Java中发送Http请求之HttpURLConnection
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Java中发送Http请求之HttpURLConnection
Java中发送Http请求的方式有很多,记录一下相关的请求方式,本次记录Jdk自带的HttpURLConnection,简单简洁,使用简单.
1 HttpURLConnection
HttpURLConnection是Jdk自带的请求工具,不用依赖第三方jar包,适用简单的场景使用.
使用方式是, 通过调用URL.openConnection方法,得到一个URLConnection对象,并强转为HttpURLConnection对象.
java.net.URL部分源码:
public URLConnection openConnection() throws java.io.IOException {
return handler.openConnection(this);
}
java.net.HttpURLConnection部分源码:
abstract public class HttpURLConnection extends URLConnection {
// ...
}
从代码可知HttpURLConnection是URLConnection子类, 其内类中主要放置的是一些父类的方法和请求码信息.
发送GET请求, 其主要的参数从URI中获取,还有请求头,cookies等数据.
发送POST请求, HttpURLConnection实例必须设置setDoOutput(true),其请求体数据写入由HttpURLConnection的getOutputStream()方法返回的输出流来传输数据.
1 准备一个SpringBoot项目环境
2 添加一个控制器
@Controller
@Slf4j
public class HelloWorld {
@Override
@GetMapping("/world/getData")
@ResponseBody
public String getData(@RequestParam Map<String, Object> param) {
System.out.println(param.toString());
return "<h1> Hello World getData 方法</h1>";
}
@PostMapping("/world/getResult")
@ResponseBody
public String getResult(@RequestBody Map<String, Object> param) {
System.out.println(param.toString());
return "<h1> Hello World getResult 方法</h1>";
}
}
3 添加一个发送请求的工具类
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请求工具类
*/
@Slf4j
@Data
public class JdkHttpUtils {
/**
* 获取 POST请求
*
* @return 请求结果
*/
public static String getPost(String url, Integer connectTimeout,
Integer readTimeout, String contentType, Map<String, String> heads,
Map<String, String> 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);
// POST请求必须设置该属性
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();
// 获取请求返回的数据流
InputStream is = connection.getInputStream();
ByteArrayOutputStream baos = new ByteArrayOutputStream();
// 封装输入流is，并指定字符集
int i;
while ((i = is.read()) != -1) {
baos.write(i);
}
return baos.toString();
} catch (Exception e) {
log.error("请求发生异常,信息为= {} ", e.getMessage());
}
return null;
}
/**
* 获取 POST请求
*
* @return 请求结果
*/
public static String getGet(String url, Integer connectTimeout,
Integer readTimeout, String contentType, Map<String, String> heads,
Map<String, String> params) throws IOException {
// 拼接请求参数
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());
}
}
// 获取请求返回的数据流
InputStream is = connection.getInputStream();
ByteArrayOutputStream baos = new ByteArrayOutputStream();
// 封装输入流is，并指定字符集
int i;
while ((i = is.read()) != -1) {
baos.write(i);
}
return baos.toString();
}
/**
* Map转Json字符串
*/
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(' ');
}
}
}
4 添加测试工具类
@Slf4j
public class HttpTest {
// 请求地址
public String url = "";
// 请求头参数
public Map<String, String> heads = new HashMap<>();
// 请求参数
public Map<String, String> params = new HashMap<>();
// 数据类型
public String contentType = "application/json";
// 连接超时
public Integer connectTimeout = 15000;
// 读取超时
public Integer readTimeout = 60000;
@Test
public void testGET() {
// 1 添加数据
url = "http://localhost:8080/world/getData";
heads.put("token", "hhhhhhhhhhhaaaaaaaa");
params.put("username", "libai");
String result = null;
try {
// 2 发送Http请求,获取返回结果
result = JdkHttpUtils
.getGet(url, connectTimeout, readTimeout, contentType, heads, params);
} catch (IOException e) {
e.printStackTrace();
}
// 3 打印结果
log.info(result);
}
@Test
public void testPOST() {
// 1 添加数据
url = "http://localhost:8080/world/getResult";
heads.put("token", "hhhhhhhhhhhaaaaaaaa");
params.put("username", "libai");
String result = null;
try {
// 2 发送Http请求,获取返回结果
result = JdkHttpUtils
.getPost(url, connectTimeout, readTimeout, contentType, heads, params);
} catch (IOException e) {
e.printStackTrace();
}
// 3 打印结果
log.info(result);
}
}
5 测试结果
POST请求测试结果
/*
[main] INFO com.cf.demo.HttpTest - <h1> Hello World getResult 方法</h1>
{username=libai}
*/
GET请求测试结果
/*
[main] INFO com.cf.demo.HttpTest - <h1> Hello World getData方法</h1>
{username=libai}
*/
参考资料:
https://www.baeldung.com/java-http-request
标签：Map,Java,请求,connection,sb,Http,public,HttpURLConnection 来源： https://blog.csdn.net/ABestRookie/article/details/121440168