为什么使用 slf4j + logback

logbak定位于log4j的替代者，logback同样支持slf4j，方便被替换。在Android平台上，我在使用log4中遇到tag混乱的问题。相比log4j，logback-android的jar更小巧。

下载jar包

前往 https://github.com/tony19/logback-android ，下载获得 logback-android-1.1.1-4.jar slf4j-api-1.7.6.jar

导入到工程中

将上面的两个jar文件放入项目中的libs中，并添加项目引用。

配置日志文件的位置

注意下面代码中的 configureLogbackDirectly 方法，它接收一个文件路径参数,指示存放日志文件的目录，还有一个是生成的日志文件的前缀。我下面配置了“每天生成一个新的日志文件”。

package vir56k.logdemo;

import android.os.Environment;
import org.slf4j.LoggerFactory;
import java.io.File;
import ch.qos.logback.classic.Level;
import ch.qos.logback.classic.Logger;
import ch.qos.logback.classic.LoggerContext;
import ch.qos.logback.classic.android.LogcatAppender;
import ch.qos.logback.classic.encoder.PatternLayoutEncoder;
import ch.qos.logback.classic.spi.ILoggingEvent;
import ch.qos.logback.core.rolling.RollingFileAppender;
import ch.qos.logback.core.rolling.TimeBasedRollingPolicy;

/**
 * Created by zhangyunfei on 15/9/21.
 */
public class LogConfigurator {
    public static void confifure() {
        final String LOG_DIR = Environment.getExternalStorageDirectory() + File.separator + "logback";
        final String PREFIX = "log";
        configureLogbackDirectly(LOG_DIR, PREFIX);
    }

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


        RollingFileAppender<ILoggingEvent> rollingFileAppender = new RollingFileAppender<ILoggingEvent>();
        rollingFileAppender.setAppend(true);
        rollingFileAppender.setContext(context);

        // OPTIONAL: Set an active log file (separate from the rollover files).
        // If rollingPolicy.fileNamePattern already set, you don't need this.
        //rollingFileAppender.setFile(LOG_DIR + "/log.txt");

        TimeBasedRollingPolicy<ILoggingEvent> rollingPolicy = new TimeBasedRollingPolicy<ILoggingEvent>();
        rollingPolicy.setFileNamePattern(log_dir + "/" + filePrefix + "_%d{yyyyMMdd}.txt");
        rollingPolicy.setMaxHistory(7);
        rollingPolicy.setParent(rollingFileAppender);  // parent and context required!
        rollingPolicy.setContext(context);
        rollingPolicy.start();

        rollingFileAppender.setRollingPolicy(rollingPolicy);

        PatternLayoutEncoder encoder = new PatternLayoutEncoder();
        encoder.setPattern("%d{yyyy-MM-dd HH:mm:ss.SSS} [%thread] %-5level %logger{36} - %msg%n");
        encoder.setContext(context);
        encoder.start();

        rollingFileAppender.setEncoder(encoder);
        rollingFileAppender.start();

        LogcatAppender logcatAppender = new LogcatAppender();
        logcatAppender.setContext(context);
        logcatAppender.setEncoder(encoder);
        logcatAppender.setName("logcat1");
        logcatAppender.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.setLevel(Level.TRACE);
        root.addAppender(rollingFileAppender);
        root.addAppender(logcatAppender);

        // print any status messages (warnings, etc) encountered in logback config
        //StatusPrinter.print(context);
    }


}

使用方法

先声明和创建实例

private static final Logger logger = LoggerFactory.getLogger(MainActivity.class);　

写入日志

logger.debug("debug Some log message. Details: {}", "debug 输出");
logger.info("info Some log message. Details: {}", "debug 输出");
logger.error("error Some log message. Details: {}", "debug 输出");

代码混淆注意

请在你的混淆设置里加入下面这些：

　　-keep class ch.qos.** { *; }
　　-keep class org.slf4j.** { *; }
　　-keepattributes *Annotation*

示例代码下载地址

https://github.com/vir56k/demo/tree/master/logBackDemo

参考资料：

https://github.com/tony19/logback-android

https://github.com/tony19/logback-android/wiki/Appender-Notes

http://logback.qos.ch/documentation.html

http://blog.csdn.net/zgmzyr/article/details/8267072