如何将新数据附加到属性文件中的现有数据？

Question

我使用以下代码将数据写入属性文件

public void WritePropertiesFile(String key, String data)
{
Properties configProperty = new Properties();
configProperty.setProperty(key, data);
File file = new File("D:\\Helper.properties");
FileOutputStream fileOut = new FileOutputStream(file,true);
configProperty.store(fileOut, "sample properties");
fileOut.close();
}

I am calling the above method 3 times as follows:
help.WritePropertiesFile("appwrite1","write1");
help.WritePropertiesFile("appwrite2","write2");
help.WritePropertiesFile("appwrite3","write3");

但是，Helper.properties文件中的数据显示如下：

#sample properties
#Mon Jul 01 15:01:45 IST 2013
appwrite1=write1
#sample properties
#Mon Jul 01 15:01:45 IST 2013
appwrite2=write2
appwrite1=write1
#sample properties
#Mon Jul 01 15:01:45 IST 2013
appwrite3=write3
appwrite2=write2
appwrite1=write1

我希望将数据追加到现有数据，并且不想要重复的数据，如下所示：

appwrite3=write3
appwrite2=write2
appwrite1=write1

请建议一下怎么做？

Answer 1

只是不要在追加模式下打开文件。

您可以从文件中读取现有属性，然后重新写入它们。如果您附加到文件中，则会附加Properties对象的所有内容，因为这就是您所要求的。

只需替换：

FileOutputStream fileOut = new FileOutputStream(file,true);

通过以下方式：

FileOutputStream fileOut = new FileOutputStream(file);

附注:您应该在finally块中.close()您的输出流。

Answer 2

我知道这个问题已经得到了回答，但仅供将来参考，代码应该看起来更像-不像这样：

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.Properties;
import java.util.logging.Level;
import java.util.logging.Logger;

class WritePropertiesFile {

    public void WritePropertiesFile(String key, String data) {
        FileOutputStream fileOut = null;
        FileInputStream fileIn = null;
        try {
            Properties configProperty = new Properties();

            File file = new File("D:\\Helper.properties");
            fileIn = new FileInputStream(file);
            configProperty.load(fileIn);
            configProperty.setProperty(key, data);
            fileOut = new FileOutputStream(file);
            configProperty.store(fileOut, "sample properties");

        } catch (Exception ex) {
            Logger.getLogger(WritePropertiesFile.class.getName()).log(Level.SEVERE, null, ex);
        } finally {

            try {
                fileOut.close();
            } catch (IOException ex) {
                Logger.getLogger(WritePropertiesFile.class.getName()).log(Level.SEVERE, null, ex);
            }
        }
    }

    public static void main(String[] args) {
        WritePropertiesFile help = new WritePropertiesFile();
        help.WritePropertiesFile("appwrite1", "write1");
        help.WritePropertiesFile("appwrite2", "write2");
        help.WritePropertiesFile("appwrite3", "write3");
    }
}