src/be/nikiroo/utils/TraceHandler.java

   1 package be.nikiroo.utils;
   2
   3 /**
   4  * A handler when a trace message is sent or when a recoverable exception was
   5  * caught by the program.
   6  *
   7  * @author niki
   8  */
   9 public class TraceHandler {
  10         private final boolean showErrors;
  11         private final boolean showErrorDetails;
  12         private final int traceLevel;
  13         private final int maxPrintSize;
  14
  15         /**
  16          * Create a default {@link TraceHandler} that will print errors on stderr
  17          * (without details) and no traces.
  18          */
  19         public TraceHandler() {
  20                 this(true, false, false);
  21         }
  22
  23         /**
  24          * Create a default {@link TraceHandler}.
  25          *
  26          * @param showErrors
  27          *            show errors on stderr
  28          * @param showErrorDetails
  29          *            show more details when printing errors
  30          * @param showTraces
  31          *            show level 1 traces on stdout, or no traces at all
  32          */
  33         public TraceHandler(boolean showErrors, boolean showErrorDetails,
  34                         boolean showTraces) {
  35                 this(showErrors, showErrorDetails, showTraces ? 1 : 0);
  36         }
  37
  38         /**
  39          * Create a default {@link TraceHandler}.
  40          *
  41          * @param showErrors
  42          *            show errors on stderr
  43          * @param showErrorDetails
  44          *            show more details when printing errors
  45          * @param traceLevel
  46          *            show traces of this level or lower (0 means "no traces",
  47          *            higher means more traces)
  48          */
  49         public TraceHandler(boolean showErrors, boolean showErrorDetails,
  50                         int traceLevel) {
  51                 this(showErrors, showErrorDetails, traceLevel, -1);
  52         }
  53
  54         /**
  55          * Create a default {@link TraceHandler}.
  56          *
  57          * @param showErrors
  58          *            show errors on stderr
  59          * @param showErrorDetails
  60          *            show more details when printing errors
  61          * @param traceLevel
  62          *            show traces of this level or lower (0 means "no traces",
  63          *            higher means more traces)
  64          * @param maxPrintSize
  65          *            the maximum size at which to truncate traces data (or -1 for
  66          *            "no limit")
  67          */
  68         public TraceHandler(boolean showErrors, boolean showErrorDetails,
  69                         int traceLevel, int maxPrintSize) {
  70                 this.showErrors = showErrors;
  71                 this.showErrorDetails = showErrorDetails;
  72                 this.traceLevel = Math.max(traceLevel, 0);
  73                 this.maxPrintSize = maxPrintSize;
  74         }
  75
  76         /**
  77          * The trace level of this {@link TraceHandler}.
  78          *
  79          * @return the level
  80          */
  81         public int getTraceLevel() {
  82                 return traceLevel;
  83         }
  84
  85         /**
  86          * An exception happened, log it.
  87          *
  88          * @param e
  89          *            the exception
  90          */
  91         public void error(Exception e) {
  92                 if (showErrors) {
  93                         if (showErrorDetails) {
  94                                 e.printStackTrace();
  95                         } else {
  96                                 error(e.getMessage());
  97                         }
  98                 }
  99         }
 100
 101         /**
 102          * An error happened, log it.
 103          *
 104          * @param message
 105          *            the error message
 106          */
 107         public void error(String message) {
 108                 if (showErrors) {
 109                         System.err.println(message);
 110                 }
 111         }
 112
 113         /**
 114          * A trace happened, show it.
 115          * <p>
 116          * By default, will only be effective if {@link TraceHandler#traceLevel} is
 117          * not 0.
 118          * <p>
 119          * A call to this method is equivalent to a call to
 120          * {@link TraceHandler#trace(String, int)} with a level of 1.
 121          *
 122          * @param message
 123          *            the trace message
 124          */
 125         public void trace(String message) {
 126                 trace(message, 1);
 127         }
 128
 129         /**
 130          * A trace happened, show it.
 131          * <p>
 132          * By default, will only be effective if {@link TraceHandler#traceLevel} is
 133          * not 0 and the level is lower or equal to it.
 134          *
 135          * @param message
 136          *            the trace message
 137          * @param level
 138          *            the trace level
 139          */
 140         public void trace(String message, int level) {
 141                 if (traceLevel > 0 && level <= traceLevel) {
 142                         if (maxPrintSize > 0 && message.length() > maxPrintSize) {
 143                                 System.out
 144                                                 .println(message.substring(0, maxPrintSize) + "[...]");
 145                         } else {
 146                                 System.out.println(message);
 147                         }
 148                 }
 149         }
 150 }