost(String url, HttpParamers paramers, HttpHeader header, int connectTimeout, int readTimeout) throws IOException {
    String responseData = "";
    CloseableHttpClient httpClient = null;
    CloseableHttpResponse httpResponse = null;    
    try{
      String query = null;          
      HttpPost httpPost = new HttpPost(url);
      setHeader(httpPost, header);            
      if (paramers.isJson()) {
        //json数据
        httpPost.setHeader(HTTP.CONTENT_TYPE, JSON_CONTENT_FORM);        
        query = paramers.getJsonParamer();
      } else {
        //表单数据
        httpPost.setHeader(HTTP.CONTENT_TYPE, CONTENT_FORM);
        query = paramers.getQueryString(DEFAULT_CHARSET);
      }
      if(query != null){
        HttpEntity reqEntity = new StringEntity(query);
        httpPost.setEntity(reqEntity);
      }      
      httpClient = HttpClients.createDefault();            
      httpResponse = httpClient.execute(httpPost);
      HttpEntity resEntity = httpResponse.getEntity();
      responseData = EntityUtils.toString(resEntity);
    } catch (Exception e){
      e.printStackTrace();
    } finally{
      httpResponse.close();
      httpClient.close();
    }
    return responseData;
  }
  
  
  /**
   * get方法
   * @param url
   * @param params
   * @param header
   * @param connectTimeout
   * @param readTimeout
   * @return
   * @throws IOException
   */
  public static String doGet(String url, HttpParamers params, HttpHeader header, int connectTimeout, int readTimeout) throws IOException {
    String responseData = "";
    CloseableHttpClient httpClient = null;
    CloseableHttpResponse httpResponse = null;    
    try{  
      String query = params.getQueryString(DEFAULT_CHARSET);  
      url = buildGetUrl(url, query);
      HttpGet httpGet = new HttpGet(url);
      setHeader(httpGet, header);  
      httpClient = HttpClients.createDefault();            
      httpResponse = httpClient.execute(httpGet);
      HttpEntity resEntity = httpResponse.getEntity();
      responseData = EntityUtils.toString(resEntity);
    } catch (Exception e){
      e.printStackTrace();
    } finally{
      httpResponse.close();
      httpClient.close();
    }
    return responseData;
  }
  
  private static void setHeader(HttpRequestBase httpRequestBase, HttpHeader header){
    if(header != null){
      Map headerMap = header.getParams();
      if (headerMap != null && !headerMap.isEmpty()) {    
        Set> entries = headerMap.entrySet();  
        for (Map.Entry entry : entries) {
          String name = entry.getKey();
          String value = entry.getValue();
          httpRequestBase.setHeader(name, value);
        }
      }
    }
  }
  
  private static String buildGetUrl(String url, String query) throws IOException {
    if (query == null || query.equals("")) {
      return url;
    }
    StringBuilder newUrl = new StringBuilder(url);
    boolean hasQuery = url.contains("?");
    boolean hasPrepend = (url.endsWith("?")) || (url.endsWith("&"));
    if (!hasPrepend) {
      if (hasQuery) {
        newUrl.append("&");
      } else {
        newUrl.append("?");
        hasQuery = true;
      }
    }
    newUrl.append(query);
    hasPrepend = false;
    return newUrl.toString();
  }
}

HttpService.java

package demo;

import java.util.Map;

import com.alibaba.fastjson.JSONObject;
import com.alibaba.fastjson.TypeReference;

public class HttpService {
  private String serverUrl;
  private int connectTimeout = 15000;
  private int readTimeout = 30000;
  public HttpService(String serverUrl) {
    this.serverUrl = serverUrl.trim();
  }
  public Map commonService(String serviceUrl, HttpParamers paramers) throws Exception{
    return commonService(serviceUrl, paramers, null);
  }
  public Map commonService(String serviceUrl, HttpParamers paramers, HttpHeader header) throws Exception{
    String response = service(serviceUrl, paramers, header);
    try {
      Map result = JSONObject.parseObject(response, new TypeReference>() {});
      if ((result == null) || (result.isEmpty())) {
        throw new Exception("远程服务返回的数据无法解析");
      }
      Integer code = (Integer) result.get("code");
      if ((code == null) || (code.intValue() != 0)) {
        throw new Exception((String) result.get("message"));
      }
      return result;
    } catch (Exception e) {
      throw new Exception("返回结果异常,response:" + response, e);
    }
  }
  public String service(String serviceUrl, HttpParamers paramers) throws Exception {
    return service(serviceUrl, paramers, null);
  }
  public String service(String serviceUrl, HttpParamers paramers, HttpHeader header) throws Exception {
    String url = this.serverUrl + serviceUrl;
    String responseData = "";
    try {
      responseData = HttpClient.doService(url, paramers, header, this.connectTimeout, this.readTimeout);
    } catch (Exception e) {
      throw new Exception(e.getMessage(), e);
    }
    return responseData;
  }
  
  public String getServerUrl() {
    return this.serverUrl;
  }

  public int getConnectTimeout() {
    return this.connectTimeout;
  }

  public int getReadTimeout() {
    return this.readTimeout;
  }

  public void setConnectTimeout(int connectTimeout) {
    this.connectTimeout = connectTimeout;
  }

  public void setReadTimeout(int readTimeout) {
    this.readTimeout = readTimeout;
  }
}

测试例子Test1.java

package demo;

import org.junit.Ignore;
import org.junit.Test;

public class Test1 {

  //免费的在线REST服务, 提供测试用的HTTP请求假数据
  //接口信息说明可见：http://www.hangge.com/blog/cache/detail_2020.html
  String uri = "http://jsonplaceholder.typicode.com";
  
  //get方式请求数据
  //请求地址：http://jsonplaceholder.typicode.com/posts
  @Ignore("暂时忽略")
  @Test
  public void test1() {
    System.out.print("n" + "test1---------------------------"+ "n");
    HttpParamers paramers = HttpParamers.httpGetParamers();
    String response = "";
    try {
      HttpService httpService = new HttpService(uri);
      response = httpService.service("/posts", paramers);      
    } catch (Exception e) {
      e.printStackTrace();
    }
    System.out.print(response);
  }
  
  //get方式请求数据
  //请求地址：http://jsonplaceholder.typicode.com/posts?userId=5
  @Ignore("暂时忽略")
  @Test
  public void test2() {
    System.out.print("n" + "test2---------------------------"+ "n");
    HttpParamers paramers = HttpParamers.httpGetParamers();
    paramers.addParam("userId", "5");
    String response = "";
    try {
      HttpService httpService = new HttpService(uri);      
      response = httpService.service("/posts", paramers);      
    } catch (Exception e) {
      e.printStackTrace();
    }
    System.out.print(response);
  }
  
  //post方式请求数据
  //请求地址：http://jsonplaceholder.typicode.com/posts  
  @Test
  public void test3() {
    System.out.print("n" + "test3---------------------------"+ "n");
    HttpParamers paramers = HttpParamers.httpPostParamers();
    paramers.addParam("time", String.valueOf(System.currentTimeMillis()));
    String response = "";
    try {
      HttpService httpService = new HttpService(uri);
      response = httpService.service("/posts", paramers);      
    } catch (Exception e) {
      e.printStackTrace();
    }
    System.out.print(response);
  }
}