设置post方法的header,增加红色字体部分的配置:
HttpClient client = new HttpClient();
client.getParams().setBooleanParameter(
"http.protocol.expect-continue", false);
PostMethod method = new PostMethod(url);
method.addRequestHeader("Connection", "close");
一。 http 工作 大至 原理
HTTP工作原理
1.客户端和服务器。
2.建立连接,客户端向服务器发送一个请求。
3.服务器接受到请求后,向客户端发出响应信息。
4.客户端与服务器断开链接。
请求报文与响应报文。
请求报文格式:
请求行-->通用信息头-->请求头-->实体头-->报文主体
响应报文格式:
状态行-->通用信息头-->相应头-->实体头-->报文主体
android 集成了org.apache.http.client.HttpClient; 可以直接实现简单的htttp Get 和 Post 操作 但是不支持 多部post 操作 。 要实现 多部分post 操作还需要导 额外 jar包 这里就不介绍了。
实现一个 http 操作
1 。需要生成一个Http Client 客户端对象 。
2。 生成响应的请求对象 。
3。接受发回的信息 。
4.。解析返回的信息。
直接看 get 请求操作 。
public String httpGet(String url, String params) throws Exception{
String result=""; //返回信息
if (null!=params&&!params.equals(""))
{
url += "?" + params;
}
//创建一个httpGet请求
HttpGet request=new HttpGet(url);
//创建一个htt客户端
HttpClient httpClient=new DefaultHttpClient();
//接受客户端发回的响应
HttpResponse httpResponse=httpClient.execute(request);
int statusCode=httpResponse.getStatusLine().getStatusCode();
if(statusCode==HttpStatus.SC_OK){
//得到客户段响应的实体内容
HttpEntity responseHttpEntity=httpResponse.getEntity();
//得到输入流
InputStream in=responseHttpEntity.getContent();
//得到输入流的内容
result=getData(in);
}
Log.d(TAG, statusCode+"");
return result;
}
post 操作
几个额外的辅助方法
/**
* 读取返回的信息
* @param in
* @return
*/
private String getData(InputStream in) {
String result="";
StringBuilder sb=new StringBuilder();
BufferedReader br = new BufferedReader(new InputStreamReader(in));
String line = "";
try {
while ((line = br.readLine()) != null) {
//result = result + line;
sb.append(line);
}
br.close();
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
} finally {
if (result != null) {
try {
br.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
return sb.toString();
}
/**
* 输入流转换成字符串
* @param is: 输入流
* @return 字符串对象
*/
private static String InputStreamToString(InputStream is){
BufferedReader reader = null;
StringBuffer responseText = null;
String readerText = null;
try {
reader = new BufferedReader(new InputStreamReader(is, "UTF-8"));
responseText = new StringBuffer();
readerText = reader.readLine();
while(readerText != null){
responseText.append(readerText);
responseText.append(System.getProperty("line.separator"));
readerText = reader.readLine();
}
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
return responseText.toString();
}
/**
* 将cookie写入指定文件
* @param cookies: cookie
* @param fileName: 文件名
*/
private static void write(Cookie[] cookies, String fileName){
try {
String path = System.getProperty("user.home") + "\\" + fileName;
File file = new File(path);
BufferedWriter bw = new BufferedWriter(new FileWriter(file));
for(Cookie c : cookies){
bw.append(c.toString());
bw.append(System.getProperty("line.separator"));
}
bw.flush();
bw.close();
Runtime.getRuntime().exec("explorer " + path + "");
} catch (IOException e) {
e.printStackTrace();
}
}
如何 post json格式的数据,并附加http头,接受返回数据,请看下面的代码:
[java] view plaincopy
private void HttpPostData() {
try {
HttpClient httpclient = new DefaultHttpClient();
String uri = "http://www.yourweb.com";
HttpPost httppost = new HttpPost(uri);
//添加http头信息
httppost.addHeader("Authorization", "your token"); //认证token
httppost.addHeader("Content-Type", "application/json");
httppost.addHeader("User-Agent", "imgfornote");
//http post的json数据格式: {"name": "your name","parentId": "id_of_parent"}
JSONObject obj = new JSONObject();
obj.put("name", "your name");
obj.put("parentId", "your parentid");
httppost.setEntity(new StringEntity(obj.toString()));
HttpResponse response;
response = httpclient.execute(httppost);
//检验状态码,如果成功接收数据
int code = response.getStatusLine().getStatusCode();
if (code == 200) {
String rev = EntityUtils.toString(response.getEntity());//返回json格式: {"id": "27JpL~j4vsL0LX00E00005","version": "abc"}
obj = new JSONObject(rev);
String id = obj.getString("id");
String version = obj.getString("version");
}
} catch (ClientProtocolException e) {
} catch (IOException e) {
} catch (Exception e) {
}
}
主要用到的类有:org.apache.http.client.HttpClient 、org.apache.http.client.methods.HttpPost 和 org.json.JSONObject
请求行 ,是一个方法符号开头 ,后面跟着请求 URI和协议的版本, 以CRLF作为结尾 . 请求后以空格分隔. 除了作为结尾的 CRLF(回车换行)外,不允许出现单独的CR和LF字符,格式如下:
Method Request-URI HTTP-Version CRLF
例如 : GET /test.html HTTP/1.1 (CRLF)
HTTP请求方法 : GET POST HEAD DELETE PUT
POST方法用于向服务器发送请求,要求服务器接受附在请求后面的数据.POST方法在表单提交的时候用的最多 .
例如:
POST /login.jsp HTTP/1.1 (CRLF)
Accept:image/gif (CRLF) (...)
........
Host:www.sample.com (CRLF)
(CRLF)
username=hell@password=123456 两个(CRLF)之后加上参数
HEAD方法只是请求消息报头,而不是完整的内容. 通常用于测试超链接的有效性.
HTTP响应
HTTP-Version Status-Code Reason-Phrase CRLF
例如 : HTTP/1.1 200 OK (CRLF)
状态分类
1xx 提示信息
2xx 请求成功
3xx 重定向
4xx 客户端错误
5xx 服务器错误
HTTP消息有客户端到服务器的请求和服务器到客户端的响应组成.
消息都是由开始行,消息报头(可选),空行(只有CRLF的行),消息正文(可选)组成.
对于请求消息,开始行就是请求行,对于响应消息,开始行就是状态行.
Apache HttpClient 是很方便的 Java 开源的访问 HTTP 资源的组件。网站上的资源不总是能匿名访问的,很多都需要登陆后才能操作,且不说论坛里登陆后才能发言,就是某些稍显敏感的 XML 等信息也是登陆后才能获取到的。
没问题,HttpClient 能让你做到,它提供了 Basic 和 Form-Based 两种验证方式。登陆后获得服务器端发来的 Cookie 作为下一次访问的凭证, 让服务端认为你还是个合法用户。服务端不是用 Session 来维护会话的吗?是的,Session 也要有个载体,Cookie 了。或有时 Java Web 会用 jsessionid 参数在服务端与客户端来回关联 Session 信息,也没问题,HttpClient 同样能胜任。
下面主要说明 Form-Based 的验证方式,Basic 的验证简单列了几行代码,还未实践,具体可参考文后的链接。
看 Form-Based 方式的演示代码,如果登陆时需要一个验证码的话,那只有自己想办法怎么得到这个码了,登陆时谁都想无码:
package cc.unmi.httpclient;
import org.apache.commons.httpclient.Cookie;
import org.apache.commons.httpclient.HttpClient;
import org.apache.commons.httpclient.NameValuePair;
import org.apache.commons.httpclient.cookie.CookiePolicy;
import org.apache.commons.httpclient.methods.GetMethod;
import org.apache.commons.httpclient.methods.PostMethod;
import org.junit.Test;
public class HttpClientLogin {
public static void main(String[] args){
//登陆 Url
String loginUrl = "http://localhost/unmi/login.html";
//需登陆后访问的 Url
String dataUrl = "http://localhost/unmi/user_info.html?userid=123456";
HttpClient httpClient = new HttpClient();
//模拟登陆,按实际服务器端要求选用 Post 或 Get 请求方式
PostMethod postMethod = new PostMethod(loginUrl);
//设置登陆时要求的信息,一般就用户名和密码,验证码自己处理了
NameValuePair[] data = {
new NameValuePair("username", "Unmi"),
new NameValuePair("password", "123456"),
new NameValuePair("code", "anyany")
};
postMethod.setRequestBody(data);
try {
//设置 HttpClient 接收 Cookie,用与浏览器一样的策略
httpClient.getParams().setCookiePolicy(CookiePolicy.BROWSER_COMPATIBILITY);
httpClient.executeMethod(postMethod);
//获得登陆后的 Cookie
Cookie[] cookies=httpClient.getState().getCookies();
String tmpcookies= "";
for(Cookie c:cookies){
tmpcookies += c.toString()+";";
}
//进行登陆后的操作
GetMethod getMethod = new GetMethod(dataUrl);
//每次访问需授权的网址时需带上前面的 cookie 作为通行证
getMethod.setRequestHeader("cookie",tmpcookies);
//你还可以通过 PostMethod/GetMethod 设置更多的请求后数据
//例如,referer 从哪里来的,UA 像搜索引擎都会表名自己是谁,无良搜索引擎除外
postMethod.setRequestHeader("Referer", "http://unmi.cc");
postMethod.setRequestHeader("User-Agent","Unmi Spot");
httpClient.executeMethod(getMethod);
//打印出返回数据,检验一下是否成功
String text = getMethod.getResponseBodyAsString();
System.out.println(text);
} catch (Exception e) {
e.printStackTrace();
}
}
}
Basic 验证的简单代码导引,还未亲试:
HttpClient client = new HttpClient();
// 1
client.getState().setCredentials(
new AuthScope("unmi.cc", 80, AuthScope.ANY_REALM),
new UsernamePasswordCredentials("username", "password")
);
// 2
client.getParams().setAuthenticationPreemptive(true);
// 3
GetMethod getMothod = new GetMethod("http://unmi.cc/twitter");
// 4
getMothod.setDoAuthentication( true );
// 5
int status = client.executeMethod( getMothod );
http://unmi.cc/httpclient-login-session
999999999999999999999999
post步骤 解析json数据(向服务器传递,接受服务器传递))
www.MyException.Cn 发布于:2012-08-11 20:50:31 浏览:13次
httpClient post方法 解析json数据(向服务器传递,接受服务器传递))
public class json extends Activity {
public Context context;
private TextView textView1;
public static String URL = "http://webservice.webxml.com.cn/WebServices/WeatherWebService.asmx?wsdl";
private DefaultHttpClient httpClient;
StringBuilder result = new StringBuilder();
private static final int TIMEOUT = 60;
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
HttpParams paramsw = createHttpParams();
httpClient = new DefaultHttpClient(paramsw);
HttpPost post = new HttpPost( "http://webservice.webxml.com.cn/WebServices/WeatherWebService.asmx?wsdl");
List<NameValuePair> params = new ArrayList<NameValuePair>();
params.add(new BasicNameValuePair("name", "this is post"));
try {
//向服务器写json
JSONObject json = new JSONObject();
Object email = null;
json.put("email", email);
Object pwd = null;
json.put("password", pwd);
StringEntity se = new StringEntity( "JSON: " + json.toString());
se.setContentEncoding(new BasicHeader(HTTP.CONTENT_TYPE, "application/json"));
post.setEntity(se);
post.setEntity(new UrlEncodedFormEntity(params, HTTP.UTF_8));
HttpResponse httpResponse = httpClient.execute(post);
int httpCode = httpResponse.getStatusLine().getStatusCode();
if (httpCode == HttpURLConnection.HTTP_OK&&httpResponse!=null) {
Header[] headers = httpResponse.getAllHeaders();
HttpEntity entity = httpResponse.getEntity();
Header header = httpResponse.getFirstHeader("content-type");
//读取服务器返回的json数据(接受json服务器数据)
InputStream inputStream = entity.getContent();
InputStreamReader inputStreamReader = new InputStreamReader(inputStream);
BufferedReader reader = new BufferedReader(inputStreamReader);// 读字符串用的。
String s;
while (((s = reader.readLine()) != null)) {
result.append(s);
}
reader.close();// 关闭输入流
//在这里把result这个字符串个给JSONObject。解读里面的内容。
JSONObject jsonObject = new JSONObject(result.toString());
String re_username = jsonObject.getString("username");
String re_password = jsonObject.getString("password");
int re_user_id = jsonObject.getInt("user_id");
setTitle("用户id_"+re_user_id);
Log.v("url response", "true="+re_username);
Log.v("url response", "true="+re_password);
} else {
textView1.setText("Error Response" + httpResponse.getStatusLine().toString());
}
} catch (UnsupportedEncodingException e) {
} catch (ClientProtocolException e) {
} catch (IOException e) {
} catch (JSONException e) {
e.printStackTrace();
} finally {
if (httpClient != null) {
httpClient.getConnectionManager().shutdown();// 最后关掉链接。
httpClient = null;
}
}
}
public static final HttpParams createHttpParams() {
final HttpParams params = new BasicHttpParams();
HttpConnectionParams.setStaleCheckingEnabled(params, false);
HttpConnectionParams.setConnectionTimeout(params, TIMEOUT * 1000);
HttpConnectionParams.setSoTimeout(params, TIMEOUT * 1000);
HttpConnectionParams.setSocketBufferSize(params, 8192 * 5);
return params;
}
}
348888888888888888
HttpClient程序包是一个实现了 HTTP 协议的客户端编程工具包,要想熟练的掌握它,必须熟悉 HTTP协议。一个最简单的调用如下:
import java.io.IOException;
import org.apache.http.HttpResponse;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.client.methods.HttpUriRequest;
import org.apache.http.impl.client.DefaultHttpClient;
public class Test {
public static void main(String[] args) {
// 核心应用类
HttpClient httpClient = new DefaultHttpClient();
// HTTP请求
HttpUriRequest request =
new HttpGet("http://localhost/index.html");
// 打印请求信息
System.out.println(request.getRequestLine());
try {
// 发送请求,返回响应
HttpResponse response = httpClient.execute(request);
// 打印响应信息
System.out.println(response.getStatusLine());
} catch (ClientProtocolException e) {
// 协议错误
e.printStackTrace();
} catch (IOException e) {
// 网络异常
e.printStackTrace();
}
}
}
如果HTTP服务器正常并且存在相应的服务,则上例会打印出两行结果:
GET http://localhost/index.html HTTP/1.1
HTTP/1.1 200 OK
核心对象httpClient的调用非常直观,其execute方法传入一个request对象,返回一个response对象。使用 httpClient发出HTTP请求时,系统可能抛出两种异常,分别是ClientProtocolException和IOException。第一种异常的发生通常是协议错误导致,如在构造HttpGet对象时传入的协议不对(例如不小心将”http”写成”htp”),或者服务器端返回的内容不符合HTTP协议要求等;第二种异常一般是由于网络原因引起的异常,如HTTP服务器未启动等。
从实际应用的角度看,HTTP协议由两大部分组成:HTTP请求和HTTP响应。那么HttpClient程序包是如何实现HTTP客户端应用的呢?实现过程中需要注意哪些问题呢?
HTTP请求
HTTP 1.1由以下几种请求组成:GET, HEAD, POST, PUT, DELETE, TRACE and OPTIONS, 程序包中分别用HttpGet, HttpHead, HttpPost, HttpPut, HttpDelete, HttpTrace, and HttpOptions 这几个类创建请求。所有的这些类均实现了HttpUriRequest接口,故可以作为execute的执行参数使用。
所有请求中最常用的是GET与POST两种请求,与创建GET请求的方法相同,可以用如下方法创建一个POST请求:
HttpUriRequest request = new HttpPost(
"http://localhost/index.html");
HTTP请求格式告诉我们,有两个位置或者说两种方式可以为request提供参数:request-line方式与request-body方式。
request-line
request-line方式是指在请求行上通过URI直接提供参数。
(1)
我们可以在生成request对象时提供带参数的URI,如:
HttpUriRequest request = new HttpGet(
"http://localhost/index.html?param1=value1¶m2=value2");
(2)
另外,HttpClient程序包为我们提供了URIUtils工具类,可以通过它生成带参数的URI,如:
URI uri = URIUtils.createURI("http", "localhost", -1, "/index.html",
"param1=value1¶m2=value2", null);
HttpUriRequest request = new HttpGet(uri);
System.out.println(request.getURI());
上例的打印结果如下:
http://localhost/index.html?param1=value1¶m2=value2
(3)
需要注意的是,如果参数中含有中文,需将参数进行URLEncoding处理,如:
String param = "param1=" + URLEncoder.encode("中国", "UTF-8") + "¶m2=value2";
URI uri = URIUtils.createURI("http", "localhost", 8080,
"/sshsky/index.html", param, null);
System.out.println(uri);
上例的打印结果如下:
http://localhost/index.html?param1=%E4%B8%AD%E5%9B%BD¶m2=value2
(4)
对于参数的URLEncoding处理,HttpClient程序包为我们准备了另一个工具类:URLEncodedUtils。通过它,我们可以直观的(但是比较复杂)生成URI,如:
List params = new ArrayList();
params.add(new BasicNameValuePair("param1", "中国"));
params.add(new BasicNameValuePair("param2", "value2"));
String param = URLEncodedUtils.format(params, "UTF-8");
URI uri = URIUtils.createURI("http", "localhost", 8080,
"/sshsky/index.html", param, null);
System.out.println(uri);
上例的打印结果如下:
http://localhost/index.html?param1=%E4%B8%AD%E5%9B%BD¶m2=value2
request-body
与request-line方式不同,request-body方式是在request-body中提供参数,此方式只能用于POST请求。在 HttpClient程序包中有两个类可以完成此项工作,它们分别是UrlEncodedFormEntity类与MultipartEntity类。这两个类均实现了HttpEntity接口。
(1)
使用最多的是UrlEncodedFormEntity类。通过该类创建的对象可以模拟传统的HTML表单传送POST请求中的参数。如下面的表单:
<form action="http://localhost/index.html" method="POST">
<input type="text" name="param1" value="中国"/>
<input type="text" name="param2" value="value2"/>
<inupt type="submit" value="submit"/>
</form>
我们可以用下面的代码实现:
List formParams = new ArrayList();
formParams.add(new BasicNameValuePair("param1", "中国"));
formParams.add(new BasicNameValuePair("param2", "value2"));
HttpEntity entity = new UrlEncodedFormEntity(formParams, "UTF-8");
HttpPost request = new HttpPost(“http://localhost/index.html”);
request.setEntity(entity);
当然,如果想查看HTTP数据格式,可以通过HttpEntity对象的各种方法取得。如:
List formParams = new ArrayList();
formParams.add(new BasicNameValuePair("param1", "中国"));
formParams.add(new BasicNameValuePair("param2", "value2"));
UrlEncodedFormEntity entity = new UrlEncodedFormEntity(formParams, "UTF-8");
System.out.println(entity.getContentType());
System.out.println(entity.getContentLength());
System.out.println(EntityUtils.getContentCharSet(entity));
System.out.println(EntityUtils.toString(entity));
上例的打印结果如下:
Content-Type: application/x-www-form-urlencoded; charset=UTF-8
39
UTF-8
param1=%E4%B8%AD%E5%9B%BD¶m2=value2
(2)
除了传统的application/x-www-form-urlencoded表单,我们另一个经常用到的是上传文件用的表单,这种表单的类型为 multipart/form-data。在HttpClient程序扩展包(HttpMime)中专门有一个类与之对应,那就是 MultipartEntity类。此类同样实现了HttpEntity接口。如下面的表单:
<form action="http://localhost/index.html" method="POST"
enctype="multipart/form-data">
<input type="text" name="param1" value="中国"/>
<input type="text" name="param2" value="value2"/>
<input type="file" name="param3"/>
<inupt type="submit" value="submit"/>
</form>
我们可以用下面的代码实现:
MultipartEntity entity = new MultipartEntity();
entity.addPart("param1", new StringBody("中国", Charset.forName("UTF-8")));
entity.addPart("param2", new StringBody("value2", Charset.forName("UTF-8")));
entity.addPart("param3", new FileBody(new File("C:\\1.txt")));
HttpPost request = new HttpPost(“http://localhost/index.html”);
request.setEntity(entity);
HTTP响应
HttpClient程序包对于HTTP响应的处理较之HTTP请求来说是简单多了,其过程同样使用了HttpEntity接口。我们可以从 HttpEntity对象中取出数据流(InputStream),该数据流就是服务器返回的响应数据。需要注意的是,HttpClient程序包不负责解析数据流中的内容。如:
HttpUriRequest request = ...;
HttpResponse response = httpClient.execute(request);
// 从response中取出HttpEntity对象
HttpEntity entity = response.getEntity();
// 查看entity的各种指标
System.out.println(entity.getContentType());
System.out.println(entity.getContentLength());
System.out.println(EntityUtils.getContentCharSet(entity));
// 取出服务器返回的数据流
InputStream stream = entity.getContent();
// 以任意方式操作数据流stream
// 调用方式 略
附注:
本文说明的是HttpClient 4.0.1,该程序包(包括依赖的程序包)由以下几个JAR包组成:
commons-logging-1.1.1.jar
commons-codec-1.4.jar
httpcore-4.0.1.jar
httpclient-4.0.1.jar
apache-mime4j-0.6.jar
httpmime-4.0.1.jar
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------
现在Apache已经发布了:HttpCore 4.0-beta3、HttpClient 4.0-beta1。
到此处可以去下载这些源代码:http://hc.apache.org/downloads.cgi
另外,还需要apache-mime4j-0.5.jar 包。
在这里先写个简单的POST方法。
package test;
import java.util.ArrayList;
import java.util.List;
import org.apache.http.Header;
import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.NameValuePair;
import org.apache.http.client.entity.UrlEncodedFormEntity;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.client.params.CookiePolicy;
import org.apache.http.client.params.ClientPNames;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.message.BasicNameValuePair;
import org.apache.http.protocol.HTTP;
import org.apache.http.util.EntityUtils;
public class Test2 {
public static void main(String[] args) throws Exception {
DefaultHttpClient httpclient = new DefaultHttpClient(); //实例化一个HttpClient
HttpResponse response = null;
HttpEntity entity = null;
httpclient.getParams().setParameter(
ClientPNames.COOKIE_POLICY, CookiePolicy.BROWSER_COMPATIBILITY); //设置cookie的兼容性
HttpPost httpost = new HttpPost("http://127.0.0.1:8080/pub/jsp/getInfo"); //引号中的参数是:servlet的地址
List <NameValuePair> nvps = new ArrayList <NameValuePair>();
nvps.add(new BasicNameValuePair("jqm", "fb1f7cbdaf2bf0a9cb5d43736492640e0c4c0cd0232da9de"));
// BasicNameValuePair("name", "value"), name是post方法里的属性, value是传入的参数值
nvps.add(new BasicNameValuePair("sqm", "1bb5b5b45915c8"));
httpost.setEntity(new UrlEncodedFormEntity(nvps, HTTP.UTF_8)); //将参数传入post方法中
response = httpclient.execute(httpost); //执行
entity = response.getEntity(); //返回服务器响应
try{
System.out.println("----------------------------------------");
System.out.println(response.getStatusLine()); //服务器返回状态
Header[] headers = response.getAllHeaders(); //返回的HTTP头信息
for (int i=0; i<headers.length; i++) {
System.out.println(headers[i]);
}
System.out.println("----------------------------------------");
String responseString = null;
if (response.getEntity() != null) {
responseString = EntityUtils.toString(response.getEntity()); / /返回服务器响应的HTML代码
System.out.println(responseString); //打印出服务器响应的HTML代码
}
} finally {
if (entity != null)
entity.consumeContent(); // release connection gracefully
}
System.out.println("Login form get: " + response.getStatusLine());
if (entity != null) {
entity.consumeContent();
}
}
}
HttpClient4.0 学习实例 - 页面获取
HttpClient 4.0出来不久,所以网络上面相关的实例教程不多,搜httpclient得到的大部分都是基于原 Commons HttpClient 3.1 (legacy) 包的,官网下载页面:http://hc.apache.org/downloads.cgi,如果大家看了官网说明就明白httpclient4.0是从原包分支出来独立成包的,以后原来那个包中的httpclient不会再升级,所以以后我们是用httpclient新分支,由于4.0与之前的3.1包结构以及接口等都有较大变化,所以网上搜到的实例大部分都是不适合4.0的,当然,我们可以通过那些实例去琢磨4.0的用法,我也是新手,记录下学习过程方便以后检索
本实例我们来获取抓取网页编码,内容等信息
默认情况下,服务器端会根据客户端的请求头信息来返回服务器支持的编码,像google.cn他本身支持utf-8,gb2312等编码,所以如果你在头部中不指定任何头部信息的话他默认会返回gb2312编码,而如果我们在浏览器中直接访问google.cn,通过httplook,或者firefox 的firebug插件查看返回头部信息的话会发现他返回的是UTF-8编码
下面我们还是看实例来解说吧,注释等我也放代码里面解释,放完整代码,方便新手理解
本实例将
使用的httpclient相关包
httpclient-4.0.jar
httpcore-4.0.1.jar
httpmime-4.0.jar
commons-logging-1.0.4.jar等其它相关包
// HttpClientTest.java
package com.baihuo.crawler.test;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import org.apache.http.Header;
import org.apache.http.HttpEntity;
import org.apache.http.HttpHost;
import org.apache.http.HttpResponse;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.util.EntityUtils;
class HttpClientTest {
public final static void main(String[] args) throws Exception {
// 初始化,此处构造函数就与3.1中不同
HttpClient httpclient = new DefaultHttpClient();
HttpHost targetHost = new HttpHost("www.google.cn");
//HttpGet httpget = new HttpGet("http://www.apache.org/");
HttpGet httpget = new HttpGet("/");
// 查看默认request头部信息
System.out.println("Accept-Charset:" + httpget.getFirstHeader("Accept-Charset"));
// 以下这条如果不加会发现无论你设置Accept-Charset为gbk还是utf-8,他都会默认返回gb2312(本例针对google.cn来说)
httpget.setHeader("User-Agent", "Mozilla/5.0 (Windows; U; Windows NT 5.1; zh-CN; rv:1.9.1.2)");
// 用逗号分隔显示可以同时接受多种编码
httpget.setHeader("Accept-Language", "zh-cn,zh;q=0.5");
httpget.setHeader("Accept-Charset", "GB2312,utf-8;q=0.7,*;q=0.7");
// 验证头部信息设置生效
System.out.println("Accept-Charset:" + httpget.getFirstHeader("Accept-Charset").getValue());
// Execute HTTP request
System.out.println("executing request " + httpget.getURI());
HttpResponse response = httpclient.execute(targetHost, httpget);
//HttpResponse response = httpclient.execute(httpget);
System.out.println("----------------------------------------");
System.out.println("Location: " + response.getLastHeader("Location"));
System.out.println(response.getStatusLine().getStatusCode());
System.out.println(response.getLastHeader("Content-Type"));
System.out.println(response.getLastHeader("Content-Length"));
System.out.println("----------------------------------------");
// 判断页面返回状态判断是否进行转向抓取新链接
int statusCode = response.getStatusLine().getStatusCode();
if ((statusCode == HttpStatus.SC_MOVED_PERMANENTLY) ||
(statusCode == HttpStatus.SC_MOVED_TEMPORARILY) ||
(statusCode == HttpStatus.SC_SEE_OTHER) ||
(statusCode == HttpStatus.SC_TEMPORARY_REDIRECT)) {
// 此处重定向处理 此处还未验证
String newUri = response.getLastHeader("Location").getValue();
httpclient = new DefaultHttpClient();
httpget = new HttpGet(newUri);
response = httpclient.execute(httpget);
}
// Get hold of the response entity
HttpEntity entity = response.getEntity();
// 查看所有返回头部信息
Header headers[] = response.getAllHeaders();
int ii = 0;
while (ii < headers.length) {
System.out.println(headers[ii].getName() + ": " + headers[ii].getValue());
++ii;
}
// If the response does not enclose an entity, there is no need
// to bother about connection release
if (entity != null) {
// 将源码流保存在一个byte数组当中,因为可能需要两次用到该流,
byte[] bytes = EntityUtils.toByteArray(entity);
String charSet = "";
// 如果头部Content-Type中包含了编码信息,那么我们可以直接在此处获取
charSet = EntityUtils.getContentCharSet(entity);
System.out.println("In header: " + charSet);
// 如果头部中没有,那么我们需要 查看页面源码,这个方法虽然不能说完全正确,因为有些粗糙的网页编码者没有在页面中写头部编码信息
if (charSet == "") {
regEx="(?=<meta).*?(?<=charset=[\\'|\\\"]?)([[a-z]|[A-Z]|[0-9]|-]*)";
p=Pattern.compile(regEx, Pattern.CASE_INSENSITIVE);
m=p.matcher(new String(bytes)); // 默认编码转成字符串,因为我们的匹配中无中文,所以串中可能的乱码对我们没有影响
result=m.find();
if (m.groupCount() == 1) {
charSet = m.group(1);
} else {
charSet = "";
}
}
System.out.println("Last get: " + charSet);
// 至此,我们可以将原byte数组按照正常编码专成字符串输出(如果找到了编码的话)
System.out.println("Encoding string is: " + new String(bytes, charSet));
}
httpclient.getConnectionManager().shutdown();
}
}