LocationInfo.java
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
// Contributors: Mathias Rupprecht <mmathias.rupprecht@fja.com>
package org.apache.log4j.spi;
import org.apache.log4j.helpers.LogLog;
/**
* The internal representation of caller location information.
*
* @since 0.8.3
*/
public class LocationInfo implements java.io.Serializable {
/**
* Caller's line number.
*/
transient String lineNumber;
/**
* Caller's file name.
*/
transient String fileName;
/**
* Caller's fully qualified class name.
*/
transient String className;
/**
* Caller's method name.
*/
transient String methodName;
/**
* All available caller information, in the format
* <code>fully.qualified.classname.of.caller.methodName(Filename.java:line)</code>
*/
// ATTENTION: fullInfo is used to reconstruct the other fields post deserialization
public String fullInfo;
/**
* When location information is not available the constant <code>NA</code> is returned. Current value of this string
* constant is <b>?</b>.
*/
public final static String NA = "?";
static final long serialVersionUID = -1325822038990805636L;
/**
* NA_LOCATION_INFO is provided for compatibility with log4j 1.3.
*
* @since 1.2.15
*/
public static final LocationInfo NA_LOCATION_INFO = new LocationInfo(NA, NA, NA, NA);
/**
* Instantiate location information based on a Throwable. We expect the Throwable <code>t</code>, to be in the
* format
*
* <pre>
* java.lang.Throwable
* ...
* at org.apache.log4j.PatternLayout.format(PatternLayout.java:413)
* at org.apache.log4j.FileAppender.doAppend(FileAppender.java:183)
* at org.apache.log4j.Category.callAppenders(Category.java:131)
* at org.apache.log4j.Category.log(Category.java:512)
* at callers.fully.qualified.className.methodName(FileName.java:74)
* ...
* </pre>
*
* <p>
* However, we can also deal with JIT compilers that "lose" the location information, especially between the
* parentheses.
*
* @param t throwable used to determine location, may be null.
* @param fqnOfCallingClass class name of first class considered part of the logging framework. Location will be
* site that calls a method on this class.
*/
public LocationInfo(Throwable t, String fqnOfCallingClass) {
if (t == null || fqnOfCallingClass == null)
return;
try {
StackTraceElement[] elements = t.getStackTrace();
String prevClass = NA;
for (int i = elements.length - 1; i >= 0; i--) {
String thisClass = elements[i].getClassName();
if (fqnOfCallingClass.equals(thisClass)) {
int caller = i + 1;
if (caller < elements.length) {
className = prevClass;
methodName = elements[caller].getMethodName();
fileName = elements[caller].getFileName();
if (fileName == null) {
fileName = NA;
}
int line = elements[caller].getLineNumber();
if (line < 0) {
lineNumber = NA;
} else {
lineNumber = Integer.toString(line);
}
StringBuilder buf = new StringBuilder();
buf.append(className);
buf.append(".");
buf.append(methodName);
buf.append("(");
buf.append(fileName);
buf.append(":");
buf.append(lineNumber);
buf.append(")");
this.fullInfo = buf.toString();
}
return;
}
prevClass = thisClass;
}
return;
} catch (RuntimeException ex) {
LogLog.debug("LocationInfo construction failed", ex);
}
}
/**
* Appends a location fragment to a buffer to build the full location info.
*
* @param buf StringBuffer to receive content.
* @param fragment fragment of location (class, method, file, line), if null the value of NA will be appended.
* @since 1.2.15
*/
private static final void appendFragment(final StringBuilder buf, final String fragment) {
if (fragment == null) {
buf.append(NA);
} else {
buf.append(fragment);
}
}
/**
* Create new instance.
*
* @param file source file name
* @param classname class name
* @param method method
* @param line source line number
* @since 1.2.15
*/
public LocationInfo(final String file, final String classname, final String method, final String line) {
this.fileName = file;
this.className = classname;
this.methodName = method;
this.lineNumber = line;
StringBuilder buf = new StringBuilder();
appendFragment(buf, classname);
buf.append(".");
appendFragment(buf, method);
buf.append("(");
appendFragment(buf, file);
buf.append(":");
appendFragment(buf, line);
buf.append(")");
this.fullInfo = buf.toString();
}
/**
* Return the fully qualified class name of the caller making the logging request.
*/
public String getClassName() {
if (fullInfo == null)
return NA;
if (className != null) {
return className;
} else {
// Starting the search from '(' is safer because there is
// potentially a dot between the parentheses.
int iend = fullInfo.lastIndexOf('(');
if (iend == -1)
className = NA;
else {
iend = fullInfo.lastIndexOf('.', iend);
int ibegin = 0;
if (iend == -1)
className = NA;
else
className = this.fullInfo.substring(ibegin, iend);
}
return className;
}
}
/**
* Return the file name of the caller.
*
* <p>
* This information is not always available.
*/
public String getFileName() {
if (fullInfo == null)
return NA;
if (fileName == null) {
int iend = fullInfo.lastIndexOf(':');
if (iend == -1)
fileName = NA;
else {
int ibegin = fullInfo.lastIndexOf('(', iend - 1);
fileName = this.fullInfo.substring(ibegin + 1, iend);
}
}
return fileName;
}
/**
* Returns the line number of the caller.
*
* <p>
* This information is not always available.
*/
public String getLineNumber() {
if (fullInfo == null)
return NA;
if (lineNumber == null) {
int iend = fullInfo.lastIndexOf(')');
int ibegin = fullInfo.lastIndexOf(':', iend - 1);
if (ibegin == -1)
lineNumber = NA;
else
lineNumber = this.fullInfo.substring(ibegin + 1, iend);
}
return lineNumber;
}
/**
* Returns the method name of the caller.
*/
public String getMethodName() {
if (fullInfo == null)
return NA;
if (methodName == null) {
int iend = fullInfo.lastIndexOf('(');
int ibegin = fullInfo.lastIndexOf('.', iend);
if (ibegin == -1)
methodName = NA;
else
methodName = this.fullInfo.substring(ibegin + 1, iend);
}
return methodName;
}
}