我遵循了有关将使用 wamp 服务器(在 Windows 上)运行的 MyQSL 数据库连接到 Android 应用程序的 youtube 教程。 (视频链接为:https://www.youtube.com/watch?v=eldh8l8yPew)
在我的 Android Studio 代码中,我创建了一个扩展 AsyncTask 的类(名为“BackgroundWorker”),它应该处理与连接到数据库的 PHP 文件的通信。
为了打开到数据库的写入 channel ,我使用了连接到 httpURLConnection 对象的 BufferedWriter 和 OutputStream,该对象具有位于 WAMPSERVER 的 www 文件夹中的相关 php 脚本的 URL。
经过这么长时间的介绍,我的问题是在尝试执行以下行时出现 IOException:
OutputStream outputStream = httpURLConnection.getOutputStream();
我几乎从视频教程中复制了整个代码,所以我怀疑它有什么问题。 我更多地考虑 URL 设置的方向 - 我的 URL 对象获取具有地址的字符串:
String loginURL = "http://10.0.2.2/login.php";
其中“login.php”是我的 php 脚本,它位于 wamp 服务器的 www 文件夹中。 我知道 10.0.0.2 是一种默认地址,代表 Android Emulators 中的本地主机,我怎么使用 Genymotion Emulator 所以也许这不是正确的地址? 我还尝试输入我在运行 IPCONFIG 时看到的所有其他 IP 地址,但没有改变结果。
我不太擅长调试,所以我使用了 AsyncTask 的 Toasts 和 PublishProgress 方法来查找和隔离 IOException。
这是我认为可能与 IOException 相关的部分代码:
我的 BackgroundWorker 类(扩展了 AsyncTask):
public class BackgroundWorker extends AsyncTask <String , Integer , String> {
Context context;
AlertDialog alertDialog;
public BackgroundWorker(Context userContext) {
this.context = userContext;
}
@Override
protected String doInBackground(String... params) {
// Reading the arguments in the order I sent them in MainActivity
String username = params[0];
String pass = params[1];
String type = params[2];
// Making structure for updating during the wat using Toasts (and showing the first one
int progressValue = 0; // Before if
publishProgress(progressValue);
// Initial String that will hold the text to read from server
String result = "";
// Initial the URL String , the IP address if standart for Android LocalHost
String loginURL = "http://10.0.2.2/login.php";
if (type.equals("login")) {
progressValue++; //1
publishProgress(progressValue);
try {
URL url = new URL(loginURL);
progressValue++; //2
publishProgress(progressValue);
// Building the HttpUrlConnection object
HttpURLConnection httpURLConnection = (HttpURLConnection) url.openConnection();
httpURLConnection.setRequestMethod("POST");
httpURLConnection.setDoOutput(true);
httpURLConnection.setDoInput(true);
progressValue++; //3
publishProgress(progressValue);
// Building the writing infrastructure
// IOException occurs after the commit of the next line
OutputStream outputStream = httpURLConnection.getOutputStream();
BufferedWriter bufferedWriter = new BufferedWriter(new OutputStreamWriter(outputStream,"UTF-8"));
progressValue++; //4
publishProgress(progressValue);
// Building the message to the PHP script
String post_data = URLEncoder.encode("user_name" , "UTF-8") + "=" + URLEncoder.encode(username , "UTF-8")
+ "&" + URLEncoder.encode("user_pass" , "UTF-8") + "=" + URLEncoder.encode(pass , "UTF-8");
progressValue++; //5
publishProgress(progressValue);
// Writing the data
bufferedWriter.write(post_data);
progressValue++; //6
publishProgress(progressValue);
// Closing all writing structures
bufferedWriter.flush();
bufferedWriter.close();
outputStream.close();
// Building the Reading Infrastructure
InputStream inputStream = httpURLConnection.getInputStream();
BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(inputStream , "iso-8859-1"));
// Reading the data
String line;
while ((line = bufferedReader.readLine()) != null) {
result += line;
}
// Closing all reading structures
bufferedReader.close();
inputStream.close();
httpURLConnection.disconnect();
} catch (MalformedURLException e) {
e.printStackTrace();
progressValue = 10;
publishProgress(progressValue);
} catch (IOException e) {
progressValue = 11;
publishProgress(progressValue);
e.printStackTrace();
}
}
return result;
}
@Override
protected void onProgressUpdate(Integer... values) {
int progressValue = values[0];
// Before IF statement
if (progressValue == 0) Toast.makeText(this.context , "Before if" , Toast.LENGTH_SHORT).show();
// After IF statement
if (progressValue == 1) Toast.makeText(this.context , "After if" , Toast.LENGTH_SHORT).show();
// After URL statement
if (progressValue == 2) Toast.makeText(this.context , "After URL Setting" , Toast.LENGTH_SHORT).show();
// Before Writing data
if (progressValue == 3) Toast.makeText(this.context , "After making HTML" , Toast.LENGTH_SHORT).show();
// After Writing data
if (progressValue == 4) Toast.makeText(this.context , "After making writing infra" , Toast.LENGTH_SHORT).show();
// After Writing data
if (progressValue == 5) Toast.makeText(this.context , "Before Writing data" , Toast.LENGTH_SHORT).show();
// After Writing data
if (progressValue == 6) Toast.makeText(this.context , "After Writing data" , Toast.LENGTH_SHORT).show();
// After Writing data
if (progressValue == 10) Toast.makeText(this.context , "First exception" , Toast.LENGTH_SHORT).show();
// After Writing data
if (progressValue == 11) Toast.makeText(this.context , "IO Exception" , Toast.LENGTH_SHORT).show();
}
@Override
protected void onPreExecute() {
alertDialog = new AlertDialog.Builder(context).create();
alertDialog.setTitle("Login Status");
}
@Override
protected void onPostExecute(String result) {
alertDialog.setMessage(result);
alertDialog.show();
}
}
这是我的 login.php 代码:
<?php
require "conn.php";
$user_name = $_POST["user_name"];
$user_pass = $_POST["user_pass"];
$mysql_qry = "select * from employee_data where user like '$user_name' and password like '$user_pass';";
$result = mysqli_query($conn ,$mysql_qry);
if(mysqli_num_rows($result) > 0) {
echo "login success";
}
else {
echo "login not seccess";
}
?>
conn.php 是另一个将连接与数据库建立连接的脚本。 当我直接通过浏览器运行我的 login.php 脚本时 - 它工作正常。
非常感谢, 我希望你能理解这个问题, 诺姆
最佳答案
我自己解决了。 IP 地址不正确,因为我使用 Genymotion 模拟器,所以我必须将 IP 更改为 192.168.56.1 现在一切正常。
关于java - 将 BufferedWriter 与 HTTP 结合使用时出现 IOException,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/37237642/