Java实现HTTP请求方法-优快云博客

本文链接：https://blog.youkuaiyun.com/zhangsweet1991/article/details/80804864

目前JAVA实现HTTP请求的方法用的最多的有两种：
1、通过HttpURLConnection去实现，HttpURLConnection是JAVA的标准类，是JAVA比较原生的一种实现方式。
2、通过HTTPClient这种第三方的开源框架去实现。应用最广泛的就是apache的HTTPClient，有两大版本，HttpClient3.1 是 org.apache.commons.httpclient下操作远程 url的工具包，虽然已不再更新，但实现工作中使用httpClient3.1的代码还是很多，HttpClient4.5.x是org.apache.http.client下操作远程 url的工具包；

HttpURLConnection

package com.demo;

import java.io.ByteArrayOutputStream;
import java.io.Closeable;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.HttpURLConnection;
import java.net.URL;
import java.util.Map;

public class HttpURLConDemo {
    public static final String charsetName = "UTF-8";

    public static String doGet(String strUrl) {
        return doGet(strUrl, null);
    }

    public static String doGet(String strUrl, Map<String, String> headers) {
        HttpURLConnection connection = null;
        String out = null;
        InputStream inputStream = null;
        try {
            URL _url = new URL(strUrl);
            // 打开连接
            connection = (HttpURLConnection) _url.openConnection();
            // 设置请求方式：get请求
            connection.setRequestMethod("GET");
            // 设置超时时间，单位毫秒：5秒
            connection.setConnectTimeout(5000);
            // 设置读取远程服务器时间，单位毫秒：10秒
            connection.setReadTimeout(10000);
            // 设置请求头
            if (headers != null) {
                for (String headName : headers.keySet()) {
                    String headValue = headers.get(headName);
                    connection.setRequestProperty(headName, headValue);
                }
            }
            // 发送请求
            connection.connect();
            // 通过connection获取输入流数据
            if (connection.getResponseCode() == 200) {
                inputStream = connection.getInputStream();
                out = inToString(inputStream);
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            // 关闭资源
            close(inputStream);
            // 关闭连接
            connection.disconnect();
        }
        return out;
    }

    public static String doPost(String strUrl, String params, Map<String, String> headers) {
        HttpURLConnection connection = null;
        String out = null;
        InputStream inputStream = null;
        OutputStream outputStream = null;
        try {
            URL _url = new URL(strUrl);
            // 打开连接
            connection = (HttpURLConnection) _url.openConnection();
            // 设置请求方式：get请求
            connection.setRequestMethod("POST");
            // 设置超时时间，单位毫秒：5秒
            connection.setConnectTimeout(5000);
            // 设置读取远程服务器时间，单位毫秒：10秒
            connection.setReadTimeout(10000);
            // 设置请求头
            if (headers != null) {
                for (String headName : headers.keySet()) {
                    String headValue = headers.get(headName);
                    connection.setRequestProperty(headName, headValue);
                }
            }
            // 默认值为：true，当前向远程服务读取数据时，设置为true，该参数可有可无
            connection.setDoInput(true);
            if (params != null) {
                // 默认值为：false，当向远程服务器传送数据/写数据时，需要设置为true
                connection.setDoOutput(true);
                outputStream = connection.getOutputStream();
                outputStream.write(params.getBytes(charsetName));
            }
            // 发送请求
            connection.connect();
            // 通过connection获取输入流数据
            if (connection.getResponseCode() == 200) {
                inputStream = connection.getInputStream();
                out = inToString(inputStream);
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            // 关闭资源
            close(outputStream);
            close(inputStream);
            // 关闭连接
            connection.disconnect();
        }
        return out;
    }

    public static String doPost(String strUrl) {
        return doPost(strUrl, null, null);
    }
    //ByteArrayOutputStream无需关闭
    private static String inToString(InputStream inputStream) throws IOException {
        ByteArrayOutputStream result = new ByteArrayOutputStream();
        byte[] buffer = new byte[1024];
        int length;
        while ((length = inputStream.read(buffer)) != -1) {
            result.write(buffer, 0, length);
        }
        String str = result.toString(charsetName);
        return str;
    }

    private static void close(Closeable closeable) {
        try {
            if (closeable != null) {
                closeable.close();
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public static void main(String[] args) {
        String result = doGet("https://blog.youkuaiyun.com/zhangsweet1991");
        System.out.println(result);
    }
}

HttpClient3.1

package com.demo;

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

import org.apache.commons.httpclient.DefaultHttpMethodRetryHandler;
import org.apache.commons.httpclient.HttpClient;
import org.apache.commons.httpclient.HttpException;
import org.apache.commons.httpclient.HttpMethod;
import org.apache.commons.httpclient.HttpStatus;
import org.apache.commons.httpclient.methods.GetMethod;
import org.apache.commons.httpclient.methods.PostMethod;
import org.apache.commons.httpclient.params.HttpMethodParams;

public class HttpClientUtils {
    public static final String charsetName = "UTF-8";

    public static String doGet(String url) {
        /*
         * 使用 GetMethod 来访问一个 URL 对应的网页,实现步骤: 1:生成一个 HttpClinet 对象并设置相应的参数。
         * 2:生成一个 GetMethod 对象并设置响应的参数。 3:用 HttpClinet 生成的对象来执行 GetMethod 生成的Get
         * 方法。 4:处理响应状态码。 5:若响应正常，处理 HTTP 响应内容。 6:释放连接。
         */

        /* 1 生成 HttpClinet 对象并设置参数 */
        HttpClient httpClient = new HttpClient();
        // 设置 Http 连接超时为5秒
        httpClient.getHttpConnectionManager().getParams().setConnectionTimeout(5000);

        /* 2 生成 GetMethod 对象并设置参数 */
        GetMethod getMethod = new GetMethod(url);
        // 设置 get 请求超时为 5 秒
        getMethod.getParams().setParameter(HttpMethodParams.SO_TIMEOUT, 5000);
        // 设置请求重试处理，用的是默认的重试处理：请求三次
        getMethod.getParams().setParameter(HttpMethodParams.RETRY_HANDLER, new DefaultHttpMethodRetryHandler());

        String out = null;
        /* 3 执行 HTTP GET 请求 */
        try {
            int statusCode = httpClient.executeMethod(getMethod);
            /* 4 判断访问的状态码 */
            if (statusCode == HttpStatus.SC_OK) {
                // 读取为 InputStream，在网页内容数据量大时候推荐使用
                out = inToString(getMethod.getResponseBodyAsStream());
            }
        } catch (HttpException e) {
            // 发生致命的异常，可能是协议不对或者返回的内容有问题
            e.printStackTrace();
        } catch (IOException e) {
            // 发生网络异常
            e.printStackTrace();
        } finally {
            /* 6 .释放连接 */
            getMethod.releaseConnection();
        }
        return out;
    }

    public static String doPost(String url, Map<String, String> params) {

        String out = null;
        HttpClient client = new HttpClient();
        HttpMethod method = new PostMethod(url);

        // 设置Http Post数据
        if (params != null) {
            HttpMethodParams p = new HttpMethodParams();
            for (Map.Entry<String, String> entry : params.entrySet()) {
                p.setParameter(entry.getKey(), entry.getValue());
            }
            method.setParams(p);
        }
        try {
            client.executeMethod(method);
            if (method.getStatusCode() == HttpStatus.SC_OK) {
                // 读取为 InputStream，在网页内容数据量大时候推荐使用
                out = inToString(method.getResponseBodyAsStream());
            }
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            method.releaseConnection();
        }
        return out;
    }

    private static String inToString(InputStream inputStream) throws IOException {
        ByteArrayOutputStream result = new ByteArrayOutputStream();
        byte[] buffer = new byte[1024];
        int length;
        while ((length = inputStream.read(buffer)) != -1) {
            result.write(buffer, 0, length);
        }
        String str = result.toString(charsetName);
        return str;
    }

    public static void main(String[] args) {
        String result = doGet("https://blog.youkuaiyun.com/zhangsweet1991");
        System.out.println(result);
    }
}

HttpClient4.5.5

package com.youyu.util.http;

import java.io.IOException;
import java.io.InputStream;
import java.nio.charset.Charset;
import java.security.GeneralSecurityException;
import java.security.cert.CertificateException;
import java.security.cert.X509Certificate;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import javax.net.ssl.SSLContext;
import javax.net.ssl.SSLException;
import javax.net.ssl.SSLSession;
import javax.net.ssl.SSLSocket;

import org.apache.commons.io.IOUtils;
import org.apache.http.HttpEntity;
import org.apache.http.HttpStatus;
import org.apache.http.NameValuePair;
import org.apache.http.client.config.RequestConfig;
import org.apache.http.client.entity.UrlEncodedFormEntity;
import org.apache.http.client.methods.CloseableHttpResponse;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.conn.ConnectTimeoutException;
import org.apache.http.conn.ssl.SSLConnectionSocketFactory;
import org.apache.http.conn.ssl.SSLContextBuilder;
import org.apache.http.conn.ssl.TrustStrategy;
import org.apache.http.conn.ssl.X509HostnameVerifier;
import org.apache.http.entity.StringEntity;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.impl.conn.PoolingHttpClientConnectionManager;
import org.apache.http.message.BasicNameValuePair;
import org.apache.http.util.EntityUtils;


public class HttpUtils {
    private static PoolingHttpClientConnectionManager connMgr;
    private static RequestConfig requestConfig;
    private static final int MAX_TIMEOUT = 7000;// 7秒
    private static final String UTF_8 = "UTF-8";
    public static final String JSON = "json";
    public static final String XML = "xml";

    static {
        // 设置连接池
        connMgr = new PoolingHttpClientConnectionManager();
        // 设置连接池大小
        connMgr.setMaxTotal(100);
        connMgr.setDefaultMaxPerRoute(connMgr.getMaxTotal());
        RequestConfig.Builder configBuilder = RequestConfig.custom();
        // 设置连接超时
        configBuilder.setConnectTimeout(MAX_TIMEOUT);
        // 设置读取超时
        configBuilder.setSocketTimeout(MAX_TIMEOUT);
        // 设置从连接池获取连接实例的超时
        configBuilder.setConnectionRequestTimeout(MAX_TIMEOUT);
        // 在提交请求之前 测试连接是否可用
        configBuilder.setStaleConnectionCheckEnabled(true);
        requestConfig = configBuilder.build();
    }

    /**
     * 发送 GET 请求（HTTP），不带输入数据
     *
     * @param url
     * @return
     * @throws IOException
     */
    public static String doGet(String url) throws IOException {
        return doGet(url, null);
    }

    /**
     * 发送 GET 请求（HTTP），K-V形式
     * 
     * @param url
     * @param params
     * @return
     * @throws IOException
     */
    public static String doGet(String url, Map<String, String> params) throws IOException {
        int i = 0;
        if (params != null) {
            StringBuffer param = new StringBuffer();
            for (String key : params.keySet()) {
                if (i == 0)
                    param.append("?");
                else
                    param.append("&");
                param.append(key).append("=").append(params.get(key));
                i++;
            }
            url += param;
        }
        String result = null;
        CloseableHttpClient httpclient = HttpClients.createDefault();
        CloseableHttpResponse response = null;
        HttpEntity entity = null;
        try {
            HttpGet httpGet = new HttpGet(url);
            response = httpclient.execute(httpGet);
            // int statusCode = response.getStatusLine().getStatusCode();

            entity = response.getEntity();
            if (entity != null) {
                InputStream instream = entity.getContent();
                result = IOUtils.toString(instream, UTF_8);
            }
        } finally {
            // 最后别忘了关闭应该关闭的资源，适当的释放资源
            try {
                // 这个方法也可以把底层的流给关闭了
                EntityUtils.consume(entity);
                // if (null != response) {
                // response.close();
                // }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        return result;
    }

    /**
     * 发送 POST 请求（HTTP），不带输入数据
     * 
     * @param apiUrl
     * @return
     * @throws ConnectTimeoutException
     */
    public static String doPost(String apiUrl) throws IOException {
        return doPost(apiUrl, new HashMap<String, String>());
    }

    /**
     * 发送 POST 请求（HTTP），K-V形式
     * 
     * @param apiUrl API接口URL
     * @param params 参数map
     * @return
     * @throws ConnectTimeoutException
     */
    public static String doPost(String apiUrl, Map<String, String> params) throws IOException {
        CloseableHttpClient httpClient = HttpClients.createDefault();
        String httpStr = null;
        HttpPost httpPost = new HttpPost(apiUrl);
        CloseableHttpResponse response = null;

        try {
            httpPost.setConfig(requestConfig);
            List<NameValuePair> pairList = new ArrayList<>(params.size());
            for (Map.Entry<String, String> entry : params.entrySet()) {
                NameValuePair pair = new BasicNameValuePair(entry.getKey(), entry.getValue());
                pairList.add(pair);
            }
            httpPost.setEntity(new UrlEncodedFormEntity(pairList, Charset.forName("UTF-8")));
            response = httpClient.execute(httpPost);
            HttpEntity entity = response.getEntity();
            httpStr = EntityUtils.toString(entity, "UTF-8");
        } finally {
            if (response != null) {
                try {
                    EntityUtils.consume(response.getEntity());
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
        return httpStr;
    }

    /**
     * 发送 POST 请求（HTTP），JSON形式
     * 
     * @param apiUrl
     * @param content 内容
     * @return
     * @throws IOException
     */
    public static String doPost(String apiUrl, String content, String type) throws IOException {
        CloseableHttpClient httpClient = HttpClients.createDefault();
        String httpStr = null;
        HttpPost httpPost = new HttpPost(apiUrl);
        CloseableHttpResponse response = null;

        try {
            httpPost.setConfig(requestConfig);
            StringEntity stringEntity = new StringEntity(content, "UTF-8");// 解决中文乱码问题
            stringEntity.setContentEncoding("UTF-8");
            if (JSON.equals(type)) {
                stringEntity.setContentType("application/json");
            } else if (XML.equals(type)) {
                stringEntity.setContentType("application/xml");
            } else {
                stringEntity.setContentType("text/plain");
            }
            httpPost.setEntity(stringEntity);
            response = httpClient.execute(httpPost);
            HttpEntity entity = response.getEntity();
            // System.out.println(response.getStatusLine().getStatusCode());
            httpStr = EntityUtils.toString(entity, "UTF-8");
        } finally {
            if (response != null) {
                try {
                    EntityUtils.consume(response.getEntity());
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
        return httpStr;
    }
    public static String doPost(String apiUrl, String content, String type,Map<String, String> headers) throws IOException {
        CloseableHttpClient httpClient = HttpClients.createDefault();
        String httpStr = null;
        HttpPost httpPost = new HttpPost(apiUrl);
        CloseableHttpResponse response = null;

        try {
            httpPost.setConfig(requestConfig);
            if (headers != null) {
                for (String headerName : headers.keySet()) {
                    httpPost.setHeader(headerName, headers.get(headerName));
                }
            }
            StringEntity stringEntity = new StringEntity(content, "UTF-8");// 解决中文乱码问题
            stringEntity.setContentEncoding("UTF-8");
            if (JSON.equals(type)) {
                stringEntity.setContentType("application/json");
            } else if (XML.equals(type)) {
                stringEntity.setContentType("application/xml");
            } else {
                stringEntity.setContentType("text/plain");
            }
            httpPost.setEntity(stringEntity);
            response = httpClient.execute(httpPost);
            HttpEntity entity = response.getEntity();
            // System.out.println(response.getStatusLine().getStatusCode());
            httpStr = EntityUtils.toString(entity, "UTF-8");
        } finally {
            if (response != null) {
                try {
                    EntityUtils.consume(response.getEntity());
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
        return httpStr;
    }

    /**
     * 发送 SSL POST 请求（HTTPS），K-V形式
     * 
     * @param apiUrl API接口URL
     * @param params 参数map
     * @return
     */
    public static String doPostSSL(String apiUrl, Map<String, Object> params) {
        CloseableHttpClient httpClient = HttpClients.custom().setSSLSocketFactory(createSSLConnSocketFactory()).setConnectionManager(connMgr)
                .setDefaultRequestConfig(requestConfig).build();
        HttpPost httpPost = new HttpPost(apiUrl);
        CloseableHttpResponse response = null;
        String httpStr = null;

        try {
            httpPost.setConfig(requestConfig);
            List<NameValuePair> pairList = new ArrayList<NameValuePair>(params.size());
            for (Map.Entry<String, Object> entry : params.entrySet()) {
                NameValuePair pair = new BasicNameValuePair(entry.getKey(), entry.getValue().toString());
                pairList.add(pair);
            }
            httpPost.setEntity(new UrlEncodedFormEntity(pairList, Charset.forName("utf-8")));
            response = httpClient.execute(httpPost);
            int statusCode = response.getStatusLine().getStatusCode();
            if (statusCode != HttpStatus.SC_OK) {
                return null;
            }
            HttpEntity entity = response.getEntity();
            if (entity == null) {
                return null;
            }
            httpStr = EntityUtils.toString(entity, "utf-8");
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            if (response != null) {
                try {
                    EntityUtils.consume(response.getEntity());
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
        return httpStr;
    }

    /**
     * 发送 SSL POST 请求（HTTPS），JSON形式
     * 
     * @param apiUrl API接口URL
     * @param json JSON对象
     * @return
     */
    public static String doPostSSL(String apiUrl, Object json) {
        CloseableHttpClient httpClient = HttpClients.custom().setSSLSocketFactory(createSSLConnSocketFactory()).setConnectionManager(connMgr)
                .setDefaultRequestConfig(requestConfig).build();
        HttpPost httpPost = new HttpPost(apiUrl);
        CloseableHttpResponse response = null;
        String httpStr = null;

        try {
            httpPost.setConfig(requestConfig);
            StringEntity stringEntity = new StringEntity(json.toString(), "UTF-8");// 解决中文乱码问题
            stringEntity.setContentEncoding("UTF-8");
            stringEntity.setContentType("application/json");
            httpPost.setEntity(stringEntity);
            response = httpClient.execute(httpPost);
            int statusCode = response.getStatusLine().getStatusCode();
            if (statusCode != HttpStatus.SC_OK) {
                return null;
            }
            HttpEntity entity = response.getEntity();
            if (entity == null) {
                return null;
            }
            httpStr = EntityUtils.toString(entity, "utf-8");
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            if (response != null) {
                try {
                    EntityUtils.consume(response.getEntity());
                    response.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
        return httpStr;
    }

    /**
     * 创建SSL安全连接
     *
     * @return
     */
    private static SSLConnectionSocketFactory createSSLConnSocketFactory() {
        SSLConnectionSocketFactory sslsf = null;
        try {
            SSLContext sslContext = new SSLContextBuilder().loadTrustMaterial(null, new TrustStrategy() {

                public boolean isTrusted(X509Certificate[] chain, String authType) throws CertificateException {
                    return true;
                }
            }).build();
            sslsf = new SSLConnectionSocketFactory(sslContext, new X509HostnameVerifier() {

                @Override
                public boolean verify(String arg0, SSLSession arg1) {
                    return true;
                }

                @Override
                public void verify(String host, SSLSocket ssl) throws IOException {
                }

                @Override
                public void verify(String host, X509Certificate cert) throws SSLException {
                }

                @Override
                public void verify(String host, String[] cns, String[] subjectAlts) throws SSLException {
                }
            });
        } catch (GeneralSecurityException e) {
            e.printStackTrace();
        }
        return sslsf;
    }

    /**
     * 发送 SSL POST 请求（HTTPS），加载证书
     * 
     * @param apiUrl API接口URL
     * @param json JSON对象
     * @return
     */
    public static String doPostSSL(String url, String content, String type, Map<String, String> headers, SSLConnectionSocketFactory sslsf) {
        CloseableHttpClient httpClient = HttpClients.custom().setSSLSocketFactory(createSSLConnSocketFactory()).setConnectionManager(connMgr)
                .setDefaultRequestConfig(requestConfig).build();
        HttpPost httpPost = new HttpPost(url);
        CloseableHttpResponse response = null;
        String httpStr = null;

        try {
            httpPost.setConfig(requestConfig);
            if (headers != null) {
                for (String headerName : headers.keySet()) {
                    httpPost.setHeader(headerName, headers.get(headerName));
                }
            }
            StringEntity stringEntity = new StringEntity(content, "UTF-8");// 解决中文乱码问题
            stringEntity.setContentEncoding("UTF-8");
            if (JSON.equals(type)) {
                stringEntity.setContentType("application/json");
            } else if (XML.equals(type)) {
                stringEntity.setContentType("application/xml");
            } else {
                stringEntity.setContentType("text/plain");
            }
            httpPost.setEntity(stringEntity);
            response = httpClient.execute(httpPost);
            int statusCode = response.getStatusLine().getStatusCode();
            if (statusCode != HttpStatus.SC_OK) {
                return null;
            }
            HttpEntity entity = response.getEntity();
            if (entity == null) {
                return null;
            }
            httpStr = EntityUtils.toString(entity, "utf-8");
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            if (response != null) {
                try {
                    EntityUtils.consume(response.getEntity());
                    response.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
        return httpStr;
    }

}