如何用Java构建RESTful客户端 Java调用REST接口的方法

import okhttp3.*;

import java.io.IOException;

public class JWTClient {

    private final OkHttpClient client = new OkHttpClient();
    private String jwtToken;

    public JWTClient(String username, String password) throws IOException {
        // 假设有一个登录接口，返回JWT Token
        String loginUrl = "https://www.example.com/api/login";
        MediaType JSON = MediaType.parse("application/json; charset=utf-8");
        String json = String.format("{\"username\":\"%s\",\"password\":\"%s\"}", username, password);
        RequestBody body = RequestBody.create(json, JSON);
        Request request = new Request.Builder()
                .url(loginUrl)
                .post(body)
                .build();

        try (Response response = client.newCall(request).execute()) {
            if (!response.isSuccessful()) throw new IOException("Unexpected code " + response);

            // 假设登录接口返回的JSON包含token字段
            String responseBody = response.body().string();
            // 使用Gson或Jackson解析JSON
            // 这里简化处理
            this.jwtToken = "your_jwt_token"; // 替换为实际的token解析代码
        }
    }

    public String get(String url) throws IOException {
        Request request = new Request.Builder()
                .url(url)
                .header("Authorization", "Bearer " + jwtToken) // 添加JWT Token
                .build();

        try (Response response = client.newCall(request).execute()) {
            if (!response.isSuccessful()) throw new IOException("Unexpected code " + response);

            return response.body().string();
        }
    }

    public static void main(String[] args) throws IOException {
        JWTClient client = new JWTClient("user", "password");
        String response = client.get("https://www.example.com/api/protected");
        System.out.println(response);
    }
}

import okhttp3.*;

import java.io.IOException;

public class ErrorHandlingClient {

    private final OkHttpClient client = new OkHttpClient();

    public String get(String url) throws IOException {
        Request request = new Request.Builder()
                .url(url)
                .build();

        try (Response response = client.newCall(request).execute()) {
            if (!response.isSuccessful()) {
                // 检查状态码
                int statusCode = response.code();
                String errorMessage = response.body().string(); // 获取错误信息

                if (statusCode == 404) {
                    // 处理404错误
                    System.out.println("Resource not found: " + url);
                } else if (statusCode >= 500) {
                    // 处理服务器错误，可以尝试重试
                    System.out.println("Server error, retrying...");
                    // 可以在这里添加重试逻辑
                } else {
                    // 处理其他错误
                    System.out.println("Request failed with status code " + statusCode + " and message: " + errorMessage);
                }
                throw new IOException("Request failed with status code " + statusCode);
            }

            return response.body().string();
        } catch (IOException e) {
            // 处理IO异常
            System.err.println("IO Exception: " + e.getMessage());
            throw e; // 重新抛出异常，让上层处理
        }
    }

    public static void main(String[] args) throws IOException {
        ErrorHandlingClient client = new ErrorHandlingClient();
        try {
            String response = client.get("https://www.example.com/api/nonexistent");
            System.out.println(response);
        } catch (IOException e) {
            // 处理异常
            System.err.println("Main method caught exception: " + e.getMessage());
        }
    }
}

import okhttp3.*;

import java.io.IOException;
import java.util.concurrent.CompletableFuture;

public class PerformanceClient {

    private final OkHttpClient client = new OkHttpClient.Builder()
            .addInterceptor(new GzipRequestInterceptor()) // 添加Gzip拦截器
            .build();

    public CompletableFuture<String> getAsync(String url) {
        Request request = new Request.Builder()
                .url(url)
                .build();

        CompletableFuture<String> future = new CompletableFuture<>();

        client.newCall(request).enqueue(new Callback() {
            @Override
            public void onFailure(Call call, IOException e) {
                future.completeExceptionally(e);
            }

            @Override
            public void onResponse(Call call, Response response) throws IOException {
                if (!response.isSuccessful()) {
                    future.completeExceptionally(new IOException("Unexpected code " + response));
                    return;
                }
                try (ResponseBody responseBody = response.body()) {
                    future.complete(responseBody.string());
                }
            }
        });

        return future;
    }

    // Gzip 拦截器
    static class GzipRequestInterceptor implements Interceptor {
        @Override
        public Response intercept(Chain chain) throws IOException {
            Request originalRequest = chain.request();
            if (originalRequest.body() == null || originalRequest.header("Content-Encoding") != null) {
                return chain.proceed(originalRequest);
            }

            Request compressedRequest = originalRequest.newBuilder()
                    .header("Content-Encoding", "gzip")
                    .method(originalRequest.method(), gzip(originalRequest.body()))
                    .build();
            return chain.proceed(compressedRequest);
        }

        private RequestBody gzip(final RequestBody body) {
            return new RequestBody() {
                @Override
                public MediaType contentType() {
                    return body.contentType();
                }

                @Override
                public long contentLength() {
                    return -1; // 无法提前知道压缩后的长度
                }

                @Override
                public void writeTo(BufferedSink sink) throws IOException {
                    BufferedSink gzipSink = Okio.buffer(new GzipSink(sink));
                    body.writeTo(gzipSink);
                    gzipSink.close();
                }
            };
        }
    }

    public static void main(String[] args) throws Exception {
        PerformanceClient client = new PerformanceClient();
        CompletableFuture<String> future = client.getAsync("https://www.example.com");

        future.thenAccept(response -> {
            System.out.println("Response: " + response);
        }).exceptionally(e -> {
            System.err.println("Error: " + e.getMessage());
            return null;
        }).join(); // 等待异步请求完成
    }
}

implementation("com.squareup.okio:okio:3.6.0")