API调用常见问题：Java对接RESTful服务的实例分析

原创缺乏、安全感 2024-10-21 22:54 41阅读 0赞

在Java中对接RESTful服务，通常我们会使用HttpURLConnection、Apache HttpClient或者现代的Spring Boot REST客户端。以下是一个简单的例子：

1. 使用HttpURLConnection：

```java
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;

public class RestClientExample {
    public static void main(String[] args) throws Exception {
        // RESTful服务URL
        URL url = new URL("http://example.com/api/data");

// 创建HttpURLConnection
        HttpURLConnection connection = (HttpURLConnection) url.openConnection();

// 设置请求方法为GET
        connection.setRequestMethod("GET");

// 获取响应码，若非2xx，通常需要进一步处理
        int responseCode = connection.getResponseCode();
        System.out.println("Response Code: " + responseCode);

// 读取并处理响应内容
        if (responseCode == 200) {
            BufferedReader reader = new BufferedReader(new InputStreamReader(connection.getInputStream()))));
            StringBuilder contentBuilder = new StringBuilder();

String line;
            while ((line = reader.readLine()) != null)) {
                contentBuilder.append(line).append("\n");
            }

reader.close();
            System.out.println("Response Content: " + contentBuilder.toString());
        }
    }
}
```

2. 使用Apache HttpClient：

```java
import org.apache.http.HttpEntity;
import org.apache.http.client.methods.CloseableHttpResponse;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;

public class ApacheHttpClientExample {
    public static void main(String[] args) throws Exception {
        // 创建CloseableHttpClient实例
        CloseableHttpClient httpClient = HttpClients.createDefault();

// 使用HttpURLConnection方式，但是使用Apache HttpClient
        HttpGet httpGet = new HttpGet("http://example.com/api/data"));
        try (CloseableHttpResponse response = httpClient.execute(httpGet)) {
            System.out.println("Response Code: " + response.getStatusLine().getStatusCode());

if (response.getStatusLine().getStatusCode() == 200) {
                HttpEntity entity = response.getEntity();
                if (entity != null) {
                    byte[] contentBytes = entity.getContent();
                    StringBuilder contentBuilder = new StringBuilder();

if (contentBytes != null) {
                        for (byte b : contentBytes) {
                            contentBuilder.append((char) b)).append("\n");
                        }
                    }

System.out.println("Response Content: " + contentBuilder.toString());
                }
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            httpClient.close();
        }
    }
}
```

以上两种方式都是对接RESTful服务的常见方法。在实际项目中，可能还会结合使用其他工具或框架来优化开发流程和提升性能。