java多线程向数据库写入数据

任务: 从sqlserver中将一个表A（约16W条数据）导到mysql中对应的一个表B中。

思路：分段获取A表中的数据后，用多个线程同时向B表中写入。

关键代码

//将数据库中的数据条数分段
	public void division(){
		//获取要导入的总的数据条数
		String sql3="SELECT  count(*)  FROM [CMD].[dbo].[mycopy1]";
		try {
			pss=cons.prepareStatement(sql3);
			rss=pss.executeQuery();

			while(rss.next()){
			System.out.println("总记录条数:"+rss.getInt(1));
			sum=rss.getInt(1);
			}
			//每30000条记录作为一个分割点
			if(sum>=30000){
				n=sum/30000;
				residue=sum%30000;
			}else{
				residue=sum;
			}

			System.out.println(n+"  "+residue);

		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}

	}
	

线程类

public MyThread(int start,int end) {
		this.end=end;
    	this.start=start;
		System.out.println("处理掉余数");
		  try {

	        	System.out.println("--------"+Thread.currentThread().getName()+"------------");
				Class.forName(SQLSERVERDRIVER);
				System.out.println("加载sqlserver驱动...");
				cons = DriverManager.getConnection(CONTENTS,UNS,UPS);
				stas = cons.createStatement();
				System.out.println("连接SQLServer数据库成功！！");

				System.out.println("加载mysql驱动.....");
				Class.forName(MYSQLDRIVER);
				con = DriverManager.getConnection(CONTENT,UN,UP);
				sta = con.createStatement();
				// 关闭事务自动提交
				con.setAutoCommit(false);
				System.out.println("连接mysql数据库成功！！");

			} catch (Exception e) {
				e.printStackTrace();
			}
		// TODO Auto-generated constructor stub
	}

	public ArrayList<Member> getAll(){
		Member member;
		String sql1="select * from (select row_number() over (order by pmcode) as rowNum,*" +
				" from [CMD].[dbo].[mycopy1]) as t where rowNum between "+start+" and "+end;
		try {
			System.out.println("正在获取数据...");
			allmembers=new ArrayList();
			rss=stas.executeQuery(sql1);
			while(rss.next()){
				member=new Member();
				member.setAddress1(rss.getString("address1"));
				member.setBnpoints(rss.getString("bnpoints"));
				member.setDbno(rss.getString("dbno"));
				member.setExpiry(rss.getString("expiry"));
				member.setHispoints(rss.getString("hispoints"));
				member.setKypoints(rss.getString("kypoints"));
				member.setLevels(rss.getString("levels"));
				member.setNames(rss.getString("names"));
				member.setPmcode(rss.getString("pmcode"));
				member.setRemark(rss.getString("remark"));
				member.setSex(rss.getString("sex"));
				member.setTelephone(rss.getString("telephone"));
				member.setWxno(rss.getString("wxno"));
				member.setPmdate(rss.getString("pmdate"));
				allmembers.add(member);
			//	System.out.println(member.getNames());
			}
			System.out.println("成功获取sqlserver数据库数据！");
			return allmembers;

		} catch (SQLException e) {
			// TODO Auto-generated catch block
			System.out.println("获取sqlserver数据库数据发送异常！");
			e.printStackTrace();
		}
		try {
			rss.close();
			stas.close();
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		return null;
	}

	public void inputAll(ArrayList<Member> allmembers){
		System.out.println("开始向mysql中写入");
		String sql2="insert into test.mycopy2 values (?,?,?,?,?,?,?,?,?,?,?,?,?,?)";
		try {
			ps=con.prepareStatement(sql2);
			System.out.println("-------------------------等待写入数据条数: "+allmembers.size());
			for(int i=0;i<allmembers.size();i++){
				ps.setString(1, allmembers.get(i).getPmcode());
				ps.setString(2, allmembers.get(i).getNames());
				//System.out.println(allmembers.get(i).getNames());
				ps.setString(3, allmembers.get(i).getSex());
				ps.setString(4, allmembers.get(i).getTelephone());
				ps.setString(5, allmembers.get(i).getAddress1());
				ps.setString(6, allmembers.get(i).getPmdate());
				ps.setString(7, allmembers.get(i).getExpiry());
				ps.setString(8, allmembers.get(i).getLevels());
				ps.setString(9, allmembers.get(i).getDbno());
				ps.setString(10, allmembers.get(i).getHispoints());
				ps.setString(11, allmembers.get(i).getBnpoints());
				ps.setString(12, allmembers.get(i).getKypoints());
				ps.setString(13, allmembers.get(i).getWxno());
				ps.setString(14, allmembers.get(i).getRemark());
				//插入命令列表
				//ps.addBatch();
				ps.executeUpdate();
			}
			//ps.executeBatch();
			con.commit();

			ps.close();
			con.close();
			this.flag=false;
			System.out.println(Thread.currentThread().getName()+"--->OK");
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			System.out.println("向mysql中更新数据时发生异常！");
			e.printStackTrace();
		}
	}

	@Override
	public void run() {
		// TODO Auto-generated method stub

		while(true&&flag){
			this.inputAll(getAll());
		}
	}

测试类：

public class Test1 {
		DbManager dm=null;
		MyThread my1=null;
	public Test1(){
		dm=new DbManager();
		System.out.println(dm.n+"----"+dm.residue);

	 if(dm.n<1){//数据条数小于30000单线程处理
			my1=new MyThread(1,dm.sum);
			my1.start=1;
			my1.end=dm.residue;
			Thread t1=new Thread(my1);
	    	t1.start();
		}else{//大于30000时

    	//起n个线程 每个处理30000条数据
		for (int i = 1; i <=dm.n; i++) {
				new Thread(new MyThread(i)).start();
				try {
					Thread.sleep(1);
				} catch (InterruptedException e) {
					// TODO Auto-generated catch block
					e.printStackTrace();
				}
			}
		//处理掉余数
		my1=new MyThread(dm.n*30000+1,dm.sum);
		Thread t1=new Thread(my1);
    	t1.start();
		}
	}
	public static void main(String[] args) {
		//new Test1();
		//迁移完数据，自动关机
		 try {
			Runtime.getRuntime().exec("cmd  /c Shutdown -t 10");
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}	

经过多次测试：从sqlserver中读取16w条数据并写入mysql，耗时15min左右。

开始会报错： java heap space

解决方案：（myeclipse）window->Preferences->Java->Installed JREs，选择当前的JRE，然后edit它；在新窗口里设置Default VM Arguments为 -Xms512M -Xmx512M即可
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