如何加載在原生Java類中進行的修改？

Question

嗨，

我試圖執行一個jar文件，覆蓋一些Java原件接口與數據庫連接，改變方法setBoolean，包括接收參數的對象。

這是原來的接口方法：

void setBoolean(int parameterIndex, boolean x) throws SQLException; 

這就是我的變化：

void setBoolean(int parameterIndex, Boolean x) throws SQLException; 

我的變化在接口java.sql.PreparedStatement中提出。對於要叫我的變化，當我開始我使用該命令的應用程序：

java -verbose:class -Xbootclasspath/p:C:/Users/user/Desktop/myproject/src/main/java -jar safepdv.jar 

用命令「-verbose：類」我可以確認我的變化，類被加載。

然而，當方法setBoolean是由應用程序調用，他是不是成立，我的回報是：

Exception in thread "AWT-EventQueue-0" [Loaded java.lang.Throwable$WrappedPrintStream from C:\Program Files\Java\jre1.8.0_91\lib\rt.jar] 
java.lang.NoSuchMethodError: java.sql.PreparedStatement.setBoolean(IZ)V 
    at com.t2tierp.pafecf.controller.ConfigurationController.updateCS(ConfigurationController.java:613) 
    at com.t2tierp.pafecf.view.OpenMoviment.validaCamposLogin(OpenMoviment.java:448) 
    at com.t2tierp.pafecf.view.OpenMoviment.passwordTextSenhaUsuarioActionPerformed(OpenMoviment.java:403) 
    at com.t2tierp.pafecf.view.OpenMoviment.access$200(OpenMoviment.java:22) 
    at com.t2tierp.pafecf.view.OpenMoviment$4.actionPerformed(OpenMoviment.java:240) 
    at javax.swing.JTextField.fireActionPerformed(Unknown Source) 
    at javax.swing.JTextField.postActionEvent(Unknown Source) 
    at javax.swing.JTextField$NotifyAction.actionPerformed(Unknown Source) 
    at javax.swing.SwingUtilities.notifyAction(Unknown Source) 
    at javax.swing.JComponent.processKeyBinding(Unknown Source) 
    at javax.swing.JComponent.processKeyBindings(Unknown Source) 
    at javax.swing.JComponent.processKeyEvent(Unknown Source) 
    at java.awt.Component.processEvent(Unknown Source) 
    at java.awt.Container.processEvent(Unknown Source) 
    at java.awt.Component.dispatchEventImpl(Unknown Source) 
    at java.awt.Container.dispatchEventImpl(Unknown Source) 
    at java.awt.Component.dispatchEvent(Unknown Source) 
    at java.awt.KeyboardFocusManager.redispatchEvent(Unknown Source) 
    at java.awt.DefaultKeyboardFocusManager.dispatchKeyEvent(Unknown Source) 
    at java.awt.DefaultKeyboardFocusManager.preDispatchKeyEvent(Unknown Source) 
    at java.awt.DefaultKeyboardFocusManager.typeAheadAssertions(Unknown Source) 
    at java.awt.DefaultKeyboardFocusManager.dispatchEvent(Unknown Source) 
    at java.awt.Component.dispatchEventImpl(Unknown Source) 
    at java.awt.Container.dispatchEventImpl(Unknown Source) 
    at java.awt.Window.dispatchEventImpl(Unknown Source) 
    at java.awt.Component.dispatchEvent(Unknown Source) 
    at java.awt.EventQueue.dispatchEventImpl(Unknown Source) 
    at java.awt.EventQueue.access$500(Unknown Source) 
    at java.awt.EventQueue$3.run(Unknown Source) 
    at java.awt.EventQueue$3.run(Unknown Source) 
    at java.security.AccessController.doPrivileged(Native Method) 
    at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(Unknown Source) 
    at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(Unknown Source) 
    at java.awt.EventQueue$4.run(Unknown Source) 
    at java.awt.EventQueue$4.run(Unknown Source) 
    at java.security.AccessController.doPrivileged(Native Method) 
    at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(Unknown Source) 
    at java.awt.EventQueue.dispatchEvent(Unknown Source) 
    at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source) 
    at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source) 
    at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source) 
    at java.awt.WaitDispatchSupport$2.run(Unknown Source) 
    at java.awt.WaitDispatchSupport$4.run(Unknown Source) 
    at java.awt.WaitDispatchSupport$4.run(Unknown Source) 
    at java.security.AccessController.doPrivileged(Native Method) 
    at java.awt.WaitDispatchSupport.enter(Unknown Source) 
    at java.awt.Dialog.show(Unknown Source) 
    at java.awt.Component.show(Unknown Source) 
    at java.awt.Component.setVisible(Unknown Source) 
    at java.awt.Window.setVisible(Unknown Source) 
    at java.awt.Dialog.setVisible(Unknown Source) 
    at com.t2tierp.pafecf.view.Caixa.verificarMovimentoExistente(Caixa.java:3392) 
    at com.t2tierp.pafecf.view.Caixa.<init>(Caixa.java:344) 
    at com.t2tierp.pafecf.view.Caixa$41.run(Caixa.java:2393) 
    at java.awt.event.InvocationEvent.dispatch(Unknown Source) 
    at java.awt.EventQueue.dispatchEventImpl(Unknown Source) 
    at java.awt.EventQueue.access$500(Unknown Source) 
    at java.awt.EventQueue$3.run(Unknown Source) 
    at java.awt.EventQueue$3.run(Unknown Source) 
    at java.security.AccessController.doPrivileged(Native Method) 
    at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(Unknown Source) 
    at java.awt.EventQueue.dispatchEvent(Unknown Source) 
    at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source) 
    at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source) 
    at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source) 
    at java.awt.EventDispatchThread.pumpEvents(Unknown Source) 
    at java.awt.EventDispatchThread.pumpEvents(Unknown Source) 
    at java.awt.EventDispatchThread.run(Unknown Source) 

我怎樣才能讓我的方法真的叫代替原來的方法是什麼？

Answer 1

調用代碼仍在嘗試將null值傳遞給舊方法的簽名（期望boolean，而不是Boolean）。您需要重新編譯調用代碼，以便將其綁定到新的方法簽名：要調用的方法簽名在編譯時固定。

此外，請注意，PreparedStatement是一個接口 - 更改其定義可能會破壞所有實現上述接口的類。最值得注意的是，每個JDBC驅動程序將包含它自己的實現;你將不得不從源重新編譯驅動程序來解決這個問題。

這是可能的，但醜陋的和不可維護的，反編譯調用代碼，並簡單地修復它在null被傳遞的點，然後重新編譯它。你可以將它自動化到某個特定的位置（認爲字節碼編輯庫），但要點是不能訪問源代碼使得壞的調用是一個嚴重的缺點。