方法太多，只寫一種比較簡單的。
檔案test1.properties內容

test1 = 123;
test2=321

        Properties prop = new Properties();
        prop.load(new FileInputStream("src/test1.properties"));
        System.out.println(prop.get("test1"));

輸出

123;

簡單封裝一下，完整程式碼

package propertis.test;

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

public class Test {

    /**
     * @param args
     * @throws IOException 
     * @throws FileNotFoundException 
     */
    public static void main(String[] args) throws FileNotFoundException, IOException {
        // TODO Auto-generated method stub
 


        Properties prop = new Properties();
        prop.load(new FileInputStream("src/test1.properties"));
        System.out.println(prop.get("test1"));

        System.out.println(ProUtil.getTest1Value("test1"));
        System.out.println(ProUtil.getTest1Value("test2"));
    }

}

class ProUtil{
    private
 
 static Properties prop = new Properties();
    static{
        try {
            prop.load(new FileInputStream("src/test1.properties"));
        } catch (FileNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }
    public static Object getTest1Value(String key){
        return prop.get(key);
    }
}

輸出

123;
123;
321