安卓连接mysql8.0_MySQL连接在Android Studio MySQL版本8.0.13中不起作用

我正在制作一个程序，但我的MySQL不工作，我不知道为什么 . 我使用的是MySQL Server 8.0.13和Connector / J 8.0.13 . 我从视频中复制了它，但视频使用了其他版本的MySQL . [视频]：https://www.youtube.com/watch?v=bu5Y3uZ6LLM我不知道它的JDBC连接是错误的还是我使用了错误的用户名 . 它只是没有多大意义，因为它适用于他的视频 .

String msg = "";

//JDBC driver name and database URL

static final String JDBC_DRIVER = "com.mysql.jdbc.Driver";

static final String DB_URL = "jdbc:mysql://" +

DbStrings.DATABASE_URL + "/" +

DbStrings.DATABASE_NAME;

@Override

protected void onPreExecute() {

ProgressTextView.setText("Connecting to Database...");

}

@Override

protected String doInBackground(String... params) {

Connection conn = null;

Statement stmt = null;

try {

Class.forName(JDBC_DRIVER);

conn = DriverManager.getConnection(DB_URL, DbStrings.USERNAME, DbStrings.PASSWORD);

stmt = conn.createStatement();

String sql = "SELECT * FROM zimmerstamm";

ResultSet rs = stmt.executeQuery(sql);

while (rs.next()) {

String Bemerkung = rs.getString("Bemerkung");

Double Zimmer = rs.getDouble("Zimmer");

fruitsMap.put(Bemerkung, Zimmer);

}

msg = "Process complete";

rs.close();

stmt.close();

conn.close();

} catch (SQLException connError)

我得到这个错误：

W/System.err: com.mysql.cj.jdbc.exceptions.CommunicationsException: Communications link failure

The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.

at com.mysql.cj.jdbc.exceptions.SQLError.createCommunicationsException(SQLError.java:174)

at com.mysql.cj.jdbc.exceptions.SQLExceptionsMapping.translateException(SQLExceptionsMapping.java:64)

at com.mysql.cj.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:835)

at com.mysql.cj.jdbc.ConnectionImpl.(ConnectionImpl.java:455)

W/System.err: at com.mysql.cj.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:240)

at com.mysql.cj.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:207)

at java.sql.DriverManager.getConnection(DriverManager.java:569)

at java.sql.DriverManager.getConnection(DriverManager.java:219)

W/System.err: at com.example.patrick.putzapp.feature.MainActivity$GetData.doInBackground(MainActivity.java:71)

at com.example.patrick.putzapp.feature.MainActivity$GetData.doInBackground(MainActivity.java:51)

at android.os.AsyncTask$2.call(AsyncTask.java:333)

at java.util.concurrent.FutureTask.run(FutureTask.java:266)

at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:245)

at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1167)

at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:641)

W/System.err: at java.lang.Thread.run(Thread.java:764)

Caused by: com.mysql.cj.exceptions.CJCommunicationsException: Communications link failure

W/System.err: The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.

W/System.err: at java.lang.reflect.Constructor.newInstance0(Native Method)

at java.lang.reflect.Constructor.newInstance(Constructor.java:343)

at com.mysql.cj.exceptions.ExceptionFactory.createException(ExceptionFactory.java:61)

at com.mysql.cj.exceptions.ExceptionFactory.createException(ExceptionFactory.java:105)

at com.mysql.cj.exceptions.ExceptionFactory.createException(ExceptionFactory.java:151)

W/System.err: at com.mysql.cj.exceptions.ExceptionFactory.createCommunicationsException(ExceptionFactory.java:167)

W/System.err: at com.mysql.cj.protocol.a.NativeSocketConnection.connect(NativeSocketConnection.java:91)

W/System.err: at com.mysql.cj.NativeSession.connect(NativeSession.java:152)

at com.mysql.cj.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:955)

at com.mysql.cj.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:825)

... 13 more

W/System.err: Caused by: java.net.ConnectException: failed to connect to /127.0.0.1 (port 3306) from /:: (port 60052): connect failed: ECONNREFUSED (Connection refused)

at libcore.io.IoBridge.connect(IoBridge.java:137)

at java.net.PlainSocketImpl.socketConnect(PlainSocketImpl.java:137)

at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:390)

W/System.err: at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:230)

at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:212)

W/System.err: at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:436)

at java.net.Socket.connect(Socket.java:621)

at com.mysql.cj.protocol.StandardSocketFactory.connect(StandardSocketFactory.java:155)

at com.mysql.cj.protocol.a.NativeSocketConnection.connect(NativeSocketConnection.java:65)

... 16 more

Caused by: android.system.ErrnoException: connect failed: ECONNREFUSED (Connection refused)

W/System.err: at libcore.io.Linux.connect(Native Method)

at libcore.io.BlockGuardOs.connect(BlockGuardOs.java:118)

at libcore.io.IoBridge.connectErrno(IoBridge.java:151)

at libcore.io.IoBridge.connect(IoBridge.java:129)

... 24 more