1.什么是HttpClient
HttpClient是Apache提供的HTTP网络访问接口，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。HttpClient已经应用在很多的项目中，比如Apache Jakarta上很著名的另外两个开源项目Cactus和HTMLUnit都使用了HttpClient.
2.具体实现
带参数和不带参数的post，get请求，json的post请求
这里将功能实现封装为一个工具类，具体如下：
publicclassHttpClientUtils
{
/**
*携带请求参数的GET请求
*/
publicstaticString
doGet(Stringurl, Mapparam) {
Stringresult="";
// 1.创建Httpclient对象
CloseableHttpClienthttpclient= HttpClients.createDefault();
CloseableHttpResponseresponse=null;
try{
// 2.创建uri对象
URIBuilderbuilder=newURIBuilder(url);
if(param!=null) {
for(Stringkey:param.keySet()) {
builder.addParameter(key,param.get(key));
}
}
URIuri=builder.build();
// 3.创建httpGET请求
HttpGethttpGet=newHttpGet(uri);
// 4.执行请求
response=httpclient.execute(httpGet);
// 5.判断返回状态是否为200
if(response.getStatusLine().getStatusCode() == 200) {
// 6.进行UTF-8编码处理
result= EntityUtils.toString(response.getEntity(),"UTF-8");
}
}catch(Exceptione) {
e.printStackTrace();
}finally{
try{
if(response!=null) {
response.close();
}
httpclient.close();
}catch(IOExceptione) {
e.printStackTrace();
}
}
returnresult;
}
/**
*不需要携带参数的get请求
*/
publicstaticString
doGet(Stringurl) {
returndoGet(url,null);
}
/**
*携带请求参数的POST请求
*/
publicstaticString
doPost(Stringurl, Mapparam) {
Stringresult="";
// 1.创建Httpclient对象
CloseableHttpClienthttpClient= HttpClients.createDefault();
CloseableHttpResponseresponse=null;
try{
// 2.创建HttpPost请求
HttpPosthttpPost=newHttpPost(url);
// 3.创建参数列表
if(param!=null) {
ListparamList=newArrayList<>();
for(Stringkey:param.keySet()) {
paramList.add(newBasicNameValuePair(key,param.get(key)));
}
// 4.模拟表单
UrlEncodedFormEntityentity=newUrlEncodedFormEntity(paramList);
httpPost.setEntity(entity);
}
// 5.执行http请求
response=httpClient.execute(httpPost);
// 6.获取响应的结果
result= EntityUtils.toString(response.getEntity(),"utf-8");
}catch(Exceptione) {
e.printStackTrace();
}finally{
try{
response.close();
}catch(IOExceptione) {
e.printStackTrace();
}
}
returnresult;
}
/**
*发送无携带请求参数的POST请求
*/
publicstaticString
doPost(Stringurl) {
returndoPost(url,null);
}
/**
*以json的方式传递请求参数，发送POST请求
*/
publicstaticString
doPostJson(Stringurl, Stringjson) {
Stringresult="";
// 1.创建Httpclient对象
CloseableHttpClienthttpClient= HttpClients.createDefault();
CloseableHttpResponseresponse=null;
try{
// 2.创建HttpPost请求
HttpPosthttpPost=newHttpPost(url);
// 3.创建请求内容
StringEntityentity=newStringEntity(json, ContentType.APPLICATION_JSON);
httpPost.setEntity(entity);
// 4.执行http请求
response=httpClient.execute(httpPost);
// 5.获取响应结果
result= EntityUtils.toString(response.getEntity(),"utf-8");
}catch(Exceptione) {
e.printStackTrace();
}finally{
try{
response.close();
}catch(IOExceptione) {
e.printStackTrace();
}
}
returnresult;
}
}