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標簽   public static final String LOGFILE_TAG_NAME = "logfile";      // 默認的日志文件的路徑和文件名稱   private final String DEFAULT_LOG_FILE_NAME = "./logtext.log";   // 該類的唯一的實例   private static LogWriter logWriter;   // 文件輸出流   private PrintWriter writer;    // 日志文件名   private String logFileName;    /**    * 默認構造函數    */   private LogWriter() throws LogException{     this.init();   }   private LogWriter(String fileName) throws LogException{     this.logFileName = fileName;     this.init();   }   /**    * 獲取LogWriter的唯一實例。    * @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;   }    /**    * 往日志文件中寫一條日志信息    * 為了防止多線程同時操作(寫)日志文件，造成文件”死鎖”。使用synchronized關鍵字    * @param logMsg  日志消息    */   public synchronized void log(String logMsg) {     this.writer.println(new java.util.Date() + ": " + logMsg);   }   /**    * 往日志文件中寫一條異常信息    * 使用synchronized關鍵字。    * @param ex  待寫入的異常    */   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{     //如果用戶沒有在參數中指定日志文件名，則從配置文件中獲取。     if (this.logFileName == null){       this.logFileName = this.getLogFileNameFromConfigFile();       //如果配置文件不存在或者也沒有指定日志文件名，則用默認的日志文件名。       if (this.logFileName == null){         this.logFileName = DEFAULT_LOG_FILE_NAME;       }     }     File logFile = new File(this.logFileName);     try {       // 其中的FileWriter()中的第二個參數的含義是:是否在文件中追加內容       // PrintWriter()中的第二個參數的含義是：自動將數據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 = "無法打開日志文件:" + logFile.getAbsolutePath();       // System.out.println(errmsg);       throw new LogException(errmsg, ex);     }   }   /**    * 從配置文件中取日志文件名    * @return    */   private String getLogFileNameFromConfigFile() {      try {        Properties pro = new Properties();        //在類的當前位置,查找屬性配置文件log.properties        InputStream fin = getClass().getResourceAsStream(LOG_CONFIGFILE_NAME);        if (fin != null){         pro.load(fin);//載入配置文件         fin.close();          return pro.getProperty(LOGFILE_TAG_NAME);       } else {         System.err.println("無法打開屬性配置文件: log.properties" );        }     }catch (IOException ex) {        System.err.println("無法打開屬性配置文件: log.properties" );      }     return null;   }   //關閉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("第二個日志信息"); //     logger.log("Third log"); //     logger.log("第四個日志信息");       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("總消耗時間："+(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("開始執行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("總消耗時間："+(endTime-startTime));   } } 

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寫入字符串    */ public void testAppendMethodB(String fileName,String content) throws IOException{     try {       //打開一個寫文件器，構造函數中的第二個參數true表示以追加形式寫文件       FileWriter writer = new FileWriter(fileName, true);       writer.write(content);       writer.close();     } catch (IOException e) {       e.printStackTrace();     }     }  /**  *調用上面同步寫方法  */   @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("總消耗時間："+(endTime-startTime));   }   /**    * 異步調用寫方法    * @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，如果主線程掛了，調用線程也停止了     System.out.println("main Thread over");   }    }