Java學習：反射的應用，依賴加載

使用反射實現從配置文件加載類以及根據配置文件解決特定依賴關係。

配置文件reflect.properties：

1AdminDao=reflect.AdminDao
1GuestDao=reflect.GuestDao
1Manager=reflect.Manager
2Manager:AdminDao
2Manager:GuestDao

對應類文件AdminDao：

package reflect;

public class AdminDao {
    public AdminDao(){
        System.out.println("成功實例化AdminDao");
    }
    
}

對應類文件GuestDao:

package reflect;

public class GuestDao {
    public GuestDao(){
        System.out.println("成功實例化GuestDao");
    }
}

對應類文件Manager:

package reflect;

public class Manager {
    private AdminDao adminDao = null;
    private GuestDao guestDao = null;
    public Manager() {
        System.out.println("Manage實例化成功");
    }
    public void setAdminDao (Object o) {
        this.adminDao = (AdminDao)o;
        System.out.println("解決adminDao依賴");
    }
    public void setGuestDao (Object o) {
        this.guestDao = (GuestDao)o;
        System.out.println("解決guestDao依賴");
    }
}

反射測試工廠類：

package reflect;

import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;
import java.lang.reflect.Method;
import java.util.HashMap;
import java.util.Map;
import java.util.Set;

public class ObjectFactory {
    public static Map<String,Object> map = new HashMap<String,Object>();
    
    static {
        BufferedReader br = null;
        try {
            br = new BufferedReader(new FileReader("src/reflect.properties"));
            String str = br.readLine();
            while(str != null) {
                char c = str.charAt(0);
                switch (c) {
                    case '1':
                        String[] arr = str.substring(1).split("=");
                        Object o = Class.forName(arr[1]).newInstance();
                        map.put(arr[0].trim().toLowerCase(), o);
                        break;
                    case '2':
                        String[] arr2 = str.substring(1).split(":");
                        Object obj = map.get(arr2[0].trim().toLowerCase());
                        Object fieldObj = map.get(arr2[1].trim().toLowerCase());
                        String methodName = "set"+arr2[1].substring(0, 1).toUpperCase()+arr2[1].substring(1);
                        Method method = obj.getClass().getDeclaredMethod(methodName, Object.class);
                        method.invoke(obj, fieldObj);
                        break;
                }
                str = br.readLine();
            }
            
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            try {
                br.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
    
    
    public static void main(String[] args) {
        Set<String> set = map.keySet();
        for (String string:set) {
            System.out.println(string+"--"+map.get(string));
        }
    }

}

跑起來結果：

成功實例化AdminDao
成功實例化GuestDao
Manage實例化成功
解決adminDao依賴
解決guestDao依賴
admindao--reflect.AdminDao@10d1f30
manager--reflect.Manager@7aacc1
guestdao--reflect.GuestDao@1e3cabd