logback--How do I configure an AsyncAppender with code? 转载

原文地址：https://github.com/tony19/logback-android/issues/54

Please provide an example of how to configure the AsyncAppender with a FileAppender to write to the file in an async way. I am getting many StrictMode policy violations (StrictModeDiskWriteViolation) on every log write to my log file.

Thanks.

I verified the following config works in Android 4.2.2 without any exceptions.

<configuration debug="true">
<property name="LOG_DIR" value="/data/data/com.example/files" />

<appender name="FILE" class="ch.qos.logback.core.FileAppender">
<file>${LOG_DIR}/log.txt</file>
<encoder>
<pattern>%d{HH:mm:ss.SSS} [%thread] %-5level %logger{35} - %msg%n</pattern>
</encoder>
</appender>

<appender name="ASYNC" class="ch.qos.logback.classic.AsyncAppender">
<appender-ref ref="FILE" />
</appender>

<root level="DEBUG">
<appender-ref ref="ASYNC" />
</root>
</configuration>

Example: Configure by in-memory XML string

package com.example;

import java.io.ByteArrayInputStream;
import java.io.InputStream;

import org.slf4j.LoggerFactory;

import ch.qos.logback.classic.LoggerContext;
import ch.qos.logback.classic.joran.JoranConfigurator;
import ch.qos.logback.core.joran.spi.JoranException;
import android.app.Activity;
import android.os.Bundle;
import android.view.Menu;

public class MainActivity extends Activity {

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);

configureLogbackByString();

org.slf4j.Logger log = LoggerFactory.getLogger(MainActivity.class);
log.info("hello world!!");
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.activity_main, menu);
return true;
}

@Override
protected void onDestroy() {
super.onDestroy();

// Assume SLF4J is bound to logback-classic in the current environment.
// This must be called to properly shutdown AsyncAppender and flush logs
// upon application exit.
LoggerContext loggerContext = (LoggerContext) LoggerFactory.getILoggerFactory();
loggerContext.stop();
}

String LOGBACK_XML =
"<configuration debug='true'>" +
"  <property name='LOG_DIR' value='/data/data/com.example/files' />" +
"  <appender name='FILE' class='ch.qos.logback.core.FileAppender'>" +
"    <file>${LOG_DIR}/log.txt</file>" +
"    <encoder>" +
"      <pattern>%d{HH:mm:ss.SSS} [%thread] %-5level %logger{35} - %msg%n</pattern>" +
"    </encoder>" +
"  </appender>" +
"  <appender name='ASYNC' class='ch.qos.logback.classic.AsyncAppender'>" +
"    <appender-ref ref='FILE' />" +
"  </appender>" +
"  <root level='DEBUG'>" +
"    <appender-ref ref='ASYNC' />" +
"  </root>" +
"</configuration>";

private void configureLogbackByString() {
// reset the default context (which may already have been initialized)
// since we want to reconfigure it
LoggerContext lc = (LoggerContext)LoggerFactory.getILoggerFactory();
lc.reset();

JoranConfigurator config = new JoranConfigurator();
config.setContext(lc);

InputStream stream = new ByteArrayInputStream(LOGBACK_XML.getBytes());
try {
config.doConfigure(stream);
} catch (JoranException e) {
e.printStackTrace();
}
}
}

Example: Configure with direct calls into logback

package com.example;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import android.app.Activity;
import android.os.Bundle;
import android.view.Menu;
import ch.qos.logback.classic.AsyncAppender;
import ch.qos.logback.classic.LoggerContext;
import ch.qos.logback.classic.encoder.PatternLayoutEncoder;
import ch.qos.logback.classic.spi.ILoggingEvent;
import ch.qos.logback.core.FileAppender;
import ch.qos.logback.core.util.StatusPrinter;

public class MainActivity extends Activity {

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);

configureLogbackDirectly();

org.slf4j.Logger log = LoggerFactory.getLogger(MainActivity.class);
log.info("hello world!!");

}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.activity_main, menu);
return true;
}

@Override
protected void onDestroy() {
super.onDestroy();

// assume SLF4J is bound to logback-classic in the current environment
LoggerContext loggerContext = (LoggerContext) LoggerFactory.getILoggerFactory();
loggerContext.stop();
}

private void configureLogbackDirectly() {
// reset the default context (which may already have been initialized)
// since we want to reconfigure it
LoggerContext lc = (LoggerContext)LoggerFactory.getILoggerFactory();
lc.reset();

// setup FileAppender
PatternLayoutEncoder encoder1 = new PatternLayoutEncoder();
encoder1.setContext(lc);
encoder1.setPattern("%d{HH:mm:ss.SSS} [%thread] %-5level %logger{35} - %msg%n");
encoder1.start();

FileAppender<ILoggingEvent> fileAppender = new FileAppender<ILoggingEvent>();
fileAppender.setContext(lc);
fileAppender.setName("FILE");
fileAppender.setFile(this.getFileStreamPath("log.txt").getAbsolutePath());
fileAppender.setEncoder(encoder1);
fileAppender.start();

AsyncAppender asyncAppender = new AsyncAppender();
asyncAppender.setContext(lc);
asyncAppender.setName("ASYNC");

// UNCOMMENT TO TWEAK OPTIONAL SETTINGS
//    // excluding caller data (used for stack traces) improves appender's performance
//    asyncAppender.setIncludeCallerData(false);
//    // set threshold to 0 to disable discarding and keep all events
//    asyncAppender.setDiscardingThreshold(0);
//    asyncAppender.setQueueSize(256);

asyncAppender.addAppender(fileAppender);
asyncAppender.start();

// add the newly created appenders to the root logger;
// qualify Logger to disambiguate from org.slf4j.Logger
ch.qos.logback.classic.Logger root = (ch.qos.logback.classic.Logger) LoggerFactory.getLogger(Logger.ROOT_LOGGER_NAME);
root.addAppender(asyncAppender);

StatusPrinter.print(lc);
}
}