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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();
}
}
}
</div>
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));
}
}
</div>
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");
}
}
</div>
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