HttpURLConnection模拟登录方法（带Cookie的POST/GET)

https://blog.csdn.net/kimqcn4/article/details/52473085

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// http://blog.csdn.net/woxueliuyun/article/details/43267365
package tool

class MyHttpUrlConn {
    public static String cookieVal=""

    public static void Get(String url_get,String str_param_url,String charset,String cookie) throws IOException  {
        // 拼凑get请求的URL字串，使用URLEncoder.encode对特殊和不可见字符进行编码
        //    String getURL = GET_URL + "?username="  + URLEncoder.encode("fat man", "utf-8");
        String getURL = url_get + "?" + str_param_url
        URL getUrl = new URL(getURL);
        // 根据拼凑的URL，打开连接，URL.openConnection函数会根据URL的类型，
        // 返回不同的URLConnection子类的对象，这里URL是一个http，因此实际返回的是HttpURLConnection
        HttpURLConnection connection = (HttpURLConnection) getUrl
                .openConnection();

        if (cookie != null) {
            //发送cookie信息上去，以表明自己的身份，否则会被认为没有权限
            println("set cookieVal = [" + cookie + "]")
            connection.setRequestProperty("Cookie", cookie);
        }

        // 进行连接，但是实际上get request要在下一句的connection.getInputStream()函数中才会真正发到
        // 服务器
        connection.connect();
        // 取得输入流，并使用Reader读取
        BufferedReader reader = new BufferedReader(new InputStreamReader(
                connection.getInputStream(),charset));
        System.out.println("Contents of get request:");
        String lines;
        while ((lines = reader.readLine()) != null)  {
             System.out.println(lines);
        }
        println(" ")
        reader.close();
        // 断开连接
        connection.disconnect();
    }

    public static String Post(String url_post,String str_param_body,String charset,boolean b_flag,String cookies) throws IOException  {
        // Post请求的url，与get不同的是不需要带参数
        URL postUrl = new URL(url_post);
        // 打开连接
        HttpURLConnection connection = (HttpURLConnection) postUrl
                .openConnection();
        // Output to the connection. Default is
        // false, set to true because post
        // method must write something to the
        // connection
        // 设置是否向connection输出，因为这个是post请求，参数要放在
        // http正文内，因此需要设为true
        if("" != cookies){
            connection.setRequestProperty("Cookie", cookies);
        }

        connection.setDoOutput(true);
        // Read from the connection. Default is true.
        connection.setDoInput(true);
        // Set the post method. Default is GET
        connection.setRequestMethod("POST");
        // Post cannot use caches
        // Post 请求不能使用缓存
        connection.setUseCaches(false);
        // This method takes effects to
        // every instances of this class.
        // URLConnection.setFollowRedirects是static函数，作用于所有的URLConnection对象。
        // connection.setFollowRedirects(true);

        // This methods only
        // takes effacts to this
        // instance.
        // URLConnection.setInstanceFollowRedirects是成员函数，仅作用于当前函数
        connection.setInstanceFollowRedirects(b_flag);
        // Set the content type to urlencoded,
        // because we will write
        // some URL-encoded content to the
        // connection. Settings above must be set before connect!
        // 配置本次连接的Content-type，配置为application/x-www-form-urlencoded的
        // 意思是正文是urlencoded编码过的form参数，下面我们可以看到我们对正文内容使用URLEncoder.encode
        // 进行编码
        connection.setRequestProperty("Content-Type",
                "application/x-www-form-urlencoded");
        // 连接，从postUrl.openConnection()至此的配置必须要在connect之前完成，
        // 要注意的是connection.getOutputStream会隐含的进行connect。
        connection.connect();
        DataOutputStream out = new DataOutputStream(connection
                .getOutputStream());
        // The URL-encoded contend
        // 正文，正文内容其实跟get的URL中'?'后的参数字符串一致
        //    String content = "userName=" + URLEncoder.encode("console", "utf-8");
        //    content = content + "&password=" + URLEncoder.encode("12345678", "utf-8");

        println("http param body = [" + str_param_body + "]")
        // DataOutputStream.writeBytes将字符串中的16位的unicode字符以8位的字符形式写道流里面
        out.writeBytes(str_param_body);

        out.flush();

        // 取得cookie，相当于记录了身份，供下次访问时使用
        //    cookieVal = connection.getHeaderField("Set-Cookie").split(";")[0]
        cookieVal = connection.getHeaderField("Set-Cookie")
        println("get cookieVal = [" + cookieVal  + "]")

        out.close(); // flush and close
        BufferedReader reader = new BufferedReader(new InputStreamReader(
                connection.getInputStream(),charset));
        String line;
        System.out.println("Contents of post request:");
        while ((line = reader.readLine()) != null)  {
            System.out.println(line);
        }
        println(" ")

        reader.close();
        connection.disconnect();

        return cookieVal
    }
}

用法：

String cookie_login = MyHttpUrlConn.Post(URL_LOGIN,"userName=admin&password=12345678","utf-8",false,"");

MyHttpUrlConn.Post(URL_POST_SAVE,"name=mxb&yearsold=6","utf-8",false,cookie_login);
MyHttpUrlConn.Get(URL_GET_VIEW,"name=mxb&yearsold=6","utf-8",cookie_login);

说明：

向URL_POST_SAVE Post数据时，要带上URL_LOGIN时生成的cookie，否则无法save数据。

同理Get也是。