我正在尝试获取一个在安卓设备上动态创建的特定JSON文件,并使用HTTP POST请求将数据发送到一个PHP脚本中,以便存储到文本文件中以供以后使用。最终,我还需要将数据保存在MySQL数据库中,但我正在逐步进行工作。JSON文件格式的示例如下:
{"timestamp": 1351181576.64078, "name": "engine_speed", "value": 714.0}
{"timestamp": 1351181576.64578, "name": "vehicle_speed", "value": 0.0}
{"timestamp": 1351181576.6507802, "name": "brake_pedal_status", "value": true}
这个文件是在Android上逐行动态创建的,因此我不能一次性发送整个文件,但我想把每一行在创建时发送到PHP脚本。我编写了一个基本的Android应用程序,当按下一个按钮时,它会获取一个JSONObject,并使用HTTP Post将其发送到PHP脚本。现在我不关心将实际的JSON文件解析为要发送的对象,而只是使用两个测试JSONObjects。PHP脚本可以轻松获取第一个对象并将其存储到文本文件中,但另一个对象始终读取为空值,我无法弄清原因。我对PHP和Android编程相对较新,不确定我是否以正确的方式发送和接收数据。以下是相关Android应用程序代码的片段:
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
final Button button = (Button) findViewById(R.id.sendData);
button.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
// Perform action on click
Toast.makeText(MainActivity.this, "button was pressed",
Toast.LENGTH_SHORT).show();
try {
JSONObject json = new JSONObject();
json.put("timestamp", 1351181576.64078);
json.put("name", "engine_speed");
json.put("value", 714.0);
postData(json);
JSONObject json2 = new JSONObject();
json.put("timestamp", 1351181576.7207818);
json.put("name", "steering_wheel_angle");
json.put("value", 11.1633);
postData(json2);
} catch (JSONException e) {
e.printStackTrace();
}
}
});
}
public void postData(JSONObject json) throws JSONException {
HttpClient httpclient = new DefaultHttpClient();
try {
HttpPost httppost = new HttpPost(URL);
List<NameValuePair> nvp = new ArrayList<NameValuePair>(2);
nvp.add(new BasicNameValuePair("json", json.toString()));
//httppost.setHeader("Content-type", "application/json");
httppost.setEntity(new UrlEncodedFormEntity(nvp));
HttpResponse response = httpclient.execute(httppost);
if(response != null) {
InputStream is = response.getEntity().getContent();
//input stream is response that can be shown back on android
}
}catch (Exception e) {
e.printStackTrace();
}
}
以下是用PHP代码从HTTP POST获取数据并将其写入文本文件的方法:
<?php
$filename = __DIR__.DIRECTORY_SEPARATOR."jsontest.txt";
$json = $_POST['json'];
$data = json_decode($json, TRUE);
if(is_null($json) == false){
file_put_contents($filename, "$json \n", FILE_APPEND);
foreach ($data as $name => $value) {
file_put_contents($filename, "$name -> $value \t", FILE_APPEND);
}
file_put_contents($filename, "\n", FILE_APPEND);
}
$myFile = "jsontest.txt";
$fh = fopen($myFile, 'r');
$theData = fread($fh, filesize($myFile));
fclose($fh);
?>
<meta http-equiv="refresh" content="3" >
<html>
<!-- Displaying the data from text file, not really needed -->
<p><?php echo $theData; ?></p>
</html>
现在输出的文本文件看起来像这样,第一个对象保存得非常好,而第二个对象则显示为空:
{"value":714,"timestamp":1.35118157664078E9,"name":"engine_speed"}
value -> 714 timestamp -> 1351181576.64 name -> engine_speed
{}