In Java development, to make calls between services, you need to use HttpClient to send HTTP requests. The following is the code that simulates HTTP sending POST or GET requests using Java
1. Import HTTP dependencies in pom.xml
<!-- HTTP请求依赖 -->
<dependency>
<groupId>org.apache.httpcomponents</groupId>
<artifactId>httpclient</artifactId>
<version>4.5.2</version>
</dependency>
<!-- json依赖 -->
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>fastjson</artifactId>
<version>1.2.47</version>
</dependency>
2. When sending a Post or get request,
please note when you need to pass parameters: text parameters use StringEntity, parameters are placed in the json object, and file parameters use MultipartEntityBuilder
package com.dascom.smallroutine.utils;
import java.io.IOException;
import com.alibaba.fastjson.JSONObject;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.ResponseHandler;
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.StringEntity;
import org.apache.http.impl.client.BasicResponseHandler;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.util.EntityUtils;
import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
public class HttpClientUtil {
//日志输出
private static Logger logger = LogManager.getLogger(HttpClientUtil.class);
/**
* 发送get请求 调用这个方法
* @param url
* @return str //返回请求的内容
* @throws Exception
*/
public static String doGet(String url){
// 创建Httpclient对象
CloseableHttpClient httpClient = HttpClients.createDefault();;
String returnValue = null;
// 创建http GET请求
HttpGet httpGet = new HttpGet(url);
CloseableHttpResponse response = null;
try {
//执行请求
response = httpClient.execute(httpGet);
//判断返回状态是否为200
if(response.getStatusLine().getStatusCode() == 200) {
//请求体内容
returnValue = EntityUtils.toString(response.getEntity(), "UTF-8");
return returnValue;
}
} catch (ClientProtocolException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} finally {
if (response != null) {
try {
response.close();
} catch (IOException e) {
logger.error("response关闭失败！");
e.printStackTrace();
}
}
try {
httpClient.close();
} catch (IOException e) {
logger.error("httpClient关闭失败！");
e.printStackTrace();
}
}
return returnValue;
}
/**
* 发送Post请求 调用这个方法 带json参数
* @param url 要请求的地址
* @param json 要发送的json格式数据
* @return 返回的数据
*/
public static String doPostWithJson(String url,JSONObject json){
String returnValue = null;
CloseableHttpClient httpclient = null;
ResponseHandler<String> responseHandler = new BasicResponseHandler();
try {
//创建httpclient对象
httpclient = HttpClients.createDefault();
//创建http POST请求
HttpPost httpPost = new HttpPost(url);
//文本参数用StringEntity,文件参数用MultipartEntityBuilder
StringEntity requestEntity = new StringEntity(json.toJSONString(),"utf-8");
requestEntity.setContentEncoding("UTF-8");
httpPost.setHeader("Content-type","application/json");//请求头
httpPost.setEntity(requestEntity);
//发送请求，获取返回值
returnValue = httpclient.execute(httpPost,responseHandler);
}catch (Exception e) {
logger.error("发送post请求失败！"+e.getMessage());
}finally {
try {
httpclient.close();
} catch (IOException e) {
logger.error("httpclient关闭失败！"+e.getMessage());
}
}
return returnValue;
}
}
3. Testing
public class Test {
public static void main(String[] args) {
//GET请求访问
HttpClientUtil.doGet("http://baidu.com");
//POST请求访问
JSONObject json = new JSONObject();
json.put("data", "成功");//参数
HttpClientUtil.doPostWithJson("http://baidu.com", json);
}
}
If you want to request a file parameter interface, the example is as follows
Code
package com.example.demo.controller;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import org.apache.http.HttpEntity;
import org.apache.http.client.ResponseHandler;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.entity.mime.MultipartEntityBuilder;
import org.apache.http.impl.client.BasicResponseHandler;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;
import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.multipart.MultipartFile;
import com.alibaba.fastjson.JSONObject;
@RestController
@RequestMapping("/v1.0")
public class PrintController {
//日志输出
private static Logger logger = LogManager.getLogger(PrintController.class);
@RequestMapping(value="/monitprint",method=RequestMethod.POST,produces ="application/json;charset=utf-8")
public JSONObject monitoringPrint(@RequestParam(required=false) MultipartFile file) {
//POST请求访问
JSONObject json = new JSONObject();
String s=PrintController.doPostWithJson("http://127.0.0.1:20173/v2.0/print/0015CA7350020300", file);
if(s!=null&&!"".equals(s)) {
json.put("data", "访问成功");
}else{
json.put("data", "访问失败");
}
return json;
}
/**
* 发送Post请求 调用这个方法 带json参数
* @param url 要请求的地址
* @param json 要发送的json格式数据
* @return 返回的数据
*/
public static String doPostWithJson(String url,MultipartFile Mfile){
String returnValue = null;
CloseableHttpClient httpclient = null;
ResponseHandler<String> responseHandler = new BasicResponseHandler();
try {
//创建httpclient对象
httpclient = HttpClients.createDefault();
//创建http POST请求
HttpPost httpPost = new HttpPost(url);
//文本参数用StringEntity,文件参数用MultipartEntityBuilder
MultipartEntityBuilder builder = MultipartEntityBuilder.create();
//MultipartFile转File
File file=multipartFileToFile(Mfile);
builder.addBinaryBody("file", file);
httpPost.setHeader("File-Type","pdf");//请求头
HttpEntity reqEntity = builder.build();
httpPost.setEntity(reqEntity);
//发送请求，获取返回值
returnValue = httpclient.execute(httpPost,responseHandler);
}catch (Exception e) {
logger.error("发送post请求失败！"+e.getMessage());
}finally {
try {
httpclient.close();
} catch (IOException e) {
logger.error("httpclient关闭失败！"+e.getMessage());
}
}
return returnValue;
}
/**
* MultipartFile 转 File
* @param file
* @throws Exception
*/
public static File multipartFileToFile(MultipartFile file) throws Exception {
File toFile = null;
if (file.equals("") || file.getSize() <= 0) {
file = null;
} else {
InputStream ins = null;
ins = file.getInputStream();
toFile = new File(file.getOriginalFilename());
inputStreamToFile(ins, toFile);
ins.close();
}
return toFile;
}
/**
* 获取流文件
* @param ins
* @param file
*/
private static void inputStreamToFile(InputStream ins, File file) {
try {
OutputStream os = new FileOutputStream(file);
int bytesRead = 0;
byte[] buffer = new byte[8192];
while ((bytesRead = ins.read(buffer, 0, 8192)) != -1) {
os.write(buffer, 0, bytesRead);
}
os.close();
ins.close();
} catch (Exception e) {
e.printStackTrace();
}
}
}
Everyone is welcome to read. I have limited knowledge, and there are inevitably mistakes or omissions in the blog I wrote. I hope you guys can give me some advice. Thank you.