Java開源簡單實用的Http工具類

jopen 10年前發布 | 2K 次閱讀 Java
/**

@file HttpUtil.java

@brief 
HttpUtil is a single class containing methods to conveniently perform HTTP 
requests. HttpUtil only uses regular java io and net functionality and does 
not depend on external libraries. 
The class contains methods to perform a get, post, put, and delete request,
and supports posting forms. Optionally, one can provide headers.
*
Example usage:

// get
String res = HttpUtil.get("http://www.google.com&quot;);

// post
String res = HttpUtil.post("http://sendmedata.com&quot;, "This is the data");
*
// post form
Map<String, String> params = new HashMap<String, String>();
params.put("firstname", "Joe");
params.put("lastname", "Smith");
params.put("age", "28");
String res = HttpUtil.postForm("http://site.com/newuser&quot;, params);
*
// append query parameters to url
String url = "http://mydatabase.com/users&quot;;
Map<String, String> params = new HashMap<String, String>();
params.put("orderby", "name");
params.put("limit", "10");
String fullUrl = HttpUtil.appendQueryParams(url, params);
// fullUrl = "http://mydatabase.com/user?orderby=name&limit=10&quot;
*
@license
Licensed under the Apache License, Version 2.0 (the "License"); you may not
use this file except in compliance with the License. You may obtain a copy 
of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
License for the specific language governing permissions and limitations under
the License.
*
Copyright (c) 2012 Almende B.V.
*
@author  Jos de Jong, <jos@almende.org>
@date      2012-05-14
*/

package com.almende.util;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.HttpURLConnection;
import java.net.URL;
import java.net.URLDecoder;
import java.net.URLEncoder;
import java.util.HashMap;
import java.util.Map;
public class HttpUtil {
    /**

 * Send a get request
 * @param url
 * @return response
 * @throws IOException 
 */
static public String get(String url) throws IOException {
    return get(url, null);
}

/**
 * Send a get request
 * @param url         Url as string
 * @param headers     Optional map with headers
 * @return response   Response as string
 * @throws IOException 
 */
static public String get(String url,
        Map<String, String> headers) throws IOException {
    return fetch("GET", url, null, headers);
}

/**
 * Send a post request
 * @param url         Url as string
 * @param body        Request body as string
 * @param headers     Optional map with headers
 * @return response   Response as string
 * @throws IOException 
 */
static public String post(String url, String body,
        Map<String, String> headers) throws IOException {
    return fetch("POST", url, body, headers);
}

/**
 * Send a post request
 * @param url         Url as string
 * @param body        Request body as string
 * @return response   Response as string
 * @throws IOException 
 */
static public String post(String url, String body) throws IOException {
    return post(url, body, null);
}

/**
 * Post a form with parameters
 * @param url         Url as string
 * @param params      map with parameters/values
 * @return response   Response as string
 * @throws IOException 
 */
static public String postForm(String url, Map<String, String> params) 
        throws IOException {
    return postForm(url, params, null);
}

/**
 * Post a form with parameters
 * @param url         Url as string
 * @param params      Map with parameters/values
 * @param headers     Optional map with headers
 * @return response   Response as string
 * @throws IOException 
 */
static public String postForm(String url, Map<String, String> params,
        Map<String, String> headers) throws IOException {
    // set content type
    if (headers == null) {
        headers = new HashMap<String, String>();
    }
    headers.put("Content-Type", "application/x-www-form-urlencoded");

    // parse parameters
    String body = "";
    if (params != null) {
        boolean first = true;
        for (String param : params.keySet()) {
            if (first) {
                first = false;
            }
            else {
                body += "&";
            }
            String value = params.get(param);
            body += URLEncoder.encode(param, "UTF-8") + "=";
            body += URLEncoder.encode(value, "UTF-8");
        }
    }

    return post(url, body, headers);
}

/**
 * Send a put request
 * @param url         Url as string
 * @param body        Request body as string
 * @param headers     Optional map with headers
 * @return response   Response as string
 * @throws IOException 
 */
static public String put(String url, String body,
        Map<String, String> headers) throws IOException {
    return fetch("PUT", url, body, headers);
}

/**
 * Send a put request
 * @param url         Url as string
 * @return response   Response as string
 * @throws IOException 
 */
static public String put(String url, String body) throws IOException {
    return put(url, body, null);
}

/**
 * Send a delete request
 * @param url         Url as string
 * @param headers     Optional map with headers
 * @return response   Response as string
 * @throws IOException 
 */
static public String delete(String url,
        Map<String, String> headers) throws IOException {
    return fetch("DELETE", url, null, headers);
}

/**
 * Send a delete request
 * @param url         Url as string
 * @return response   Response as string
 * @throws IOException 
 */
static public String delete(String url) throws IOException {
    return delete(url, null);
}

/**
 * Append query parameters to given url
 * @param url         Url as string
 * @param params      Map with query parameters
 * @return url        Url with query parameters appended
 * @throws IOException 
 */
static public String appendQueryParams(String url, 
        Map<String, String> params) throws IOException {
    String fullUrl = new String(url);

    if (params != null) {
        boolean first = (fullUrl.indexOf('?') == -1);
        for (String param : params.keySet()) {
            if (first) {
                fullUrl += '?';
                first = false;
            }
            else {
                fullUrl += '&';
            }
            String value = params.get(param);
            fullUrl += URLEncoder.encode(param, "UTF-8") + '=';
            fullUrl += URLEncoder.encode(value, "UTF-8");
        }
    }

    return fullUrl;
}

/**
 * Retrieve the query parameters from given url
 * @param url         Url containing query parameters
 * @return params     Map with query parameters
 * @throws IOException 
 */
static public Map<String, String> getQueryParams(String url) 
        throws IOException {
    Map<String, String> params = new HashMap<String, String>();

    int start = url.indexOf('?');
    while (start != -1) {
        // read parameter name
        int equals = url.indexOf('=', start);
        String param = "";
        if (equals != -1) {
            param = url.substring(start + 1, equals);
        }
        else {
            param = url.substring(start + 1);
        }

        // read parameter value
        String value = "";
        if (equals != -1) {
            start = url.indexOf('&', equals);
            if (start != -1) {
                value = url.substring(equals + 1, start);
            }
            else {
                value = url.substring(equals + 1);
            }
        }

        params.put(URLDecoder.decode(param, "UTF-8"), 
            URLDecoder.decode(value, "UTF-8"));
    }

    return params;
}

/**
 * Returns the url without query parameters
 * @param url         Url containing query parameters
 * @return url        Url without query parameters
 * @throws IOException 
 */
static public String removeQueryParams(String url) 
        throws IOException {
    int q = url.indexOf('?');
    if (q != -1) {
        return url.substring(0, q);
    }
    else {
        return url;
    }
}

/**
 * Send a request
 * @param method      HTTP method, for example "GET" or "POST"
 * @param url         Url as string
 * @param body        Request body as string
 * @param headers     Optional map with headers
 * @return response   Response as string
 * @throws IOException 
 */
static public String fetch(String method, String url, String body,
        Map<String, String> headers) throws IOException {
    // connection
    URL u = new URL(url);
    HttpURLConnection conn = (HttpURLConnection)u.openConnection();
    conn.setConnectTimeout(10000);
    conn.setReadTimeout(10000);

    // method
    if (method != null) {
        conn.setRequestMethod(method);
    }

    // headers
    if (headers != null) {
        for(String key : headers.keySet()) {
            conn.addRequestProperty(key, headers.get(key));
        }
    }

    // body
    if (body != null) {
        conn.setDoOutput(true);
        OutputStream os = conn.getOutputStream();
        os.write(body.getBytes());
        os.flush();
        os.close();
    }

    // response
    InputStream is = conn.getInputStream();
    String response = streamToString(is);
    is.close();

    // handle redirects
    if (conn.getResponseCode() == 301) {
        String location = conn.getHeaderField("Location");
        return fetch(method, location, body, headers);
    }

    return response;
}

/**
 * Read an input stream into a string
 * @param in
 * @return
 * @throws IOException
 */
static public String streamToString(InputStream in) throws IOException {
    StringBuffer out = new StringBuffer();
    byte[] b = new byte[4096];
    for (int n; (n = in.read(b)) != -1;) {
        out.append(new String(b, 0, n));
    }
    return out.toString();
}

}</pre>
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