无法解析Android中的log4j配置

问题描述 投票：0回答：1

我正在尝试在 android 中实现 log4j，在 gradle 中使用 v2.24.1 依赖项：

implementation 'org.apache.logging.log4j:log4j-api:2.24.1'
implementation 'org.apache.logging.log4j:log4j-core:2.24.1'

我在 src/main/assets 目录中有一个 log4j2.properties 配置：

# Root logger configuration
status = error
name = PropertiesConfig

# Appenders
appender.console.type = Console
appender.console.name = Console
appender.console.target = SYSTEM_OUT
appender.console.layout.type = PatternLayout
appender.console.layout.pattern = [%d{yyyy-MM-dd HH:mm:ss.SSS}] %-5p- %m%n

# Root logger level and appenders
rootLogger.level = INFO
rootLogger.appenderRefs = stdout
rootLogger.appenderRef.stdout.ref = Console

logger.com.example.log4japi.MainActivity.name = com.example.log4japi.MainActivity
logger.com.example.log4japi.MainActivity.level = DEBUG
logger.com.example.log4japi.MainActivity.additivity = false
logger.com.example.log4japi.MainActivity.appenderRefs = stdout
logger.com.example.log4japi.MainActivity.appenderRef.stdout.ref = Console

在我的主要活动中，我尝试使用上面定义的 com.example.log4japi.MainActivity 的记录器。该活动包含一个用于显示当前日志级别的文本视图、一个用于打开对话框和更改日志级别的按钮，以及用于打印每个级别的日志消息的其他按钮：

package com.example.log4japi;

import androidx.appcompat.app.AlertDialog;
import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;
import android.widget.Button;
import android.widget.TextView;

import org.apache.logging.log4j.Level;
import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;

import org.apache.logging.log4j.core.config.Configurator;
import java.util.Arrays;

public class MainActivity extends AppCompatActivity {

    private int logLevelIdx;

    Logger log = LogManager.getLogger(MainActivity.class);

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        
        //TextView displaying Log Level
        TextView logLevelTxt = findViewById(R.id.logLevelTxt);
        logLevelTxt.setText(log.getLevel().name());
        
        //Change log level
        Button setLogLevelBtn = findViewById(R.id.setLogLevelBtn);
        setLogLevelBtn.setOnClickListener(v -> {
            AlertDialog.Builder alertDialog = new AlertDialog.Builder(this);
            alertDialog.setTitle("Set log level");

            String[] logLevels = new String[]{"OFF", "FATAL", "ERROR", "WARN", "INFO", "DEBUG", "TRACE", "ALL"};
            logLevelIdx = Arrays.asList(logLevels).indexOf(log.getLevel().name());

            alertDialog.setSingleChoiceItems(logLevels, logLevelIdx, (dialog, which) -> logLevelIdx = which);
            alertDialog.setPositiveButton("Select", (dialog, which) -> {
                Configurator.setLevel(log.getName(), Level.valueOf(Arrays.asList(logLevels).get(logLevelIdx)));
                logLevelTxt.setText(log.getLevel().name());
                dialog.dismiss();
            });
            alertDialog.setNegativeButton("Cancel", (dialog, which) -> dialog.dismiss());
            alertDialog.create();
            alertDialog.show();
        });
        
        
        //Log messages
        Button fatalLogBtn = findViewById(R.id.fatalLogBtn);
        fatalLogBtn.setOnClickListener(v -> log.fatal("Current log level is: " + log.getLevel().name()));

        Button errorLogBtn = findViewById(R.id.errorLogBtn);
        errorLogBtn.setOnClickListener(v -> log.error("Current log level is: " + log.getLevel().name()));

        Button warnLogBtn = findViewById(R.id.warnLogBtn);
        warnLogBtn.setOnClickListener(v -> log.warn("Current log level is: " + log.getLevel().name()));

        Button infoLogBtn = findViewById(R.id.infoLogBtn);
        infoLogBtn.setOnClickListener(v -> log.info("Current log level is: " + log.getLevel().name()));

        Button debugLogBtn = findViewById(R.id.debugLogBtn);
        debugLogBtn.setOnClickListener(v -> log.debug("Current log level is: " + log.getLevel().name()));

        Button traceLogBtn = findViewById(R.id.traceLogBtn);
        traceLogBtn.setOnClickListener(v -> log.trace("Current log level is: " + log.getLevel().name()));
    }
}

由于某种原因，配置未被读取或初始化。这会导致我尝试使用的任何记录器的默认日志级别为 ERROR。我也无法使用 

Configurator.setLevel
更改这些记录器的级别（除非我使用根记录器）。

我尝试从属性文件中手动导入配置，如下所示：

// Manually read in log4j2.properties
LoggerContext context = (LoggerContext) LogManager.getContext(false);
try {
    InputStream inputStream = getAssets().open("log4j2.properties");
    ConfigurationSource source = new ConfigurationSource(inputStream);
    context.start(ConfigurationFactory.getInstance().getConfiguration(context, source));
} catch (IOException e) {
    e.printStackTrace();
}

但这会产生以下堆栈跟踪：

E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.example.log4japi, PID: 10971
    java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.log4japi/com.example.log4japi.MainActivity}: java.lang.UnsupportedOperationException: This parser does not support specification "Unknown" version "0.0"
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3449)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3601)
        at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:85)
        at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135)
        at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2066)
        at android.os.Handler.dispatchMessage(Handler.java:106)
        at android.os.Looper.loop(Looper.java:223)
        at android.app.ActivityThread.main(ActivityThread.java:7656)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:592)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:947)
     Caused by: java.lang.UnsupportedOperationException: This parser does not support specification "Unknown" version "0.0"
        at javax.xml.parsers.DocumentBuilderFactory.setXIncludeAware(DocumentBuilderFactory.java:475)
        at org.apache.logging.log4j.core.config.xml.XmlConfiguration.enableXInclude(XmlConfiguration.java:226)
        at org.apache.logging.log4j.core.config.xml.XmlConfiguration.newDocumentBuilder(XmlConfiguration.java:186)
        at org.apache.logging.log4j.core.config.xml.XmlConfiguration.<init>(XmlConfiguration.java:87)
        at org.apache.logging.log4j.core.config.xml.XmlConfigurationFactory.getConfiguration(XmlConfigurationFactory.java:46)
        at org.apache.logging.log4j.core.config.ConfigurationFactory$Factory.getConfiguration(ConfigurationFactory.java:565)
        at com.example.log4japi.MainActivity.onCreate(MainActivity.java:40)
        at android.app.Activity.performCreate(Activity.java:8000)
        at android.app.Activity.performCreate(Activity.java:7984)
        at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1309)
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3422)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3601) 
        at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:85) 
        at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135) 
        at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95) 
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2066) 
        at android.os.Handler.dispatchMessage(Handler.java:106) 
        at android.os.Looper.loop(Looper.java:223) 
        at android.app.ActivityThread.main(ActivityThread.java:7656) 
        at java.lang.reflect.Method.invoke(Native Method) 
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:592) 
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:947) 

如何解决读取配置的问题？

java android logging log4j2 android-assets
1个回答
0
投票

由于某种原因，配置未被读取或初始化。

在您的项目中，配置文件位于 

src/main/assets
中，它不是部署在类路径的根目录中，而是部署在 
assets
子文件夹中。要将文件部署到类路径的根目录，请将其放入 
src/main/resources
。

我尝试从属性文件中手动导入配置，如下所示：

// Manually read in log4j2.properties
LoggerContext context = (LoggerContext) LogManager.getContext(false);
try {
    InputStream inputStream = getAssets().open("log4j2.properties");
    ConfigurationSource source = new ConfigurationSource(inputStream);
    context.start(ConfigurationFactory.getInstance().getConfiguration(context, source));
} catch (IOException e) {
   e.printStackTrace();
}


ConfigurationSource
类类似于上传文件：您需要指定上传文件的内容和类型。 Log4j Core 从 ConfigurationSource.getLocation()
 的文件扩展名推断出配置文件的
type。如果此方法返回 
null
或未知的文件扩展名，则采用默认的 XML 配置格式。 由于 Android XML 解析器中缺乏 XInclude 功能，这会触发 LOG4J2-3531 错误。

要解决此问题，您需要在创建 ConfigurationSource 时指定配置文件的 

name
:

private ConfigurationSource getConfiguration(String asset) throws IOException {
    // Create a Source to specify the name of the configuration file
    Source source = new Source(URI.create("log4j2.properties"));
    // Create a ConfigurationSource with the contents of the configuration file
    byte[] buffer = new byte[1024];
    ByteArrayOutputStream baos = new ByteArrayOutputStream();
    try (InputStream inputStream = getAssets().open(asset)) {
        int len;
        while ((len = inputStream.read(buffer)) != -1) {
            baos.write(buffer, 0, len);
        }
    }
    return new ConfigurationSource(source, baos.toByteArray(), 0L);
}
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