如何使用Java处理网络请求和响应?

原创 Bertha 。 2024-11-13 03:48 28阅读 0赞

在Java中处理网络请求和响应，通常可以使用`java.net`包中的类，或者使用更高级的库如Apache HttpClient、OkHttp等。以下是使用Java标准库和OkHttp库的基本示例。

### 使用Java标准库（`java.net`包）

#### 发送GET请求```javaimport java.io.BufferedReader;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;

public class HttpGetRequest {
 public static void main(String[] args) {
 try {
URL url = new URL("http://example.com");
 HttpURLConnection conn = (HttpURLConnection) url.openConnection();
 conn.setRequestMethod("GET");

int responseCode = conn.getResponseCode();
 System.out.println("Response Code : " + responseCode);

if (responseCode == HttpURLConnection.HTTP_OK) { // Success BufferedReader in = new BufferedReader(new InputStreamReader(conn.getInputStream()));
String inputLine;
 StringBuffer response = new StringBuffer();

while ((inputLine = in.readLine()) != null) {
 response.append(inputLine);
 }
in.close();

//打印结果 System.out.println(response.toString());
} else {
 System.out.println("GET请求没有成功");
 }
} catch (Exception e) {
e.printStackTrace();
 }
 }
}
```#### 发送POST请求```javaimport java.io.BufferedReader;
import java.io.DataOutputStream;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;

public class HttpPostRequest {
 public static void main(String[] args) {
 try {
URL url = new URL("http://example.com");
 HttpURLConnection conn = (HttpURLConnection) url.openConnection();
 conn.setRequestMethod("POST");
 conn.setDoOutput(true);

// 发送POST请求必须设置这个 conn.setRequestProperty("Content-Type", "application/x-www-form-urlencoded");

String urlParameters = "param1=value1&param2=value2";

DataOutputStream wr = new DataOutputStream(conn.getOutputStream());
 wr.writeBytes(urlParameters);
 wr.flush();
 wr.close();

int responseCode = conn.getResponseCode();
 System.out.println("Response Code : " + responseCode);

while ((inputLine = in.readLine()) != null) {
 response.append(inputLine);
 }
in.close();

//打印结果 System.out.println(response.toString());
} else {
 System.out.println("POST请求没有成功");
 }
} catch (Exception e) {
e.printStackTrace();
 }
 }
}
```### 使用OkHttp库OkHttp是一个高效的HTTP客户端，支持同步阻塞调用和异步调用。首先，你需要将OkHttp库添加到你的项目中。

#### Maven依赖```xml<dependency>
<groupId>com.squareup.okhttp3</groupId>
<artifactId>okhttp</artifactId>
<version>4.9.0</version>
</dependency>
```#### 发送GET请求```javaimport okhttp3.OkHttpClient;
import okhttp3.Request;
import okhttp3.Response;

public class OkHttpGetRequest {
 public static void main(String[] args) {
 OkHttpClient client = new OkHttpClient();

Request request = new Request.Builder()
.url("http://example.com")
.build();

try (Response response = client.newCall(request).execute()) {
 System.out.println(response.body().string());
} catch (Exception e) {
e.printStackTrace();
 }
 }
}
```#### 发送POST请求```javaimport okhttp3.*;

public class OkHttpPostRequest {
 public static void main(String[] args) {
 OkHttpClient client = new OkHttpClient();

MediaType mediaType = MediaType.parse("application/x-www-form-urlencoded");
RequestBody body = RequestBody.create(mediaType, "param1=value1&param2=value2");

Request request = new Request.Builder()
.url("http://example.com")
.post(body)
.build();

try (Response response = client.newCall(request).execute()) {
 System.out.println(response.body().string());
} catch (Exception e) {
e.printStackTrace();
 }
 }
}
```这些示例展示了如何使用Java标准库和OkHttp库来发送GET和POST请求，并处理响应。你可以根据需要选择使用哪种方法。OkHttp提供了更多的功能和更好的性能，而Java标准库则不需要额外的依赖。