HttpClient入门get post请求
1.HttpClient入门使用
注意这个版本主要是基于HttpClient4.5.2版本的来讲解的,也是现在最新的版本,之所以要提供版本说明的是因为HttpClient 3版本和HttpClient 4版本差别还是很多大的,基本HttpClient里面的接口都变了,你把HttpClient 3版本的代码拿到HttpClient 4上面都运行不起来,会报错的。所以这儿一定要注意,好了废话不多说了,开始。
2.在pom.xml加入对httpclient的必需的jar包的依赖
<!--httpclient依赖包-->
<dependency>
<groupId>org.apache.httpcomponents</groupId>
<artifactId>httpclient</artifactId>
<version>4.5.2</version>
</dependency>
<dependency>
<groupId>org.apache.httpcomponents</groupId>
<artifactId>httpclient-cache</artifactId>
<version>4.5</version>
</dependency>
<dependency>
<groupId>org.apache.httpcomponents</groupId>
<artifactId>httpmime</artifactId>
<version>4.3.2</version>
</dependency>
注意:常见的MIME类型(通用型):
超文本标记语言文本 .html text/html
xml文档 .xml text/xml
XHTML文档 .xhtml application/xhtml+xml
普通文本 .txt text/plain
RTF文本 .rtf application/rtf
PDF文档 .pdf application/pdf
Microsoft Word文件 .word application/msword
PNG图像 .png image/png
GIF图形 .gif image/gif
JPEG图形 .jpeg,.jpg image/jpeg
au声音文件 .au audio/basic
MIDI音乐文件 mid,.midi audio/midi,audio/x-midi
RealAudio音乐文件 .ra, .ram audio/x-pn-realaudio
MPEG文件 .mpg,.mpeg video/mpeg
AVI文件 .avi video/x-msvideo
TAR文件 .tar application/x-tar
任意的二进制数据 application/octet-stream
3.抓取网页的内容并打印到控制台的demo--get请求
@Test public void testHttpClientA() throws IOException { //使用默认配置的httpclient CloseableHttpClient httpClient = HttpClients.createDefault(); //即将访问的url String url = "http://www.baidu.com"; //get形式的访问 HttpGet httpGet = new HttpGet(url); //执行请求 CloseableHttpResponse response = null; try { response = httpClient.execute(httpGet); //打印请求的状态码 请求成功为200 System.out.println(response.getStatusLine().getStatusCode()); //打印请求的实体内容 返回json格式 HttpEntity entity = response.getEntity(); //获取所有头信息 Header[] allHeaders = response.getAllHeaders(); for (Header allHeader : allHeaders) { System.out.println(allHeader.getName()); System.out.println(allHeader.getValue()); System.out.println(allHeader.toString()); } //方法一 官方不推荐 if (entity != null) { //输出更详细的抓取内容(html格式) System.out.println(EntityUtils.toString(entity,"utf-8")); } //释放资源 EntityUtils.consume(entity); //方法二 官方推荐 使用流的形式处理请求结果 /* if (entity != null) { InputStream content = entity.getContent(); BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(content)); String line = ""; while ((line = bufferedReader.readLine()) != null){ System.out.println(line); } bufferedReader.close(); }*/ } catch (IOException e) { e.printStackTrace(); }finally { response.close(); }
4.带参数的请求--get请求
@Test public void testHttpClientB() throws URISyntaxException { CloseableHttpClient httpClient = HttpClients.createDefault(); URI uri = new URIBuilder() .setScheme("http") .setHost("www.google.com") .setPath("/search") .setParameter("q", "httpclient") .setParameter("btnG", "Google搜索") .setParameter("aq", "f") .setParameter("oq", "dd") .build(); HttpGet httpGet = new HttpGet(uri); System.out.println(httpGet.getURI()); }
5.带参数的请求--post请求
@Test public void testHttpClientPost() throws IOException { //定义uri String uri="http://php.weather.sina.com.cn/iframe/index/w_cl.php"; //需要传入的参数 Map<String, String> map = new HashMap<String, String>(); map.put("code", "js"); map.put("day", "0"); map.put("city", "上海"); map.put("dfc", "1"); map.put("charset", "utf-8"); String encoding = "utf-8"; //创建默认的httpclient CloseableHttpClient httpClient = HttpClients.createDefault(); //创建post请求对象 HttpPost httpPost = new HttpPost(uri); //装填请求参数 List<NameValuePair> list = new ArrayList<NameValuePair>(); for (Map.Entry<String, String> entry : map.entrySet()) { list.add(new BasicNameValuePair(entry.getKey(),entry.getValue())); } //设置参数到请求对象中 httpPost.setEntity(new UrlEncodedFormEntity(list,encoding)); System.out.println("请求地址:"+uri); System.out.println("请求参数:"+list.toString()); //设置header信息 //指定报文头【Content-type】、【User-Agent】 httpPost.setHeader("Content-type", "application/x-www-form-urlencoded"); httpPost.setHeader("User-Agent", "Mozilla/4.0 (compatible; MSIE 5.0; Windows NT; DigExt)"); //执行请求操作,并拿到结果(同步阻塞) CloseableHttpResponse response = httpClient.execute(httpPost); //获取所有的请求头信息 Header[] allHeaders = response.getAllHeaders(); for (Header allHeader : allHeaders) { System.out.println(allHeader.toString()); } //获取结果实体 HttpEntity entity = response.getEntity(); if (entity != null) { System.out.println(EntityUtils.toString(entity,encoding)); } //关流 EntityUtils.consume(entity); response.close(); }