首页 > 代码库 > JAVA: httpclient 详解；
JAVA: httpclient 详解；
相对于httpurlconnection ，httpclient更加丰富，也更加强大，其中apache有两个项目都是httpclient，一个是commonts包下的，这个是通用的，更专业的是org.apache.http.包下的，所以我一般用后者；
httpclient可以处理长连接，保存会话，重连接，以及请求过滤器，连接重用等等...
下面是测试代码（全部总结来自官方文档，以及翻译）
须要下载核心包：httpclient-4.3.4.jar ，也可在官网下载：http://hc.apache.org/downloads.cgi
package httpClientTest;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.InterruptedIOException;
import java.net.URI;
import java.net.URISyntaxException;
import java.net.UnknownHostException;
import java.nio.charset.Charset;
import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicInteger;
import javax.net.ssl.SSLException;
import org.apache.http.Consts;
import org.apache.http.HeaderElement;
import org.apache.http.HeaderElementIterator;
import org.apache.http.HttpClientConnection;
import org.apache.http.HttpEntity;
import org.apache.http.HttpEntityEnclosingRequest;
import org.apache.http.HttpException;
import org.apache.http.HttpHost;
import org.apache.http.HttpRequest;
import org.apache.http.HttpRequestInterceptor;
import org.apache.http.HttpResponse;
import org.apache.http.NameValuePair;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.HttpRequestRetryHandler;
import org.apache.http.client.ResponseHandler;
import org.apache.http.client.config.RequestConfig;
import org.apache.http.client.entity.UrlEncodedFormEntity;
import org.apache.http.client.methods.CloseableHttpResponse;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.client.protocol.HttpClientContext;
import org.apache.http.client.utils.URIBuilder;
import org.apache.http.client.utils.URIUtils;
import org.apache.http.conn.ConnectTimeoutException;
import org.apache.http.conn.ConnectionKeepAliveStrategy;
import org.apache.http.conn.ConnectionRequest;
import org.apache.http.conn.HttpClientConnectionManager;
import org.apache.http.conn.routing.HttpRoute;
import org.apache.http.entity.ContentType;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.DefaultConnectionKeepAliveStrategy;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.impl.client.LaxRedirectStrategy;
import org.apache.http.impl.conn.BasicHttpClientConnectionManager;
import org.apache.http.message.BasicHeaderElementIterator;
import org.apache.http.message.BasicNameValuePair;
import org.apache.http.protocol.HTTP;
import org.apache.http.protocol.HttpContext;
import org.apache.http.util.EntityUtils;
public class Main {
public static void main(String[] args) {
try {
test9();
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
/**
* 测试1： 构建复杂uri，这种方式会很方便的设置多个参数；
*
* HttpClients类是client的具体一个实现类；
*
* URIBuilder包含：协议，主机名，端口（可选），资源路径，和多个参数（可选）
*
*/
private static void test1() {
CloseableHttpClient client = HttpClients.createDefault();
URI uri = null;
try {
uri = new URIBuilder()
.setScheme("http")
.setHost("webservice.webxml.com.cn")
.setPath("/WebServices/MobileCodeWS.asmx/getDatabaseInfo")
.setParameter("", "")//这里可以设置多个参数
.setParameter("", "")
.setParameter("", "")
.setParameter("", "")
.build();
} catch (URISyntaxException e1) {
e1.printStackTrace();
}
//http://webservice.webxml.com.cn/WebServices/MobileCodeWS.asmx/getDatabaseInfo
HttpGet get = new HttpGet(uri);
try {
CloseableHttpResponse response = client.execute(get);
if(response.getStatusLine().getStatusCode()==200){
System.out.println(EntityUtils.toString(response.getEntity()));
//以下这种方式读取流也可以，只不过用EntityUtils会更方便
/*InputStream is = response.getEntity().getContent();
ByteArrayOutputStream os = new ByteArrayOutputStream();
byte[] buffer = new byte[1024];
int len=-1;
while((len = is.read(buffer))!=-1){
os.write(buffer,0,len);
}
os.close();
is.close();
System.out.println(os.size()+new String(os.toByteArray(),"utf-8"));*/
}
} catch (ClientProtocolException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
/**
* 为uri进行加密，并进行表单提交；
*
* 许多应用需要模拟提交的HTML表单的处理，例如，在
为了登录到Web应用程序或提交的输入数据。 HttpClient提供的实体类
UrlEncodedFormEntity可以实现该过程；
*/
private static void test2(){
CloseableHttpClient client = HttpClients.createDefault();
HttpPost httppost = new HttpPost("http://webservice.webxml.com.cn/WebServices/MobileCodeWS.asmx/getMobileCodeInfo");
//构建请求参数
List<NameValuePair> list = new ArrayList<NameValuePair>();
list.add(new BasicNameValuePair("mobileCode", "110"));
list.add(new BasicNameValuePair("userID", ""));
//构建url加密实体，并以utf-8方式进行加密；
UrlEncodedFormEntity entity = new UrlEncodedFormEntity(list, Consts.UTF_8);
httppost.setEntity(entity);
try {
CloseableHttpResponse response = client.execute(httppost);
if(response.getStatusLine().getStatusCode()==200){
//org.apache.http.util.EntityUtils类可以快速处理服务器返回实体对象
System.out.println(EntityUtils.toString(response.getEntity()));
}
} catch (ClientProtocolException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
/**
* 以回调方式处理返回结果
*
* 处理响应的最简单和最方便的方法是通过使用ResponseHandler的
接口。用户不必担心连接管理的问题。当使用一个
ResponseHandler的时候，无论是否请求执行成功或导致异常，HttpClient将会自动释放连接。
*/
private static void test3(){
CloseableHttpClient client = HttpClients.createDefault();
//==============================================================
ResponseHandler<Object> handler = new ResponseHandler<Object>() {
@Override
public Object handleResponse(final HttpResponse response) throws IOException {
HttpEntity entity = response.getEntity();
if (entity == null) {
throw new ClientProtocolException("返回结果为空");
}
if(response.getStatusLine().getStatusCode()==200){
//获取返回结果的字符集 如：utf-8 gbk，并以这种字符集来读取流信息
ContentType contentType = ContentType.getOrDefault(entity);
Charset charset = contentType.getCharset();
InputStreamReader reader = new InputStreamReader(entity.getContent(), charset);
BufferedReader br = new BufferedReader(reader);
StringBuffer sb = new StringBuffer();
char[] buffer = new char[1024];
while (br.read(buffer)!=-1) {
sb.append(new String(buffer));
}
return sb.toString();
}
return null;
}
};
//===================================================================
URI uri = null;//构建uri实体
try {
uri = new URIBuilder()
.setScheme("http")
.setHost("webservice.webxml.com.cn")
.setPath("/WebServices/MobileCodeWS.asmx/getDatabaseInfo")
.setParameter("", "")
.setParameter("", "")
.setParameter("", "")
.build();
} catch (URISyntaxException e) {
e.printStackTrace();
}
HttpPost post = new HttpPost(uri);
try {
//handler回调
Object obj = client.execute(post, handler);
System.out.println("返回结果："+obj);
} catch (ClientProtocolException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
/**
* 设置长连接策略，根据服务器的约束或者客户端的约束来设置长连接的时长；
*/
private static void test4() {
ConnectionKeepAliveStrategy strategy = new DefaultConnectionKeepAliveStrategy() {
/**
* 服务器端配置（以tomcat为例）：keepAliveTimeout=60000，表示在60s内内，服务器会一直保持连接状态。
* 也就是说，如果客户端一直请求服务器，且间隔未超过60s，则该连接将一直保持，如果60s内未请求，则超时。
*
* getKeepAliveDuration返回超时时间；
*/
@Override
public long getKeepAliveDuration(HttpResponse response, HttpContext context) {
//如果服务器指定了超时时间，则以服务器的超时时间为准
HeaderElementIterator it = new BasicHeaderElementIterator(response.headerIterator(HTTP.CONN_KEEP_ALIVE));
while (it.hasNext()) {
HeaderElement he = it.nextElement();
String param = he.getName();
String value = http://www.mamicode.com/he.getValue();>
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