1.项目中最近需要在后端访问外部系统接口，原本在前端可以用ajax发送的访问请求要改造成后端http访问，于是在网上搜了一下相关资料，最终采用了HttpClient。
2.以下列出的是 HttpClient 提供的主要的功能，要知道更多详细的功能可以参见 HttpClient 的主页。
（1）实现了所有 HTTP 的方法（GET,POST,PUT,HEAD 等）
（2）支持自动转向
（3）支持 HTTPS 协议
（4）支持代理服务器
3.演示代码如下：
import java.io.IOException;
import java.util.ArrayList;
import java.util.Date;
import java.util.List;
import net.sf.json.JSONObject;
import org.apache.http.Consts;
import org.apache.http.Header;
import org.apache.http.HttpEntity;
import org.apache.http.HttpHeaders;
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.HttpGet;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.entity.ContentType;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClientBuilder;
import org.apache.http.message.BasicNameValuePair;
import org.apache.http.util.EntityUtils;
public class HttpClientUtil {
/**
* 使用HttpClient进行http get请求
*/
public static void get(String url) {
/**
* client和response需要关闭资源
*/
// 创建client,放入try()中自动释放,不需要finally
try (CloseableHttpClient client = HttpClientBuilder.create().build()) {
// 执行得到response
try (CloseableHttpResponse response = client.execute(new HttpGet(url))) {
// 获取statusCode
Integer statusCode = response.getStatusLine().getStatusCode();
HttpEntity entity = response.getEntity();
if (entity != null) {
// body
String bodyAsString = EntityUtils.toString(entity);
// Media Type
String contentMimeType = ContentType.getOrDefault(entity).getMimeType();
// head
Header[] headers = response.getHeaders(HttpHeaders.CONTENT_TYPE);
// 输出
System.out.println("statusCode:" + statusCode);
System.out.println("contentMinmeType:" + contentMimeType);
System.out.println("body:" + bodyAsString);
System.out.println("head" + headers);
}
}
} catch (IOException e) {
e.printStackTrace();
}
}
/**
* 使用HttpClient进行http post请求
* @param url 请求url
* @param params 请求参数
* @return
*/
public static JSONObject post(String url,List<NameValuePair> params) {
JSONObject ret = new JSONObject();
// 创建client
try (CloseableHttpClient client = HttpClientBuilder.create().build()) {
//添加请求url
HttpPost postRequest = new HttpPost(url);
// 添加请求参数
/* List<NameValuePair> params = new ArrayList<>();
params.add(new BasicNameValuePair("_SRVNAME", "server.app.loginAPI"));
params.add(new BasicNameValuePair("_SRVMETHOD", "verifyAccount"));
params.add(new BasicNameValuePair("_DATA", str));*/
postRequest.setEntity(new UrlEncodedFormEntity(params, Consts.UTF_8));
// 执行并获取返回结果到response
try (CloseableHttpResponse response = client.execute(postRequest)) {
// 获取statusCode
Integer statusCode = response.getStatusLine().getStatusCode();
// Media Type
String contentMimeType = ContentType.getOrDefault(response.getEntity()).getMimeType();
// body
String bodyAsString = EntityUtils.toString(response.getEntity());
// head
Header[] headers = response.getHeaders(HttpHeaders.CONTENT_TYPE);
System.out.println("return time:" + new Date());
System.out.println("statusCode:" + statusCode);
System.out.println("contentMinmeType:" + contentMimeType);
System.out.println("body:" + bodyAsString);
System.out.println("head" + headers);
ret = JSONObject.fromObject(bodyAsString);
}
} catch (IOException e) {
e.printStackTrace();
}
return ret;
}
public static void main(String[] args) {
System.out.println("----------------开始--------------------");
//根据外部系统定义的接口组织接口需要的参数
JSONObject jo = new JSONObject();
JSONObject jo2 = new JSONObject();
jo2.put("type", "01");
jo2.put("loginname", "admin");
jo2.put("password", "123456");
jo.put("form", jo2);
List<NameValuePair> params = new ArrayList<>();
params.add(new BasicNameValuePair("_SRVNAME", "server.app.loginAPI"));
params.add(new BasicNameValuePair("_SRVMETHOD", "verifyAccount"));
params.add(new BasicNameValuePair("_DATA", jo.toString()));
String url = "http://192.168.81.107:8080/nl-app-lx/wdk?action=wdk.pub&method=call_service&ajaxparam="+new Date().getTime();
//调用工具方法
JSONObject ret = post(url,params);
//输出返回数据
System.out.println(ret.optString("code"));
System.out.println(ret.optString("desc"));
JSONObject result = ret.optJSONObject("result");
System.out.println(result.optString("account_id"));
System.out.println(result.optString("account_name"));
System.out.println(result.optString("user_name"));
}
}//代码演示结束
4.main方法RUN AS跑起来后，控制台输出的信息如下所示：
