java 读配置文件后配置均为null java从配置文件读取数据

java中使用Properties类可以方便的读取配置信息。首先需要创建一个Properties类的实例，然后使用load方法在入FileInputStream实例指向的配置文件。

假定我们要读取的配置文件内容如下：

# System configuration
# Comments will automatically be excluded by the program.

parameter1=value1
parameter2=value2

代码：

import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.util.Enumeration;
import java.util.Properties;

/**
 * Main.java
 *
 * @author outofmemory.cn
 */

public class Main {

    Properties config;

    /**
     * Loads configuration parameters from a textfile and print them out.
     */
    public void loadConfigFile() {

        //Load configuration file
        String filename = "conf/systemconfig.txt";
        config = new Properties();

        try {

            config.load(new FileInputStream(filename));

        } catch (FileNotFoundException ex) {
            ex.printStackTrace();
            return;
        } catch (IOException ex) {
            ex.printStackTrace();
            return;
        }

        //Print out the configuration parameters
        Enumeration en = config.keys();

        System.out.println("********** System configuration **********");
        while (en.hasMoreElements()) {

            String key = (String) en.nextElement();
            System.out.println(key + " => " + config.get(key));

        }
    }
    /**
     * Starts the program
     *
     * @param args the command line arguments
     */
    public static void main(String[] args) {
        new Main().loadConfigFile();
    }
}

下面是输出：

********** System configuration **********
parameter2 => value2
parameter1 => value1