[实践总结] 使用Apache HttpClient 4.x进行进行一次Http请求

使用Apache HttpClient 4.x进行进行一次Http请求

依赖

<!-- https://mvnrepository.com/artifact/org.apache.httpcomponents/httpclient -->
<dependency>
    <groupId>org.apache.httpcomponents</groupId>
    <artifactId>httpclient</artifactId>
    <version>4.5.7</version>
</dependency>

请求式样

import org.apache.commons.lang3.StringUtils;
import org.apache.http.Consts;
import org.apache.http.HttpStatus;
import org.apache.http.ParseException;
import org.apache.http.client.config.RequestConfig;
import org.apache.http.client.methods.CloseableHttpResponse;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.client.protocol.HttpClientContext;
import org.apache.http.entity.ContentType;
import org.apache.http.entity.StringEntity;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.util.EntityUtils;

import java.io.IOException;

public class HttpPostUtils {
    
    
    /**
     * @param uri  the request address
     * @param json the request data that must be a JSON string
     * @throws IOException    if HTTP connection can not opened or closed successfully
     * @throws ParseException if response data can not be parsed successfully
     */
    public String retryPostJson(String uri, String json) throws IOException, ParseException {
    
    
        if (StringUtils.isAnyBlank(uri, json)) {
    
    
            return null;
        }

        // 构建HttpClient
        CloseableHttpClient client = HttpClients.custom().setRetryHandler(new RetryHandler()).build();

        // 构建请求
        HttpPost httpPost = new HttpPost(uri);
        // 设置请求体
        StringEntity entity = new StringEntity(json, ContentType.APPLICATION_JSON);
        httpPost.setEntity(entity);
        // 设置超时时间
        RequestConfig config = RequestConfig.custom().setConnectionRequestTimeout(5000) // 超5秒还没返回新的可用链接，抛ConnectionPoolTimeoutException。默认值为0，表示无限等待。
                .setConnectTimeout(5000) // 超5秒还没建立链接，抛ConnectTimeoutException。默认值为0，表示无限等待。
                .setSocketTimeout(5000) // 超5秒还没返回数据，抛SocketTimeoutException。默认值为0，表示无限等待。
                .build();
        httpPost.setConfig(config);

        // Response
        CloseableHttpResponse response = null;
        String responseContent = null;
        try {
    
    
            response = client.execute(httpPost, HttpClientContext.create());
            if (response.getStatusLine().getStatusCode() == HttpStatus.SC_OK) {
    
    
                responseContent = EntityUtils.toString(response.getEntity(), Consts.UTF_8.name());
            }
        } finally {
    
    
            if (response != null) {
    
    
                response.close();
            }
            if (client != null) {
    
    
                client.close();
            }
        }
        return responseContent;
    }
}

失败重试机制

import org.apache.http.HttpEntityEnclosingRequest;
import org.apache.http.HttpRequest;
import org.apache.http.NoHttpResponseException;
import org.apache.http.client.HttpRequestRetryHandler;
import org.apache.http.client.protocol.HttpClientContext;
import org.apache.http.conn.ConnectTimeoutException;
import org.apache.http.protocol.HttpContext;

import javax.net.ssl.SSLException;
import javax.net.ssl.SSLHandshakeException;
import java.io.IOException;
import java.io.InterruptedIOException;
import java.net.ConnectException;
import java.net.UnknownHostException;

public class RetryHandler implements HttpRequestRetryHandler {
    
    
    @Override
    public boolean retryRequest(IOException exception, int executionCount, HttpContext context) {
    
    
        if (executionCount >= 2) {
    
    
            // 如果已经重试了2次，就放弃
            // Do not retry if over max retry count
            return false;
        }
        if (exception instanceof NoHttpResponseException) {
    
    
            // 如果服务器丢掉了连接，那么就重试
            return true;
        }
        if (exception instanceof SSLHandshakeException) {
    
    
            // 不要重试SSL握手异常
            return false;
        }
        if (exception instanceof SSLException) {
    
    
            // SSL握手异常
            // SSL handshake exception
            return false;
        }
        if (exception instanceof ConnectTimeoutException) {
    
    
            // 连接被拒绝
            return false;
        }
        if (exception instanceof InterruptedIOException) {
    
    
            // An input or output transfer has been terminated
            // 超时
            return false;
        }
        if (exception instanceof UnknownHostException) {
    
    
            // Unknown host 修改代码让不识别主机时重试，实际业务当不识别的时候不应该重试，再次为了演示重试过程，执行会显示retryCount次下面的输出
            // 目标服务器不可达
            System.out.println("不识别主机重试");
            return true;
        }
        if (exception instanceof ConnectException) {
    
    
            // Connection refused
            return false;
        }
        HttpClientContext clientContext = HttpClientContext.adapt(context);
        HttpRequest request = clientContext.getRequest();
        if (!(request instanceof HttpEntityEnclosingRequest)) {
    
    
            // Retry if the request is considered idempotent
            return true;
        }
        return false;
    }
}

模拟解析返回的Json串

public static List<User> parserJsonToUser() {
    
    
    // 模拟返回的Json串
    Map<String, List<String>> map = new HashMap<>();
    map.put("name", Arrays.asList("name1", "name2", "name3"));
    map.put("age", Arrays.asList("11", "23", "23"));
    map.put("num", Arrays.asList("123", "234", "345"));
    String json1 = JsonUtils.toJson(map);
    System.out.println(json1);
    // fastjson
    JSONObject jsonObject = JSON.parseObject(json1, Feature.OrderedField);
    // 返回的属性
    List<String> fields = new ArrayList<>(map.keySet());
    // 几份值
    int size = jsonObject.getJSONArray(fields.get(0)).size();
    List<User> users = new ArrayList<>();
    for (int i = 0; i < size; i++) {
    
    
        User user1 = new User();
        for (String field : fields) {
    
    
            Object value = jsonObject.getJSONArray(field).get(i);
            ReflectUtils.setFieldValue(user1, field, value);
        }
        users.add(user1);
    }
    System.out.println(users);
    return users;
}

结果
{
    
    "num":["123","234","345"],"name":["name1","name2","name3"],"age":["11","23","23"]}
[HttpPostUtils.User(name=name1, age=11, num=123), HttpPostUtils.User(name=name2, age=23, num=234), HttpPostUtils.User(name=name3, age=23, num=345)]

参考

使用Apache HttpClient 4.x进行异常重试

Need 学习消化

二十六、CloseableHttpClient的使用和优化