java okhttp3 工具类

下面是一个简单的 Java OkHttp3 工具类的示例代码：

import okhttp3.*;

import java.io.IOException;
import java.util.Map;

public class OkHttpUtil {
    private static final MediaType JSON = MediaType.parse("application/json; charset=utf-8");
    private static final OkHttpClient client = new OkHttpClient();

    /**
     * GET 请求
     *
     * @param url 请求地址
     * @return 响应结果字符串
     * @throws IOException 请求失败抛出异常
     */
    public static String get(String url) throws IOException {
        Request request = new Request.Builder()
                .url(url)
                .build();

        try (Response response = client.newCall(request).execute()) {
            return response.body().string();
        }
    }

    /**
     * POST 请求
     *
     * @param url    请求地址
     * @param params 请求参数
     * @return 响应结果字符串
     * @throws IOException 请求失败抛出异常
     */
    public static String post(String url, Map<String, String> params) throws IOException {
        FormBody.Builder formBuilder = new FormBody.Builder();
        for (Map.Entry<String, String> entry : params.entrySet()) {
            formBuilder.add(entry.getKey(), entry.getValue());
        }
        RequestBody requestBody = formBuilder.build();

        Request request = new Request.Builder()
                .url(url)
                .post(requestBody)
                .build();

        try (Response response = client.newCall(request).execute()) {
            return response.body().string();
        }
    }

    /**
     * POST 请求，请求体为 JSON 格式
     *
     * @param url  请求地址
     * @param json 请求体 JSON 字符串
     * @return 响应结果字符串
     * @throws IOException 请求失败抛出异常
     */
    public static String postJson(String url, String json) throws IOException {
        RequestBody requestBody = RequestBody.create(JSON, json);

        Request request = new Request.Builder()
                .url(url)
                .post(requestBody)
                .build();

        try (Response response = client.newCall(request).execute()) {
            return response.body().string();
        }
    }
}

使用示例：

public class Main {
    public static void main(String[] args) throws IOException {
        // GET 请求
        System.out.println(OkHttpUtil.get("https://www.baidu.com"));

        // POST 请求，表单参数
        Map<String, String> params = new HashMap<>();
        params.put("name", "张三");
        params.put("age", "18");
        System.out.println(OkHttpUtil.post("http://localhost:8080/user", params));

        // POST 请求，JSON 参数
        String json = "{\"name\":\"张三\",\"age\":18}";
        System.out.println(OkHttpUtil.postJson("http://localhost:8080/user", json));
    }
}