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，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}