使用線程發(fā)出數(shù)據(jù)庫請(qǐng)求我試圖了解線程在java中是如何工作的。這是一個(gè)返回ResultSet的簡單數(shù)據(jù)庫請(qǐng)求。我在使用JavaFX。 package application;import java.sql.ResultSet;import java.sql.SQLException;import javafx.fxml.FXML;import javafx.scene.control.Button;
import javafx.scene.control.Label;import javafx.scene.control.TextField;public class Controller{
@FXML
private Button getCourseBtn;
@FXML
private TextField courseId;
@FXML
private Label courseCodeLbl;
private ModelController mController;
private void requestCourseName(){
String courseName = "";
Course c = new Course();
c.setCCode(Integer.valueOf(courseId.getText()));
mController = new ModelController(c);
try {
ResultSet rs = mController.<Course>get();
if(rs.next()){
courseCodeLbl.setText(rs.getString(1));
}
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}// return courseName;
}
public void getCourseNameOnClick(){
try {// courseCodeLbl.setText(requestCourseName());
Thread t = new Thread(new Runnable(){
public void run(){
requestCourseName();
}
}, "Thread A");
t.start();
} catch (NumberFormatException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}}這將返回一個(gè)異常：線程“Thread A”中的異常java.lang.IllegalStateException：不在FX應(yīng)用程序線程上；currentThread=Thread A如何正確地實(shí)現(xiàn)線程處理，以便在第二個(gè)線程而不是主線程中執(zhí)行每個(gè)數(shù)據(jù)庫請(qǐng)求？我聽說過實(shí)現(xiàn)Runnable，但是如何在Run方法中調(diào)用不同的方法呢？以前從來沒有用過線程，但我想是時(shí)候開始了。
3 回答
慕尼黑的夜晚無繁華
TA貢獻(xiàn)1864條經(jīng)驗(yàn) 獲得超6個(gè)贊
線程“Thread A”中的異常java.lang.IllegalStateException：不在FX應(yīng)用程序線程上；currentThread=Thread A
courseCodeLbl.setText(rs.getString(1)); // <--- The culprit
如果我不能這樣做，我如何使用背景線程？
用Platform.runLater包裝場景圖元素
Plaform.runLater
Platform.runLater(() -> courseCodeLbl.setText(rs.getString(1)));
使用任務(wù)
updateMessagecourseCodeLbl
Task<Void> task = new Task<Void>() {
@Override
public Void call() {
String courseName = "";
Course c = new Course();
c.setCCode(Integer.valueOf(courseId.getText()));
mController = new ModelController(c);
try {
ResultSet rs = mController.<Course>get();
if(rs.next()) {
// update message property
updateMessage(rs.getString(1));
}
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return null;
}}public void getCourseNameOnClick(){
try {
Thread t = new Thread(task);
// To update the label
courseCodeLbl.textProperty.bind(task.messageProperty());
t.setDaemon(true); // Imp! missing in your code
t.start();
} catch (NumberFormatException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}}
HUH函數(shù)
TA貢獻(xiàn)1836條經(jīng)驗(yàn) 獲得超4個(gè)贊
public void getCourseNameOnClick(){
new Thread(new Runnable(){
public void run(){
String courseName = requestCourseName();
Platform.runLater(new Runnable(){
courseCodeLbl.setText(courseName)
});
}
}, "Thread A").start();}添加回答
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