将Throwable.getStackTrace()的结果转换为描述堆栈跟踪的字符串最简单的方法是什么?
当前回答
将堆栈跟踪打印到字符串
import java.io.PrintWriter;
import java.io.StringWriter;
public class StackTraceUtils {
public static String stackTraceToString(StackTraceElement[] stackTrace) {
StringWriter sw = new StringWriter();
printStackTrace(stackTrace, new PrintWriter(sw));
return sw.toString();
}
public static void printStackTrace(StackTraceElement[] stackTrace, PrintWriter pw) {
for(StackTraceElement stackTraceEl : stackTrace) {
pw.println(stackTraceEl);
}
}
}
当您想要打印当前线程堆栈跟踪而不创建Throwable实例时,这非常有用,但请注意,创建新的Throwable并从中获取堆栈跟踪实际上比调用thread.getStackTrace更快、更便宜。
其他回答
没有java.io.*,它可以这样做。
String trace = e.toString() + "\n";
for (StackTraceElement e1 : e.getStackTrace()) {
trace += "\t at " + e1.toString() + "\n";
}
然后跟踪变量保存堆栈跟踪。输出也包含初始原因,输出与printStackTrace()相同
例如,printStackTrace()产生:
java.io.FileNotFoundException: / (Is a directory)
at java.io.FileOutputStream.open0(Native Method)
at java.io.FileOutputStream.open(FileOutputStream.java:270)
at java.io.FileOutputStream.<init>(FileOutputStream.java:213)
at java.io.FileOutputStream.<init>(FileOutputStream.java:101)
at Test.main(Test.java:9)
当打印到stdout时,跟踪字符串保持
java.io.FileNotFoundException: / (Is a directory)
at java.io.FileOutputStream.open0(Native Method)
at java.io.FileOutputStream.open(FileOutputStream.java:270)
at java.io.FileOutputStream.<init>(FileOutputStream.java:213)
at java.io.FileOutputStream.<init>(FileOutputStream.java:101)
at Test.main(Test.java:9)
警告:这可能有点离题,但哦,好吧…;)
我不知道最初的海报是什么原因让堆栈跟踪成为字符串。当堆栈跟踪应该以SLF4J/Logback LOG结尾,但没有或应该抛出异常时,我会这样做:
public void remove(List<String> ids) {
if(ids == null || ids.isEmpty()) {
LOG.warn(
"An empty list (or null) was passed to {}.remove(List). " +
"Clearly, this call is unneccessary, the caller should " +
"avoid making it. A stacktrace follows.",
getClass().getName(),
new Throwable ("Stacktrace")
);
return;
}
// actual work, remove stuff
}
我喜欢它,因为它不需要外部库(当然,除了您的日志后端,它大部分时间都会在那里)。
使用Java 8流API,您可以执行以下操作:
Stream
.of(throwable.getStackTrace())
.map(StackTraceElement::toString)
.collect(Collectors.joining("\n"));
它将获取堆栈跟踪元素的数组,将它们转换为字符串并连接为多行字符串。
我不久前写了一些方法,所以我想为什么不花我的两分钱。
/** @param stackTraceElements The elements to convert
* @return The resulting string */
public static final String stackTraceElementsToStr(StackTraceElement[] stackTraceElements) {
return stackTraceElementsToStr(stackTraceElements, "\n");
}
/** @param stackTraceElements The elements to convert
* @param lineSeparator The line separator to use
* @return The resulting string */
public static final String stackTraceElementsToStr(StackTraceElement[] stackTraceElements, String lineSeparator) {
return stackTraceElementsToStr(stackTraceElements, lineSeparator, "");
}
/** @param stackTraceElements The elements to convert
* @param lineSeparator The line separator to use
* @param padding The string to be used at the start of each line
* @return The resulting string */
public static final String stackTraceElementsToStr(StackTraceElement[] stackTraceElements, String lineSeparator, String padding) {
String str = "";
if(stackTraceElements != null) {
for(StackTraceElement stackTrace : stackTraceElements) {
str += padding + (!stackTrace.toString().startsWith("Caused By") ? "\tat " : "") + stackTrace.toString() + lineSeparator;
}
}
return str;
}
/** @param stackTraceElements The elements to convert
* @return The resulting string */
public static final String stackTraceCausedByElementsOnlyToStr(StackTraceElement[] stackTraceElements) {
return stackTraceCausedByElementsOnlyToStr(stackTraceElements, "\n");
}
/** @param stackTraceElements The elements to convert
* @param lineSeparator The line separator to use
* @return The resulting string */
public static final String stackTraceCausedByElementsOnlyToStr(StackTraceElement[] stackTraceElements, String lineSeparator) {
return stackTraceCausedByElementsOnlyToStr(stackTraceElements, lineSeparator, "");
}
/** @param stackTraceElements The elements to convert
* @param lineSeparator The line separator to use
* @param padding The string to be used at the start of each line
* @return The resulting string */
public static final String stackTraceCausedByElementsOnlyToStr(StackTraceElement[] stackTraceElements, String lineSeparator, String padding) {
String str = "";
if(stackTraceElements != null) {
for(StackTraceElement stackTrace : stackTraceElements) {
str += (!stackTrace.toString().startsWith("Caused By") ? "" : padding + stackTrace.toString() + lineSeparator);
}
}
return str;
}
/** @param e The {@link Throwable} to convert
* @return The resulting String */
public static final String throwableToStrNoStackTraces(Throwable e) {
return throwableToStrNoStackTraces(e, "\n");
}
/** @param e The {@link Throwable} to convert
* @param lineSeparator The line separator to use
* @return The resulting String */
public static final String throwableToStrNoStackTraces(Throwable e, String lineSeparator) {
return throwableToStrNoStackTraces(e, lineSeparator, "");
}
/** @param e The {@link Throwable} to convert
* @param lineSeparator The line separator to use
* @param padding The string to be used at the start of each line
* @return The resulting String */
public static final String throwableToStrNoStackTraces(Throwable e, String lineSeparator, String padding) {
if(e == null) {
return "null";
}
String str = e.getClass().getName() + ": ";
if((e.getMessage() != null) && !e.getMessage().isEmpty()) {
str += e.getMessage() + lineSeparator;
} else {
str += lineSeparator;
}
str += padding + stackTraceCausedByElementsOnlyToStr(e.getStackTrace(), lineSeparator, padding);
for(Throwable suppressed : e.getSuppressed()) {
str += padding + throwableToStrNoStackTraces(suppressed, lineSeparator, padding + "\t");
}
Throwable cause = e.getCause();
while(cause != null) {
str += padding + "Caused by:" + lineSeparator + throwableToStrNoStackTraces(e.getCause(), lineSeparator, padding);
cause = cause.getCause();
}
return str;
}
/** @param e The {@link Throwable} to convert
* @return The resulting String */
public static final String throwableToStr(Throwable e) {
return throwableToStr(e, "\n");
}
/** @param e The {@link Throwable} to convert
* @param lineSeparator The line separator to use
* @return The resulting String */
public static final String throwableToStr(Throwable e, String lineSeparator) {
return throwableToStr(e, lineSeparator, "");
}
/** @param e The {@link Throwable} to convert
* @param lineSeparator The line separator to use
* @param padding The string to be used at the start of each line
* @return The resulting String */
public static final String throwableToStr(Throwable e, String lineSeparator, String padding) {
if(e == null) {
return "null";
}
String str = padding + e.getClass().getName() + ": ";
if((e.getMessage() != null) && !e.getMessage().isEmpty()) {
str += e.getMessage() + lineSeparator;
} else {
str += lineSeparator;
}
str += padding + stackTraceElementsToStr(e.getStackTrace(), lineSeparator, padding);
for(Throwable suppressed : e.getSuppressed()) {
str += padding + "Suppressed: " + throwableToStr(suppressed, lineSeparator, padding + "\t");
}
Throwable cause = e.getCause();
while(cause != null) {
str += padding + "Caused by:" + lineSeparator + throwableToStr(e.getCause(), lineSeparator, padding);
cause = cause.getCause();
}
return str;
}
例子:
try(InputStream in = new FileInputStream(file)) {
...
} catch(IOException e) {
String exceptionToString = throwableToStr(e);
someLoggingUtility.println(exceptionToString);
...
}
打印:
java.io.FileNotFoundException: C:\test.txt (The system cannot find the file specified)
at java.io.FileInputStream.open0(Native Method)
at java.io.FileInputStream.open(Unknown Source)
at java.io.FileInputStream.<init>(Unknown Source)
at com.gmail.br45entei.Example.main(Example.java:32)
我的oneliner将堆栈跟踪转换为封闭的多行字符串:
Stream.of(e.getStackTrace()).map((a) -> a.toString()).collect(Collectors.joining("\n", "[", "]"))
易于传递给记录器“原样”。
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