我正在构建一个监视文件更改的项目，当文件发生更改时，它会将文件的最后一行作为ID，并在添加ID后将ID上传到数据库，计数器开始某个时间X.下面是我的4个类，它们单独工作但我对如何使用线程感到困惑：
任何帮助都会很棒，如果我的编码很差，我会道歉，对所有这些都是新的!!
谢谢Jonny
文件观察者类。
import static java.nio.file.StandardWatchEventKinds.ENTRY_MODIFY;
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.nio.file.FileSystems;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.nio.file.WatchEvent;
import java.nio.file.WatchKey;
import java.nio.file.WatchService;
public class watcherClock implements Runnable{
static String clkID;
static boolean done = false;
public static void main(String[] args) throws IOException, InterruptedException {
checkFile();
if(!done){
}
System.out.println(clkID);
}
public static String dancerID(){
return clkID;
}
public static void checkFile() {
try {
WatchService watcher = FileSystems.getDefault().newWatchService();
Path dir = Paths.get("/home/jonathan/Desktop/");
dir.register(watcher, ENTRY_MODIFY);
System.out.println("Watch Service registered for dir: " + dir.getFileName());
while (!done) {
WatchKey key;
try {
key = watcher.take();
} catch (InterruptedException ex) {
return;
}
for (WatchEvent<?> event : key.pollEvents()) {
WatchEvent.Kind<?> kind = event.kind();
@SuppressWarnings("unchecked")
WatchEvent<Path> ev = (WatchEvent<Path>) event;
Path fileName = ev.context();
System.out.println(kind.name() + ": " + fileName);
if (kind == ENTRY_MODIFY &&
fileName.toString().equals("example.txt")) {
System.out.println("My source file has changed!!!");
String sCurrentLine = null;
try (BufferedReader br = new BufferedReader(new FileReader("/home/jonathan/Desktop/example.txt")))
{
while ((sCurrentLine = br.readLine()) != null) {
System.out.println(sCurrentLine);
clkID = sCurrentLine;
System.out.println(clkID);
}
} catch (IOException e) {
e.printStackTrace();
}
File inputFile = new File("/home/jonathan/Desktop/example.txt"); // Your file
File tempFile = new File("myTempFile.txt");// temp file
BufferedReader reader = new BufferedReader(new FileReader(inputFile));
BufferedWriter writer = new BufferedWriter(new FileWriter(tempFile));
String currentLine;
while((currentLine = reader.readLine()) != null) {
currentLine=("");
writer.write(currentLine);
}
writer.close();
reader.close();
boolean successful = tempFile.renameTo(inputFile);
System.out.println(successful);
done = true;
}
}
boolean valid = key.reset();
if (!valid) {
break;
}
}
} catch (IOException ex) {
System.err.println(ex);
}
}
@Override
public void run() {
// TODO Auto-generated method stub
checkFile();
}
}
计时器的计数器类。
import java.sql.Timestamp;
import java.util.Timer;
import java.util.TimerTask;
public class Counter implements Runnable{
private static TimerTask myTask = null;
public static void main(String[] args) {
Thread count = new Thread(new Counter());
count.start();
}
@Override
public void run() {
// TODO Auto-generated method stub
}
public static void CounterStart() {
Timer timer = new Timer("My Timer", false);
int count = 10;
System.out.println("LIGHTS ON");
myTask = new MyTimerTask(count, new Runnable() {
public void run() {
System.exit(0);
}
});
long delay = 1000L;
timer.scheduleAtFixedRate(myTask, delay, delay);
}
}
class MyTimerTask extends TimerTask {
private int count;
private Runnable doWhenDone;
public MyTimerTask(int count, Runnable doWhenDone) {
this.count = count;
this.doWhenDone = doWhenDone;
}
@Override
public void run() {
count--;
System.out.println("Count is: " + count);
if (count == 0) {
getTimeStamp();
System.out.println("LIGHTS OFF");
cancel();
doWhenDone.run();
}
}
private static void getTimeStamp() {
java.util.Date date= new java.util.Date();
System.out.println(new Timestamp(date.getTime()));
}
}
数据库连接类
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.Calendar;
import com.mysql.jdbc.PreparedStatement;
import com.mysql.jdbc.StatementImpl;
public class DbConn implements Runnable {
public static void connection() {
try {
Class.forName("com.mysql.jdbc.Driver");
System.out.println("worked");
} catch (ClassNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
public void connectionToMySql() {
watcherClock id = new watcherClock();
String host ="jdbc:mysql://localhost/test";
String username ="root";
String password ="password";
String dancerID = watcherClock.clkID;
//System.out.println(dancerID);
try {
Connection conn = DriverManager.getConnection(host, username, password);
System.out.println("Connected:");
// the mysql insert statement
String query = " insert into dancers (id)"
+ " values (?)";
// create the mysql insert preparedstatement
PreparedStatement preparedStmt = (PreparedStatement) conn.prepareStatement(query);
preparedStmt.setString (1, dancerID);
// execute the preparedstatement
preparedStmt.execute();
conn.close();
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
System.err.println("Got an exception!");
System.err.println(e.getMessage());
}
}
public static void main(String args []){
Thread thDB = new Thread(new DbConn());
thDB.start();
//connection();
}
@Override
public void run() {
// TODO Auto-generated method stub
connectionToMySql();
}
}
最后是我的主要课程
public class Main implements Runnable{
watcherClock wc = new watcherClock();
Counter c = new Counter();
public static void main(String args[]){
Thread th1 = new Thread(new watcherClock());
Thread th3 = new Thread(new Counter());
try {
th1.start();
th1.join();
th3.start();
th3.join();
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
@Override
public void run() {
// TODO Auto-generated method stub
}
}
答案 0 :(得分：0)
不是答案，但是，这没有任何意义：
th1.start();
th1.join();
它没有任何意义，因为main（）线程在th1线程运行的整个时间内什么都不做。
如果你在th1正在做的时候不想做任何其他事情，那为什么还要费心去创建线程呢？为什么不在main（）线程中完成工作呢？
th1.run();
拥有线程的全部意义在于，不同的线程可以同时执行不同的事情。
th1.start();
doSomethingElseWhileTh1ThreadIsRunning();
th1.join();