使用JAVA发送HTTP请求(Http Request)，返回HTTP响应(Http Response)内容，代码程序例子及原理说明

JDK中提供了一些对无状态协议请求（HTTP）的支持，下面我就将我所写的一个小例子（组件）进行描述：

首先让我们先构建一个请求类（HttpRequester）。

该类封装了JAVA实现简单请求的代码，如下：

import java.io.BufferedReader;

import java.io.IOException;

import java.io.InputStream;

import java.io.InputStreamReader;

import java.net.HttpURLConnection;

import java.net.URL;

import java.nio.charset.Charset;

import java.util.Map;

import java.util.Vector;

 

/**

 *HTTP请求对象

 *

 *@authorYYmmiinngg

 */

publicclass HttpRequester {

    private String defaultContentEncoding;

 

    public HttpRequester() {

        this.defaultContentEncoding = Charset.defaultCharset().name();

    }

 

    /**

     *发送GET请求

     *

     *@paramurlString

     *            URL地址

     *@return响应对象

     *@throwsIOException

     */

    public HttpRespons sendGet(String urlString) throws IOException {

        returnthis.send(urlString, "GET", null, null);

    }

 

    /**

     *发送GET请求

     *

     *@paramurlString

     *            URL地址

     *@paramparams

     *            参数集合

     *@return响应对象

     *@throwsIOException

     */

    public HttpRespons sendGet(String urlString, Map<String, String> params)

            throws IOException {

        returnthis.send(urlString, "GET", params, null);

    }

 

    /**

     *发送GET请求

     *

     *@paramurlString

     *            URL地址

     *@paramparams

     *            参数集合

     *@parampropertys

     *            请求属性

     *@return响应对象

     *@throwsIOException

     */

    public HttpRespons sendGet(String urlString, Map<String, String> params,

            Map<String, String> propertys) throws IOException {

        returnthis.send(urlString, "GET", params, propertys);

    }

 

    /**

     *发送POST请求

     *

     *@paramurlString

     *            URL地址

     *@return响应对象

     *@throwsIOException

     */

    public HttpRespons sendPost(String urlString) throws IOException {

        returnthis.send(urlString, "POST", null, null);

    }

 

    /**

     *发送POST请求

     *

     *@paramurlString

     *            URL地址

     *@paramparams

     *            参数集合

     *@return响应对象

     *@throwsIOException

     */

    public HttpRespons sendPost(String urlString, Map<String, String> params)

            throws IOException {

        returnthis.send(urlString, "POST", params, null);

    }

 

    /**

     *发送POST请求

     *

     *@paramurlString

     *            URL地址

     *@paramparams

     *            参数集合

     *@parampropertys

     *            请求属性

     *@return响应对象

     *@throwsIOException

     */

    public HttpRespons sendPost(String urlString, Map<String, String> params,

            Map<String, String> propertys) throws IOException {

        returnthis.send(urlString, "POST", params, propertys);

    }

 

    /**

     *发送HTTP请求

     *

     *@paramurlString

     *@return响映对象

     *@throwsIOException

     */

    private HttpRespons send(String urlString, String method,

            Map<String, String> parameters, Map<String, String> propertys)

            throws IOException {

        HttpURLConnection urlConnection = null;

 

        if (method.equalsIgnoreCase("GET") && parameters != null) {

            StringBuffer param = new StringBuffer();

            int i = 0;

            for (String key : parameters.keySet()) {

                if (i == 0)

                    param.append("?");

                else

                    param.append("&");

                param.append(key).append("=").append(parameters.get(key));

                i++;

            }

            urlString += param;

        }

        URL url = new URL(urlString);

        urlConnection = (HttpURLConnection) url.openConnection();

 

        urlConnection.setRequestMethod(method);

        urlConnection.setDoOutput(true);

        urlConnection.setDoInput(true);

        urlConnection.setUseCaches(false);

 

        if (propertys != null)

            for (String key : propertys.keySet()) {

                urlConnection.addRequestProperty(key, propertys.get(key));

            }

 

        if (method.equalsIgnoreCase("POST") && parameters != null) {

            StringBuffer param = new StringBuffer();

            for (String key : parameters.keySet()) {

                param.append("&");

                param.append(key).append("=").append(parameters.get(key));

            }

            urlConnection.getOutputStream().write(param.toString().getBytes());

            urlConnection.getOutputStream().flush();

            urlConnection.getOutputStream().close();

        }

 

        returnthis.makeContent(urlString, urlConnection);

    }

 

    /**

     *得到响应对象

     *

     *@paramurlConnection

     *@return响应对象

     *@throwsIOException

     */

    private HttpRespons makeContent(String urlString,

            HttpURLConnection urlConnection) throws IOException {

        HttpRespons httpResponser = new HttpRespons();

        try {

            InputStream in = urlConnection.getInputStream();

            BufferedReader bufferedReader = new BufferedReader(

                    new InputStreamReader(in));

            httpResponser.contentCollection = new Vector<String>();

            StringBuffer temp = new StringBuffer();

            String line = bufferedReader.readLine();

            while (line != null) {

                httpResponser.contentCollection.add(line);

                temp.append(line).append("/r/n");

                line = bufferedReader.readLine();

            }

            bufferedReader.close();

 

            String ecod = urlConnection.getContentEncoding();

            if (ecod == null)

                ecod = this.defaultContentEncoding;

 

            httpResponser.urlString = urlString;

 

            httpResponser.defaultPort = urlConnection.getURL().getDefaultPort();

            httpResponser.file = urlConnection.getURL().getFile();

            httpResponser.host = urlConnection.getURL().getHost();

            httpResponser.path = urlConnection.getURL().getPath();

            httpResponser.port = urlConnection.getURL().getPort();

            httpResponser.protocol = urlConnection.getURL().getProtocol();

            httpResponser.query = urlConnection.getURL().getQuery();

            httpResponser.ref = urlConnection.getURL().getRef();

            httpResponser.userInfo = urlConnection.getURL().getUserInfo();

 

            httpResponser.content = new String(temp.toString().getBytes(), ecod);

            httpResponser.contentEncoding = ecod;

            httpResponser.code = urlConnection.getResponseCode();

            httpResponser.message = urlConnection.getResponseMessage();

            httpResponser.contentType = urlConnection.getContentType();

            httpResponser.method = urlConnection.getRequestMethod();

            httpResponser.connectTimeout = urlConnection.getConnectTimeout();

            httpResponser.readTimeout = urlConnection.getReadTimeout();

 

            return httpResponser;

        } catch (IOException e) {

            throw e;

        } finally {

            if (urlConnection != null)

                urlConnection.disconnect();

        }

    }

 

    /**

     *默认的响应字符集

     */

    public String getDefaultContentEncoding() {

        returnthis.defaultContentEncoding;

    }

 

    /**

     *设置默认的响应字符集

     */

    publicvoid setDefaultContentEncoding(String defaultContentEncoding) {

        this.defaultContentEncoding = defaultContentEncoding;

    }

}

 

其次我们来看看响应对象（HttpRespons）。

响应对象其实只是一个数据BEAN，由此来封装请求响应的结果数据，如下：

 

import java.util.Vector;

 

/**

 *响应对象

 */

publicclass HttpRespons {

 

    String urlString;

 

    intdefaultPort;

 

    String file;

 

    String host;

 

    String path;

 

    intport;

 

    String protocol;

 

    String query;

 

    String ref;

 

    String userInfo;

 

    String contentEncoding;

 

    String content;

 

    String contentType;

 

    intcode;

 

    String message;

 

    String method;

 

    intconnectTimeout;

 

    intreadTimeout;

 

    Vector<String> contentCollection;

 

    public String getContent() {

        returncontent;

    }

 

    public String getContentType() {

        returncontentType;

    }

 

    publicint getCode() {

        returncode;

    }

 

    public String getMessage() {

        returnmessage;

    }

 

    public Vector<String> getContentCollection() {

        returncontentCollection;

    }

 

    public String getContentEncoding() {

        returncontentEncoding;

    }

 

    public String getMethod() {

        returnmethod;

    }

 

    publicint getConnectTimeout() {

        returnconnectTimeout;

    }

 

    publicint getReadTimeout() {

        returnreadTimeout;

    }

 

    public String getUrlString() {

        returnurlString;

    }

 

    publicint getDefaultPort() {

        returndefaultPort;

    }

 

    public String getFile() {

        returnfile;

    }

 

    public String getHost() {

        returnhost;

    }

 

    public String getPath() {

        returnpath;

    }

 

    publicint getPort() {

        returnport;

    }

 

    public String getProtocol() {

        returnprotocol;

    }

 

    public String getQuery() {

        returnquery;

    }

 

    public String getRef() {

        returnref;

    }

 

    public String getUserInfo() {

        returnuserInfo;

    }

 

}

 

最后，让我们写一个应用类，测试以上代码是否正确

import com.yao.http.HttpRequester;

import com.yao.http.HttpRespons;

 

publicclass Test {

    publicstaticvoid main(String[] args) {

        try {

            HttpRequester request = new HttpRequester();

            HttpRespons hr = request.sendGet("http://www.csdn.net");

 

            System.out.println(hr.getUrlString());

            System.out.println(hr.getProtocol());

            System.out.println(hr.getHost());

            System.out.println(hr.getPort());

            System.out.println(hr.getContentEncoding());

            System.out.println(hr.getMethod());

           

            System.out.println(hr.getContent());

 

        } catch (Exception e) {

            e.printStackTrace();

        }

    }

}