HttpClient实现远程调用
简单理解
远程调用，是我们在做项目的时候经常遇到的。EJB可以实现远程调用；Dubbo+ZK可以实现远程调用；Spring Cloude中使用Resttemplate和Feign均可实现远程调用。今天要总结的是HttpClient，他也可以实现远程调用。而且爬虫就是用HttpClient来访问互联网，然后将数据保存到本地，然后用jsonp来提取需要的信息。
使用
引用httpclient的依赖
<dependency>
<groupId>org.apache.httpcomponentsgroupId>
<artifactId>httpclientartifactId>
dependency>get请求
@Test
public void testHttpGet() throws Exception {
//第一步：把HttpClient使用的jar包添加到工程中。
//第二步：创建一个HttpClient的测试类
//第三步：创建测试方法。
//第四步：创建一个HttpClient对象
CloseableHttpClient httpClient = HttpClients.createDefault();
//第五步：创建一个HttpGet对象，需要制定一个请求的url
HttpGet get = new HttpGet("http://www.sogou.com");
//第六步：执行请求。
CloseableHttpResponse response = httpClient.execute(get);
//第七步：接收返回结果。HttpEntity对象。
HttpEntity entity = response.getEntity();
//第八步：取响应的内容。
String html = EntityUtils.toString(entity);
System.out.print(html);
//第九步：关闭response、HttpClient。
response.close();
httpClient.close();
}
运行后可返回搜狗主页面的html代码
post请求
@Test
public void testHttpPost() throws Exception {
// 第一步：创建一个httpClient对象
CloseableHttpClient httpClient = HttpClients.createDefault();
// 第二步：创建一个HttpPost对象。需要指定一个url
HttpPost post = new HttpPost("http://localhost:8083/posttest.html");
// 第三步：创建一个list模拟表单，list中每个元素是一个NameValuePair对象
List formList = new ArrayList<>();
formList.add(new BasicNameValuePair("name", "张三"));
formList.add(new BasicNameValuePair("pass", "1243"));
// 第四步：需要把表单包装到Entity对象中。StringEntity
StringEntity entity = new UrlEncodedFormEntity(formList, "utf-8");
post.setEntity(entity);
// 第五步：执行请求。
CloseableHttpResponse response = httpClient.execute(post);
// 第六步：接收返回结果
HttpEntity httpEntity = response.getEntity();
String result = EntityUtils.toString(httpEntity);
System.out.println(result);
// 第七步：关闭流。
response.close();
httpClient.close();
}
可以将httpclient封装成工具类，方便使用
public class HttpClientUtil {
public static String doGet(String url, Map param) {
// 创建Httpclient对象
CloseableHttpClient httpclient = HttpClients.createDefault();
String resultString = "";
CloseableHttpResponse response = null;
try {
// 创建uri
URIBuilder builder = new URIBuilder(url);
if (param != null) {
for (String key : param.keySet()) {
builder.addParameter(key, param.get(key));
}
}
URI uri = builder.build();
// 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) {
resultString = EntityUtils.toString(response.getEntity(), "UTF-8");
}
} catch (Exception e) {
e.printStackTrace();
} finally {
try {
if (response != null) {
response.close();
}
httpclient.close();
} catch (IOException e) {
e.printStackTrace();
}
}
return resultString;
}
public static String doGet(String url) {
return doGet(url, null);
}
public static String doPost(String url, Map param) {
// 创建Httpclient对象
CloseableHttpClient httpClient = HttpClients.createDefault();
CloseableHttpResponse response = null;
String resultString = "";
try {
// 创建Http Post请求
HttpPost httpPost = new HttpPost(url);
// 创建参数列表
if (param != null) {
List paramList = new ArrayList<>();
for (String key : param.keySet()) {
paramList.add(new BasicNameValuePair(key, param.get(key)));
}
// 模拟表单
UrlEncodedFormEntity entity = new UrlEncodedFormEntity(paramList);
httpPost.setEntity(entity);
}
// 执行http请求
response = httpClient.execute(httpPost);
resultString = EntityUtils.toString(response.getEntity(), "utf-8");
} catch (Exception e) {
e.printStackTrace();
} finally {
try {
response.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
return resultString;
}
public static String doPost(String url) {
return doPost(url, null);
}
public static String doPostJson(String url, String json) {
// 创建Httpclient对象
CloseableHttpClient httpClient = HttpClients.createDefault();
CloseableHttpResponse response = null;
String resultString = "";
try {
// 创建Http Post请求
HttpPost httpPost = new HttpPost(url);
// 创建请求内容
StringEntity entity = new StringEntity(json, ContentType.APPLICATION_JSON);
httpPost.setEntity(entity);
// 执行http请求
response = httpClient.execute(httpPost);
resultString = EntityUtils.toString(response.getEntity(), "utf-8");
} catch (Exception e) {
e.printStackTrace();
} finally {
try {
response.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
return resultString;
}
} 工具类 的使用
“`
@Service
public class ContentServiceImpl implements ContentService {
@Value("${REST_BASE_URL}")
private String REST_BASE_URL;
@Value("${REST_CONTENT_URL}")
private String REST_CONTENT_URL;
@Value("${REST_CONTENT_AD1_CID}")
private String REST_CONTENT_AD1_CID;
/**
* 获得大广告位的内容
*/
@Override
public String getAd1List() {
//调用服务获得数据
//将路径放到配置文件
//HttpClientUtil.doGet("http:localhost:8082/rest/content/89");
String json = HttpClientUtil.doGet(REST_BASE_URL + REST_CONTENT_URL + REST_CONTENT_AD1_CID);
//把json转换成java对象
TaotaoResult taotaoResult = TaotaoResult.formatToList(json, TbContent.class);
//取data属性，内容列表
List contentList = (List) taotaoResult.getData();
//把内容列表转换成AdNode列表
List resultList = new ArrayList<>();
for (TbContent tbContent : contentList) {
AdNode node = new AdNode();
node.setHeight(240);
node.setWidth(670);
node.setSrc(tbContent.getPic());
node.setHeightB(240);
node.setWidthB(550);
node.setSrcB(tbContent.getPic2());
node.setAlt(tbContent.getSubTitle());
node.setHref(tbContent.getUrl());
resultList.add(node);
}
//需要把resultList转换成json数据
String resultJson = JsonUtils.objectToJson(resultList);
return resultJson;
}
}