HttpURLConnection Demo

HttpUtils

package com.seliote.stockanalyzer.util;

import com.seliote.stockanalyzer.exc.http.HttpException;
import org.springframework.util.Assert;

import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
import java.nio.charset.Charset;
import java.util.List;
import java.util.Map;
import java.util.zip.GZIPInputStream;

/**
 * HTTP 相关工具类
 *
 * @author LiYangDi
 * @since 2020/2/22
 */
public class HttpUtils {

    // HTTP GET 方法常量
    private static final String HTTP_GET = "GET";

    // 连接超时
    private static final int CONNECT_TIMEOUT = 5000;
    // 读取超时
    private static final int READ_TIMEOUT = 5000;
    // HTTP ACCEPT 常量
    private static final String ACCEPT_KEY = "Accept";
    // Accept 信息
    private static final String ACCEPT_VALUE = "text/html,application/xhtml+xml,application/xml;q=0.9," +
            "image/webp,image/apng,*/*;q=0.8,application/signed-exchange;v=b3;q=0.9";
    // HTTP ACCEPT_ENCODING 常量
    private static final String ACCEPT_ENCODING_KEY = "Accept-Encoding";
    // ACCEPT_ENCODING 信息
    private static final String ACCEPT_ENCODING_VALUE = "gzip, deflate, br";
    // HTTP ACCEPT_LANGUAGE 常量
    private static final String ACCEPT_LANGUAGE_KEY = "Accept-Language";
    // ACCEPT_LANGUAGE 信息
    private static final String ACCEPT_LANGUAGE_VALUE = "zh-CN,zh;q=0.9,en;q=0.8";
    // HTTP CONNECTION 常量
    private static final String CONNECTION_KEY = "Connection";
    // CONNECTION 信息
    private static final String CONNECTION_VALUE = "keep-alive";
    // HTTP USER-AGENT 常量
    private static final String USER_AGENT_KEY = "User-Agent";
    // USER-AGENT 信息
    private static final String USER_AGENT_VALUE = "Mozilla/5.0 (Windows NT 10.0; Win64; x64) " +
            "AppleWebKit/537.36 (KHTML, like Gecko) Chrome/80.0.3987.116 Safari/537.36";

    // 响应中的 content-encoding 键
    private static final String RESP_CONTENT_ENCODING_KEY = "content-encoding";

    /**
     * HTTP GET 方法请求 URL 编码后的响应 byte[]
     *
     * @param url 需要请求的 URL，GET 参数加在链接后
     * @return 请求接口后返回数据的 byte[]
     * @throws HttpException URL 编码、HTTP 请求中产生异常
     */
    public static byte[] getByBytes(String url) throws HttpException {
        HttpURLConnection httpURLConnection = null;
        try {
            // encode URL 并创建连接
            httpURLConnection = (HttpURLConnection) ((new URL(url)).openConnection());
            httpURLConnection.setRequestMethod(HTTP_GET);
            // 配置超时与请求头
            setProperties(httpURLConnection);
            // 设置写入与输出
            httpURLConnection.setDoOutput(true);
            // 开始请求
            httpURLConnection.connect();
            // 处理响应
            if (HttpURLConnection.HTTP_OK == httpURLConnection.getResponseCode()) {
                return readResp(httpURLConnection);
            } else {
                throw new HttpException("HTTP response code exception：" + httpURLConnection.getResponseCode());
            }
        } catch (MalformedURLException exc) {
            throw new HttpException("MalformedURLException: " + url + ", " + exc.getMessage(), exc);
        } catch (IOException exc) {
            throw new HttpException("IOException, URL: " + url + ", " + exc.getMessage(), exc);
        } finally {
            if (null != httpURLConnection) {
                httpURLConnection.disconnect();
            }
        }
    }

    /**
     * HTTP GET 方法请求 URL 编码后的响应 String
     *
     * @param url     需要请求的 URL，GET 参数加在链接后
     * @param charset URL 编码以及解析响应时所用的字符集
     * @return 请求接口后返回数据的 String
     * @throws HttpException URL 编码、HTTP 请求中产生异常
     */
    public static String getByString(String url, Charset charset) throws HttpException {
        return new String(getByBytes(url), charset);
    }

    /**
     * 设置 HttpURLConnection 超时与请求头参数
     *
     * @param httpURLConnection 需要设置的 HttpURLConnection 对象
     */
    private static void setProperties(HttpURLConnection httpURLConnection) {
        // 超时相关
        httpURLConnection.setConnectTimeout(CONNECT_TIMEOUT);
        httpURLConnection.setReadTimeout(READ_TIMEOUT);
        // 请求头相关
        httpURLConnection.setRequestProperty(ACCEPT_KEY, ACCEPT_VALUE);
        httpURLConnection.setRequestProperty(ACCEPT_ENCODING_KEY, ACCEPT_ENCODING_VALUE);
        httpURLConnection.setRequestProperty(ACCEPT_LANGUAGE_KEY, ACCEPT_LANGUAGE_VALUE);
        httpURLConnection.setRequestProperty(CONNECTION_KEY, CONNECTION_VALUE);
        httpURLConnection.setRequestProperty(USER_AGENT_KEY, USER_AGENT_VALUE);
    }

    /**
     * 读取 HTTP 响应
     *
     * @param httpURLConnection 读取响应的 HttpURLConnection 对象
     * @return 读取的 byte[]
     * @throws IOException 读取响应时发生异常
     */
    private static byte[] readResp(HttpURLConnection httpURLConnection) throws IOException {
        // 响应头，用来检测是否有压缩
        Map<String, List<String>> respHeader = httpURLConnection.getHeaderFields();
        String compressMethod = null;
        // 循环 Map 以获得大小写无关的比较
        for (Map.Entry<String, List<String>> entry : respHeader.entrySet()) {
            if (null != entry.getKey() && entry.getKey().equalsIgnoreCase(RESP_CONTENT_ENCODING_KEY)) {
                Assert.isTrue(null != entry.getValue() && 1 == entry.getValue().size(),
                        "HTTP response header 'content-encoding' value is empty or more than one");
                compressMethod = entry.getValue().get(0);
                break;
            }
        }
        return uncompressInputStream(compressMethod, httpURLConnection.getInputStream());
    }

    /**
     * 解压 InputStream
     *
     * @param compressMethod 压缩方法
     * @param inputStream    需要读取的 InputStream
     * @return 解压缩后的 byte[]
     * @throws IOException 读取时发生异常
     */
    private static byte[] uncompressInputStream(String compressMethod, InputStream inputStream) throws IOException {
        if (null == compressMethod) {
            return IOUtils.readInputStream(inputStream);
        } else if ("gzip".equalsIgnoreCase(compressMethod)) {
            GZIPInputStream gzipInputStream = new GZIPInputStream(inputStream);
            return IOUtils.readInputStream(gzipInputStream);
        } else {
            throw new IOException("Response had unknown 'content-encoding': " + compressMethod);
        }
    }
}

IOUtils

package com.seliote.stockanalyzer.util;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;

/**
 * IO 相关工具类
 *
 * @author LiYangDi
 * @since 2020/2/23
 */
public class IOUtils {

    /**
     * 读取 InputStream 中的所有 byte[] 数据，内存中保存，不适合大量数据
     *
     * @param inputStream 输入的流
     * @return 流中的 byte[] 数据
     */
    public static byte[] readInputStream(InputStream inputStream) throws IOException {
        // 缓存
        ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
        int readLength;
        byte[] readBuffer = new byte[1024];
        // 读取数据
        while ((readLength = inputStream.read(readBuffer)) != -1) {
            byteArrayOutputStream.write(readBuffer, 0, readLength);
        }
        return byteArrayOutputStream.toByteArray();
    }
}

原文地址：https://www.cnblogs.com/seliote/p/12353146.html