将属性保存到文件

/*
n o w j a v a . c o m - 时  代  Java 提 供
*/

import java.util.Properties;

import java.io.FileInputStream;

import java.io.FileOutputStream;

import java.io.IOException;


public class PersistentEcho {

    public static void main(String[] args) {

        String argString = "";

        boolean notProperty = true;


        // Are there arguments? 

        // If so retrieve them.
        /**
        N o  w  J a v a . c o m - 时  代  Java
        **/

        if (args.length > 0) {

            for (String arg : args) {

                argString += arg + " ";

            }

            argString = argString.trim();

        }

        // No arguments, is there

        // an environment variable?

        // If so, //retrieve it.

        else if ((argString = System.getenv("PERSISTENTECHO")) != null) {

        }

        // No environment variable

        // either. Retrieve property value.

        else {

            notProperty = false;

            // Set argString to null.

            // If it's still null after

            // we exit the try block,

            // we've failed to retrieve

            // the property value.

            argString = null;

            FileInputStream fileInputStream = null;

            try {

                fileInputStream = new FileInputStream("PersistentEcho.txt");

                Properties inProperties = new Properties();

                inProperties.load(fileInputStream);

                argString = inProperties.getProperty("argString");

            } catch (IOException e) {

                System.err.println("Can't read property file.");

                System.exit(1);

            } finally {

                if (fileInputStream != null) {

                    try {

                        fileInputStream.close();

                    } catch (IOException e) {

                    }

                    ;

                }

            }

        }

        if (argString == null) {

            System.err.println("Couldn't find argString property");

            System.exit(1);

        }


        // Somehow, we got the

        // value. Echo it already!

        System.out.println(argString);


        // If we didn't retrieve the

        // value from the property,

        // save it //in the property.

        if (notProperty) {

            Properties outProperties = new Properties();

            outProperties.setProperty("argString", argString);

            FileOutputStream fileOutputStream = null;

            try {

                fileOutputStream = new FileOutputStream(

                        "PersistentEcho.txt");

                outProperties.store(fileOutputStream,

                        "PersistentEcho properties");

            } catch (IOException e) {

            } finally {

                if (fileOutputStream != null) {

                    try {

                        fileOutputStream.close();

                    } catch (IOException e) {

                    }

                    ;

                }

            }

        }

    }

}