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/*
 * 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 

package org.apache.log4j.spi;

import org.apache.log4j.Layout;
import org.apache.log4j.helpers.LogLog;

import java.io.PrintWriter;
import java.io.StringWriter;
import java.io.InterruptedIOException;
import java.lang.reflect.Method;
import java.lang.reflect.InvocationTargetException;

/**
   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
     fully.qualified.classname.of.caller.methodName(Filename.java:line)
    */
  public String fullInfo;

  private static StringWriter sw = new StringWriter();
  private static PrintWriter pw = new PrintWriter(sw);

  private static Method getStackTraceMethod;
  private static Method getClassNameMethod;
  private static Method getMethodNameMethod;
  private static Method getFileNameMethod;
  private static Method getLineNumberMethod;


  /**
     When location information is not available the constant
     NA is returned. Current value of this string
     constant is ?.  */
  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);



  // Check if we are running in IBM's visual age.
  static boolean inVisualAge = false;
  static {
    try {
      inVisualAge = Class.forName("com.ibm.uvm.tools.DebugSupport") != null;
      LogLog.debug("Detected IBM VisualAge environment.");
    } catch(Throwable e) {
      // nothing to do
    }
      try {
          Class[] noArgs = null;
          getStackTraceMethod = Throwable.class.getMethod("getStackTrace", noArgs);
          Class stackTraceElementClass = Class.forName("java.lang.StackTraceElement");
          getClassNameMethod = stackTraceElementClass.getMethod("getClassName", noArgs);
          getMethodNameMethod = stackTraceElementClass.getMethod("getMethodName", noArgs);
          getFileNameMethod = stackTraceElementClass.getMethod("getFileName", noArgs);
          getLineNumberMethod = stackTraceElementClass.getMethod("getLineNumber", noArgs);
      } catch(ClassNotFoundException ex) {
          LogLog.debug("LocationInfo will use pre-JDK 1.4 methods to determine location.");
      } catch(NoSuchMethodException ex) {
          LogLog.debug("LocationInfo will use pre-JDK 1.4 methods to determine location.");
      }
  }

  /**
     Instantiate location information based on a Throwable. We
     expect the Throwable t, to be in the format

       
        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)
	...
       

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; if (getLineNumberMethod != null) { try { Object[] noArgs = null; Object[] elements = (Object[]) getStackTraceMethod.invoke(t, noArgs); String prevClass = NA; for(int i = elements.length - 1; i >= 0; i--) { String thisClass = (String) getClassNameMethod.invoke(elements[i], noArgs); if(fqnOfCallingClass.equals(thisClass)) { int caller = i + 1; if (caller < elements.length) { className = prevClass; methodName = (String) getMethodNameMethod.invoke(elements[caller], noArgs); fileName = (String) getFileNameMethod.invoke(elements[caller], noArgs); if (fileName == null) { fileName = NA; } int line = ((Integer) getLineNumberMethod.invoke(elements[caller], noArgs)).intValue(); if (line < 0) { lineNumber = NA; } else { lineNumber = String.valueOf(line); } StringBuffer buf = new StringBuffer(); 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(IllegalAccessException ex) { LogLog.debug("LocationInfo failed using JDK 1.4 methods", ex); } catch(InvocationTargetException ex) { if (ex.getTargetException() instanceof InterruptedException || ex.getTargetException() instanceof InterruptedIOException) { Thread.currentThread().interrupt(); } LogLog.debug("LocationInfo failed using JDK 1.4 methods", ex); } catch(RuntimeException ex) { LogLog.debug("LocationInfo failed using JDK 1.4 methods", ex); } } String s; // Protect against multiple access to sw. synchronized(sw) { t.printStackTrace(pw); s = sw.toString(); sw.getBuffer().setLength(0); } //System.out.println("s is ["+s+"]."); int ibegin, iend; // Given the current structure of the package, the line // containing "org.apache.log4j.Category." should be printed just // before the caller. // This method of searching may not be fastest but it's safer // than counting the stack depth which is not guaranteed to be // constant across JVM implementations. ibegin = s.lastIndexOf(fqnOfCallingClass); if(ibegin == -1) return; // // if the next character after the class name exists // but is not a period, see if the classname is // followed by a period earlier in the trace. // Minimizes mistakeningly matching on a class whose // name is a substring of the desired class. // See bug 44888. if (ibegin + fqnOfCallingClass.length() < s.length() && s.charAt(ibegin + fqnOfCallingClass.length()) != '.') { int i = s.lastIndexOf(fqnOfCallingClass + "."); if (i != -1) { ibegin = i; } } ibegin = s.indexOf(Layout.LINE_SEP, ibegin); if(ibegin == -1) return; ibegin+= Layout.LINE_SEP_LEN; // determine end of line iend = s.indexOf(Layout.LINE_SEP, ibegin); if(iend == -1) return; // VA has a different stack trace format which doesn't // need to skip the inital 'at' if(!inVisualAge) { // back up to first blank character ibegin = s.lastIndexOf("at ", iend); if(ibegin == -1) return; // Add 3 to skip "at "; ibegin += 3; } // everything between is the requested stack item this.fullInfo = s.substring(ibegin, iend); } /** * 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 StringBuffer 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; StringBuffer buf = new StringBuffer(); 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) { // 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); // This is because a stack trace in VisualAge looks like: //java.lang.RuntimeException // java.lang.Throwable() // java.lang.Exception() // java.lang.RuntimeException() // void test.test.B.print() // void test.test.A.printIndirect() // void test.test.Run.main(java.lang.String []) int ibegin = 0; if (inVisualAge) { ibegin = fullInfo.lastIndexOf(' ', iend)+1; } if(iend == -1) className = NA; else className = this.fullInfo.substring(ibegin, iend); } } return className; } /** Return the file name of the caller.

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.

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; } }





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