使用httpClient模擬http請求

在很多場景下都需要用到java代碼來發送http請求：如和短信后台接口的數據發送，發送數據到微信后台接口中；

這里以apache下的httpClient類來模擬http請求：以get和Post請求為例 分別包含同步和異步請求：

首先例子中的代碼用的是maven構建的一個簡單的java項目：

同步請求所用到的包是：

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

異步請求用到的包是：

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

這個實例中只需要導入這兩個類庫即可，如果你希望用單元測試，也可導入junit的jar包：

以下是代碼部分：

1：同步get方式的請求 其中 uri 是請求的地址如：http://www.baidu.com 

主要http不能省略，否則會報 沒有指明協議 的錯誤 如果需要帶數據 則以uri?a=sss 形式即可

public void doGet() throws ClientProtocolException, IOException{
        //創建CloseableHttpClient
        HttpClientBuilder builder = HttpClientBuilder.create();
        CloseableHttpClient client = builder.build();
        //執行
        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請求方式： 請求中需要帶的數據通過

 httpPost.setEntity(new StringEntity("beppe", "UTF-8"));的方式，
如果需要帶的數據是對象的形式，則轉化為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：異步get請求：

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

4:異步的post方式請求：其中可以在回調函數中加入自己的業務邏輯

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);
    }