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java - 如何从服务器获取回声

问题描述

我正在尝试从我的服务器获得回声回复。这样做的目的是检查互联网连接并检查服务器状态。如果我得到回复，将出现一个对话框，其中包含一条简单的消息。没有得到回复也是如此。

收到回复时出现对话框，但未收到回复时不会出现。

在我的 uploadDB.class 中，我有多个案例将在 PHP 文件中执行不同的功能。一种情况是“ping”功能，另一种情况是“updatecounter”功能。

当我删除uploadDB.class 中的“updatecounter”案例时，一切似乎都正常。由于我的要求，我不应该删除“updatecounter”案例。

有人可以建议我如何解决这个问题吗？

以下是我在 Logcat 中的代码和错误。

PHP 文件

        if (isset($_POST['type'])){
        if ($_POST['type'] == "ping"){
        echo "success";
        }

MainActivity.class

public boolean isInternetConnected = false;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        pingTask();
    }

    private void pingTask() {
        new uploadDB(new uploadDB.returnResult() {
            @Override
            public void onFinish(String result) {
                if (result.equalsIgnoreCase("success")) {
                    isInternetConnected = true;
                    showdialog("Server Status", "Working");
                } else {
                    isInternetConnected = false;
                    showdialog("Server Status", "Not Working");
                }
            }
        }).execute("ping");
    }

上传数据库类

protected String doInBackground(String... params) {
        String method = params[0];
        String data = "";
        String link = "www.example.com/example.php";

        switch (method){
            case "ping": {
                try{
                    data = URLEncoder.encode("type", "UTF-8") + "=" + URLEncoder.encode("ping", "UTF-8");
                    Log.e(TAG,"DATA: " + data);
                }catch (UnsupportedEncodingException e){
                    Log.e(TAG, "UnsupportedEncodingException: " + e.toString());
                }
                try {
                    URL url = new URL(link);
                    HttpURLConnection h = (HttpURLConnection) url.openConnection();
                    h.setDoInput(true);
                    h.setDoOutput(true);
                    OutputStreamWriter owriter =
                            new OutputStreamWriter(h.getOutputStream());
                    owriter.write(data);
                    owriter.flush();
                    BufferedReader b = new BufferedReader
                            (new InputStreamReader(h.getInputStream(), "UTF-8"), 8);
                    StringBuilder builder = new StringBuilder();
                    String line;
                    while ((line = b.readLine()) != null) {
                        builder.append(line);
                    }
                    return builder.toString();
                } catch (IOException e) {
                    Log.e(TAG, "IOException: " + e.toString());
                }
            }

          case "updatecounter": {
                String macAddress = params[1];
                String sensorname = params[2];
                String counter = params[3];
                try {
                    data = URLEncoder.encode("type", "UTF-8") + "=" + URLEncoder.encode("counter", "UTF-8")
                            + "&" + URLEncoder.encode("gate_name", "UTF-8") + "=" + URLEncoder.encode(sensorname, "UTF-8")
                            + "&" + URLEncoder.encode("mac", "UTF-8") + "=" + URLEncoder.encode(macAddress, "UTF-8")
                            + "&" + URLEncoder.encode("counter", "UTF-8") + "=" + URLEncoder.encode(counter, "UTF-8");
                    Log.e(TAG,"DATA: " + data);
                } catch (UnsupportedEncodingException e) {
                    Log.e(TAG, "UnsupportedEncodingException: " + e.toString());
                }

                try {
                    URL url = new URL(link);
                    HttpURLConnection h = (HttpURLConnection) url.openConnection();
                    h.setDoInput(true);
                    h.setDoOutput(true);
                    OutputStreamWriter owriter =
                            new OutputStreamWriter(h.getOutputStream());
                    owriter.write(data);
                    owriter.flush();
                    BufferedReader b = new BufferedReader
                            (new InputStreamReader(h.getInputStream(), "UTF-8"), 8);
                    StringBuilder builder = new StringBuilder();
                    String line;
                    while ((line = b.readLine()) != null) {
                        builder.append(line);
                    }
                    return builder.toString();
                } catch (IOException e) {
                    //activity.isInternetConnected = false;
                    Log.e(TAG, "IOException: " + e.toString());
                }
            }

Logcat 中的错误

Process: com.example.postserver, PID: 21624
    java.lang.RuntimeException: An error occurred while executing doInBackground()
        at android.os.AsyncTask$3.done(AsyncTask.java:353)
        at java.util.concurrent.FutureTask.finishCompletion(FutureTask.java:383)
        at java.util.concurrent.FutureTask.setException(FutureTask.java:252)
        at java.util.concurrent.FutureTask.run(FutureTask.java:271)
        at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:245)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1162)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:636)
        at java.lang.Thread.run(Thread.java:764)
     Caused by: java.lang.ArrayIndexOutOfBoundsException: length=1; index=1
        at com.example.postserver.uploadDB.doInBackground(uploadDB.java:69)
        at com.example.postserver.uploadDB.doInBackground(uploadDB.java:16)

标签： javaandroid

解决方案

您需要在案例末尾添加一个中断。如果你不添加它，之后的每个案例都将被执行：

   switch (method){
        case "ping": {
            try{
                data = URLEncoder.encode("type", "UTF-8") + "=" + URLEncoder.encode("ping", "UTF-8");
                Log.e(TAG,"DATA: " + data);
            }catch (UnsupportedEncodingException e){
                Log.e(TAG, "UnsupportedEncodingException: " + e.toString());
            }
            try {
                URL url = new URL(link);
                HttpURLConnection h = (HttpURLConnection) url.openConnection();
                h.setDoInput(true);
                h.setDoOutput(true);
                OutputStreamWriter owriter =
                        new OutputStreamWriter(h.getOutputStream());
                owriter.write(data);
                owriter.flush();
                BufferedReader b = new BufferedReader
                        (new InputStreamReader(h.getInputStream(), "UTF-8"), 8);
                StringBuilder builder = new StringBuilder();
                String line;
                while ((line = b.readLine()) != null) {
                    builder.append(line);
                }
                return builder.toString();
            } catch (IOException e) {
                Log.e(TAG, "IOException: " + e.toString());
            }
        }
        break;
    case "updatecounter": {

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