HttpClient 學習1
阿新 • • 發佈：2019-02-13
HttpClient不是一個瀏覽器。它是一個客戶端的 HTTP 通訊實現庫。HttpClient 的目標是傳送和接收 HTTP 報文。 HttpClient 不會去快取內容，執行嵌入在 HTML 頁面中
獲取返回資訊的頭資料：
的 javascript 程式碼，猜測內容型別，重新格式化請求/重定向 URI，或者其它和 HTTP運輸無關的功能。
HttpClient最重要的功能是執行HTTP方法。一個HTTP方法的執行，包含一個或多個http請求/http響應。
簡單的請求過程的例項：
package ch1; import java.io.InputStream; import org.apache.http.HttpEntity; import org.apache.http.HttpResponse; import org.apache.http.client.HttpClient; import org.apache.http.client.methods.HttpGet; import org.apache.http.impl.client.HttpClients; public class Test1 { public static void main(String[] args) throws Exception { //建立一個HttpClient; HttpClient hc=HttpClients.createDefault(); //建立一個get請求 HttpGet httpGet=new HttpGet("http://www.baidu.com"); //執行請求，返回Response HttpResponse httpResponse=hc.execute(httpGet); HttpEntity httpEntity=httpResponse.getEntity(); //獲取內容 InputStream is=httpEntity.getContent(); byte[] b=new byte[1024]; int i; StringBuffer sb=new StringBuffer(); while((i=is.read(b))!=-1){ sb.append(new String(b)); } is.close(); System.out.println(sb.toString()); } }
使用httpclient提供的方法建立帶引數的uri:
package ch1; import java.io.InputStream; import java.net.URI; import java.util.ArrayList; import java.util.List; import org.apache.http.HttpEntity; import org.apache.http.HttpResponse; import org.apache.http.NameValuePair; import org.apache.http.client.HttpClient; import org.apache.http.client.methods.HttpGet; import org.apache.http.client.utils.URIUtils; import org.apache.http.client.utils.URLEncodedUtils; import org.apache.http.impl.client.HttpClients; import org.apache.http.message.BasicNameValuePair; public class Test2 { public static void main(String[] args) throws Exception { //http://www.baidu.com/s?tn=baiduhome_pg&ie=utf-8&bs=httpclient+中文+pdf&f=8 //&rsv_bp=1&wd=csdn&rsv_sug3=5&rsv_sug4=229&rsv_sug1=6&rsv_sug2=0&inputT=4 HttpClient hc=HttpClients.createDefault(); //將請求的引數存在這個集合中 List<NameValuePair> nameValues=new ArrayList<NameValuePair>(); nameValues.add(new BasicNameValuePair("tn", "baiduhome_pg")); nameValues.add(new BasicNameValuePair("ie", "utf-8")); nameValues.add(new BasicNameValuePair("bs", "httpclient+中文+pdf")); nameValues.add(new BasicNameValuePair("f", "8")); nameValues.add(new BasicNameValuePair("rsv_bp", "1")); nameValues.add(new BasicNameValuePair("wd", "csdn")); nameValues.add(new BasicNameValuePair("rsv_sug3", "5")); nameValues.add(new BasicNameValuePair("rsv_sug4", "299")); nameValues.add(new BasicNameValuePair("rsv_sug1", "6")); nameValues.add(new BasicNameValuePair("rsv_sug2", "0")); nameValues.add(new BasicNameValuePair("inputT", "4")); //建立一個URI @SuppressWarnings("deprecation") URI uri=URIUtils.createURI("http", "www.baidu.com", -1, "/s",URLEncodedUtils.format(nameValues, "utf-8") ,null); System.out.println(uri); HttpGet httpGet=new HttpGet(uri); HttpResponse httpResponse=hc.execute(httpGet); HttpEntity httpEntity=httpResponse.getEntity(); //獲取內容 InputStream is=httpEntity.getContent(); byte[] b=new byte[1024]; int i; StringBuffer sb=new StringBuffer(); while((i=is.read(b))!=-1){ sb.append(new String(b)); } is.close(); System.out.println(sb.toString()); } }
Http響應：
package ch1; import org.apache.http.HttpResponse; import org.apache.http.HttpStatus; import org.apache.http.HttpVersion; import org.apache.http.message.BasicHttpResponse; public class Test3 { public static void main(String[] args) { //模擬建立一個HttpResponse HttpResponse httpRes = new BasicHttpResponse(HttpVersion.HTTP_1_1,HttpStatus.SC_OK,"OK"); System.out.println(httpRes.getProtocolVersion()); System.out.println(httpRes.getStatusLine()); } }
獲取返回資訊的頭資料：
//執行請求，返回Response
HttpResponse httpResponse=hc.execute(httpGet);
//獲取狀態
System.out.println(httpResponse.getStatusLine());
//獲取頭資訊
System.out.println(httpResponse.getFirstHeader("Content-Type"));
Header[] h= httpResponse.getHeaders("Content-Type");
for (int i = 0; i < h.length; i++) {
System.out.println(h[i]);
}
//獲取所有頭資訊
HeaderIterator hi=httpResponse.headerIterator();
while(hi.hasNext()){
Header he=hi.nextHeader();
System.out.println(he.getName()+":"+he.getValue());
}