使用鏈接池和緩存機制，處理鏈接數據庫操做

由於最近在研究kettle，用到參數轉換的功能，領導讓用java代碼寫處理轉換的功能，而後用kettle調用，發現若是java代碼不作優化，4萬多的數據，要6分鐘左右才能跑完，如下是我代碼的優化處理，處理完後，4萬數據，11秒左右就抽取和處理完畢。由於我這如今沒什麼複雜的處理業務邏輯，你們能夠參考看看

1.首先，建立轉換的實體類

package entity;

public class Comparison {
	private String id;
	private String codetype;
	private String codename;
	private String newcode;
	private String newcodename;
	private String oldcode;
	private String oldcodename;
	private String filename;
	private String remark;
	public String getId() {
		return id;
	}
	public void setId(String id) {
		this.id = id;
	}
	public String getCodetype() {
		return codetype;
	}
	public void setCodetype(String codetype) {
		this.codetype = codetype;
	}
	public String getCodename() {
		return codename;
	}
	public void setCodename(String codename) {
		this.codename = codename;
	}
	public String getNewcode() {
		return newcode;
	}
	public void setNewcode(String newcode) {
		this.newcode = newcode;
	}
	public String getNewcodename() {
		return newcodename;
	}
	public void setNewcodename(String newcodename) {
		this.newcodename = newcodename;
	}
	public String getOldcode() {
		return oldcode;
	}
	public void setOldcode(String oldcode) {
		this.oldcode = oldcode;
	}
	public String getOldcodename() {
		return oldcodename;
	}
	public void setOldcodename(String oldcodename) {
		this.oldcodename = oldcodename;
	}
	public String getFilename() {
		return filename;
	}
	public void setFilename(String filename) {
		this.filename = filename;
	}
	public String getRemark() {
		return remark;
	}
	public void setRemark(String remark) {
		this.remark = remark;
	}
	
	

}

 2，建立鏈接池和數據庫的鏈接

package util;



import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.util.Vector;

public class JdbcUtil {
	private static final Vector<Connection> pool = new Vector<Connection>();
	private static final int MAX_SIZE = 50;
	private static final int MIN_SIZE = 10;
	private static Connection createConnection(){
		Connection conn = null;
		try {
			Class.forName("com.mysql.jdbc.Driver");
			conn = DriverManager.getConnection(
					"jdbc:mysql://192.168.4.143:3306/loan2","root","123456");
		} catch (ClassNotFoundException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		return conn;
	}

	static {
		for (int i = 0; i < MIN_SIZE; i++) {
			pool.add(createConnection());
		}
	}

	public static synchronized Connection getConnection() {
		Connection conn = null;
		//conn = createConnection();
		if (pool.isEmpty()) {
			conn = createConnection();
		} else {
			int last_idx = pool.size() - 1;
			conn = (Connection) pool.get(last_idx);
			pool.remove(conn);
		}
		return conn;
	}

	public static synchronized void close(Connection conn) {
		if (pool.size() < MAX_SIZE) {
			pool.add(conn);
		} else {
			try {
				conn.close();
			} catch (SQLException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
		}

	}
	
}

 3，使用緩存，把數據庫讀到的數據放到緩存裏

package transform;

import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.HashMap;
import java.util.Map;
import java.util.concurrent.locks.Lock;

import util.JdbcUtil;

public class trans {
	public static void main(String[] args) {
		trans trans = new trans();
		
			String code = trans.transCode("SEXCODE", "");
		
		}
	

	static int num;
	static Map<String, Map<String, String>> paramTypeKeyValueMap = new HashMap<String, Map<String, String>>();
	static Lock lock = new java.util.concurrent.locks.ReentrantLock();//同步，須要手動釋放資源

	public String transCode(String codetype, String oldcode) {

		num++;
		Thread.currentThread().setName("zhengxin" + num);
		if (oldcode == null) {
			return null;
		}
		Map<String, String> keyValue = paramTypeKeyValueMap.get(codetype);
		if (keyValue == null) {
			try {
				lock.lock();//獲取鎖
				keyValue = paramTypeKeyValueMap.get(codetype);
				if (keyValue == null) {
					keyValue = load2Cache(codetype);
				}
			} finally {
				lock.unlock();// 釋放鎖
			}
		}
		if (keyValue.get(oldcode) != null) {
			return keyValue.get(oldcode);
		} else {
			return oldcode;
		}

	}

	private Map<String, String> load2Cache(String codetype) {
		Map<String, String> keyValue = new HashMap<String, String>();
		Connection conn = JdbcUtil.getConnection();
		Statement stmt = null;
		try {
			stmt = conn.createStatement();
			String sql = "select newcode,oldcode from comparison where codetype='" + codetype + "'";

			ResultSet rs = stmt.executeQuery(sql);
			paramTypeKeyValueMap.put(codetype, keyValue);
			while (rs.next()) {
				String newcode = rs.getString(1);
				String oldc = rs.getString(2);
				if (oldc == null) {
					continue;
				}
				String[] codes = oldc.split(",");
				for (String s : codes) {
					if (s == null) {
						continue;
					}
					keyValue.put(s, newcode);
				}
			}

		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} finally {
			if (stmt != null) {
				try {
					stmt.close();
				} catch (Throwable e) {
					// TODO Auto-generated catch block
					e.printStackTrace();
				}
			}
			if (conn != null) {
				JdbcUtil.close(conn);
			}
		}
		return keyValue;
	}
}