DBUtil数据库操作工具类

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

/**
* 数据库操作帮助类
* @author wpj_service
*
*/
public class DBUtil {

private static Connection getConnection(){
Connection conn = null;
try {
//获取数据库链接，可以使用JDBC或者连接池
conn = C3P0ConnentionProvider.getConnection();
} catch (SQLException e) {
LoggerUtil.insertLog("数据库连接出错");
// TODO Auto-generated catch block
e.printStackTrace();
}
return conn;
}

/**
* 关闭所有连接
*/
@SuppressWarnings("null")
private static boolean closeAll(ResultSet rst,PreparedStatement pst, Connection conn) {
// TODO 关闭所有连接
boolean flag = false;
try {
if(rst!=null){
rst.close();
}
if(pst!=null||!pst.isClosed()){
pst.close();
}
if(conn!=null||!conn.isClosed()){
conn.close();
flag = true;
}
} catch (SQLException e) {
e.printStackTrace();
}
return flag;
}

/**
* 更新数据库操作
* @param sql
* @return
*/
public static int update(String sql){
int i = 0 ;
Connection conn = getConnection();
ResultSet rs = null;
PreparedStatement pst = null;
try {
conn = C3P0ConnentionProvider.getConnection();
pst = conn.prepareStatement(sql);
i = pst.executeUpdate();
} catch (SQLException e) {
LoggerUtil.insertLogError("数据库连接错误");
// TODO Auto-generated catch block
e.printStackTrace();
}finally{
LoggerUtil.insertLogError("更新数据库："+i);
closeAll(rs, pst, conn);
}
return  i ;
}

/**
* 查询数据
* @return
*/
public static List<Map<String,Object>> query(String sql){
List<Map<String,Object>> list = null;
Connection conn = getConnection();
ResultSet rs = null;
PreparedStatement pst = null;
try {
conn = C3P0ConnentionProvider.getConnection();
pst = conn.prepareStatement(sql);
rs = pst.executeQuery();
list = getResultList(rs);
} catch (SQLException e) {
// TODO Auto-generated catch block
LoggerUtil.insertLogError("数据库连接错误");
e.printStackTrace();
}finally{
LoggerUtil.insertLog("查询数据库");
closeAll(rs, pst, conn);
}

return list;
}

/*
* 解析ResultSet 表列数据
*/
private static Map<String,Object> getResultMap(ResultSet rs) throws SQLException{
Map<String, Object> rawMap = new HashMap<String, Object>();
ResultSetMetaData  rsmd = rs.getMetaData(); // 表对象信息
int count = rsmd.getColumnCount();          // 列数
// 遍历之前需要调用 next()方法
for (int i = 1; i <= count; i++) {
String key = rsmd.getColumnLabel(i);
Object value = rs.getObject(key);
rawMap.put(key, value);
}
return rawMap;
}

/*
* 解析ResultSet 表数据
*/
private static List<Map<String,Object>> getResultList(ResultSet rs) throws SQLException{
List<Map<String,Object>> rawList = new ArrayList<Map<String,Object>>();
while(rs.next()){
Map<String, Object> rawMap = getResultMap(rs);
rawList.add(rawMap);
}
return rawList;
}
}