HttpUtils

import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.net.HttpURLConnection;
import java.net.URL;
import java.net.URLConnection;
import java.nio.charset.StandardCharsets;
import java.util.Collections;
import java.util.Map;
import java.util.Optional;
import java.util.stream.Collectors;

/**
 * @author ParanoidCAT
 * @since JDK 1.8
 */
public class HttpUtils {
    private static final String POST = "POST";

    private HttpUtils() throws Exception {
        throw new Exception("no HttpUtils instance should be created");
    }

    /**
     * 发送GET请求
     *
     * @param urlAddress        请求地址
     * @param requestProperties 请求属性
     * @param parameterMap      参数
     * @return 响应字符串
     */
    public static String get(String urlAddress, Map<String, String> requestProperties, Map<String, String> parameterMap) {
        try {
            String requestParameters = Optional
                    .ofNullable(parameterMap)
                    .orElseGet(Collections::emptyMap)
                    .entrySet()
                    .stream()
                    .map(entry -> entry.getKey() + "=" + entry.getValue())
                    .collect(Collectors.joining("&"));
            HttpURLConnection httpUrlConnection = (HttpURLConnection) generateUrlConnection(isNotEmpty(requestParameters) ? urlAddress + "?" + requestParameters : urlAddress);
            Optional
                    .ofNullable(requestProperties)
                    .orElseGet(Collections::emptyMap)
                    .forEach(httpUrlConnection::addRequestProperty);
            httpUrlConnection.connect();
            return getResponseBody(httpUrlConnection);
        } catch (IOException e) {
            throw new RuntimeException(e);
        }
    }

    /**
     * 发送POST请求
     *
     * @param urlAddress        请求地址
     * @param requestProperties 请求属性
     * @param output            参数
     * @return 响应字符串
     */
    public static String post(String urlAddress, Map<String, String> requestProperties, String output) {
        try {
            HttpURLConnection httpUrlConnection = (HttpURLConnection) generateUrlConnection(urlAddress);
            Optional.ofNullable(requestProperties).orElseGet(Collections::emptyMap).forEach(httpUrlConnection::addRequestProperty);
            httpUrlConnection.setRequestMethod(POST);
            if (isNotEmpty(output)) {
                httpUrlConnection.setDoOutput(Boolean.TRUE);
                try (PrintWriter printWriter = new PrintWriter(httpUrlConnection.getOutputStream())) {
                    printWriter.print(output);
                }
            }
            httpUrlConnection.connect();
            return getResponseBody(httpUrlConnection);
        } catch (IOException e) {
            throw new RuntimeException(e);
        }
    }

    /**
     * 获取Url链接
     *
     * @param urlAddress 请求地址
     * @return Url链接
     * @throws IOException IO异常
     */
    private static URLConnection generateUrlConnection(String urlAddress) throws IOException {
        URLConnection urlConnection = new URL(urlAddress).openConnection();
        urlConnection.setDoInput(Boolean.TRUE);
        urlConnection.setUseCaches(Boolean.FALSE);
        urlConnection.setConnectTimeout(60 * 1000);
        urlConnection.setReadTimeout(60 * 1000);
        return urlConnection;
    }

    /**
     * 获取响应报文
     *
     * @param httpUrlConnection Url链接
     * @return 响应报文
     * @throws IOException IO异常
     */
    private static String getResponseBody(HttpURLConnection httpUrlConnection) throws IOException {
        int responseCode = httpUrlConnection.getResponseCode();
        String responseBody;
        if (HttpURLConnection.HTTP_OK == responseCode) {
            try (InputStream inputStream = httpUrlConnection.getInputStream()) {
                return getTextFromStream(inputStream);
            }
        } else {
            try (InputStream inputStream = httpUrlConnection.getErrorStream()) {
                responseBody = getTextFromStream(inputStream);
            } catch (IOException e) {
                responseBody = null;
            }
            throw new IOException("Http请求失败-responseCode:" + responseCode + ",responseMessage:" + httpUrlConnection.getResponseMessage() + ",responseBody:" + responseBody);
        }
    }

    /**
     * 从输入流中获取文本
     *
     * @param inputStream 输入流
     * @return 文本
     * @throws IOException IO异常
     */
    private static String getTextFromStream(InputStream inputStream) throws IOException {
        StringBuilder stringBuilder = new StringBuilder();
        if (inputStream != null) {
            byte[] buffer = new byte[1024];
            int length;
            while ((length = inputStream.read(buffer)) != -1) {
                stringBuilder.append(new String(buffer, 0, length, StandardCharsets.UTF_8));
            }
        }
        return stringBuilder.toString();
    }

    /**
     * 判断对象字符串不是空字符串
     *
     * @param string 对象字符串
     * @return true/false
     */
    private static boolean isNotEmpty(String string) {
        return string != null && !"".equals(string);
    }
}