使用HttpClient调用接口的实例讲解

一，编写返回对象

public class HttpResult {
// 响应的状态码
private int code;

// 响应的响应体
private String body;
get/set…
}

二，封装HttpClient

package cn.xxxxxx.httpclient;

import java.util.ArrayList;
import java.util.List;
import java.util.Map;

import org.apache.http.NamevaluePair;
import org.apache.http.client.entity.UrlEncodedFormEntity;
import org.apache.http.client.methods.CloseableHttpResponse;
import org.apache.http.client.methods.HttpDelete;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.client.methods.HttpPut;
import org.apache.http.client.utils.URIBuilder;
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;

public class APIService {

 private CloseableHttpClient httpClient;

 public APIService() {
  // 1 创建HttpClinet，相当于打开浏览器
  this.httpClient = HttpClients.createDefault();
 }

 
 public HttpResult doGet(String url, Map map) throws Exception {

  // 声明URIBuilder
  URIBuilder uriBuilder = new URIBuilder(url);

  // 判断参数map是否为非空
  if (map != null) {
   // 遍历参数
   for (Map.Entry entry : map.entrySet()) {
    // 设置参数
    uriBuilder.setParameter(entry.getKey(), entry.getValue().toString());
   }
  }

  // 2 创建httpGet对象，相当于设置url请求地址
  HttpGet httpGet = new HttpGet(uriBuilder.build());

  // 3 使用HttpClient执行httpGet，相当于按回车，发起请求
  CloseableHttpResponse response = this.httpClient.execute(httpGet);

  // 4 解析结果，封装返回对象httpResult，相当于显示相应的结果
  // 状态码
  // response.getStatusLine().getStatusCode();
  // 响应体，字符串，如果response.getEntity()为空，下面这个代码会报错,所以解析之前要做非空的判断
  // EntityUtils.toString(response.getEntity(), "UTF-8");
  HttpResult httpResult = null;
  // 解析数据封装HttpResult
  if (response.getEntity() != null) {
   httpResult = new HttpResult(response.getStatusLine().getStatusCode(),
     EntityUtils.toString(response.getEntity(), "UTF-8"));
  } else {
   httpResult = new HttpResult(response.getStatusLine().getStatusCode(), "");
  }

  // 返回
  return httpResult;
 }

 
 public HttpResult doGet(String url) throws Exception {
  HttpResult httpResult = this.doGet(url, null);
  return httpResult;
 }

 
 public HttpResult doPost(String url, Map map) throws Exception {
  // 声明httpPost请求
  HttpPost httpPost = new HttpPost(url);

  // 判断map不为空
  if (map != null) {
   // 声明存放参数的List集合
   List params = new ArrayList();

   // 遍历map，设置参数到list中
   for (Map.Entry entry : map.entrySet()) {
    params.add(new BasicNamevaluePair(entry.getKey(), entry.getValue().toString()));
   }

   // 创建form表单对象
   UrlEncodedFormEntity formEntity = new UrlEncodedFormEntity(params, "UTF-8");

   // 把表单对象设置到httpPost中
   httpPost.setEntity(formEntity);
  }

  // 使用HttpClient发起请求，返回response
  CloseableHttpResponse response = this.httpClient.execute(httpPost);

  // 解析response封装返回对象httpResult
  HttpResult httpResult = null;
  if (response.getEntity() != null) {
   httpResult = new HttpResult(response.getStatusLine().getStatusCode(),
     EntityUtils.toString(response.getEntity(), "UTF-8"));
  } else {
   httpResult = new HttpResult(response.getStatusLine().getStatusCode(), "");
  }

  // 返回结果
  return httpResult;
 }

 
 public HttpResult doPost(String url) throws Exception {
  HttpResult httpResult = this.doPost(url, null);
  return httpResult;
 }

 
 public HttpResult doPut(String url, Map map) throws Exception {
  // 声明httpPost请求
  HttpPut httpPut = new HttpPut(url);

  // 判断map不为空
  if (map != null) {
   // 声明存放参数的List集合
   List params = new ArrayList();

   // 遍历map，设置参数到list中
   for (Map.Entry entry : map.entrySet()) {
    params.add(new BasicNamevaluePair(entry.getKey(), entry.getValue().toString()));
   }

   // 创建form表单对象
   UrlEncodedFormEntity formEntity = new UrlEncodedFormEntity(params, "UTF-8");

   // 把表单对象设置到httpPost中
   httpPut.setEntity(formEntity);
  }

  // 使用HttpClient发起请求，返回response
  CloseableHttpResponse response = this.httpClient.execute(httpPut);

  // 解析response封装返回对象httpResult
  HttpResult httpResult = null;
  if (response.getEntity() != null) {
   httpResult = new HttpResult(response.getStatusLine().getStatusCode(),
     EntityUtils.toString(response.getEntity(), "UTF-8"));
  } else {
   httpResult = new HttpResult(response.getStatusLine().getStatusCode(), "");
  }

  // 返回结果
  return httpResult;
 }

 
 public HttpResult doDelete(String url, Map map) throws Exception {

  // 声明URIBuilder
  URIBuilder uriBuilder = new URIBuilder(url);

  // 判断参数map是否为非空
  if (map != null) {
   // 遍历参数
   for (Map.Entry entry : map.entrySet()) {
    // 设置参数
    uriBuilder.setParameter(entry.getKey(), entry.getValue().toString());
   }
  }

  // 2 创建httpGet对象，相当于设置url请求地址
  HttpDelete httpDelete = new HttpDelete(uriBuilder.build());

  // 3 使用HttpClient执行httpGet，相当于按回车，发起请求
  CloseableHttpResponse response = this.httpClient.execute(httpDelete);

  // 4 解析结果，封装返回对象httpResult，相当于显示相应的结果
  // 状态码
  // response.getStatusLine().getStatusCode();
  // 响应体，字符串，如果response.getEntity()为空，下面这个代码会报错,所以解析之前要做非空的判断
  // EntityUtils.toString(response.getEntity(), "UTF-8");
  HttpResult httpResult = null;
  // 解析数据封装HttpResult
  if (response.getEntity() != null) {
   httpResult = new HttpResult(response.getStatusLine().getStatusCode(),
     EntityUtils.toString(response.getEntity(), "UTF-8"));
  } else {
   httpResult = new HttpResult(response.getStatusLine().getStatusCode(), "");
  }

  // 返回
  return httpResult;
 }

}

三，调用接口

package cn.xxxxxx.httpclient.test;

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

import org.junit.Before;
import org.junit.Test;

import cn.itcast.httpclient.APIService;
import cn.itcast.httpclient.HttpResult;

public class APIServiceTest {

 private APIService apiService;

 @Before
 public void init() {
  this.apiService = new APIService();
 }

 // 查询
 @Test
 public void testQueryItemById() throws Exception {
  // http://manager.aaaaaa.com/rest/item/interface/{id}

  String url = "http://manager.aaaaaa.com/rest/item/interface/42";

  HttpResult httpResult = this.apiService.doGet(url);

  System.out.println(httpResult.getCode());
  System.out.println(httpResult.getBody());

 }

 // 新增
 @Test
 public void testSaveItem() throws Exception {
  // http://manager.aaaaaa.com/rest/item/interface/{id}

  String url = "http://manager.aaaaaa.com/rest/item/interface";

  Map map = new HashMap();
  // title=测试RESTful风格的接口&price=1000&num=1&cid=888&status=1
  map.put("title", "测试APIService调用新增接口");
  map.put("price", "1000");
  map.put("num", "1");
  map.put("cid", "666");
  map.put("status", "1");

  HttpResult httpResult = this.apiService.doPost(url, map);

  System.out.println(httpResult.getCode());
  System.out.println(httpResult.getBody());

 }

 // 修改

 @Test
 public void testUpdateItem() throws Exception {
  // http://manager.aaaaaa.com/rest/item/interface/{id}

  String url = "http://manager.aaaaaa.com/rest/item/interface";

  Map map = new HashMap();
  // title=测试RESTful风格的接口&price=1000&num=1&cid=888&status=1
  map.put("title", "测试APIService调用修改接口");
  map.put("id", "44");

  HttpResult httpResult = this.apiService.doPut(url, map);

  System.out.println(httpResult.getCode());
  System.out.println(httpResult.getBody());

 }

 // 删除
 @Test
 public void testDeleteItemById() throws Exception {
  // http://manager.aaaaaa.com/rest/item/interface/{id}

  String url = "http://manager.aaaaaa.com/rest/item/interface/44";

  HttpResult httpResult = this.apiService.doDelete(url, null);

  System.out.println(httpResult.getCode());
  System.out.println(httpResult.getBody());

 }

}

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