背景
虽然有了dubbo提供的服务接口，但是在项目与项目之间仍旧存在着http访问的接口。那么怎么调用呢？httpClient这个工具包用起来就十分的方便了。一般获取到接口返回的数据时，都需要做json反序列化为对象。可以使用spring-mvc依赖的 com.fasterxml.jackson.core。也可以使用com.alibaba.fastjson
参考资料：
https://www.cnblogs.com/sharpest/p/6406013.html
https://blog.csdn.net/xiaoxian8023/article/details/49865335
https://blog.csdn.net/xiaoxian8023/article/details/49619777
引用jar包
<!-- https://mvnrepository.com/artifact/org.apache.httpcomponents/httpclient -->
<dependency>
<groupId>org.apache.httpcomponents</groupId>
<artifactId>httpclient</artifactId>
<version>4.5.5</version>
</dependency>
json的jar包，选择其中一个就可以
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>fastjson</artifactId>
<version>1.2.6</version>
</dependency>
<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-databind</artifactId>
<version>2.9.5</version>
</dependency>
http进行访问的基本步骤
使用HttpClient发送请求、接收响应很简单，一般需要如下几步即可。
1. 创建HttpClient对象。一般都使用连接池来创建
2. 创建请求方法的实例，并指定请求URL。如果需要发送GET请求，创建HttpGet对象；如果需要发送POST请求，创建HttpPost对象。
3. 如果需要发送请求参数，可调用HttpGet、HttpPost共同的setParams(HetpParams params)方法来添加请求参数；对于HttpPost对象而言，也可调用setEntity(HttpEntity entity)方法来设置请求参数。
4. 调用HttpClient对象的execute(HttpUriRequest request)发送请求，该方法返回一个HttpResponse。一般HttpClient是从http连接池里获取。
5. 调用HttpResponse的getAllHeaders()、getHeaders(String name)等方法可获取服务器的响应头；调用HttpResponse的getEntity()方法可获取HttpEntity对象，该对象包装了服务器的响应内容。程序可通过该对象获取服务器的响应内容。
6. 释放连接。无论执行方法是否成功，都必须释放连接。
代码篇
连接池对象
import org.apache.http.config.Registry;
import org.apache.http.config.RegistryBuilder;
import org.apache.http.conn.socket.ConnectionSocketFactory;
import org.apache.http.conn.socket.LayeredConnectionSocketFactory;
import org.apache.http.conn.socket.PlainConnectionSocketFactory;
import org.apache.http.conn.ssl.SSLConnectionSocketFactory;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.impl.conn.PoolingHttpClientConnectionManager;
import javax.annotation.PostConstruct;
import javax.net.ssl.SSLContext;
/**
* @author WGP
* @description 连接池管理对象
* @date 2018/5/6
**/
public class HttpConnectionManager {
PoolingHttpClientConnectionManager cm = null;
@PostConstruct
public void init(){
LayeredConnectionSocketFactory sslsf = null;
try{
sslsf = new SSLConnectionSocketFactory(SSLContext.getDefault());
}catch (Exception e){
e.printStackTrace();
}
Registry<ConnectionSocketFactory> socketFactoryRegistry =
RegistryBuilder.<ConnectionSocketFactory>create().register("https",sslsf)
.register("http",new PlainConnectionSocketFactory()).build();
cm = new PoolingHttpClientConnectionManager(socketFactoryRegistry);
cm.setMaxTotal(200);
cm.setDefaultMaxPerRoute(20);
}
public CloseableHttpClient getHttpClient(){
CloseableHttpClient httpClient = HttpClients.custom().setConnectionManager(cm).build();
return httpClient;
}
}
基本使用的方法
public class HttpClient {
public void postJson() throws Exception {
String url = "http:/localhost/shop";
//1、创建http连接
CloseableHttpClient httpClient = new HttpConnectionManager().getHttpClient();
CloseableHttpResponse response = null;
try {
//2、创建请求对象
HttpPost httpPost = new HttpPost(url);
// 3、设置请求头及数据
httpPost.addHeader(HTTP.CONTENT_TYPE,
"application/x-www-form-urlencoded");
String json = "{'ids':['html1','html2'}";
StringEntity se = new StringEntity(json);
se.setContentEncoding("UTF-8");
httpPost.setEntity(se);
//4、访问http接口
response = httpClient.execute(httpPost);
if(response != null && response.getStatusLine().getStatusCode() == 200){
HttpEntity entity = response.getEntity();
if (entity != null) {
String res = EntityUtils.toString(entity, "UTF-8");
//5、下面可以对res做json反序列化处理
}
}
} catch (Exception e) {
throw e;
} finally {
closeHttp(httpClient,response);
}
}
public void postForm() throws Exception {
CloseableHttpClient httpClient = new HttpConnectionManager().getHttpClient();
CloseableHttpResponse response = null;
try {
String url = "your/path";
HttpPost httpPost = new HttpPost(url);
List<NameValuePair> formParams = new ArrayList<>(8);
formParams.add(new BasicNameValuePair("username", "yourname"));
formParams.add(new BasicNameValuePair("password", "pass"));
UrlEncodedFormEntity uefEntity = new UrlEncodedFormEntity(formParams, "UTF-8");
httpPost.setEntity(uefEntity);
response = httpClient.execute(httpPost);
if(response != null && response.getStatusLine().getStatusCode() == 200){
HttpEntity entity = response.getEntity();
if (entity != null) {
String res = EntityUtils.toString(entity, "UTF-8");
//下面可以对res做json反序列化处理
}
}
} catch (Exception e) {
throw e;
} finally {
closeHttp(httpClient, response);
}
}
public void getRequest() throws Exception {
CloseableHttpClient httpClient = new HttpConnectionManager().getHttpClient();
CloseableHttpResponse response = null;
try {
String url = "your/get/path";
HttpGet httpGet = new HttpGet(url);
response = httpClient.execute(httpGet);
if(response != null && response.getStatusLine().getStatusCode() == 200){
HttpEntity entity = response.getEntity();
if (entity != null) {
String res = EntityUtils.toString(entity, "UTF-8");
//下面可以对res做json反序列化处理
}
}
} catch (Exception e) {
throw e;
} finally {
closeHttp(httpClient, response);
}
}
private void closeHttp(CloseableHttpClient httpClient, CloseableHttpResponse response) throws IOException {
try {
if (httpClient != null) {
httpClient.close();
}
if (response != null) {
response.close();
}
} catch (IOException ex) {
throw ex;
}
}
}