java - 在某些手机上存在连接错误
问题描述
我为 android 创建应用程序,我的应用程序连接到数据库。连接数据库时不等待两个智能手机弹出。最后经过测试的手机可以正常工作。这两款手机都有 4.2.2 Android 版本。
代码:
import android.annotation.SuppressLint;
import android.os.StrictMode;
import android.util.Log;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
public class Database {
String ip,db,DBUserNameStr,DBPasswordStr;
@SuppressLint("NewApi")
public Connection connectionclasss()
{
// Declaring Server ip, username, database name and password
ip = "123.123.123.123:20833";
db = "top";
DBUserNameStr = "userp";
DBPasswordStr = "secret";
// Declaring Server ip, username, database name and password
StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder().permitAll().build();
StrictMode.setThreadPolicy(policy);
java.sql.Connection connection = null;
String ConnectionURL = null;
try
{
Class.forName("net.sourceforge.jtds.jdbc.Driver");
ConnectionURL = "jdbc:jtds:sqlserver://" + ip +";databaseName="+ db + ";user=" + DBUserNameStr+ ";password=" + DBPasswordStr + ";";
connection = DriverManager.getConnection(ConnectionURL);
}
catch (SQLException se)
{
Log.e("error here 1 : ", se.getMessage());
}
catch (ClassNotFoundException e)
{
Log.e("error here 2 : ", e.getMessage());
}
catch (Exception e)
{
Log.e("error here 3 : ", e.getMessage());
}
return connection;
}
}
应用程序在标尺上崩溃:
connection = DriverManager.getConnection(ConnectionURL);
日志 :
04-04 08:58:03.959 8401-8401/com.example.verdent E/error here 1 :: Network error IOException: failed to connect to /12.123.133.123(port 20833): connect failed: ENETUNREACH (Network is unreachable)
--------- beginning of crash
04-04 08:58:03.965 8401-8401/com.example.verdent E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.verdent, PID: 8401
java.lang.IllegalStateException: Could not execute method for android:onClick
at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:389)
at android.view.View.performClick(View.java:5280)
at android.view.View$PerformClick.run(View.java:21768)
at android.os.Handler.handleCallback(Handler.java:815)
at android.os.Handler.dispatchMessage(Handler.java:104)
at android.os.Looper.loop(Looper.java:207)
at android.app.ActivityThread.main(ActivityThread.java:5917)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:888)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:749)
Caused by: java.lang.reflect.InvocationTargetException
at java.lang.reflect.Method.invoke(Native Method)
at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:384)
at android.view.View.performClick(View.java:5280)
at android.view.View$PerformClick.run(View.java:21768)
at android.os.Handler.handleCallback(Handler.java:815)
at android.os.Handler.dispatchMessage(Handler.java:104)
at android.os.Looper.loop(Looper.java:207)
at android.app.ActivityThread.main(ActivityThread.java:5917)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:888)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:749)
Caused by: java.lang.NullPointerException: Attempt to invoke interface method 'java.sql.Statement java.sql.Connection.createStatement()' on a null object reference
at com.example.verdent.MainActivity.ChcekDate(MainActivity.java:56)
at com.example.verdent.MainActivity.DownloandData(MainActivity.java:43)
at java.lang.reflect.Method.invoke(Native Method)
at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:384)
at android.view.View.performClick(View.java:5280)
at android.view.View$PerformClick.run(View.java:21768)
at android.os.Handler.handleCallback(Handler.java:815)
at android.os.Handler.dispatchMessage(Handler.java:104)
at android.os.Looper.loop(Looper.java:207)
at android.app.ActivityThread.main(ActivityThread.java:5917)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:888)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:749)
04-04 08:58:03.970 1199-2287/? E/WindowManager: Unknown window type: 1000
有谁知道为什么应用程序在这里关闭?