获取相应头信息Response Headers的内容类型Content-Type

Content-Type内容类型，也是键值对的形式：

我们在代码中获取：

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，有些事text/html的，有些事其他的，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");

代码如下：

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：application/javascript

我们请求一个图片，代码如下：

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://static.bootcss.com/www/assets/img/null.png?1505127079951"); //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：image/png

我们获取内容类型是为了将来能够过滤掉一些类型。选出我们需要的然后jsoup来解析。