跨域请求
一、JsonP
1.概念：
Jsonp其实就是一个跨域解决方案。Js跨域请求数据是不可以的，但是js跨域请求js脚本是可以的。可以把数据封装成一个js语句，做一个方法的调用。跨域请求js脚本可以得到此脚本。得到js脚本之后会立即执行。可以把数据做为参数传递到方法中。就可以获得数据。从而解决跨域问题
2.原理
浏览器在js请求中，是允许通过script标签的src跨域请求，可以在请求的结果中添加回调方法名，在请求页面中定义方法，既可获取到跨域请求的数据。
3.实现
A. 请求的url必须有一个回调函数的名字的请求参数
B：使用jsonp来实现跨域请求
注：必须有一个category.getDataService的回调函数
C：服务端返回的json数据必须是个js片段，（一个名字为请求参数的名字的函数的js片段）类似于：
category.getDataService(Json对象);
二、使用HttpClient跨域请求（客户端使用进行跨域请求）
1.导包：
二、实现代码部分
//Get请求
@Test
public void doGet()throws Exception{
//创建HttpClient
CloseableHttpClient httpClient = HttpClients.createDefault();
//创建get 请求
HttpGet get = new HttpGet("http://www.sogou.com");
//执行请求
CloseableHttpResponse response = httpClient.execute(get);
//获取请求结果
int code = response.getStatusLine().getStatusCode();
System.out.println(code);
HttpEntity entity = response.getEntity();
String result = EntityUtils.toString(entity, "utf-8");
System.out.println(result);
//关闭
response.close();
httpClient.close();
}
//Get请求带参数
@Test
public void doGetWithParam()throws Exception{
//创建HttpClient
CloseableHttpClient httpClient = HttpClients.createDefault();
//创建Get 请求
//创建URL对象
URIBuilder uriBuilder = new URIBuilder("http://www.sogou.com/web");
//添加请求参数
uriBuilder.addParameter("query", "花千骨");
HttpGet get = new HttpGet(uriBuilder.build());
//执行请求
CloseableHttpResponse response = httpClient.execute(get);
//获取请求结果
int code = response.getStatusLine().getStatusCode();
System.out.println(code);
HttpEntity entity = response.getEntity();
String result = EntityUtils.toString(entity, "utf-8");
System.out.println(result);
//关闭
response.close();
httpClient.close();
}
//Post请求
@Test
public void doPost()throws Exception{
CloseableHttpClient httpClient = HttpClients.createDefault();
//创建POST请求
HttpPost post = new HttpPost("http://localhost:8089/rest/httpclient");
//执行请求
CloseableHttpResponse response = httpClient.execute(post);
int code = response.getStatusLine().getStatusCode();
System.out.println(code);
HttpEntity entity = response.getEntity();
String result = EntityUtils.toString(entity,"utf-8");
System.out.println(result);
}
//Post请求带参数
@Test
public void doPostWithParam()throws Exception{
CloseableHttpClient httpClient = HttpClients.createDefault();
//创建POST请求
HttpPost post = new HttpPost("http://localhost:8089/rest/httpclient/withparam");
post.setHeader("Content-Type", "application/x-www-form-urlencoded;charset=UTF-8");
//设置请求头，中文乱码问题
//创建请求体
//new String("张三".getBytes("utf-8"),"utf-8"))
List<NameValuePair> list = new ArrayList<NameValuePair>();
list.add(new BasicNameValuePair("userName","张三"));
list.add(new BasicNameValuePair("passWord","112"));
//包装Entity
UrlEncodedFormEntity entity = new UrlEncodedFormEntity(list,"utf-8");
//post.setHeader("Content-type", "application/json");
//设置请求体
post.setEntity(entity);
//执行请求
CloseableHttpResponse response = httpClient.execute(post);
int code = response.getStatusLine().getStatusCode();
System.out.println(code);
HttpEntity httpEntity = response.getEntity();
String result = EntityUtils.toString(httpEntity,"utf-8");
System.out.println(result);
}
