如何在Java中获取当前代码行行号

为了实现自定义的log类，能够输出具体的代码行行号，我通过使用StackTraceElement对象实现了。


这里指出需要注意的几个问题：
1. 程序中返回的代码行行号，是新建StackTrackElement对象的那一行。
2. 可以通过传参的方法实现输出特定行行号。具体实现见代码。

1/** 


 2 * 
 3 */
 4package leo.demo.training;
 5
 6/** 


 7 * Get current java file name and current code line number
 8 * @author Leo Xie
 9 */
10public class CurrentLine { 
11    /** *//** http://www.mscto.com 
12     * @param args
13     */
14    public static void main(String[] args) { 
15        StackTraceElement ste1 = null;
16        
17        // get current thread and its related stack trace 
18        StackTraceElement[] steArray = Thread.currentThread().getStackTrace();
19        int steArrayLength = steArray.length;
20
21        String s = null; 


22        
23        // output all related info of the existing stack traces
24        if(steArrayLength==0) { 
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25            System.err.println("No Stack Trace.");
26        } else { 
27            for (int i=0; i<steArrayLength; i++) { 
28                System.out.println("Stack Trace-" + i);
29                ste1 = steArray[i];
30                s = ste1.getFileName() + ": Line " + ste1.getLineNumber(); 


31                System.out.println(s);
32            }
33        }
34        // the following code segment will output the line number of the "new " clause 
35        // that's to say the line number of "StackTraceElement ste2 = new Throwable().getStackTrace()[0];"
36        StackTraceElement ste2 = new Throwable().getStackTrace()[0]; http://www.mscto.com 
37        System.out.println(ste2.getFileName() + ": Line " + ste2.getLineNumber());
38        // the following clause will output the line number in the external method "getLineInfo()" 

39        System.out.println(getLineInfo());
40        // the following clause will output its current line number
41        System.out.println(getLineInfo(new Throwable().getStackTrace()[0])); 
42    }
43    
44    /** *//** 
45     * return current java file name and code line number
46     * @return String
47     */
48    public static String getLineInfo() { 


49        StackTraceElement ste3 = new Throwable().getStackTrace()[0];
50        return (ste3.getFileName() + ": Line " + ste3.getLineNumber()); http://www.mscto.com 
51    }
52    
53    /** *//** http://www.mscto.com 
54     * return current java file name and code line name
55     * @return String
56     */
57    public static String getLineInfo(StackTraceElement ste4) { 

58        return (ste4.getFileName() + ": Line " + (ste4.getLineNumber()));
59    }
60}