使用URLConnection与httpClient发送get/post请求

使用URLConnection实现GET/POST请求

1. 实例化一个java.net.URL对象；
2. 通过URL对象的openConnection()方法得到一个java.net.URLConnection;
3. 通过URLConnection对象的getInputStream()方法获得输入流；
4. 读取输入流；
5. 关闭资源

//GET
public void get() throws Exception{

    URL url = new URL("http://127.0.0.1/http/test?name=neeson&age=10");
    URLConnection urlConnection = url.openConnection();                                                    // 打开连接
    BufferedReader br = new BufferedReader(new InputStreamReader(urlConnection.getInputStream(),"utf-8")); // 获取输入流
    String line = null;
    StringBuilder sb = new StringBuilder();
    while ((line = br.readLine()) != null) {
        sb.append(line + "\n");
    }

    System.out.println(sb.toString());
}

//POST
public void post() throws IOException{

    URL url = new URL("http://127.0.0.1/http/test");
    HttpURLConnection httpURLConnection = (HttpURLConnection) url.openConnection();

    httpURLConnection.setDoInput(true);
    httpURLConnection.setDoOutput(true);        // 设置该连接是可以输出的
    httpURLConnection.setRequestMethod("POST"); // 设置请求方式
    httpURLConnection.setRequestProperty("charset", "utf-8");

    PrintWriter pw = new PrintWriter(new BufferedOutputStream(httpURLConnection.getOutputStream()));
    pw.write("name=neeson");                   // 向连接中输出数据（相当于发送数据给服务器）
    pw.write("&age=14");
    pw.flush();
    pw.close();

    BufferedReader br = new BufferedReader(new InputStreamReader(httpURLConnection.getInputStream(),"utf-8"));
    String line = null;
    StringBuilder sb = new StringBuilder();
    while ((line = br.readLine()) != null) {    // 读取数据
        sb.append(line + "\n");
    }

    System.out.println(sb.toString());
}

使用httpclient进行GET/POST请求

//GET
public void httpclientGet() throws Exception{

    // 创建HttpClient对象
    HttpClient client = HttpClients.createDefault();

    // 创建GET请求（在构造器中传入URL字符串即可）
    HttpGet get = new HttpGet("http://127.0.0.1/http/test?name=admin&age=40");

    // 调用HttpClient对象的execute方法获得响应
    HttpResponse response = client.execute(get);

    // 调用HttpResponse对象的getEntity方法得到响应实体
    HttpEntity httpEntity = response.getEntity();

    // 使用EntityUtils工具类得到响应的字符串表示
    String result = EntityUtils.toString(httpEntity,"utf-8");
    System.out.println(result);
}

//POST
public void httpclientPost() throws Exception{

    // 创建HttpClient对象
    HttpClient client = HttpClients.createDefault();

    // 创建POST请求
    HttpPost post = new HttpPost("http://127.0.0.1/http/test");

    // 创建一个List容器，用于存放基本键值对（基本键值对即：参数名-参数值）
    List<BasicNameValuePair> parameters = new ArrayList<>();
    parameters.add(new BasicNameValuePair("name", "张三"));
    parameters.add(new BasicNameValuePair("age", "25"));

    // 向POST请求中添加消息实体
    post.setEntity(new UrlEncodedFormEntity(parameters, "utf-8"));

    // 得到响应并转化成字符串
    HttpResponse response = client.execute(post);
    HttpEntity httpEntity = response.getEntity();
    String result = EntityUtils.toString(httpEntity,"utf-8");
    System.out.println(result);
}