基于JAVA线程池读取单个SQL数据库表

任务：基于线程池来操作MySQL，测试单台机器读写MySQL单表的效率。

思路：创建一个大小合适的线程池，让每个线程分别连接到数据库并进行读取输出操作。

• 连接到数据库
  

import java.sql.DriverManager;
import java.sql.SQLException;

import com.mysql.jdbc.Statement;

public class TEXT {

}

class MySQLOpen {
	private Connection con = null;
	private static String driver = "com.mysql.jdbc.Driver";
	private static String url = "jdbc:mysql://localhost:3306/phpmyadmin";
	private static String username = "root";
	private static String password = "root";
	private static Statement NULL = null;

	public void MysqlOpen() {
		try {
			Class.forName(driver);  //加载驱动类
			con = DriverManager.getConnection(url, username, password);  //连接数据库
			if (!con.isClosed()) 
				System.out.println("***数据库成功连接***");
		} catch (ClassNotFoundException e) {
			System.out.println("找不到驱动程序类，加载驱动失败");
			e.printStackTrace();
		} catch (SQLException e) {
			System.out.println("数据库连接失败");
			e.printStackTrace();
		}
	}
}

• 利用statement类中的executeQuery方法操作MySQL

Statement state = (Statement) con.createStatement();
ResultSet sql = state.executeQuery("select * from user where id between 1 and 5");

• 利用sql.next()循环遍历取出想要的数据

while (sql.next()) {
	String id = sql.getString(1);
	String username = sql.getString(3);
	String text = sql.getString(6);
        System.out.println(id+"\t"+username+"\t"+text);
}

以上就已经实现了主线程访问并操作数据库的相应内容。

• 创建线程池，设置好相应参数

ThreadPoolExecutor executor = new ThreadPoolExecutor(5, 15, 200, TimeUnit.MILLISECONDS,
				new ArrayBlockingQueue(5));

利用for循环去创建线程即可。

• 计算效率

long start = System.currentTimeMillis();
long end = System.currentTimeMillis();
System.out.println("平均每秒可输出: " + 100000 / (end - start) + " 条");

• 要注意主线程创建好其他线程后就继续往下执行了，所以要有一个判断其他线程是否结束的语句

while (true) {
		if (executor.getActiveCount() == 0)
			break;
		}

• 可以利用Thread.activeCount()看一还有多少 活跃的线程。

System.out.println("activeCountMain1 : " + Thread.activeCount());

主要的思路就再上面，现在贴出整理好的代码：

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;

import com.mysql.jdbc.Statement;

public class Main {

	public static void main(String[] args) {
		ThreadPoolExecutor executor = new ThreadPoolExecutor(5, 15, 200, TimeUnit.MILLISECONDS,
				new ArrayBlockingQueue(5));
		long start = System.currentTimeMillis();
		System.out.println("activeCountMain1 : " + Thread.activeCount());
		for (int i = 1; i <= 20; i++) {
			MySQL mysql = new MySQL(i);
			executor.execute(mysql);
			System.out.println("线程池中线程数目：" + executor.getPoolSize() + "，队列中等待执行的任务数目：" + executor.getQueue().size()
					+ "，已执行玩别的任务数目：" + executor.getCompletedTaskCount());
		}
		executor.shutdown();
		while (true) {
			if (executor.getActiveCount() == 0)
				break;
		}
		System.out.println("activeCountMain2 : " + Thread.activeCount());
		long end = System.currentTimeMillis();
		System.out.println("平均每秒可输出: " + 100000 / (end - start) + " 条");
	}
}

class MySQL implements Runnable {
	private Connection con = null;
	private static String driver = "com.mysql.jdbc.Driver";
	private static String url = "jdbc:mysql://localhost:3306/phpmyadmin";
	private static String username = "root";
	private static String password = "root";
	private static Statement NULL = null;
	private final int taskNum;

	public MySQL(int taskNum) {
		this.taskNum = taskNum;
	}

	public Statement MysqlOpen() {
		try {
			Class.forName(driver); //加载驱动类
			con = DriverManager.getConnection(url, username, password); //连接数据库
			if (!con.isClosed())
				System.out.println("***数据库成功连接***");
			Statement state = (Statement) con.createStatement();
			return state;
		} catch (ClassNotFoundException e) {
			System.out.println("找不到驱动程序类，加载驱动失败");
			e.printStackTrace();
		} catch (SQLException e) {
			System.out.println("数据库连接失败");
			e.printStackTrace();
		}
		return NULL;
	}
	@Override
	public void run() {
		readMySQL();
	}

	public void readMySQL() {
		ResultSet sql = null;
		Statement state = MysqlOpen();
		try {
			sql = state.executeQuery("select * from sina_user_weibos_1386622641 where id between "
					+ ((taskNum - 1) * 5000) + " and " + (taskNum * 5000));
			System.out.println("---------task " + taskNum + "正在执行---------");
			while (sql.next()) {
				String id = sql.getString(1);
				String wid = sql.getString(2);
				String username = sql.getString(3);
				String repostscount = sql.getString(4);
				String commentscount = sql.getString(5);
				String text = sql.getString(6);
				String createat = sql.getString(7);
				String source = sql.getString(15);
				String lasttime = sql.getString(17);
				System.out.println(id + "\t" + wid + "\t" + username + "\t" + repostscount + "\t" + commentscount + "\t"
						+ text + "\t" + createat + "\t" + source + "\t" + lasttime);
			}
		} catch (SQLException e) {
			e.printStackTrace();
		} finally {
			try {
				sql.close();
				state.close();
				con.close();
			} catch (Exception e) {
				e.printStackTrace();
			}
		}
		System.out.println("---------task " + taskNum + "执行完毕---------");
	}
}