HttpClient配置及运用
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HttpComponents是Apache 旗下的项目。其中有一个HttpClient,即HTTP客户端。
之后我们建立项目,导入jar包,开始开发
一、获取网页内容:
package com.zhi.httpClient; import java.io.IOException; import org.apache.http.HttpEntity; import org.apache.http.ParseException; import org.apache.http.client.ClientProtocolException; import org.apache.http.client.methods.CloseableHttpResponse; import org.apache.http.client.methods.HttpGet; import org.apache.http.impl.client.CloseableHttpClient; import org.apache.http.impl.client.HttpClients; import org.apache.http.util.EntityUtils; public class Demo { public static void main(String[] args) { CloseableHttpClient closeableHttpClient=HttpClients.createDefault(); //1、创建实例 //CloseableHttpClient意思是:可关闭的 HttpGet httpGet=new HttpGet("http://www.huimsoft.com"); //2、创建实例 //限制类型http://www.tuicool.com/ CloseableHttpResponse closeableHttpResponse=null; try { closeableHttpResponse=closeableHttpClient.execute(httpGet); //3、执行 } catch (ClientProtocolException e) { //客户端协议异常 // TODO Auto-generated catch block e.printStackTrace(); } catch (IOException e) { //IO异常 // TODO Auto-generated catch block e.printStackTrace(); } HttpEntity httpEntity=closeableHttpResponse.getEntity(); //4、获取实体 String str=""; try { str=EntityUtils.toString(httpEntity, "utf-8"); //获取网页内容,并且指定编码 } catch (ParseException e) { //解析异常 // TODO Auto-generated catch block e.printStackTrace(); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } System.out.println(str); //关闭closeableHttpResponse try { closeableHttpResponse.close(); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } //关闭closeableHttpClient try { closeableHttpClient.close(); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } } }
代码有很多,但是很多是在处理异常,所以我们也可以使用throws在方法上抛出,以简化代码格式,让其更好看。
package com.zhi.httpClient; import org.apache.http.HttpEntity; import org.apache.http.client.methods.CloseableHttpResponse; import org.apache.http.client.methods.HttpGet; import org.apache.http.impl.client.CloseableHttpClient; import org.apache.http.impl.client.HttpClients; import org.apache.http.util.EntityUtils; public class Test { public static void main(String[] args) throws Exception { CloseableHttpClient closeableHttpClient=HttpClients.createDefault(); //1、创建实例 HttpGet httpGet=new HttpGet("http://www.huimsoft.com"); //2、创建请求 CloseableHttpResponse closeableHttpResponse=closeableHttpClient.execute(httpGet); //3、执行 HttpEntity httpEntity=closeableHttpResponse.getEntity(); //4、获取实体 System.out.println(EntityUtils.toString(httpEntity, "utf-8")); //5、获取网页内容,并且指定编码 closeableHttpResponse.close(); closeableHttpClient.close(); } }
二、设置请求头信息
设置请求头信息的目的是为了模拟浏览器
package com.zhi.httpClient2; import org.apache.http.HttpEntity; import org.apache.http.client.methods.CloseableHttpResponse; import org.apache.http.client.methods.HttpGet; import org.apache.http.impl.client.CloseableHttpClient; import org.apache.http.impl.client.HttpClients; import org.apache.http.util.EntityUtils; public class Demo { public static void main(String[] args) throws Exception { CloseableHttpClient closeableHttpClient=HttpClients.createDefault(); //1、创建实例 HttpGet httpGet=new HttpGet("http://www.tuicool.com"); //2、创建请求 httpGet.setHeader("User-Agent", "Mozilla/5.0 (Windows NT 5.1) AppleWebKit/537.36 (Khtml, like Gecko) Chrome/38.0.2125.122 Safari/537.36 SE 2.X MetaSr 1.0"); CloseableHttpResponse closeableHttpResponse=closeableHttpClient.execute(httpGet); //3、执行 HttpEntity httpEntity=closeableHttpResponse.getEntity(); //4、获取实体 System.out.println(EntityUtils.toString(httpEntity, "utf-8")); //5、获取网页内容,并且指定编码 closeableHttpResponse.close(); closeableHttpClient.close(); } }
三、获取相应头信息Response Headers的内容类型Content-type
package com.zhi.httpClient2; import org.apache.http.Header; import org.apache.http.HttpEntity; import org.apache.http.client.methods.CloseableHttpResponse; import org.apache.http.client.methods.HttpGet; import org.apache.http.impl.client.CloseableHttpClient; import org.apache.http.impl.client.HttpClients; public class Demo { public static void main(String[] args) throws Exception { CloseableHttpClient closeableHttpClient=HttpClients.createDefault(); //1、创建实例 HttpGet httpGet=new HttpGet("http://www.tuicool.com"); //2、创建请求 httpGet.setHeader("User-Agent", "Mozilla/5.0 (Windows NT 5.1) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/38.0.2125.122 Safari/537.36 SE 2.X MetaSr 1.0"); CloseableHttpResponse closeableHttpResponse=closeableHttpClient.execute(httpGet); //3、执行 HttpEntity httpEntity=closeableHttpResponse.getEntity(); //4、获取实体 Header header=httpEntity.getContentType(); System.out.println(header.toString()); //获取头信息内容 System.out.println(header.getName().toString()); //这是获取key System.out.println(header.getValue().toString()); //这是获取value //System.out.println(EntityUtils.toString(httpEntity, "utf-8")); //5、获取网页内容,并且指定编码 closeableHttpResponse.close(); closeableHttpClient.close(); } }
运行输出:
Content-Type: text/html; charset=utf-8
Content-Type
text/html; charset=utf-8
我们的重点是获取的value的值,有些是text/html的,有些是其他的,比如我们请求一个js文件。
https://cdn.bootcss.com/jquery/1.12.4/jquery.min.js
HttpGet httpGet=new HttpGet("http://cdn.bootcss.com/jquery/1.12.4/jquery.min.js");
public class Demo { public static void main(String[] args) throws Exception { CloseableHttpClient closeableHttpClient=HttpClients.createDefault(); //1、创建实例 HttpGet httpGet=new HttpGet("http://cdn.bootcss.com/jquery/1.12.4/jquery.min.js"); //2、创建实例 httpGet.setHeader("User-Agent", "Mozilla/5.0 (Windows NT 5.1) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/38.0.2125.122 Safari/537.36 SE 2.X MetaSr 1.0"); CloseableHttpResponse closeableHttpResponse=closeableHttpClient.execute(httpGet); //3、执行 HttpEntity httpEntity=closeableHttpResponse.getEntity(); //4、获取实体 Header header=httpEntity.getContentType(); System.out.println(header.getValue().toString()); //这是获取value closeableHttpResponse.close(); closeableHttpClient.close(); } }
运行结果:
运行结果:application/javascript
如果请求一个图片,同上
运行结果:image/png
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