使用连接池和缓存机制，处理连接数据库操作

因为最近在研究kettle，用到参数转换的功能，领导让用java代码写处理转换的功能，然后用kettle调用，发现如果java代码不做优化，4万多的数据，要6分钟左右才能跑完，以下是我代码的优化处理，处理完后，4万数据，11秒左右就抽取和处理完毕。因为我这现在没什么复杂的处理业务逻辑，大家可以参考看看

1.首先，创建转换的实体类

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，创建连接池和数据库的连接

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，使用缓存，把数据库读到的数据放到缓存里

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，需要手动释放资源

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();//获取锁
keyValue = paramTypeKeyValueMap.get(codetype);
if (keyValue == null) {
keyValue = load2Cache(codetype);
}
} finally {
lock.unlock();// 释放锁
}
}
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;
}
}