Question

我已根据log4j的ConsoleAppender编写了一个Log4j Custom Appender。

我正在根据我得到的异常堆栈跟踪构建一个String，我面临的问题是我在其中看到字符'\ n'

请参阅以下字符串我得到的字符有 \ n 。

(Test.java:<sendSymbol>:40)- THE ERROR IS \norg.springframework.remoting.RemoteLookupFailureException: Lookup of RMI stub failed; nested exception is java.rmi.ConnectException: Connection refused to host: 19.9.199.155; nested exception is: \n

这是我的CustomAppender班级

请让我知道为什么我会\n inside my String。

package com;

import org.apache.log4j.AppenderSkeleton;
import org.apache.log4j.Layout;
import org.apache.log4j.spi.LoggingEvent;
import org.apache.log4j.spi.ThrowableInformation;

public class TestAppender extends AppenderSkeleton {
    public TestAppender() {



    }
    public TestAppender(Layout layout) {
        this.layout = layout;
    }
    public void append(LoggingEvent event) {

        ThrowableInformation throwableInfo = null;
        Throwable throwable = null;
        Throwable cause = null;
        StackTraceElement[] stackTrace = null;
        String smallIndent = "";
        String largeIndent = " at ";
        StringBuffer stringBuffer = new StringBuffer();
        stringBuffer.append(this.layout.format(event));
        if ((throwableInfo = event.getThrowableInformation()) != null) {
            if ((throwable = throwableInfo.getThrowable()) != null) {
                cause = throwable;
                while (cause != null) {
                    stringBuffer.append(smallIndent);
                    if (cause != throwable) {
                        stringBuffer.append("Caused by: ");
                    }
                    stringBuffer.append(cause.toString());
                    stackTrace = cause.getStackTrace();
                    for (int i = 0; i < stackTrace.length; i++) {
                        stringBuffer.append(largeIndent + stackTrace[i]);
                    }

                    cause = cause.getCause();
                }
            }
        }


        System.out.println(stringBuffer.toString());

    }

    public boolean requiresLayout() {
        return true;
    }

    public void close() {
        if (this.closed) {
            return;
        }
        this.closed = true;
    }

}

Answer 1

我非常怀疑换行符来自除stringBuffer.append(this.layout.format(event));之外的其他任何地方。其他四个调用不应添加任何新行。从输出示例：

stringBuffer.append(largeIndent + stackTrace[i]); // -- is never called
stringBuffer.append(smallIndent); // -- won't add newline
stringBuffer.append("Caused by: "); // -- won't add newline (and not called)
stringBuffer.append(cause.toString()); // -- shouldn't add newline

通过“不应该”我的意思是，任何Throwable子类都可以覆盖toString（）方法，以便在末尾添加\ n，但它们通常不会，而org.springframework.remoting.RemoteLookupFailureException则不会。

您的类初始化的布局实现是什么？那个布局的format()方法是如何实现的？希望您的IDE支持条件断点，如果stringBuffer.toString().contains("\n");

，您可以在追加后停止调试器

如何在对Log4j ConsoleAppender进行子类化时避免使用String

1 个答案: