【我要编程】Java技术手册之调用http请求的示例

该示例展示如何调用对方写好的http接口,数据格式对方需要双方协调定义好。

思路如下:我方调用对方接口(另一个服务器上已写好,不同域名,不同端口,需要进行跨域),传递必要参数,如id等,对方接受参数进行查询,查询到的数据封装成json格式返回,我方接收到的是一个流对象,需要转换成json字符串,再把json字符串转换成对象,封装到结果集里返回(这里返回的是调用我方接口的使用者,如手机app调用我的接口)。

@RequestMapping(value = "details", method = RequestMethod.GET)

public ResponseResult details(@RequestParam("processInstanceId") String processInstanceId,

String recordNumber,Integer pageSize, HttpServletRequest request, HttpServletResponse response) {

String url =

"http://218.95.182.35:5555/dcxm/Compass/workflow/data/hisInfo?processInstanceId="+processInstanceId;

String jo = HttpUtils.httpRequest(url, "GET", null,null);

//双方定义好的数据格式

CapResultBean jb = JsonUtil.jsonStrToPo(jo, CapResultBean.class);

    boolean success = jb.isSuccess();

if(success == true) {

return ResponseResult.ok(jb.getObj()); //ResponseResult是自定义的结果集

}

return ResponseResult.build(500, "服务器异常");

}

HttpUtils工具类:

package com.hollysmart.app.common.utils;


import java.io.BufferedReader;

import java.io.IOException;

import java.io.InputStream;

import java.io.InputStreamReader;

import java.io.OutputStream;

import java.net.ConnectException;

import java.net.HttpURLConnection;

import java.net.URL;


import org.apache.http.HttpEntity;

import org.apache.http.HttpStatus;

import org.apache.http.client.methods.CloseableHttpResponse;

import org.apache.http.client.methods.HttpGet;

import org.apache.http.impl.client.CloseableHttpClient;

import org.apache.http.impl.client.HttpClients;

import org.apache.http.util.EntityUtils;

import org.slf4j.Logger;

import org.slf4j.LoggerFactory;


import net.sf.json.JSONObject;


public abstract class HttpUtils {


private static final Logger logger = LoggerFactory.getLogger(HttpUtils.class);


private HttpUtils() {

}


/**

*根据Url发送GET请求

 *

 * @param url

 * @return

 */

public static String get(String url) {

CloseableHttpClient httpClient = HttpClients.createDefault();

HttpGet httpGet = new HttpGet(url);

CloseableHttpResponse response = null;

String result = "";

try {

response = httpClient.execute(httpGet);


/**请求发送成功,并得到响应 **/

if (response.getStatusLine().getStatusCode() == HttpStatus.SC_OK) {

HttpEntity entity = response.getEntity();


result = EntityUtils.toString(entity, "UTF-8");


EntityUtils.consume(entity);

}

} catch (Exception e) {

logger.error("远程数据获取失败!", e);

e.printStackTrace();

} finally {

try {

if (response != null)

response.close();

} catch (IOException e) {

e.printStackTrace();

}

}


return result;

}

/**

*描述: 发起http请求并获取结果

 *

 * @param requestUrl

*请求地址

 * @param requestMethod

*请求方式(GET、POST)

 * @param outputStr

*提交的数据

* @return JSONObject(通过JSONObject.get(key)的方式获取json对象的属性值)

 */

public static String httpRequest(String requestUrl, String requestMethod, String outputStr,String dataType) {

StringBuffer buffer = new StringBuffer();

String result = null;

try {


URL url = new URL(requestUrl);

HttpURLConnection httpUrlConn = (HttpURLConnection) url.openConnection();

httpUrlConn.setDoOutput(true);

httpUrlConn.setDoInput(true);

httpUrlConn.setUseCaches(false);


//设置请求方式(GET/POST)

httpUrlConn.setRequestMethod(requestMethod);

if(StringUtils.equals(dataType, "json")) {

httpUrlConn.setRequestProperty("Content-type", "application/json");

}


if ("GET".equalsIgnoreCase(requestMethod))

httpUrlConn.connect();


//当有数据需要提交时

if (null != outputStr) {

OutputStream outputStream = httpUrlConn.getOutputStream();

//注意编码格式,防止中文乱码

outputStream.write(outputStr.getBytes("UTF-8"));

outputStream.close();

}


//将返回的输入流转换成字符串

InputStream inputStream = httpUrlConn.getInputStream();

InputStreamReader inputStreamReader =

new InputStreamReader(inputStream, "utf-8");

BufferedReader bufferedReader = new BufferedReader(inputStreamReader);


String str = null;

while ((str = bufferedReader.readLine()) != null) {

buffer.append(str);

}

bufferedReader.close();

inputStreamReader.close();

//释放资源

inputStream.close();

inputStream = null;

httpUrlConn.disconnect();

result = buffer.toString();

//jsonObject = JSONObject.fromObject(buffer.toString());

} catch (ConnectException ce) {

ce.printStackTrace();

} catch (Exception e) {

e.printStackTrace();

}

return result;

}

}


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