如何解决无法使用 javaFX 连接到在线 mysql 数据库
我最近做了一个项目，涉及使用 java 中的 Swing 在线连接到 mysql 数据库。然后我决定将项目转换为 javaFX 并尝试复制代码以连接到 mysql 数据库。
这是我的代码：
package virtlib;
import java.net.URL;
import java.util.ResourceBundle;
import javafx.event.ActionEvent;
import javafx.fxml.FXML;
import javafx.fxml.Initializable;
import javafx.scene.control.Button;
import javafx.scene.control.Label;
import javafx.scene.control.PasswordField;
import javafx.scene.control.TextField;
import java.sql.*;
import javafx.fxml.FXMLLoader;
import javafx.scene.Node;
import javafx.scene.Parent;
import javafx.scene.Scene;
import javafx.stage.Stage;
/**
*
* @author param
*/
public class FXMLDocumentController implements Initializable {
private Connection con;
private Statement st;
private ResultSet rs;
private ResultSet rs2;
private Stage stage;
@FXML
private Label label;
@FXML
private Button login;
@FXML
private PasswordField password;
@FXML
private TextField username;
@FXML
private void handleButtonAction(ActionEvent event) {
try{
Class.forName("com.mysql.cj.jdbc.Driver");
con=DriverManager.getConnection("jdbc:mysql://db4free.net:3306/parambase","theboss12k","Password");//Password has been changed
st=con.createStatement();
label.setText("Connection success !");
}
catch(Exception ae){
label.setText("We are unable to connect to our servers. Please check your internet connection and restart the app !");
}
}
@Override
public void initialize(URL url,ResourceBundle rb) {
// TODO
}
}
这是FXML文件的代码
<?xml version="1.0" encoding="UTF-8"?>
<?import javafx.scene.control.Button?>
<?import javafx.scene.control.Label?>
<?import javafx.scene.control.PasswordField?>
<?import javafx.scene.control.TextField?>
<?import javafx.scene.layout.AnchorPane?>
<?import javafx.scene.layout.Pane?>
<AnchorPane id="AnchorPane" prefHeight="494.0" prefWidth="409.0" xmlns:fx="http://javafx.com/fxml/1" xmlns="http://javafx.com/javafx/16" fx:controller="virtlib.FXMLDocumentController">
<children>
<Label fx:id="label" layoutX="126" layoutY="120" minHeight="16" minWidth="69" prefHeight="18.0" prefWidth="276.0" />
<Pane maxHeight="1.7976931348623157E308" maxWidth="1.7976931348623157E308" prefHeight="297.0" prefWidth="410.0" style="-fx-background-color: white;" AnchorPane.bottomAnchor="0.0" AnchorPane.leftAnchor="0.0" AnchorPane.rightAnchor="0.0" AnchorPane.topAnchor="0.0">
<children>
<Button fx:id="login" layoutX="129.0" layoutY="331.0" onAction="#handleButtonAction" prefHeight="26.0" prefWidth="70.0" text="Login" />
<PasswordField fx:id="password" layoutX="129.0" layoutY="276.0" maxHeight="1.7976931348623157E308" maxWidth="1.7976931348623157E308" prefHeight="26.0" prefWidth="222.0" />
<TextField fx:id="username" layoutX="129.0" layoutY="229.0" maxHeight="1.7976931348623157E308" maxWidth="1.7976931348623157E308" prefHeight="26.0" prefWidth="222.0" />
<Label layoutX="40.0" layoutY="280.0" text="Password" />
<Label layoutX="38.0" layoutY="233.0" text="Username" />
<Label layoutX="129.0" layoutY="400.0" prefHeight="17.0" prefWidth="222.0" textFill="#e70d1b" />
</children>
</Pane>
</children>
</AnchorPane>
但是，当我点击运行时，它会崩溃，并且我收到“Java SE 二进制平台已停止工作”的错误消息。它在我之前使用 Swing 的应用程序中运行良好。我在切换到 javafx 时所做的唯一更改是我使用 jdk 1.8 而不是 jdk 11，因为我被迫使用 netbeans 8.2，而 netbeans 8.2 似乎不支持 jdk 11（使用我以前的项目开发）。
解决方法
我刚刚遇到了同样的问题并重写了我的 SQL 连接库。 也许你可以在你的项目中使用它，它对我来说在本地和在线都适用。
我的 HandleSqlBdSimple 类：
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.Vector;
public class HandleSqlDbSimple {
private Connection connection = null;
private Statement statement;
private ResultSet resultSet;
private boolean isConnected = false;
// Creating objects for connection
private String aHost;
private String aPort;
private String aDatabase;
private String aUser;
private String aPassword;
private String aDriver;
private String aPrefix;
public HandleSqlDbSimple(String host,String port,String database,String user,String psw,String driver,String prefix){
this.aHost = host;
this.aPort = port;
this.aDatabase = database;
this.aUser = user;
this.aPassword = psw;
this.aDriver = driver;
this.aPrefix = prefix;
// Connection example:
// aHost = "localhost";
// aPort = "3306";
// aDatabase = "testdb";
// aUser = "root";
// aPassword = "kungfu";
// aDriver = "com.mysql.jdbc.Driver";
// aPrefix = "jdbc:mysql:";
}
private synchronized void loadConnection(){
try {
Class.forName(aDriver);
connection = DriverManager.getConnection(aPrefix + "//" + aHost + ":" + aPort + "/" + aDatabase +
"?user=" + aUser + "&password=" + aPassword);
isConnected = true;
} catch (ClassNotFoundException e) {
isConnected=false;
e.printStackTrace();
} catch (SQLException e) {
isConnected=false;
e.printStackTrace();
}
if(isConnected){
try {
connection.setAutoCommit(false);
statement = connection.createStatement();
statement.setFetchSize(100000);
System.out.println("Connection open!");
} catch (SQLException e) {
e.printStackTrace();
}
}else{
System.out.println("Is not connected!");
}
}
private synchronized void closeConnection(){
if (isConnected) {
try {
if (resultSet != null){
resultSet.close();
};
statement.close();
connection.close();
System.out.println("Connection Closed!");
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
System.out.println("My Error in connection close: " + e);
}
}
}
public boolean writeToDB(String stmt){
boolean aResult = false;
// Open the connection to the database
loadConnection();
try {
if(isConnected){
statement.executeUpdate(stmt);
connection.commit();
aResult = true;
}
} catch (SQLException e) {
e.printStackTrace();
}
// Close the DB again
closeConnection();
return aResult;
}
public String[][] readFromDB(String stmt) {
String[][] data = null;
Vector<String[]> aVectorBuffer = new Vector<String[]>();
String[] colData = null;
loadConnection();
if(isConnected){
try {
resultSet = statement.executeQuery(stmt);
ResultSetMetaData aResultSetMetaData = resultSet.getMetaData();
// Get number of columns
int aColCount = aResultSetMetaData.getColumnCount();
colData = new String[aColCount];
while (resultSet.next()) {
for(int col=0; col<aColCount; col++){
colData[col] = resultSet.getString(col+1);
}
aVectorBuffer.add(colData);
colData = new String[aColCount];
}
closeConnection();
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
data = new String[aVectorBuffer.size()][colData.length];
for(int row=0;row<aVectorBuffer.size(); row++){
for(int col=0;col<colData.length; col++){
data[row][col] = aVectorBuffer.get(row)[col];
}
}
return data;
}
}
当然记得包含mysql .jar 文件。我使用“mysql-connector-java-8.0.26.jar”。但我看你已经有了这个。
然后你可以使用这样的方法..
@FXML
private void handleButtonAction(ActionEvent event) {
HandleSqlDbSimple db = new HandleSqlDbSimple("host","port","database","user","psw","driver","prefix");
db.writeToDB("your write statement");
String[][] result = db.readFromDB("your read statement here");
}
希望有帮助;)
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