如何在Android下编码互联网连接？

我正在用Android编写不同的应用程序，他们中的大多数人使用互联网与服务器通信。我想知道如何编写这个项目，让Android与服务器通信。我已经编写了需要检查的代码： 1） 该设备已连接到Internet 2） 目标的url已更正并写入 3） 服务器启动了

所以我不是问如何检查这些东西，而是问如何在代码中放置这些方法。 例如，我的应用程序需要向服务器发送带有字符串（例如名称）的http请求。所以我编写了一个AsynTask，它需要两个字符串作为输入（IP和参数），仅此而已。在发送AsynTask之前或在该类中，我是否应该检查一切是否正常？

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提前感谢您的回复。

首先，您不能在主线程上运行网络，这一点需要您知道。现在，我将为您发布两个代码。第一个是将某个文件上载到服务器，第二个是如何在android上与mysql服务器通信。第二个是我提供了一个链接，介绍如何在android上完全使用源代码下载。让我们开始吧。第一个将文件上传到服务器的代码

   package com.androidexample.uploadtoserver;

import java.io.DataOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
import android.app.Activity;
import android.app.ProgressDialog;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.TextView;
import android.widget.Toast;

public class UploadToServer extends Activity {

    TextView messageText;
    Button uploadButton;
    int serverResponseCode = 0;
    ProgressDialog dialog = null;

    String upLoadServerUri = null;

    /**********  File Path *************/
    final String uploadFilePath = "/mnt/sdcard/";
    final String uploadFileName = "test.jpg";

    @Override
    public void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_upload_to_server);

        uploadButton = (Button)findViewById(R.id.uploadButton);
        messageText  = (TextView)findViewById(R.id.messageText);

        messageText.setText("Uploading file path :- '/mnt/sdcard/"+uploadFileName+"'");

        /************* Php script path ****************/
        upLoadServerUri = "http://54.148.41.171/UploadToServer.php";

        uploadButton.setOnClickListener(new OnClickListener() {            
            @Override
            public void onClick(View v) {

                dialog = ProgressDialog.show(UploadToServer.this, "", "Uploading file...", true);

                new Thread(new Runnable() {
                        public void run() {
                             runOnUiThread(new Runnable() {
                                    public void run() {
                                        messageText.setText("uploading started.....");
                                    }
                                });                      

                             uploadFile(uploadFilePath + "" + uploadFileName);

                        }
                      }).start();        
                }
            });
    }

    public int uploadFile(String sourceFileUri) {


          String fileName= sourceFileUri;

          HttpURLConnection conn = null;
          DataOutputStream dos = null;  
          String lineEnd = "\r\n";
          String twoHyphens = "--";
          String boundary = "*****";
          int bytesRead, bytesAvailable, bufferSize;
          byte[] buffer;
          int maxBufferSize = 1 * 1024 * 1024; 
          File sourceFile = new File(sourceFileUri);
          if (!sourceFile.isFile()) {



               dialog.dismiss(); 

               Log.e("uploadFile", "Source File not exist :"
                                   +uploadFilePath + "" + uploadFileName);

               runOnUiThread(new Runnable() {
                   public void run() {
                       messageText.setText("Source File not exist :"
                               +uploadFilePath + "" + uploadFileName);
                   }
               }); 

               return 0;

          }
          else
          {

               try { 

                     // open a URL connection to the Servlet
                   FileInputStream fileInputStream = new FileInputStream(sourceFile);
                   URL url = new URL(upLoadServerUri);

                   // Open a HTTP  connection to  the URL
                   conn = (HttpURLConnection) url.openConnection(); 
                   conn.setDoInput(true); // Allow Inputs
                   conn.setDoOutput(true); // Allow Outputs
                   conn.setUseCaches(false); // Don't use a Cached Copy
                   conn.setRequestMethod("POST");
                   conn.setRequestProperty("Connection", "Keep-Alive");
                   conn.setRequestProperty("ENCTYPE", "multipart/form-data");
                   conn.setRequestProperty("Content-Type", "multipart/form-data;boundary=" + boundary);
                   conn.setRequestProperty("uploaded_file", fileName); 


                   dos = new DataOutputStream(conn.getOutputStream());

                   dos.writeBytes(twoHyphens + boundary + lineEnd); 
                   dos.writeBytes("Content-Disposition: form-data; name=\"uploaded_file\";filename=\""
                                             + fileName + "\"" + lineEnd);

                   dos.writeBytes(lineEnd);

                   // create a buffer of  maximum size
                   bytesAvailable = fileInputStream.available(); 

                   bufferSize = Math.min(bytesAvailable, maxBufferSize);
                   buffer = new byte[bufferSize];

                   // read file and write it into form...
                   bytesRead = fileInputStream.read(buffer, 0, bufferSize);  

                   while (bytesRead > 0) {

                     dos.write(buffer, 0, bufferSize);
                     bytesAvailable = fileInputStream.available();
                     bufferSize = Math.min(bytesAvailable, maxBufferSize);
                     bytesRead = fileInputStream.read(buffer, 0, bufferSize);   

                    }

                   // send multipart form data necesssary after file data...
                   dos.writeBytes(lineEnd);
                   dos.writeBytes(twoHyphens + boundary + twoHyphens + lineEnd);

                   // Responses from the server (code and message)
                   serverResponseCode = conn.getResponseCode();
                   String serverResponseMessage = conn.getResponseMessage();

                   Log.i("uploadFile", "HTTP Response is : " 
                           + serverResponseMessage + ": " + serverResponseCode);

                   if(serverResponseCode == 200){

                       runOnUiThread(new Runnable() {
                            public void run() {

                                String msg = "File Upload Completed.\n\n See uploaded file here : \n\n"
                                              +" http://www.androidexample.com/media/uploads/"
                                              +uploadFileName;

                                messageText.setText(msg);
                                Toast.makeText(UploadToServer.this, "File Upload Complete.", 
                                             Toast.LENGTH_SHORT).show();
                            }
                        });                
                   }    

                   //close the streams //
                   fileInputStream.close();
                   dos.flush();
                   dos.close();

              } catch (MalformedURLException ex) {

                  dialog.dismiss();  
                  ex.printStackTrace();

                  runOnUiThread(new Runnable() {
                      public void run() {
                          messageText.setText("MalformedURLException Exception : check script url.");
                          Toast.makeText(UploadToServer.this, "MalformedURLException", Toast.LENGTH_SHORT).show();
                      }
                  });

                  Log.e("Upload file to server", "error: " + ex.getMessage(), ex);  
              } catch (Exception e) {

                  dialog.dismiss();  
                  e.printStackTrace();

                  runOnUiThread(new Runnable() {
                      public void run() {
                          messageText.setText("Got Exception : see logcat ");
                          Toast.makeText(UploadToServer.this, "Got Exception : see logcat ", 
                                  Toast.LENGTH_SHORT).show();
                      }
                  });
                  Log.e("Upload file to server Exception", "Exception : " 
                                                   + e.getMessage(), e);  
              }
              dialog.dismiss();       
              return serverResponseCode; 

           } // End else block 
         } 
}

这是服务器端代码

$file_path = "uploads/";
$file_path = $file_path . basename( $_FILES['uploaded_file']['name']);
if(move_uploaded_file($_FILES['uploaded_file']['tmp_name'], $file_path)) {
    echo "success";
} else{
    echo "fail";
}
?>

这段代码的魅力在于你可以粘贴到MainActivity中，这意味着你可以在主线程上运行这段代码，而无需在后台运行，不是吗？：）现在让我们来看第二段代码，在这里你可以与mysql服务器进行很好的通信！几乎没有忘记您必须在服务器端创建上载文件夹：）

这是教程，非常棒，相信我！

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享受：）

对于程序设计问题，我建议您访问。似乎您只需要确定一组原则/模式。单一责任原则是一个良好的开端。谢谢您的回复。嗯，你可能会回答我一直在寻找的一个可能的解决方案。从编码的角度来看，这个类似乎太长了，但它可以工作。您认为可以在异步任务中创建try-and-catch吗？如果连接良好，您认为最好检查活动？在这种情况下，SR原则是不受尊重的。好吧，首先你不需要使用异步任务，因为你不能使用try-and-catch，所以你很难知道如果java不能执行asynvtask会发生什么，相信我，我已经为此奋斗了4个月了！那么活动检查连接呢？它是最棒的一个，因为它可以全面检查任何互联网的可能性，它就像一个线程，很小但功能强大，所以我很高兴听到我能帮助你相信我，我很高兴：）））哦，那长时间呢没有什么好的代码是短的记住