在
Java 中可以借助不同方式实现 HTTP 的 GET、POST、PUT 等常见
请求，以下给出几种实现方法。
### 使用 HttpURLConnection 实现
`HttpURLConnection` 属于
Java 标准库的一部分，可用于发起各类 HTTP
请求。
#### GET
请求示例
```
java
import
java.io.BufferedReader;
import
java.io.InputStreamReader;
import
java.net.HttpURLConnection;
import
java.net.URL;
public class HttpGetExample {
public static void main(String[] args) throws Exception {
URL url = new URL("http://example.com/api/data");
HttpURLConnection connection = (HttpURLConnection) url.openConnection();
connection.setRequestMethod("GET");
int responseCode = connection.getResponseCode();
if (responseCode == HttpURLConnection.HTTP_OK) {
BufferedReader in = new BufferedReader(new InputStreamReader(connection.getInputStream()));
String inputLine;
StringBuilder response = new StringBuilder();
while ((inputLine = in.readLine()) !=
null) {
response.append(inputLine);
}
in.close();
System.out.println(response.toString());
} else {
System.out.println("GET request failed. Response Code: " + responseCode);
}
}
}
```
#### POST
请求示例
```
java
import
java.io.DataOutputStream;
import
java.io.InputStreamReader;
import
java.net.HttpURLConnection;
import
java.net.URL;
import
java.nio.charset.StandardCharsets;
public class HttpPostExample {
public static void main(String[] args) throws Exception {
URL url = new URL("http://example.com/api/submit");
HttpURLConnection connection = (HttpURLConnection) url.openConnection();
connection.setRequestMethod("POST");
connection.setDoOutput(true);
String postData = "param1=value1¶m2=value2";
byte[] postDataBytes = postData.getBytes(StandardCharsets.UTF_8);
connection.setRequestProperty("Content-Type", "application/x-www-form-urlencoded");
connection.setRequestProperty("Content-Length", String.valueOf(postDataBytes.length));
DataOutputStream wr = new DataOutputStream(connection.getOutputStream());
wr.write(postDataBytes);
wr.flush();
wr.close();
int responseCode = connection.getResponseCode();
if (responseCode == HttpURLConnection.HTTP_OK) {
BufferedReader in = new BufferedReader(new InputStreamReader(connection.getInputStream()));
String inputLine;
StringBuilder response = new StringBuilder();
while ((inputLine = in.readLine()) !=
null) {
response.append(inputLine);
}
in.close();
System.out.println(response.toString());
} else {
System.out.println("POST request failed. Response Code: " + responseCode);
}
}
}
```
#### PUT
请求示例
```
java
import
java.io.DataOutputStream;
import
java.io.InputStreamReader;
import
java.net.HttpURLConnection;
import
java.net.URL;
import
java.nio.charset.StandardCharsets;
public class HttpPutExample {
public static void main(String[] args) throws Exception {
URL url = new URL("http://example.com/api/update");
HttpURLConnection connection = (HttpURLConnection) url.openConnection();
connection.setRequestMethod("PUT");
connection.setDoOutput(true);
String putData = "param1=newValue1¶m2=newValue2";
byte[] putDataBytes = putData.getBytes(StandardCharsets.UTF_8);
connection.setRequestProperty("Content-Type", "application/x-www-form-urlencoded");
connection.setRequestProperty("Content-Length", String.valueOf(putDataBytes.length));
DataOutputStream wr = new DataOutputStream(connection.getOutputStream());
wr.write(putDataBytes);
wr.flush();
wr.close();
int responseCode = connection.getResponseCode();
if (responseCode == HttpURLConnection.HTTP_OK) {
BufferedReader in = new BufferedReader(new InputStreamReader(connection.getInputStream()));
String inputLine;
StringBuilder response = new StringBuilder();
while ((inputLine = in.readLine()) !=
null) {
response.append(inputLine);
}
in.close();
System.out.println(response.toString());
} else {
System.out.println("PUT request failed. Response Code: " + responseCode);
}
}
}
```
### 使用 Apache HttpClient 实现
Apache HttpClient 是一个功能强大的 HTTP 客户端库，能让 HTTP
请求的实现更为简便。
#### 添加依赖
若使用 Maven 项目，在 `pom.xml` 中添加以下依赖：
```xml
<dependency>
<groupId>org.apache.httpcomponents</groupId>
<artifactId>httpclient</artifactId>
<version>4.5.13</version>
</dependency>
```
#### GET
请求示例
```
java
import org.apache.http.HttpResponse;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.util.EntityUtils;
public class HttpClientGetExample {
public static void main(String[] args) throws Exception {
HttpClient httpClient = HttpClients.createDefault();
HttpGet httpGet = new HttpGet("http://example.com/api/data");
HttpResponse response = httpClient.execute(httpGet);
int statusCode = response.getStatusLine().getStatusCode();
if (statusCode == 200) {
String responseBody = EntityUtils.toString(response.getEntity());
System.out.println(responseBody);
} else {
System.out.println("GET request failed. Status Code: " + statusCode);
}
}
}
```
#### POST
请求示例
```
java
import org.apache.http.HttpResponse;
import org.apache.http.NameValuePair;
import org.apache.http.client.HttpClient;
import org.apache.http.client.entity.UrlEncodedFormEntity;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.message.BasicNameValuePair;
import org.apache.http.util.EntityUtils;
import
java.util.ArrayList;
import
java.util.List;
public class HttpClientPostExample {
public static void main(String[] args) throws Exception {
HttpClient httpClient = HttpClients.createDefault();
HttpPost httpPost = new HttpPost("http://example.com/api/submit");
List<NameValuePair> params = new ArrayList<>();
params.add(new BasicNameValuePair("param1", "value1"));
params.add(new BasicNameValuePair("param2", "value2"));
httpPost.setEntity(new UrlEncodedFormEntity(params));
HttpResponse response = httpClient.execute(httpPost);
int statusCode = response.getStatusLine().getStatusCode();
if (statusCode == 200) {
String responseBody = EntityUtils.toString(response.getEntity());
System.out.println(responseBody);
} else {
System.out.println("POST request failed. Status Code: " + statusCode);
}
}
}
```
#### PUT
请求示例
```
java
import org.apache.http.HttpResponse;
import org.apache.http.NameValuePair;
import org.apache.http.client.HttpClient;
import org.apache.http.client.entity.UrlEncodedFormEntity;
import org.apache.http.client.methods.HttpPut;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.message.BasicNameValuePair;
import org.apache.http.util.EntityUtils;
import
java.util.ArrayList;
import
java.util.List;
public class HttpClientPutExample {
public static void main(String[] args) throws Exception {
HttpClient httpClient = HttpClients.createDefault();
HttpPut httpPut = new HttpPut("http://example.com/api/update");
List<NameValuePair> params = new ArrayList<>();
params.add(new BasicNameValuePair("param1", "newValue1"));
params.add(new BasicNameValuePair("param2", "newValue2"));
httpPut.setEntity(new UrlEncodedFormEntity(params));
HttpResponse response = httpClient.execute(httpPut);
int statusCode = response.getStatusLine().getStatusCode();
if (statusCode == 200) {
String responseBody = EntityUtils.toString(response.getEntity());
System.out.println(responseBody);
} else {
System.out.println("PUT request failed. Status Code: " + statusCode);
}
}
}
```
本文介绍在跨语言调用中，如何处理Java传来的null参数，在Python中将其转换为等价的None。这对于理解不同编程语言间的数据类型转换至关重要。
扫一扫
414
被折叠的 条评论
为什么被折叠?
到【灌水乐园】发言
