java异步写日志到文件中实现代码

java异步写日志到文件中详解

实现代码：

package com.tydic.ESUtil; 

import java.io.File;
import java.io.FileWriter;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.Properties; 

public class LogWriter {
// 日志的配置文件
  public static final String LOG_CONFIGFILE_NAME = "log.properties";
  // 日志文件名在配置文件中的标签
  public static final String LOGFILE_TAG_NAME = "logfile"; 

  // 默认的日志文件的路径和文件名称
  private final String DEFAULT_LOG_FILE_NAME = "./logtext.log";
  // 该类的唯一的实例
  private static LogWriter logWriter;
  // 文件输出流
  private PrintWriter writer;
  // 日志文件名
  private String logFileName;
  /**
   * 默认构造函数
   */
  private LogWriter() throws LogException{
    this.init();
  }
  private LogWriter(String fileName) throws LogException{
    this.logFileName = fileName;
    this.init();
  }
  /**
   * 获取LogWriter的唯一实例。
   * @return
   * @throws LogException
   */
  public synchronized static LogWriter getLogWriter()throws LogException{
    if (logWriter == null){
      logWriter = new LogWriter();
    }
    return logWriter;
  }
  public synchronized static LogWriter getLogWriter(String logFileName)throws LogException{
    if (logWriter == null){
      logWriter = new LogWriter(logFileName);
    }
    return logWriter;
  } 

  /**
   * 往日志文件中写一条日志信息
   * 为了防止多线程同时操作(写)日志文件，造成文件”死锁”。使用synchronized关键字
   * @param logMsg  日志消息
   */
  public synchronized void log(String logMsg) {
    this.writer.println(new java.util.Date() + ": " + logMsg);
  }
  /**
   * 往日志文件中写一条异常信息
   * 使用synchronized关键字。
   * @param ex  待写入的异常
   */
  public synchronized void log(Exception ex) {
    writer.println(new java.util.Date() + ": ");
    ex.printStackTrace(writer);
  } 

  /**
   * 初始化LogWriter
   * @throws LogException
   */
  private void init() throws LogException{
    //如果用户没有在参数中指定日志文件名，则从配置文件中获取。
    if (this.logFileName == null){
      this.logFileName = this.getLogFileNameFromConfigFile();
      //如果配置文件不存在或者也没有指定日志文件名，则用默认的日志文件名。
      if (this.logFileName == null){
        this.logFileName = DEFAULT_LOG_FILE_NAME;
      }
    }
    File logFile = new File(this.logFileName);
    try {
      // 其中的FileWriter()中的第二个参数的含义是:是否在文件中追加内容
      // PrintWriter()中的第二个参数的含义是：自动将数据flush到文件中
      writer = new PrintWriter(new FileWriter(logFile, true), true);
      System.out.println("日志文件的位置：" + logFile.getAbsolutePath());
    } catch (IOException ex) {
      String errmsg = "无法打开日志文件:" + logFile.getAbsolutePath();
      // System.out.println(errmsg);
      throw new LogException(errmsg, ex);
    }
  }
  /**
   * 从配置文件中取日志文件名
   * @return
   */
  private String getLogFileNameFromConfigFile() {
    try {
      Properties pro = new Properties();
      //在类的当前位置,查找属性配置文件log.properties
      InputStream fin = getClass().getResourceAsStream(LOG_CONFIGFILE_NAME);
      if (fin != null){
        pro.load(fin);//载入配置文件
        fin.close();
        return pro.getProperty(LOGFILE_TAG_NAME);
      } else {
        System.err.println("无法打开属性配置文件: log.properties" );
      }
    }catch (IOException ex) {
      System.err.println("无法打开属性配置文件: log.properties" );
    }
    return null;
  }
  //关闭LogWriter
  public void close() {
    logWriter = null;
    if (writer != null){
      writer.close();
    }
  } 

  public static void main(String[] args) {
    LogWriter logger = null;
    try {
      String fileName = "d:/temp/logger.log";
      logger = LogWriter.getLogWriter(fileName);
//     logger.log("First log!");
//     logger.log("第二个日志信息");
//     logger.log("Third log");
//     logger.log("第四个日志信息");
      String content="tableaA|device_number|13701010";
      StringBuffer sb=new StringBuffer();
      for(int i=0;i<1000000;i++){
        sb.append(content).append(i).append(";\n");
      }
      content=sb.toString();
      long startTime=System.currentTimeMillis();
      logger.log(content);
      long endTime=System.currentTimeMillis();
      System.out.println("总消耗时间："+(endTime-startTime));
      logger.close();
//     ReadFromFile.readFileByLines(fileName);
    } catch (LogException e) {
      e.printStackTrace();
    }
  }
}

package com.tydic.ESUtil; 

public class AychWriter extends Thread {
  private String content;
  public AychWriter(String content){
    this.content=content;
  }
  @Override
  public void run(){
    System.out.println("开始执行run()");
    LogWriter logger = null;
    String fileName = "d:/temp/logger.log";
    long startTime=System.currentTimeMillis();
    try {
      logger = LogWriter.getLogWriter(fileName);
      logger.log(this.content);
    } catch (LogException e1) {
      // TODO Auto-generated catch block
      e1.printStackTrace();
    } 

    long endTime=System.currentTimeMillis();
    System.out.println("总消耗时间："+(endTime-startTime));
  }
}

测试类：

package com.tydic.ESUtil; 

import java.io.FileWriter;
import java.io.IOException; 

import org.junit.Test; 

public class test_test {
  /**
   * 同步向指定文件尾部写入字符串
   */
public void testAppendMethodB(String fileName,String content) throws IOException{
    try {
      //打开一个写文件器，构造函数中的第二个参数true表示以追加形式写文件
      FileWriter writer = new FileWriter(fileName, true);
      writer.write(content);
      writer.close();
    } catch (IOException e) {
      e.printStackTrace();
    }
    } 

/**
 *调用上面同步写方法
 */
  @Test
  public void testWriteTOFile() throws IOException{
    String fileName = "d:\\test.txt";
    String content="tableaA|device_number|13701010";
    StringBuffer sb=new StringBuffer();
    for(int i=0;i<100000;i++){
      sb.append(content).append(i).append(";\n");
    }
    content=sb.toString();
    long startTime=System.currentTimeMillis();
    testAppendMethodB(fileName,content);
    long endTime=System.currentTimeMillis();
    System.out.println("总消耗时间："+(endTime-startTime));
  }
  /**
   * 异步调用写方法
   * @throws IOException
   * @throws InterruptedException
   */
  @Test
  public void testAsyncWriteTOFile() throws IOException, InterruptedException{
    String fileName = "d:\\test.txt";
    String content="tableaA|device_number|13701010";
    StringBuffer sb=new StringBuffer();
    for(int i=0;i<100000;i++){
      sb.append(content).append(i).append(";\n");
    }
    content=sb.toString();
    System.out.println("start write...");
    new AychWriter(content).start();
    System.out.println("write over...");
    Thread.sleep(30000); //重要，如果主线程挂了，调用线程也停止了
    System.out.println("main Thread over");
  } 

}

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