程式師世界 >> 編程語言 >> JAVA編程 >> JAVA編程入門知識 >> JAVA發送HTTP請求,返回HTTP響應內容,應用及實例代碼

JAVA發送HTTP請求,返回HTTP響應內容,應用及實例代碼

編輯：JAVA編程入門知識

JDK 中提供了一些對無狀態協議請求（HTTP ）的支持，下面我就將我所寫的一個小例子（組件）進行描述：
首先讓我們先構建一個請求類（HttpRequester ）。
該類封裝了 JAVA 實現簡單請求的代碼，如下：

代碼如下：

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請求對象
*
* @author YYmmiinngg
*/
public class HttpRequester {
    private String defaultContentEncoding;

    public HttpRequester() {
        this.defaultContentEncoding = Charset.defaultCharset().name();
    }

    /**
     * 發送GET請求
     *
     * @param urlString
     *            URL地址
     * @return 響應對象
     * @throws IOException
     */
    public HttpRespons sendGet(String urlString) throws IOException {
        return this.send(urlString, "GET", null, null);
    }

    /**
     * 發送GET請求
     *
     * @param urlString
     *            URL地址
     * @param params
     *            參數集合
     * @return 響應對象
     * @throws IOException
     */
    public HttpRespons sendGet(String urlString, Map<String, String> params)
            throws IOException {
        return this.send(urlString, "GET", params, null);
    }

    /**
     * 發送GET請求
     *
     * @param urlString
     *            URL地址
     * @param params
     *            參數集合
     * @param propertys
     *            請求屬性
     * @return 響應對象
     * @throws IOException
     */
    public HttpRespons sendGet(String urlString, Map<String, String> params,
            Map<String, String> propertys) throws IOException {
        return this.send(urlString, "GET", params, propertys);
    }

    /**
     * 發送POST請求
     *
     * @param urlString
     *            URL地址
     * @return 響應對象
     * @throws IOException
     */
    public HttpRespons sendPost(String urlString) throws IOException {
        return this.send(urlString, "POST", null, null);
    }

    /**
     * 發送POST請求
     *
     * @param urlString
     *            URL地址
     * @param params
     *            參數集合
     * @return 響應對象
     * @throws IOException
     */
    public HttpRespons sendPost(String urlString, Map<String, String> params)
            throws IOException {
        return this.send(urlString, "POST", params, null);
    }

    /**
     * 發送POST請求
     *
     * @param urlString
     *            URL地址
     * @param params
     *            參數集合
     * @param propertys
     *            請求屬性
     * @return 響應對象
     * @throws IOException
     */
    public HttpRespons sendPost(String urlString, Map<String, String> params,
            Map<String, String> propertys) throws IOException {
        return this.send(urlString, "POST", params, propertys);
    }

    /**
     * 發送HTTP請求
     *
     * @param urlString
     * @return 響映對象
     * @throws IOException
     */
    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();
        }

        return this.makeContent(urlString, urlConnection);
    }

    /**
     * 得到響應對象
     *
     * @param urlConnection
     * @return 響應對象
     * @throws IOException
     */
    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();
        }
    }

    /**
     * 默認的響應字符集
     */
    public String getDefaultContentEncoding() {
        return this.defaultContentEncoding;
    }

    /**
     * 設置默認的響應字符集
     */
    public void setDefaultContentEncoding(String defaultContentEncoding) {
        this.defaultContentEncoding = defaultContentEncoding;
    }
}

其次我們來看看響應對象（HttpRespons ）。響應對象其實只是一個數據BEAN ，由此來封裝請求響應的結果數據，如下：
代碼如下：

import java.util.Vector;

/**
* 響應對象
*/
public class HttpRespons {

    String urlString;

    int defaultPort;

    String file;

    String host;

    String path;

    int port;

    String protocol;

    String query;

    String ref;

    String userInfo;

    String contentEncoding;

    String content;

    String contentType;

    int code;

    String message;

    String method;

    int connectTimeout;

    int readTimeout;

    Vector<String> contentCollection;

    public String getContent() {
        return content;
    }

    public String getContentType() {
        return contentType;
    }

    public int getCode() {
        return code;
    }

    public String getMessage() {
        return message;
    }

    public Vector<String> getContentCollection() {
        return contentCollection;
    }

    public String getContentEncoding() {
        return contentEncoding;
    }

    public String getMethod() {
        return method;
    }

    public int getConnectTimeout() {
        return connectTimeout;
    }

    public int getReadTimeout() {
        return readTimeout;
    }

    public String getUrlString() {
        return urlString;
    }

    public int getDefaultPort() {
        return defaultPort;
    }

    public String getFile() {
        return file;
    }

    public String getHost() {
        return host;
    }

    public String getPath() {
        return path;
    }

    public int getPort() {
        return port;
    }

    public String getProtocol() {
        return protocol;
    }

    public String getQuery() {
        return query;
    }

    public String getRef() {
        return ref;
    }

    public String getUserInfo() {
        return userInfo;
    }

}

最後，讓我們寫一個應用類，測試以上代碼是否正確
代碼如下：

import com.yao.http.HttpRequester;
import com.yao.http.HttpRespons;

public class Test {
    public static void main(String[] args) {
        try {
            HttpRequester request = new HttpRequester();
            HttpRespons hr = request.sendGet("http://www.jb51.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();
        }
    }
}