远程接口调用
1.1 第二部分：远程接口调用方式HttpClient
问题：现在我们已经开发好了接口了，那该如何调用这个接口呢？
答：使用Httpclient客户端。
1.1.1 Httpclient简介
1.1.1.1 什么是httpclient
HttpClient 是 Apache Jakarta Common 下的子项目，用来提供高效的、最新的、功能丰富的支持 HTTP 协议的客户端编程工具包，并且它支持 HTTP 协议最新的版本和建议。实现了所有 HTTP 的方法（GET,POST,PUT,HEAD 等）
1.1.1.2 httpclient作用
在java代码中，发送Http请求。通常用来实现远程接口调用。
1.1.2 HttpClient测试
说明：在ego-base中测试
在ego-base工程中添加httpclient的pom依赖。
|
<dependency> <groupId>org.apache.httpcomponents</groupId> <artifactId>httpclient</artifactId> </dependency> |
1.1.2.1 执行GET请求
|
public static void doGet(){ // 创建Httpclient对象 CloseableHttpClient httpclient = HttpClients.createDefault();
// 创建http GET请求 HttpGet httpGet = new HttpGet("http://www.oschina.net/");
CloseableHttpResponse response = null; try { // 执行请求 response = httpclient.execute(httpGet); System.out.println(response.getStatusLine()); // 判断返回状态是否为200 if (response.getStatusLine().getStatusCode() == 200) { String content = EntityUtils.toString(response.getEntity(), "UTF-8"); System.out.println("内容长度：" + content.length()); } }catch(Exception e){ e.printStackTrace();
} finally { if (response != null) { try { response.close(); } catch (IOException e) { e.printStackTrace(); } } try { httpclient.close(); } catch (IOException e) { e.printStackTrace(); } } |
1.1.2.2 执行GET带参数
|
public static void doGetParam(){ // 创建Httpclient对象 CloseableHttpClient httpclient = HttpClients.createDefault(); CloseableHttpResponse response = null; try {
// 定义请求的参数 URI uri = new URIBuilder("http://www.baidu.com/s").setParameter("wd", "数据库").build();
System.out.println(uri);
// 创建http GET请求 HttpGet httpGet = new HttpGet(uri);
// 执行请求 response = httpclient.execute(httpGet); // 判断返回状态是否为200 if (response.getStatusLine().getStatusCode() == 200) { String content = EntityUtils.toString(response.getEntity(), "UTF-8"); System.out.println(content); } }catch(Exception e){ e.printStackTrace();
}finally { if (response != null) { try { response.close(); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } } try { httpclient.close(); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } } } |
1.1.2.3 执行post请求
|
public static void doPost(){ // 创建Httpclient对象 CloseableHttpClient httpclient = HttpClientBuilder.create().setRedirectStrategy(new LaxRedirectStrategy()).build();
// 创建http POST请求 HttpPost httpPost = new HttpPost("http://www.oschina.net/");
CloseableHttpResponse response = null; try { // 执行请求 response = httpclient.execute(httpPost); System.out.println(response.getStatusLine()); // 判断返回状态是否为200 if (response.getStatusLine().getStatusCode() == 200) { String content = EntityUtils.toString(response.getEntity(), "UTF-8"); System.out.println(content); } }catch(Exception e){ e.printStackTrace();
}finally { if (response != null) { try { response.close(); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } } try { httpclient.close(); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } } } |
1.1.2.4 执行post带参数
|
public static void doPostParam() throws Exception{ // 创建Httpclient对象 CloseableHttpClient httpclient = HttpClientBuilder.create().setRedirectStrategy(new LaxRedirectStrategy()).build();
// 创建http POST请求 HttpPost httpPost = new HttpPost("http://www.oschina.net/search");
// 设置2个post参数，一个是scope、一个是q List<NameValuePair> parameters = new ArrayList<NameValuePair>(); parameters.add(new BasicNameValuePair("scope", "project")); parameters.add(new BasicNameValuePair("q", "java")); // 构造一个form表单式的实体 UrlEncodedFormEntity formEntity = new UrlEncodedFormEntity(parameters); // 将请求实体设置到httpPost对象中 httpPost.setEntity(formEntity);
CloseableHttpResponse response = null; try { // 执行请求 response = httpclient.execute(httpPost); System.out.println(response.getStatusLine()); // 判断返回状态是否为200 if (response.getStatusLine().getStatusCode() == 200) { String content = EntityUtils.toString(response.getEntity(), "UTF-8"); System.out.println(content); } } finally { if (response != null) { response.close(); } httpclient.close(); } } |
1.1.3 httpclient常见问题及解决方案
1.1.3.1 请求参数乱码
设置请求的编码格式：
|
obj.addHeader("Content-Type","application/x-www-form-urlencoded; charset=UTF-8"); |
1.1.3.2 响应HTTP/1.1 403 Forbidden
原因：网站设置了反爬虫机制，禁止非法访问。
解决方案：伪装浏览器。
|
obj.addHeader("User-Agent"," Mozilla/5.0 (Windows NT 6.1) AppleWebKit/537. 36 (KHTML, like Gecko) Chrome/31.0.1650.63")
|
