當文件名被修改時文件無法保存

Question

我有一個按鈕，打開一個保存對話框窗口，默認擴展名過濾器設置，但是當用戶沒有提供文件名的擴展名時，它應該自動添加擴展名。問題是，發生這種情況時文件不會保存（或保存失敗），但不會拋出任何異常。文件保存成功彈出窗口顯示告訴用戶文件已成功保存，但目錄中未找到文件。這裏是我的代碼：

private void saveRecordsButtonActionPerformed(java.awt.event.ActionEvent evt)             
    {              
     if(evt.getSource() == this.saveRecordsButton) 
     { 
      String recordName = JOptionPane.showInputDialog(this, "Please type in the name of the record you are about to export: ", "Input Notice", JOptionPane.INFORMATION_MESSAGE); 
      if(recordName == null || recordName.equals("")) 
      { 
       JOptionPane.showMessageDialog(this, "You must type in the name of the record in order to save!", "Input Error!", JOptionPane.ERROR_MESSAGE); 
       return; 
      } 

      int returnVal = this.fileChooser.showSaveDialog(this); 
      if(returnVal == JFileChooser.APPROVE_OPTION) 
      { 
       //ObjectOutput oos = null; 
       try 
       { 
        File file = this.fileChooser.getSelectedFile(); 
        String recordDate = this.viewByDateCB.getSelectedItem().toString(); 
        XMLTableProducer xmlTableProducer = new XMLTableProducer(this.cbtm, "Cash Book Table", recordName, recordDate, new Date()); 

        if(!file.getName().contains(".")) 
        { 
         FileNameExtensionFilter filter = (FileNameExtensionFilter)this.fileChooser.getFileFilter(); 
         file = new File(file.getName()+(filter.getExtensions())[0]); 
         System.out.println(file.getName()); //This actually prints out the exact file name with extension the way I want 
        } 

        // if file doesnt exists, then create it 
        if(!file.exists()) 
        { 
         file.createNewFile(); 
        } 

        FileWriter fw = new FileWriter(file.getAbsoluteFile()); 
        BufferedWriter bw = new BufferedWriter(fw); 
        PrintWriter out = new PrintWriter(bw); 
        out.print(xmlTableProducer.getDynamicText()); 
        out.close(); 
        bw.close(); 

        JOptionPane.showMessageDialog(this, "File Saved Successfully!", "Saved", JOptionPane.INFORMATION_MESSAGE); 
       } 
       catch(IOException xcp) 
       { 
        xcp.printStackTrace(System.err); 
       } 
      } 
     } 
    }   

Answer 1

這file = new File(file.getName()+(filter.getExtensions())[0]);被剝離File的路徑...

假設用戶選擇將文件保存在C:\My Documents\Boss中。當你作爲File#getName它只會返回Boss。現在意味着該文件將被保存到

相反file = new File(file.getName()+(filter.getExtensions())[0]);，你應該使用file = new File(file.getPath()+(filter.getExtensions())[0]);其返回由File代表的「完整」路徑和文件名，該方案正在由（即.\Bosss）執行相同的位置

更新...

你的文件寫入過程中也有點過。

一般的經驗法則，如果你打開流，你應該關閉它...

你不應該關閉try-catch內的資源，如果發生Exception的try-catch內，該close方法將永遠不會被調用，使資源開...

try 
{ 
    /*...*/ 
    FileWriter fw = new FileWriter(file.getAbsoluteFile()); 
    BufferedWriter bw = new BufferedWriter(fw); 
    PrintWriter out = new PrintWriter(bw); 
    out.print(xmlTableProducer.getDynamicText()); 
    out.close(); 
    bw.close(); 

    JOptionPane.showMessageDialog(this, "File Saved Successfully!", "Saved", JOptionPane.INFORMATION_MESSAGE); 
} 
catch(IOException xcp) 
{ 
    // If an exception occurs, the file will remain open 
    xcp.printStackTrace(System.err); 
} 

相反，你應該使用finally塊嘗試關閉所有的資源，例如...

BufferedWriter bw = null; 
try 
{ 
    /*...*/ 
    FileWriter fw = new FileWriter(file.getAbsoluteFile()); 
    bw = new BufferedWriter(fw); 
    PrintWriter out = new PrintWriter(bw); 
    out.print(xmlTableProducer.getDynamicText()); 

    JOptionPane.showMessageDialog(this, "File Saved Successfully!", "Saved", JOptionPane.INFORMATION_MESSAGE); 
} 
catch(IOException xcp) 
{ 
    xcp.printStackTrace(System.err); 
} finally { 
    try 
    { 
     bw.close(); 
    } 
    catch (Exception exp) { 
    } 
} 

Answer 2

代碼看起來沒問題。既然你沒有看到異常，我懷疑你沒有看到正確的目錄。

// if file doesn't exists, then create it 
         if(!file.exists()) 
         { 
          file.createNewFile(); 
         } 

後添加

System.out.println(file.getAbsolutePath()); 

確認你正在尋找到該目錄中有顯示的路徑..