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<runnable>(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<runnable>(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---------");
 }
}

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持。