1 package org.hyphenType.debug;
2
3 import java.io.PrintStream;
4
5 /**
6 * A logger that only outputs things to a {@link PrintStream} if the
7 * {@link HTLogger#HYPHEN_TYPE_DEBUG_MODE} environment variable is set to true (ignoring case).
8 * This class also allows for the user to replace the {@link PrintStream}. The default
9 * {@link PrintStream} is {@link System#out}.
10 *
11 * @author akira
12 */
13 public class HTLogger {
14
15 /**
16 * System environment key to allow for users to change the debug mode when calling the JVM
17 */
18 public static final String HYPHEN_TYPE_DEBUG_MODE = "org.hyphenType.debug.debug-mode";
19
20 /**
21 * If true, this class was already initialized.
22 */
23 private static boolean initialized = false;
24 /**
25 * The debug mode. If true, this class writes to the print writer. If false, this class does
26 * nothing when {@link HTLogger#log(String)} is called.
27 */
28 private static boolean debugMode = false;
29 /**
30 * The {@link PrintStream} to be used. Can be replaced at runtime by calling
31 * {@link HTLogger#setOutput(PrintStream)}.
32 */
33 private static PrintStream ps = null;
34
35 /**
36 * Lazy initialization of this class. This initialization reads the environment variable and
37 * makes sure that {@link HTLogger#ps} is not null;
38 */
39 private static void lazyInitialize() {
40 if(!initialized) {
41 debugMode = Boolean.parseBoolean(System.getProperty(HYPHEN_TYPE_DEBUG_MODE));
42 /*
43 * ps may be not null if the user already set it to be something different from null
44 * before calling the log method.
45 */
46 if(ps == null) {
47 ps = System.out;
48 }
49 initialized = true;
50 }
51 }
52
53 /**
54 * Logs a message to the {@link PrintStream}, if debug mode is true.
55 *
56 * @param message The message to log
57 */
58 public static void log(final String message) {
59 lazyInitialize();
60
61 if(debugMode) {
62 StackTraceElement ste = Thread.currentThread().getStackTrace()[2];
63 ps.println(String.format("[%s.%s(%d)] %s", ste.getClassName(), ste.getMethodName(), ste.getLineNumber(), message));
64 }
65 }
66
67 /**
68 * Logs the full stack trace of a throwable.
69 *
70 * @param message The throwable to log
71 */
72 public static void log(final Throwable t) {
73 lazyInitialize();
74 if(debugMode) {
75 t.printStackTrace(ps);
76 }
77 }
78
79 /**
80 * Replaces the {@link PrintStream} used by this class to log messages. Does nothing if the
81 * provided argument is null. If you want this class to stop writing log outputs, you should
82 * set the debug mode to false using the method {@link HTLogger#setDebugMode(boolean)}.
83 *
84 * @param newPs The new print stream to be used
85 */
86 public static void setOutput(final PrintStream newPs) {
87 if(newPs!=null) {
88 ps = newPs;
89 }
90 }
91
92 /**
93 * Allows it for programmatic change of the debug mode.
94 *
95 * @param newDebugMode The new debug mode
96 */
97 public static void setDebugMode(final boolean newDebugMode) {
98 debugMode = newDebugMode;
99 }
100
101 public static boolean debugMode() {
102 return debugMode;
103 }
104 }