httpclient教程

pengx 2009-09-11

展開全文

Commons-httpclient項(xiàng)目就是專門設(shè)計(jì)來簡化HTTP客戶端與服務(wù)器進(jìn)行各種通訊編程。

1．讀取網(wǎng)頁(HTTP/HTTPS)內(nèi)容

最簡單的HTTP客戶端,用來演示通過GET或者POST方式訪問某個(gè)頁面

Java代碼

package http.demo;
import java.io.IOException;
import org.apache.commons.httpclient.*;
import org.apache.commons.httpclient.methods.*;
public class SimpleClient {
public static void main(String[] args) throws IOException
{
HttpClient client = new HttpClient();
//設(shè)置代理服務(wù)器地址和端口
//client.getHostConfiguration().setProxy("proxy_host_addr",proxy_port);
//使用GET方法，如果服務(wù)器需要通過HTTPS連接，那只需要將下面URL中的http換成https
HttpMethod method = new GetMethod("http://java.");
//使用POST方法
//HttpMethod method = new PostMethod("http://java.");
client.executeMethod(method);
//打印服務(wù)器返回的狀態(tài)
System.out.println(method.getStatusLine());
//打印返回的信息
System.out.println(method.getResponseBodyAsString());
//釋放連接
method.releaseConnection();
}
}

package http.demo;
import java.io.IOException;
import org.apache.commons.httpclient.*;
import org.apache.commons.httpclient.methods.*;
public class SimpleClient {
public static void main(String[] args) throws IOException
{
HttpClient client = new HttpClient();
//設(shè)置代理服務(wù)器地址和端口
//client.getHostConfiguration().setProxy("proxy_host_addr",proxy_port);
//使用GET方法，如果服務(wù)器需要通過HTTPS連接，那只需要將下面URL中的http換成https
HttpMethod method = new GetMethod("http://java.");
//使用POST方法
//HttpMethod method = new PostMethod("http://java.");
client.executeMethod(method);
//打印服務(wù)器返回的狀態(tài)
System.out.println(method.getStatusLine());
//打印返回的信息
System.out.println(method.getResponseBodyAsString());
//釋放連接
method.releaseConnection();
}
}

2．以GET或者POST方式向網(wǎng)頁提交參數(shù)

Java代碼

package http.demo;
import java.io.IOException;
import org.apache.commons.httpclient.*;
import org.apache.commons.httpclient.methods.*;
/**
* 提交參數(shù)演示
* 該程序連接到一個(gè)用于查詢手機(jī)號碼所屬地的頁面
* 以便查詢號碼段1330227所在的省份以及城市
*/
public class SimpleHttpClient {
public static void main(String[] args) throws IOException
{
HttpClient client = new HttpClient();
client.getHostConfiguration().setHost("www.imobile.com.cn", 80, "http");
HttpMethod method = getPostMethod();//使用POST方式提交數(shù)據(jù)
client.executeMethod(method);
//打印服務(wù)器返回的狀態(tài)
System.out.println(method.getStatusLine());
//打印結(jié)果頁面
String response =
new String(method.getResponseBodyAsString().getBytes("8859_1"));
//打印返回的信息
System.out.println(response);
method.releaseConnection();
}
/**
* 使用GET方式提交數(shù)據(jù)
* @return
*/
private static HttpMethod getGetMethod(){
return new GetMethod("/simcard.php?simcard=1330227");
}
/**
* 使用POST方式提交數(shù)據(jù)
* @return
*/
private static HttpMethod getPostMethod(){
PostMethod post = new PostMethod("/simcard.php");
NameValuePair simcard = new NameValuePair("simcard","1330227");
post.setRequestBody(new NameValuePair[] { simcard});
return post;
}
}

package http.demo;
import java.io.IOException;
import org.apache.commons.httpclient.*;
import org.apache.commons.httpclient.methods.*;
/**
* 提交參數(shù)演示
* 該程序連接到一個(gè)用于查詢手機(jī)號碼所屬地的頁面
* 以便查詢號碼段1330227所在的省份以及城市
*/
public class SimpleHttpClient {
public static void main(String[] args) throws IOException
{
HttpClient client = new HttpClient();
client.getHostConfiguration().setHost("www.imobile.com.cn", 80, "http");
HttpMethod method = getPostMethod();//使用POST方式提交數(shù)據(jù)
client.executeMethod(method);
//打印服務(wù)器返回的狀態(tài)
System.out.println(method.getStatusLine());
//打印結(jié)果頁面
String response =
new String(method.getResponseBodyAsString().getBytes("8859_1"));
//打印返回的信息
System.out.println(response);
method.releaseConnection();
}
/**
* 使用GET方式提交數(shù)據(jù)
* @return
*/
private static HttpMethod getGetMethod(){
return new GetMethod("/simcard.php?simcard=1330227");
}
/**
* 使用POST方式提交數(shù)據(jù)
* @return
*/
private static HttpMethod getPostMethod(){
PostMethod post = new PostMethod("/simcard.php");
NameValuePair simcard = new NameValuePair("simcard","1330227");
post.setRequestBody(new NameValuePair[] { simcard});
return post;
}
}

3．處理頁面重定向

詳細(xì)描述:

狀態(tài)碼對應(yīng)HttpServletResponse的常量

301   SC_MOVED_PERMANENTLY 頁面已經(jīng)永久移到另外一個(gè)新地址

302   SC_MOVED_TEMPORARILY 頁面暫時(shí)移動到另外一個(gè)新的地址

303   SC_SEE_OTHER 客戶端請求的地址必須通過另外的URL來訪問

307   SC_TEMPORARY_REDIRECT 同 SC_MOVED_TEMPORARILY

下面的代碼片段演示如何處理頁面的重定向

Java代碼

client.executeMethod(post);
System.out.println(post.getStatusLine().toString());
post.releaseConnection();
//檢查是否重定向
int statuscode = post.getStatusCode();
if ((statuscode == HttpStatus.SC_MOVED_TEMPORARILY) ||
(statuscode == HttpStatus.SC_MOVED_PERMANENTLY) ||
(statuscode == HttpStatus.SC_SEE_OTHER) ||
statuscode == HttpStatus.SC_TEMPORARY_REDIRECT))
//讀取新的URL地址
Header header = post.getResponseHeader("location");
if (header != null)
{
String newuri = header.getValue();
if ((newuri == null) || (newuri.equals("")))
newuri = "/";
GetMethod redirect = new GetMethod(newuri);
client.executeMethod(redirect);
System.out.println("Redirect:"+
redirect.getStatusLine().toString());
redirect.releaseConnection();
} else
System.out.println("Invalid redirect");
}

        client.executeMethod(post);
System.out.println(post.getStatusLine().toString());
post.releaseConnection();
//檢查是否重定向
int statuscode = post.getStatusCode();
if ((statuscode == HttpStatus.SC_MOVED_TEMPORARILY) ||
(statuscode == HttpStatus.SC_MOVED_PERMANENTLY) ||
(statuscode == HttpStatus.SC_SEE_OTHER) ||
statuscode == HttpStatus.SC_TEMPORARY_REDIRECT))
{
//讀取新的URL地址
Header header = post.getResponseHeader("location");
if (header != null)
{
String newuri = header.getValue();
if ((newuri == null) || (newuri.equals("")))
newuri = "/";
GetMethod redirect = new GetMethod(newuri);
client.executeMethod(redirect);
System.out.println("Redirect:"+
redirect.getStatusLine().toString());
redirect.releaseConnection();
} else
System.out.println("Invalid redirect");
}
}

4．模擬輸入用戶名和口令進(jìn)行登錄

     本小節(jié)應(yīng)該說是HTTP客戶端編程中最常碰見的問題，很多網(wǎng)站的內(nèi)容都只是對注冊用戶可見的，這種情況下就必須要求使用正確的用戶名和口令登錄成功后，方可瀏覽到想要的頁面。因?yàn)镠TTP協(xié)議是無狀態(tài)的，也就是連接的有效期只限于當(dāng)前請求，請求內(nèi)容結(jié)束后連接就關(guān)閉了。在這種情況下為了保存用戶的登錄信息必須使用到Cookie機(jī)制。以JSP/Servlet為例，當(dāng)瀏覽器請求一個(gè)JSP或者是Servlet的頁面時(shí)，應(yīng)用服務(wù)器會返回一個(gè)參數(shù)，名為jsessionid（因不同應(yīng)用服務(wù)器而異），值是一個(gè)較長的唯一字符串的Cookie，這個(gè)字符串值也就是當(dāng)前訪問該站點(diǎn)的會話標(biāo)識。瀏覽器在每訪問該站點(diǎn)的其他頁面時(shí)候都要帶上jsessionid這樣的Cookie信息，應(yīng)用服務(wù)器根據(jù)讀取這個(gè)會話標(biāo)識來獲取對應(yīng)的會話信息。

     對于需要用戶登錄的網(wǎng)站，一般在用戶登錄成功后會將用戶資料保存在服務(wù)器的會話中，這樣當(dāng)訪問到其他的頁面時(shí)候，應(yīng)用服務(wù)器根據(jù)瀏覽器送上的Cookie中讀取當(dāng)前請求對應(yīng)的會話標(biāo)識以獲得對應(yīng)的會話信息，然后就可以判斷用戶資料是否存在于會話信息中，如果存在則允許訪問頁面，否則跳轉(zhuǎn)到登錄頁面中要求用戶輸入賬號和口令進(jìn)行登錄。這就是一般使用JSP開發(fā)網(wǎng)站在處理用戶登錄的比較通用的方法。

     對于HTTP的客戶端來講，如果要訪問一個(gè)受保護(hù)的頁面時(shí)就必須模擬瀏覽器所做的工作，首先就是請求登錄頁面，然后讀取Cookie值；再次請求登錄頁面并加入登錄頁所需的每個(gè)參數(shù)；最后就是請求最終所需的頁面。當(dāng)然在除第一次請求外其他的請求都需要附帶上 Cookie信息以便服務(wù)器能判斷當(dāng)前請求是否已經(jīng)通過驗(yàn)證。

Java代碼

package http.demo;
import org.apache.commons.httpclient.*;
import org.apache.commons.httpclient.cookie.*;
import org.apache.commons.httpclient.methods.*;
/**
* 用來演示登錄表單的示例
*/
public class FormLoginDemo {
static final String LOGON_SITE = "localhost";
static final int LOGON_PORT = 8080;
public static void main(String[] args) throws Exception{
HttpClient client = new HttpClient();
client.getHostConfiguration().setHost(LOGON_SITE, LOGON_PORT);
//模擬登錄頁面login.jsp->main.jsp
PostMethod post = new PostMethod("/main.jsp");
NameValuePair name = new NameValuePair("name", "ld");
NameValuePair pass = new NameValuePair("password", "ld");
post.setRequestBody(new NameValuePair[]{name,pass});
int status = client.executeMethod(post);
System.out.println(post.getResponseBodyAsString());
post.releaseConnection();
//查看cookie信息
CookieSpec cookiespec = CookiePolicy.getDefaultSpec();
Cookie[] cookies = cookiespec.match(LOGON_SITE, LOGON_PORT, "/", false, client.getState().getCookies());
if (cookies.length == 0) {
System.out.println("None");
} else {
for (int i = 0; i < cookies.length; i++) {
System.out.println(cookies[i].toString());
}
}
//訪問所需的頁面main2.jsp
GetMethod get = new GetMethod("/main2.jsp");
client.executeMethod(get);
System.out.println(get.getResponseBodyAsString());
get.releaseConnection();
}
}

package http.demo;
import org.apache.commons.httpclient.*;
import org.apache.commons.httpclient.cookie.*;
import org.apache.commons.httpclient.methods.*;
/**
* 用來演示登錄表單的示例
*/
public class FormLoginDemo {
static final String LOGON_SITE = "localhost";
static final int    LOGON_PORT = 8080;
public static void main(String[] args) throws Exception{
HttpClient client = new HttpClient();
client.getHostConfiguration().setHost(LOGON_SITE, LOGON_PORT);
//模擬登錄頁面login.jsp->main.jsp
PostMethod post = new PostMethod("/main.jsp");
NameValuePair name = new NameValuePair("name", "ld");
NameValuePair pass = new NameValuePair("password", "ld");
post.setRequestBody(new NameValuePair[]{name,pass});
int status = client.executeMethod(post);
System.out.println(post.getResponseBodyAsString());
post.releaseConnection();
//查看cookie信息
CookieSpec cookiespec = CookiePolicy.getDefaultSpec();
Cookie[] cookies = cookiespec.match(LOGON_SITE, LOGON_PORT, "/", false, client.getState().getCookies());
if (cookies.length == 0) {
System.out.println("None");
} else {
for (int i = 0; i < cookies.length; i++) {
System.out.println(cookies[i].toString());
}
}
//訪問所需的頁面main2.jsp
GetMethod get = new GetMethod("/main2.jsp");
client.executeMethod(get);
System.out.println(get.getResponseBodyAsString());
get.releaseConnection();
}
}

5．提交XML格式參數(shù)

提交XML格式的參數(shù)很簡單，僅僅是一個(gè)提交時(shí)候的ContentType問題，下面的例子演示從文件文件中讀取XML信息并提交給服務(wù)器的過程，該過程可以用來測試Web服務(wù)。

Java代碼

import java.io.File;
import java.io.FileInputStream;
import org.apache.commons.httpclient.HttpClient;
import org.apache.commons.httpclient.methods.EntityEnclosingMethod;
import org.apache.commons.httpclient.methods.PostMethod;
/**
* 用來演示提交XML格式數(shù)據(jù)的例子
*/
public class PostXMLClient {
public static void main(String[] args) throws Exception {
File input = new File(“test.xml”);
PostMethod post = new PostMethod(“http://localhost:8080/httpclient/xml.jsp”);
// 設(shè)置請求的內(nèi)容直接從文件中讀取
post.setRequestBody(new FileInputStream(input));
if (input.length() < Integer.MAX_VALUE)
post.setRequestContentLength(input.length());
else post.setRequestContentLength(EntityEnclosingMethod.CONTENT_LENGTH_CHUNKED);
// 指定請求內(nèi)容的類型
post.setRequestHeader("Content-type", "text/xml; charset=GBK");
HttpClient httpclient = new HttpClient();
int result = httpclient.executeMethod(post);
System.out.println("Response status code: " + result);
System.out.println("Response body: ");
System.out.println(post.getResponseBodyAsString());
post.releaseConnection();
}
}

import java.io.File;
import java.io.FileInputStream;
import org.apache.commons.httpclient.HttpClient;
import org.apache.commons.httpclient.methods.EntityEnclosingMethod;
import org.apache.commons.httpclient.methods.PostMethod;
/**
* 用來演示提交XML格式數(shù)據(jù)的例子
*/
public class PostXMLClient {
public static void main(String[] args) throws Exception {
File input = new File(“test.xml”);
PostMethod post = new PostMethod(“http://localhost:8080/httpclient/xml.jsp”);
// 設(shè)置請求的內(nèi)容直接從文件中讀取
post.setRequestBody(new FileInputStream(input));
if (input.length() < Integer.MAX_VALUE)
post.setRequestContentLength(input.length());
else            post.setRequestContentLength(EntityEnclosingMethod.CONTENT_LENGTH_CHUNKED);
// 指定請求內(nèi)容的類型
post.setRequestHeader("Content-type", "text/xml; charset=GBK");
HttpClient httpclient = new HttpClient();
int result = httpclient.executeMethod(post);
System.out.println("Response status code: " + result);
System.out.println("Response body: ");
System.out.println(post.getResponseBodyAsString());
post.releaseConnection();
}
}

6．通過HTTP上傳文件

httpclient使用了單獨(dú)的一個(gè)HttpMethod子類來處理文件的上傳，這個(gè)類就是MultipartPostMethod，該類已經(jīng)封裝了文件上傳的細(xì)節(jié)，我們要做的僅僅是告訴它我們要上傳文件的全路徑即可，下面的代碼片段演示如何使用這個(gè)類。

Java代碼

MultipartPostMethod filePost = new MultipartPostMethod(targetURL);
filePost.addParameter("fileName", targetFilePath);
HttpClient client = new HttpClient();
//由于要上傳的文件可能比較大,因此在此設(shè)置最大的連接超時(shí)時(shí)間
client.getHttpConnectionManager().getParams().setConnectionTimeout(5000);
int status = client.executeMethod(filePost);

MultipartPostMethod filePost = new MultipartPostMethod(targetURL);
filePost.addParameter("fileName", targetFilePath);
HttpClient client = new HttpClient();
//由于要上傳的文件可能比較大,因此在此設(shè)置最大的連接超時(shí)時(shí)間
client.getHttpConnectionManager().getParams().setConnectionTimeout(5000);
int status = client.executeMethod(filePost);

上面代碼中，targetFilePath即為要上傳的文件所在的路徑。

7．訪問啟用認(rèn)證的頁面

     我們經(jīng)常會碰到這樣的頁面，當(dāng)訪問它的時(shí)候會彈出一個(gè)瀏覽器的對話框要求輸入用戶名和密碼后方可，這種用戶認(rèn)證的方式不同于我們在前面介紹的基于表單的用戶身份驗(yàn)證。

    這是HTTP的認(rèn)證策略，httpclient支持三種認(rèn)證方式包括：基本、摘要以及NTLM認(rèn)證。

    其中基本認(rèn)證最簡單、通用但也最不安全；摘要認(rèn)證是在HTTP 1.1中加入的認(rèn)證方式，
而NTLM則是微軟公司定義的而不是通用的規(guī)范，最新版本的NTLM是比摘要認(rèn)證還要安全的一種方式。

Java代碼

import org.apache.commons.httpclient.HttpClient;
import org.apache.commons.httpclient.UsernamePasswordCredentials;
import org.apache.commons.httpclient.methods.GetMethod;
public class BasicAuthenticationExample {
public BasicAuthenticationExample() {
}
public static void main(String[] args) throws Exception {
HttpClient client = new HttpClient();
client.getState().setCredentials(
"www.",
"realm",
new UsernamePasswordCredentials("username", "password")
);
GetMethod get = new GetMethod("https://www./products/index.html");
get.setDoAuthentication( true );
int status = client.executeMethod( get );
System.out.println(status+""+ get.getResponseBodyAsString());
get.releaseConnection();
}
}

import org.apache.commons.httpclient.HttpClient;
import org.apache.commons.httpclient.UsernamePasswordCredentials;
import org.apache.commons.httpclient.methods.GetMethod;
public class BasicAuthenticationExample {
public BasicAuthenticationExample() {
}
public static void main(String[] args) throws Exception {
HttpClient client = new HttpClient();
client.getState().setCredentials(
"www.",
"realm",
new UsernamePasswordCredentials("username", "password")
);
GetMethod get = new GetMethod("https://www./products/index.html");
get.setDoAuthentication( true );
int status = client.executeMethod( get );
System.out.println(status+""+ get.getResponseBodyAsString());
get.releaseConnection();
}
}

8．多線程模式下使用httpclient

多線程同時(shí)訪問httpclient，例如同時(shí)從一個(gè)站點(diǎn)上下載多個(gè)文件。對于同一個(gè)HttpConnection 同一個(gè)時(shí)間只能有一個(gè)線程訪問，為了保證多線程工作環(huán)境下不產(chǎn)生沖突，httpclient使用了一個(gè)多線程連接管理器類：MultiThreadedHttpConnectionManager，要使用這個(gè)類很簡單，只需要在構(gòu)造HttpClient實(shí)例的時(shí)候傳入即可，代碼如下：

Java代碼

MultiThreadedHttpConnectionManager connectionManager =
new MultiThreadedHttpConnectionManager();
HttpClient client = new HttpClient(connectionManager);

MultiThreadedHttpConnectionManager connectionManager =
new MultiThreadedHttpConnectionManager();
HttpClient client = new HttpClient(connectionManager);

以后盡管訪問client實(shí)例即可。

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