问题描述
我想在 JTextArea 上设置自定义背景图片。我曾经看过谷歌，但没有结果，背景可能是一个标志，我也想知道如何设置背景的分辨率。
I want to set a custom background image on a JTextArea. I had looked in google but without a result, the background could be a logo, also I want to know how to set the background's resolution.
我只有一个班级一套。我有一个MySQL连接器驱动程序作为Referenced Library，我的工作台是Eclipse，使用Fat-jar插件导出jar
I Have only one class in a package. I have a MySQL connector driver as Referenced Library, my workbench is Eclipse, exporting jar with the Fat-jar plugin
代码：
public class panel extends JPanel implements ActionListener {
protected JTextField textField, textField2;
protected static JTextArea textArea;
private final static String newline = "\n";
public panel() {
super(new GridBagLayout());
textField = new JTextField(30);
textField.addActionListener(this);
textField.setBackground(Color.LIGHT_GRAY);
textField2 = new JTextField(30);
textField2.addActionListener(this);
textField2.setEnabled(false);
textArea = new JTextArea(30, 100);
textArea.setEditable(false);
JScrollPane scrollPane = new JScrollPane(textArea);
//Add Components to this panel.
GridBagConstraints c = new GridBagConstraints();
c.gridwidth = GridBagConstraints.REMAINDER;
c.fill = GridBagConstraints.HORIZONTAL;
add(textField, c);
add(textField2, c);
c.fill = GridBagConstraints.BOTH;
c.weightx = 1.0;
c.weighty = 1.0;
add(scrollPane, c);
}
public void actionPerformed(ActionEvent evt) {
String select = textField.getText();
if(textField.getText().equalsIgnoreCase("connect")){
textArea.setForeground(Color.BLACK);
connect();
textField.setText("");
}else if(textField.getText().equalsIgnoreCase("select test")){
textArea.setForeground(Color.BLACK);
viewTest();
textField.setText("");;
}else if(textField.getText().equalsIgnoreCase("clear")){
textArea.setForeground(Color.BLACK);
textField.setText("");
clear();
}else if(textField.getText().equalsIgnoreCase("commands")){
textArea.setForeground(Color.BLACK);
commandsmenu();
textField.setText("");
}else if(textField.getText().equalsIgnoreCase("insertinto test")){
textField2.setEnabled(true);
if(textField2.getText().equals("")){
textArea.append("Please add the VALUES of the table on the second textfield! Syntax: 'Agevaulue', namevalue, adressvalue !" + newline);
}else{
textArea.setForeground(Color.BLACK);
InsertIntoTest();
textField2.setText("");
textField2.setEnabled(false);
}
}
else {
clear();
textArea.setForeground(Color.RED);
textArea.append("Uknown Command -- use: commands -- to see all commands!");
textField.selectAll();
}
//Make sure the new text is visible, even if there
//was a selection in the text area.
textArea.setCaretPosition(textArea.getDocument().getLength());
}
/**
* Create the GUI and show it. For thread safety,
* this method should be invoked from the
* event dispatch thread.
*/
private static void createAndShowGUI() {
//Create and set up the window.
JFrame frame = new JFrame("Java + MySQL Example");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
//Add contents to the window.
frame.add(new panel());
//Display the window.
frame.pack();
frame.setVisible(true);
}
public void connect(){
Connection conn = null;
try
{
String url = "jdbc:mysql://localhost/users";
Class.forName("com.mysql.jdbc.Driver");
textArea.append("Database connection established");
conn = DriverManager.getConnection(url, "root", "kristian76");
}
catch (Exception e){
e.printStackTrace();
}
}
public void viewTest()
{
Connection conn = null;
try{
String url = "jdbc:mysql://localhost/users";
Class.forName("com.mysql.jdbc.Driver");
conn = DriverManager.getConnection(url, "root", "kristian76");
String query = "SELECT * FROM test";
Statement stmt = conn.createStatement();
ResultSet rs = stmt.executeQuery(query);
while (rs.next()){
int age = rs.getInt("age");
String name = rs.getString("name");
String adress = rs.getString("adress");
textArea.append("AGE: " + age + " |Name: " + name + " |Adress: " + adress + newline);
}
}catch(Exception e){
textArea.setForeground(Color.RED);
textArea.append("Got an Exception!" + newline);
textArea.append(e.getMessage());
}
}public void InsertIntoTest() {
Connection conn = null;
try{
String url = "jdbc:mysql://localhost/users";
Class.forName("com.mysql.jdbc.Driver");
conn = DriverManager.getConnection(url, "root", "kristian76");
String query = "INSERT INTO test(age, name, adress)VALUES(" + textField2.getText() + ")";
Statement stmt = conn.createStatement();
stmt.executeUpdate("INSERT INTO test(age, name, adress)VALUES(" + textField2.getText() + ")");
textArea.append("Data Imported!" + newline);
}catch(Exception e){
textArea.setForeground(Color.RED);
textArea.append("Got an Exception" + newline);
textArea.append(e.getMessage());
}
}
public void clear(){
textArea.setText("");
}
public void commandsmenu() {
textArea.append("select <table> - read a <table>" + newline);
textArea.append("clear - clear output" + newline);
textArea.append("commands - see Commands" + newline);
textArea.append("insertinto <table> - insert data into <table>" + newline);
}
public static void main(String[] args) {
//Schedule a job for the event dispatch thread:
//creating and showing this application's GUI.
javax.swing.SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGUI();
}
});
}
}
推荐答案
这非常简单，你只需要创建自己的TextArea类，它从JTextArea扩展，然后覆盖paintComponent方法以包含你的背景图像，这里是类：
This is very simple, you just need to create your own TextArea class that extends from JTextArea and then override the paintComponent method to include your background image, here is the class:
public class MyTextArea extends JTextArea {
private Image img;
public MyTextArea(int a, int b) {
super(a,b);
try{
img = ImageIO.read(new File("background.jpg"));
} catch(IOException e) {
System.out.println(e.toString());
}
}
@Override
protected void paintComponent(Graphics g) {
g.drawImage(img,0,0,null);
super.paintComponent(g);
}
}
然后在面板中你仍然可以在代码中使用JTextArea类型：
Then in panel you can still use the type JTextArea in your code:
protected static JTextArea textArea;
但是在初始化时调用最近创建的类的构造函数：
But when initializing call the constructor of your recently created class:
textArea = new MyTextArea(30, 100);
像这样，文本不会让你在后台看到图像，所以我们需要制作透明：
Like this, the text will not let you see the image in the background, so we need to make it transparent:
textArea.setBackground(new Color(1,1,1, (float) 0.01));
我没有详细看到你的代码，但一个好的编程习惯是类的名称，但由于Panel是一个Java关键字（Panel是AWT组件），那么你可以将其命名为MyPanel或SQLPanel。
I didn't see your code in detail, but a good programming practice is to CamelCase the name of the class, but since "Panel" is a Java keyword (Panel is a AWT component) then you can name it something like MyPanel or SQLPanel.
这篇关于如何将背景图像设置为JPanel中的JTextArea的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！