使用httpClient模拟http请求

在很多场景下都需要用到java代码来发送http请求：如和短信后台接口的数据发送，发送数据到微信后台接口中；

这里以apache下的httpClient类来模拟http请求：以get和Post请求为例 分别包含同步和异步请求：

首先例子中的代码用的是maven构建的一个简单的java项目：

同步请求所用到的包是：

<dependency>
        <groupId>org.apache.httpcomponents</groupId>
        <artifactId>httpclient</artifactId>
        <version>4.5.2</version>
    </dependency>

异步请求用到的包是：

<dependency>
        <groupId>org.apache.httpcomponents</groupId>
        <artifactId>httpasyncclient</artifactId>
        <version>4.1.2</version>
    </dependency>

这个实例中只需要导入这两个类库即可，如果你希望用单元测试，也可导入junit的jar包：

以下是代码部分：

1：同步get方式的请求 其中 uri 是请求的地址如：http://www.baidu.com 

主要http不能省略，否则会报 没有指明协议 的错误 如果需要带数据 则以uri?a=sss 形式即可

public void doGet() throws ClientProtocolException, IOException{
//创建CloseableHttpClient
        HttpClientBuilder builder = HttpClientBuilder.create();
        CloseableHttpClient client = builder.build();
//执行
        HttpUriRequest httpGet = new HttpGet(uri);
        CloseableHttpResponse response = client.execute(httpGet);
        HttpEntity entity = response.getEntity();
if(entity!=null){
            String  entityStr= EntityUtils.toString(entity,"utf-8");
            System.out.println(entityStr);
        }
//        System.out.println(response.toString());
    }

2：同步post请求方式： 请求中需要带的数据通过

 httpPost.setEntity(new StringEntity("beppe", "UTF-8"));的方式，
如果需要带的数据是对象的形式，则转化为json字符串格式

public void doPost() throws ClientProtocolException, IOException{
        HttpClientBuilder builder = HttpClientBuilder.create();
        CloseableHttpClient client = builder.build();
        HttpPost httpPost= new HttpPost(uri);
        httpPost.setEntity(new StringEntity("beppe", "UTF-8"));
        CloseableHttpResponse response = client.execute(httpPost);
        HttpEntity entity = response.getEntity();
if(entity!=null){
            String  entityStr= EntityUtils.toString(entity,"utf-8");
            System.out.println(entityStr);
        }
//        System.out.println(response.toString());
    }

3：异步get请求：

public void doGetAsyn() throws InterruptedException, ExecutionException{
        CloseableHttpAsyncClient httpclient = HttpAsyncClients.createDefault();
//开启httpclient
        httpclient.start();
//开始执行
        HttpGet httpGet = new HttpGet(uri);
        Future<HttpResponse> future = httpclient.execute(httpGet, null);
        HttpResponse httpResponse = future.get();
        System.out.println(httpResponse.getStatusLine()+"==="+httpGet.getRequestLine());
    }

4:异步的post方式请求：其中可以在回调函数中加入自己的业务逻辑

public static void doPostAsyn(String url,String outStr) throws ParseException, IOException, InterruptedException, ExecutionException{
        CloseableHttpAsyncClient httpAsyncClient =  HttpAsyncClients.createDefault();
        httpAsyncClient.start();
        HttpPost httpost = new HttpPost(url);
//        httpost.addHeader(HTTP.CONTENT_TYPE, "application/json");
        StringEntity se=new StringEntity(outStr,"UTF-8");
        se.setContentType("application/json");
        se.setContentEncoding(new BasicHeader("Content-Type", "application/json"));
        httpost.setEntity(se);
        Future<HttpResponse> future = httpAsyncClient.execute(httpost,null);
        System.out.println(future.get().toString());
//String result = EntityUtils.toString(response.getEntity(),"UTF-8");
//jsonObject = JSONObject.fromObject(result);
    }