项目A和项目B部署在不同的主机上，或者部署在同一个主机的不同端口下，AB之间的访问涉及跨域。

A需要B响应数据，而B的数据格式不是A想要的，此时可以使用HttpClient实现跨域访问,并且用java代码完成数格式转换。

添加依赖

<dependency>
    <groupId>org.apache.httpcomponents</groupId>
    <artifactId>httpclient</artifactId>
    <version>4.3.5</version>
</dependency>

demo

package com.clc.test;

import java.io.IOException;
import java.net.URI;

import org.apache.http.client.methods.CloseableHttpResponse;
import org.apache.http.client.methods.HttpGet;
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.util.EntityUtils;

public class HttpClientTest {
	public static void main(String[] args) throws IOException {
		CloseableHttpClient httpClient = HttpClients.createDefault();
		CloseableHttpResponse response = null;
		try {
			//创建请求地址
			URI uri = new URIBuilder("https://www.baidu.com/s").setParameter("wd", "csdn").build();
			HttpGet httpGet = new HttpGet(uri);
			//HttpGet httpGet = new HttpGet("https://www.baidu.com/s?wd=csdn");
			
			//发送请求，接收响应数据
			response = httpClient.execute(httpGet);
			
			//获取状态码
			System.out.println(response.getStatusLine().getStatusCode());
			
			//获取响应数据
			String content = EntityUtils.toString(response.getEntity(),"utf-8");
			System.out.println(content);
		} catch (Exception e) {
			e.printStackTrace();
		}finally {
			//关闭资源
			if (response != null) {
				response.close();
			}
			if (httpClient != null) {
				httpClient.close();
			}
		}
	}

}