SpringAOP本質(3)

package org.apache.struts.action; 

public class Action { 


    public ActionForward execute(ActionMapping actionMapping, ActionForm actionForm, ServletRequest servletRequest, ServletResponse servletResponse) throws java.lang.Exception { /* compiled code */ } 


    public ActionForward execute(ActionMapping actionMapping, ActionForm actionForm, http.HttpServletRequest httpServletRequest, http.HttpServletResponse httpServletResponse) throws java.lang.Exception { /* compiled code */ } 


    …. 

} 

public class CheckAction extends Action{ 


    public ActionForward execute(ActionMapping actionMapping, ActionForm actionForm, http.HttpServletRequest httpServletRequest, http.HttpServletResponse httpServletResponse) throws java.lang.Exception { 

    //todo: 安全檢查邏輯 

    return real(actionMapping,actionForm,httpServletRequest,httpServletResponse); 


    } 


    public abstract ActionForward real(ActionMapping actionMapping, ActionForm actionForm, http.HttpServletRequest httpServletRequest, http.HttpServletResponse httpServletResponse) throws java.lang.Exception; 


}

public class DoSomethingAction extends CheckAction{ 


    public abstract ActionForward real(ActionMapping actionMapping, ActionForm actionForm, http.HttpServletRequest httpServletRequest, http.HttpServletResponse httpServletResponse) throws java.lang.Exception{ 

    //todo: 單純處理實際的業務請求 

    return … 

    } 


    …. 

}

/** 

* 使用者登入資訊載體 

*/ 
public class UserInfo { 

    private String userName; 


    private String password; 


    public UserInfo(String userName, String password) { 

        this.userName = userName; 

        this.password = password; 

    } 

     

    public String getPassword() { 

        return password; 

    } 

    public String getUserName() { 

        return userName; 

    } 

}

/** 

* 業務元件：被代理的物件 

*/ 
public class SecureBean { 


    /** 

     * 示範性的業務方法，這個方法將被攔截，加入一些附加邏輯 

     */ 

    public void businessOperate() { 

        System.out.println(“業務方法businessOperate()被呼叫了！”); 

    } 

}

/** 

* 安全管理類：檢查使用者登入和管理使用者登出登入的業務邏輯。 

*/ 
public class SecurityManager { 

    //為每一個SecurityManager建立一個本地執行緒變數threadLocal，用來儲存使用者登入資訊UserInfo 

    private static ThreadLocal threadLocal = new ThreadLocal(); 


    /** 

     * 使用者登入方法，允許任何使用者登入。 

     * @param userName 

     * @param password 

     */ 

    public void login(String userName, String password) { 

        // 假定任何的使用者名稱和密碼都可以登入 

        // 將使用者登入資訊封裝為UerInfo物件，儲存在ThreadLocal類的物件threadLocal裡面 

        threadLocal.set(new UserInfo(userName, password)); 

    } 


    public void logout() { 

        // 設定threadLocal物件為null 

        threadLocal.set(null); 

        int x = 0; 

    } 


    public UserInfo getLoggedOnUser() { 

        // 從本地執行緒變數中獲取使用者資訊UerInfo物件 

        return (UserInfo) threadLocal.get(); 

    } 

}

import java.lang.reflect.Method; 
import org.springframework.aop.MethodBeforeAdvice; 

/** 

* 前置通知類 

*/ 
public class SecurityAdvice implements MethodBeforeAdvice { 


    private SecurityManager securityManager; 


    public SecurityAdvice() { 

        this.securityManager = new SecurityManager(); 

    } 


    /** 

     * 前置通知的介面方法實現。僅允許robh使用者登入，強制設定的。 

     */ 

    public void before(Method method, Object[] args, Object target) 

            throws Throwable { 

        UserInfo user = securityManager.getLoggedOnUser(); 


        if (user == null) { 

            System.out.println(“沒有使用者憑證資訊！，本前置通知僅僅允許robh使用者登入，不信你試試看！”); 

            throw new SecurityException( 

                    “你必須在呼叫此方法” + method.getName() + “前進行登入：”); 

        } else if (“robh”.equals(user.getUserName())) { 

            System.out.println(“使用者robh成功登入：OK！”); 

        } else { 

            System.out.println(“非法使用者”+user.getUserName()+“，請使用robh登入，使用者呼叫的方法是：” + method.getName()); 

            throw new SecurityException(“使用者” + user.getUserName() 

                    + ” 不允許呼叫” + method.getName() + “方法！”); 

        } 

    } 

}

import org.springframework.aop.framework.ProxyFactory; 

/** 

* 測試類，客戶端 

*/ 
public class SecurityExample { 


    public static void main(String[] args) { 

        //得到一個 security manager 

        SecurityManager mgr = new SecurityManager(); 


        //獲取一個SecureBean的代理物件 

        SecureBean bean = getSecureBean(); 


        //嘗試用robh登入 

        mgr.login(“robh”, “pwd”);   //檢查登入情況 

        bean.businessOperate();     //業務方法呼叫 

        mgr.logout();               //登出登入 


        //嘗試用janm登入 

        try { 

            mgr.login(“janm”, “pwd”);       //檢查登入情況 

            bean.businessOperate();         //業務方法呼叫 

        } catch (SecurityException ex) { 

            System.out.println(“發生了異常: “ + ex.getMessage()); 

        } finally { 

            mgr.logout();                   //登出登入 

        } 


        // 嘗試不使用任何使用者名稱身份呼叫業務方法 

        try { 

            bean.businessOperate();         //業務方法呼叫 

        } catch (SecurityException ex) { 

            System.out.println(“發生了異常: “ + ex.getMessage()); 

        } 


    } 


    /** 

     * 獲取SecureBean的代理物件 

     * 

     * @return SecureBean的代理 

     */ 

    private static SecureBean getSecureBean() { 

        //建立一個目標物件 

        SecureBean target = new SecureBean(); 


        //建立一個通知 

        SecurityAdvice advice = new SecurityAdvice(); 


        //獲取代理物件 

        ProxyFactory factory = new ProxyFactory(); 

        factory.setTarget(target); 

        factory.addAdvice(advice); 

        SecureBean proxy = (SecureBean) factory.getProxy(); 


        return proxy; 

    } 

}

– Using JDK 1.4 collections 

使用者robh成功登入：OK！ 

業務方法businessOperate()被呼叫了！ 

非法使用者janm，請使用robh登入，使用者呼叫的方法是：businessOperate 

發生了異常: 使用者janm 不允許呼叫businessOperate方法！ 

沒有使用者憑證資訊！，本前置通知僅僅允許robh使用者登入，不信你試試看！ 

發生了異常: 你必須在呼叫此方法businessOperate前進行登入： 


Process finished with exit code 0