This is the 11th day of my participation in the Novembermore Challenge
There are many ways to send Http requests in Java, record the relevant request methods, this record Jdk built-in HttpURLConnection, simple and concise, simple to use.
1 HttpURLConnection
HttpURLConnection is a built-in request tool of the Jdk. It is applicable to simple scenarios without relying on third-party JAR packages.
To use this method, you get an URLConnection object by calling url. openConnection and forcing it into an HttpURLConnection object.
java.net.URL
public URLConnection openConnection(a) throws java.io.IOException {
return handler.openConnection(this);
}
Copy the codeJava.net.HttpURLConnection part source code:
abstract public class HttpURLConnection extends URLConnection {
// ...
}
Copy the codeHttpURLConnection is a subclass of URLConnection. Its inner class contains the methods and request codes of its parent class.
Send a GET request, whose main parameters are taken from the URI, as well as request headers,cookies, and other data.
To send a POST request, an HttpURLConnection instance must set setDoOutput(True), whose request body data is written to the output stream returned by HttpURLConnection’s getOutputStream() method.
1 Prepare a SpringBoot project environment
2 Add a controller
@Controller
@Slf4j
public class HelloWorld {
@Override
@GetMapping("/world/getData")
@ResponseBody
public String getData(@RequestParam Map<String, Object> param) {
System.out.println(param.toString());
return Hello World getData method
;
}
@PostMapping("/world/getResult")
@ResponseBody
public String getResult(@RequestBody Map<String, Object> param) {
System.out.println(param.toString());
return Hello World getResult
; }}Copy the codeAdd a utility class that sends requests
package com.cf.demo.http;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.UnsupportedEncodingException;
import java.net.HttpURLConnection;
import java.net.URL;
import java.net.URLEncoder;
import java.util.Iterator;
import java.util.Map;
import java.util.Map.Entry;
import lombok.Data;
import lombok.extern.slf4j.Slf4j;
/** * Http request tool class */
@Slf4j
@Data
public class JdkHttpUtils {
/** * Get the POST request **@returnRequest result */
public static String getPost(String url, Integer connectTimeout, Integer readTimeout, String contentType, Map
heads, Map
params)
,>
,> throws IOException {
URL u;
HttpURLConnection connection = null;
OutputStream out;
try {
u = new URL(url);
connection = (HttpURLConnection) u.openConnection();
connection.setRequestMethod("POST");
connection.setConnectTimeout(connectTimeout);
connection.setReadTimeout(readTimeout);
connection.setRequestProperty("Content-Type", contentType);
// This property must be set for POST requests
connection.setDoOutput(true);
connection.setDoInput(true);
if(heads ! =null) {
for (Map.Entry<String, String> stringStringEntry : heads.entrySet()) {
connection.setRequestProperty(stringStringEntry.getKey(),
stringStringEntry.getValue());
}
}
out = connection.getOutputStream();
if(params ! =null && !params.isEmpty()) {
out.write(toJSONString(params).getBytes());
}
out.flush();
out.close();
// Get the data stream returned by the request
InputStream is = connection.getInputStream();
ByteArrayOutputStream baos = new ByteArrayOutputStream();
// Encapsulate the input stream is and specify the character set
int i;
while((i = is.read()) ! = -1) {
baos.write(i);
}
return baos.toString();
} catch (Exception e) {
log.error("Request exception, message = {}", e.getMessage());
}
return null;
}
/** * Get the POST request **@returnRequest result */
public static String getGet(String url, Integer connectTimeout, Integer readTimeout, String contentType, Map
heads, Map
params)
,>
,> throws IOException {
// Concatenate request parameters
if(params ! =null && !params.isEmpty()) {
url += "?";
if(params ! =null && !params.isEmpty()) {
StringBuilder sb = new StringBuilder();
for (Map.Entry<String, String> stringObjectEntry : params.entrySet()) {
try {
sb.append(stringObjectEntry.getKey()).append("=").append(
URLEncoder.encode(stringObjectEntry.getValue(), "UTF-8"))
.append("&");
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
}
}
sb.delete(sb.length() - 1, sb.length());
url += sb.toString();
}
}
URL u;
HttpURLConnection connection;
u = new URL(url);
connection = (HttpURLConnection) u.openConnection();
connection.setRequestMethod("GET");
connection.setConnectTimeout(connectTimeout);
connection.setReadTimeout(readTimeout);
connection.setRequestProperty("Content-Type", contentType);
if(heads ! =null) {
for(Map.Entry<String, String> stringStringEntry : heads.entrySet()) { connection.setRequestProperty(stringStringEntry.getKey(), stringStringEntry.getValue()); }}// Get the data stream returned by the request
InputStream is = connection.getInputStream();
ByteArrayOutputStream baos = new ByteArrayOutputStream();
// Encapsulate the input stream is and specify the character set
int i;
while((i = is.read()) ! = -1) {
baos.write(i);
}
return baos.toString();
}
/** * Map to Json string */
public static String toJSONString(Map<String, String> map) {
Iterator<Entry<String, String>> i = map.entrySet().iterator();
if(! i.hasNext()) {return "{}";
}
StringBuilder sb = new StringBuilder();
sb.append('{');
for(; ;) { Map.Entry<String, String> e = i.next(); String key = e.getKey(); String value = e.getValue(); sb.append("\" ");
sb.append(key);
sb.append("\" ");
sb.append(':');
sb.append("\" ");
sb.append(value);
sb.append("\" ");
if(! i.hasNext()) {return sb.append('} ').toString();
}
sb.append(', ').append(' '); }}}Copy the code4 Add a test tool class
@Slf4j
public class HttpTest {
// Request an address
public String url = "";
// Request header parameters
public Map<String, String> heads = new HashMap<>();
// Request parameters
public Map<String, String> params = new HashMap<>();
// Data type
public String contentType = "application/json";
// Connection timed out
public Integer connectTimeout = 15000;
// Read times out
public Integer readTimeout = 60000;
@Test
public void testGET(a) {
// 1 Add data
url = "http://localhost:8080/world/getData";
heads.put("token"."hhhhhhhhhhhaaaaaaaa");
params.put("username"."libai");
String result = null;
try {
// 2 Send an Http request and obtain the returned result
result = JdkHttpUtils
.getGet(url, connectTimeout, readTimeout, contentType, heads, params);
} catch (IOException e) {
e.printStackTrace();
}
// 3 Print the result
log.info(result);
}
@Test
public void testPOST(a) {
// 1 Add data
url = "http://localhost:8080/world/getResult";
heads.put("token"."hhhhhhhhhhhaaaaaaaa");
params.put("username"."libai");
String result = null;
try {
// 2 Send an Http request and obtain the returned result
result = JdkHttpUtils
.getPost(url, connectTimeout, readTimeout, contentType, heads, params);
} catch (IOException e) {
e.printStackTrace();
}
// 3 Print the resultlog.info(result); }}Copy the code5 Test Results
POST requests test results
/*
[main] INFO com.cf.demo.HttpTest - <h1> Hello World getResult 方法</h1>
{username=libai}
*/
Copy the codeGET request test results
/* [main] info.cf.demo. HttpTest - Hello World getData method
{username=libai} */
Copy the codeReferences:
www.baeldung.com/java-http-r…