先来看一段http的请求：

URL url = new URL(serverUrl);
HttpURLConnection conn = url.openConnection()
conn.conect();
//获取文件大小
int length = conn.getContentLength();
//获取输入流
InputStream is = conn.getInputStream();
 
//do something, such as  write2File or write2String
 

private File write2File(InputStream is){
     File file = new File(filePath);
     FileOutputStream fos = new FileOutputStream(file)
      //缓存数据 
     byte buf[] = new byte[1024];
     int len = 0;
     while((len = is.read(buf))  != -1){
          fos.write(buf,0,len)  
    }
    fos.close();
    is.close();
}

private String write2String(InputStream is){
    StringBuilder sb = new StringBuilder();
    String line;

    BufferedReader br = new BufferedReader(new InputStreamReader(is));
    while ((line = br.readLine()) != null) {
        sb.append(line);
    }
    String str = sb.toString();
    fos.close();
    is.close();
    return str; 
}

http改成https，只要将，HttpURLConnection 换成 HttpsURLConnection 即可。

当然一般https都需要证书。只要调用setSSLSocketFactory设置一个SSLSocketFactory就可以了。

conn.setSSLSocketFactory(ssContext.getSocketFactory());

如何通过证书封装SSLContext?

private SSLContext getSSLContext (){

        try {
            CertificateFactory cf = CertificateFactory.getInstance("X.509");
            //privatekey.crt证书文件，将它放在Assets目录下
            InputStream is =  mContext.getAssets().open("privatekey.crt");

            Certificate ca = cf.generateCertificate(is);
            Log.i("getSSLContext ", "ca=" + ((X509Certificate) ca).getSubjectDN());

            KeyStore keyStore = KeyStore.getInstance(KeyStore.getDefaultType());
            keyStore.load(null,null);
            keyStore.setCertificateEntry("ca",ca);

            TrustManagerFactory tmf = TrustManagerFactory.getInstance(TrustManagerFactory.getDefaultAlgorithm());
            tmf.init(keyStore);

            SSLContext ssContext = SSLContext.getInstance("TLSv1", "AndroidOpenSSL");
            ssContext.init(null,tmf.getTrustManagers(),null);

            return ssContext;

        } catch (CertificateException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        } catch (KeyStoreException e) {
            e.printStackTrace();
        } catch (NoSuchAlgorithmException e) {
            e.printStackTrace();
        } catch (NoSuchProviderException e) {
            e.printStackTrace();
        } catch (KeyManagementException e) {
            e.printStackTrace();
        } 
        return null;
    }

修改发起连接处：

URL url = new URL(serverUrl);

//将HttpURLConnection 替换成HttpsURLConnection 
HttpsURLConnection conn = (HttpsURLConnection) url.openConnection();

//获取SSLContext
SSLContext ssContext = getSSLContext ();

// 设置setSSLSocketFactory
conn.setSSLSocketFactory(ssContext.getSocketFactory());

conn.conect();
int length = conn.getContentLength();
InputStream is = conn.getInputStream();
....

其他的就更http的一样了。