Roller 4のExceptionを学ぶ
3058 ワード
Roller 4では、すべての例外が直接または間接的にRoller Exceptionのサブクラスであり、そのコードから例外のStackTrace構造をどのように構築するかを見ることができます.
/**
* Base Roller exception class.
*/
public abstract class RollerException extends Exception {
private final Throwable mRootCause;
/**
* Construct emtpy exception object.
*/
public RollerException() {
super();
mRootCause = null;
}
/**
* Construct RollerException with message string.
* @param s Error message string.
*/
public RollerException(String s) {
super(s);
mRootCause = null;
}
/**
* Construct RollerException, wrapping existing throwable.
* @param s Error message
* @param t Existing connection to wrap.
*/
public RollerException(String s, Throwable t) {
super(s);
mRootCause = t;
}
/**
* Construct RollerException, wrapping existing throwable.
* @param t Existing exception to be wrapped.
*/
public RollerException(Throwable t) {
mRootCause = t;
}
/**
* Get root cause object, or null if none.
* @return Root cause or null if none.
*/
public Throwable getRootCause() {
return mRootCause;
}
/**
* Get root cause message.
* @return Root cause message.
*/
public String getRootCauseMessage() {
String rcmessage = null;
if (getRootCause()!=null) {
if (getRootCause().getCause()!=null) {
rcmessage = getRootCause().getCause().getMessage();
}
rcmessage = (rcmessage == null) ? getRootCause().getMessage() : rcmessage;
rcmessage = (rcmessage == null) ? super.getMessage() : rcmessage;
rcmessage = (rcmessage == null) ? "NONE" : rcmessage;
}
return rcmessage;
}
/**
* Print stack trace for exception and for root cause exception if htere is one.
* @see java.lang.Throwable#printStackTrace()
*/
public void printStackTrace() {
super.printStackTrace();
if (mRootCause != null) {
System.out.println("--- ROOT CAUSE ---");
mRootCause.printStackTrace();
}
}
/**
* Print stack trace for exception and for root cause exception if htere is one.
* @param s Stream to print to.
*/
public void printStackTrace(PrintStream s) {
super.printStackTrace(s);
if (mRootCause != null) {
s.println("--- ROOT CAUSE ---");
mRootCause.printStackTrace(s);
}
}
/**
* Print stack trace for exception and for root cause exception if htere is one.
* @param s Writer to write to.
*/
public void printStackTrace(PrintWriter s) {
super.printStackTrace(s);
if (null != mRootCause) {
s.println("--- ROOT CAUSE ---");
mRootCause.printStackTrace(s);
}
}
}
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