使用HttpClient访问接口（Rest接口和普通接口）

这里总结一下使用HttpClient访问外部接口的用法。后期如果发现有什么缺陷会更改。欢迎读者指出此方法的不足之处。

首先，创建一个返回实体：

public class HttpResult {
// 响应的状态码
private int code; // 响应的响应体
private String body; public HttpResult(int code, String body) {
this.code = code;
this.body = body;
}
//省略get/set
}


创建一个HttpClientUtil：

public class HttpClientUtil { private static CloseableHttpClient httpClient = HttpClients.createDefault();//用static实现单例，此处不完善，当多线程时会出现问题。 /**
* 带参数的get请求
*
* @param url
* @param map
* @return
* @throws Exception
*/
public static HttpResult doGet(String url, Map<String, Object> 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<String, Object> 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 = 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;
} /**
* 不带参数的get请求
*
* @param url
* @return
* @throws Exception
*/
public static HttpResult doGet(String url) throws Exception {
HttpResult httpResult = doGet(url, null);
return httpResult;
} /**
* 带参数的post请求
*
* @param url
* @return
* @throws Exception
*/
public static HttpResult doPost(String url, Map<String, Object> reqMap, Map<String,String> headersMap) throws Exception {
// 声明httpPost请求
HttpPost httpPost = new HttpPost(url);
for (Map.Entry<String, String> entry: headersMap.entrySet())
httpPost.addHeader(entry.getKey(), entry.getValue()); // 判断map不为空
if (reqMap != null) { // 创建form表单对象
StringEntity formEntity = new StringEntity(JSON.toJSONString(reqMap), "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 = 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;
} /**
* 不带参数的post请求
*
* @param url
* @return
* @throws Exception
*/
public static HttpResult doPost(String url) throws Exception {
HttpResult httpResult = doPost(url, null,null);
return httpResult;
} /**
* 带参数的Put请求
*
* @param url
* @param map
* @return
* @throws Exception
*/
public static HttpResult doPut(String url, Map<String, Object> 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<NameValuePair> params = new ArrayList<NameValuePair>(); // 遍历map，设置参数到list中
for (Map.Entry<String, Object> 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 = 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;
} /**
* 带参数的Delete请求
*
* @param url
* @param map
* @return
* @throws Exception
*/
public static HttpResult doDelete(String url, Map<String, Object> 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<String, Object> 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 = 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;
} /**
* 返回常用请求头
* @return
*/
public static Map<String, String> commentHeader(){
Map<String, String> map = new HashMap<>();
map.put("Content-Type", "application/json");
return map;
}
}


测试一下：

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 { // 查询
@Test
public void testGet() throws Exception {
// http://manager.aaaaaa.com/rest/item/interface/{id} String url = "http://manager.aaaaaa.com/rest/item/interface/42"; HttpResult httpResult = HttpClientUtil.doGet(url); System.out.println(httpResult.getCode());
System.out.println(httpResult.getBody()); }// 查询
@Test
public void testPost() throws Exception {
//设置参数
Map reqMap = new HashMap();
reqMap.put("distCode", arsArg.getDistCode());
HttpResult httpResult = null;
try {
//RestUrlsCommons.RMDS_DISTRICT_FINDBYDISTCODE为url
//reqMap：请求参数
//HttpClientUtil.commentHeader()：请求头
httpResult = HttpClientUtil.doPost(RestUrlsCommons.RMDS_DISTRICT_FINDBYDISTCODE, reqMap, HttpClientUtil.commentHeader());
} catch (Exception e) {
e.printStackTrace();
} System.out.println(httpResult.getCode());
System.out.println(httpResult.getBody());
}}


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参考资料：使用HttpClient调用接口