我正在使用log4j编写一个记录器.一旦我加载了log4j.properties或log4j.xml文件,我就想知道是否有办法检测记录器配置文件是否有效.如果它无效,我希望加载默认设置(位于另一个文件中).
谢谢
解决方法
我们通过在加载配置之前重定向System.err并检查错误是否记录到流来解决了这个问题：
class ConfigurationLoader {
class Log4jConfigStderrStream extends ByteArrayOutputStream {
private int lineCount;
private StringBuilder output;
private PrintStream underlying;
public Log4jConfigStderrStream(PrintStream underlying) {
this.lineCount = 0;
this.output = new StringBuilder("");
this.underlying = underlying;
}
@Override
public void flush() throws IOException {
String[] buffer;
synchronized (this) {
buffer = this.toString().split("\n");
super.flush();
super.reset();
for (int i = 0; i < buffer.length; i++) {
String line = buffer[i].replace("\n","").replace("\r","");
if (line.length() > 0) {
this.lineCount++;
this.output.append(line);
this.output.append("\n");
}
}
}
}
public String getOutput() {
return this.output.toString();
}
public PrintStream getUnderlying() {
return this.underlying;
}
public boolean hasErrors() {
return this.lineCount == 0 ? false : true;
}
}
private String output;
public void flushOutput() {
if (!"".equals(this.output))
System.err.print(this.output);
}
public boolean loadConfiguration(String filename) {
Log4jConfigStderrStream confErr;
confErr = new Log4jConfigStderrStream(System.err);
System.setErr(new PrintStream(confErr,true));
LogManager.resetConfiguration();
DOMConfigurator.configure(filename);
System.setErr(confErr.getUnderlying());
this.output = confErr.getOutput();
return !confErr.hasErrors();
}
}