java如何在檔案中讀取一個字串並建立以這個字元為名字的類的對象

標籤：java

<span style="font-family: Arial, Helvetica, sans-serif; background-color: rgb(255, 255, 255);">我們一般用properties或者XML檔案作為資源儲存的檔案，現在主要介紹一下對properties的操作</span>

1.我們在src檔案下建立一個名稱為config的包

2.在config下建立一個file，把它命名為demo.properties

3. 把下面的幾段文字複製到demo.properties中

#commentsusername=oseye

4.建立一個叫RunMain.java的class ，在裡面添加textProperties方法如下：

public  static void textProperties(){Properties prop=new Properties();try {prop.load(RunMain.class.getResourceAsStream("/config/demo.properties"));} catch (IOException e) {// TODO Auto-generated catch blocke.printStackTrace();}String username = prop.getProperty("username");//此方法實現了在demo.properties讀出屬性為username的值System.out.println("username的值："+username);}

5.建立一個自己的類，這個類名就隨便取了，我建了一個叫People的類，另外需要至少兩個類實現通過更改demo.propertie來建立不同的對象，所以我寫了People1和People2來繼承People：

People

package config;public abstract class People {private String sname;private String sex;public People() {super();// TODO Auto-generated constructor stub}public People(String sname, String sex) {super();this.sname = sname;this.sex = sex;}//get&set方法@Overridepublic String toString() {return "People [sname=" + sname + ", sex=" + sex + "]";}public abstract void setAge(String age);public abstract void setHigh(String high);}

People1：

package config;public class People1 extends People {private String age ;public People1() {super();// TODO Auto-generated constructor stub}public People1(String sname, String sex,String age) {super(sname, sex);this.age = age;// TODO Auto-generated constructor stub}//getset方法@Overridepublic String toString() {return "People1 [name=" + super.getSname()+ ",sex="+super.getSex()+",age=" + age + "]";}}

People2：

package config;public class People2 extends People {private String high ;public People2() {super();// TODO Auto-generated constructor stub}public People2(String sname, String sex,String high) {super(sname, sex);this.high = high;// TODO Auto-generated constructor stub}@Overridepublic String toString() {return "People2 [name=" + super.getSname()+ ",sex="+super.getSex()+",high=" + high + "]";}@Overridepublic void setAge(String age) {// TODO Auto-generated method stub}@Overridepublic void setHigh(String high) {// TODO Auto-generated method stubthis.high=high;}}

6.在RunMain中建立一個名稱為textAll的方法：

public static void textAll(){Properties prop=new Properties();People p = null;try {prop.load(RunMain.class.getResourceAsStream("/config/demo.properties"));Class people = Class.forName("config."+prop.getProperty("People"));p = (People)people.newInstance();} catch (ClassNotFoundException e) {// TODO Auto-generated catch blocke.printStackTrace();} catch (InstantiationException e) {// TODO Auto-generated catch blocke.printStackTrace();} catch (IllegalAccessException e) {// TODO Auto-generated catch blocke.printStackTrace();} catch (IOException e) {// TODO Auto-generated catch blocke.printStackTrace();}p.setSex("nv");p.setSname("xww");if(p instanceof People1){p.setAge("20");}else if(p instanceof People2){p.setHigh("180");}System.out.println(p);}

7.修改demo.properties的值，添加上我們要建立的類

People=People2

8.在主方法中運行一下textAll()這個方法，再改成People1再運行一下，兩者分別輸出各自類的資訊

9.至此我們就實現了在檔案中讀取一個字串並建立以這個字元為名字的類的對象

java如何在檔案中讀取一個字串並建立以這個字元為名字的類的對象