Java 重连机制的几种实现方法

import okhttp3.*;

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

public class HttpRetryClient {
    private final OkHttpClient client;

    public HttpRetryClient() {
        this.client = new OkHttpClient.Builder()
                .connectTimeout(5, TimeUnit.SECONDS)
                .readTimeout(5, TimeUnit.SECONDS)
                .retryOnConnectionFailure(true) // 启用连接失败自动重试
                .build();
    }

    public String get(String url) {
        int maxRetries = 3;
        int attempt = 0;

        while (attempt < maxRetries) {
            try {
                Request request = new Request.Builder().url(url).build();
                Response response = client.newCall(request).execute();
                if (response.isSuccessful()) {
                    return response.body().string();
                }
            } catch (IOException e) {
                System.out.println("请求失败，正在重试: " + attempt);
            }
            attempt++;
            try {
                Thread.sleep((long) Math.pow(2, attempt) * 1000); // 指数退避
            } catch (InterruptedException ignored) {}
        }
        throw new RuntimeException("请求失败超过最大次数");
    }

    public static void main(String[] args) {
        HttpRetryClient client = new HttpRetryClient();
        System.out.println(client.get("http://example.com"));
    }
}

import okhttp3.*;

public class WebSocketReconnect {
    private OkHttpClient client = new OkHttpClient();
    private WebSocket webSocket;
    private final String url = "ws://localhost:8080/ws";
    private int retryCount = 0;

    public void connect() {
        Request request = new Request.Builder().url(url).build();
        webSocket = client.newWebSocket(request, new WebSocketListener() {
            @Override
            public void onFailure(WebSocket ws, Throwable t, Response resp) {
                System.out.println("连接失败: " + t.getMessage());
                reconnect();
            }

            @Override
            public void onClosed(WebSocket ws, int code, String reason) {
                System.out.println("连接关闭: " + reason);
                reconnect();
            }
        });
    }

    private void reconnect() {
        if (retryCount < 5) {
            retryCount++;
            try {
                Thread.sleep(2000L * retryCount); // 逐渐延迟重连
            } catch (InterruptedException ignored) {}
            connect();
        } else {
            System.out.println("超过最大重连次数");
        }
    }

    public static void main(String[] args) {
        new WebSocketReconnect().connect();
    }
}

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;

public class JdbcReconnect {
    private static final String URL = "jdbc:mysql://localhost:3306/test";
    private static final String USER = "root";
    private static final String PASS = "123456";

    public static Connection getConnection() {
        int retries = 0;
        while (retries < 5) {
            try {
                return DriverManager.getConnection(URL, USER, PASS);
            } catch (SQLException e) {
                retries++;
                System.out.println("数据库连接失败，重试中..." + retries);
                try {
                    Thread.sleep(2000 * retries);
                } catch (InterruptedException ignored) {}
            }
        }
        throw new RuntimeException("数据库连接失败超过最大次数");
    }

    public static void main(String[] args) {
        Connection conn = getConnection();
        System.out.println("数据库连接成功: " + conn);
    }
}