写JDBC应用的人常常为关闭资源而头痛不已,这些代码枯燥无味,如何才能用简单的代码进行关闭呢,下面我写了一个方法,可以解除你的痛苦:
/**
* 关闭所有可关闭资源
*
* @param objs 可关闭的资源对象有Connection、Statement、ResultSet,别的类型资源自动忽略
*/
public static void closeAll(Object... objs) {
for (Object obj : objs) {
if (obj instanceof Connection) close((Connection) obj);
if (obj instanceof Statement) close((Statement) obj);
if (obj instanceof ResultSet) close((ResultSet) obj);
}
}
这个方法,带了“...”参数,这个实际上是Java5中的可变参数方法。可以不论顺序,不论个数,调用时候直接关闭想要关闭的资源对象就ok了。例如:
catch (SQLException e) {
e.printStackTrace();
} finally {
DBTools.closeAll(stmt, pstmt1, pstmt2, conn);
}
下面给出这个类完整的写法:
package com.lavasoft.ibatistools.common;
import com.lavasoft.ibatistools.bean.Table;
import com.lavasoft.ibatistools.metadata.DataSourceMetaData;
import com.lavasoft.ibatistools.metadata.MySQLDataSourceMetaData;
import java.io.IOException;
import java.io.InputStream;
import java.sql.*;
import java.util.List;
import java.util.Properties;
/**
* 简单的Java数据库连接和关闭工具类
*
* @author leizhimin 11-12-20 下午4:32
*/
public class DBTools {
private static String driverClassName, url, user, password;
static {
init();
}
private static void init() {
InputStream in = DBTools.class.getResourceAsStream("/com/lavasoft/ibatistools/jdbc.properties");
Properties preps = new Properties();
try {
preps.load(in);
driverClassName = preps.getProperty("jdbc.driver");
url = preps.getProperty("jdbc.url");
user = preps.getProperty("jdbc.username");
password = preps.getProperty("jdbc.password");
} catch (IOException e) {
e.printStackTrace();
}
}
/**
* 创建一个JDBC连接
*
* @return 一个JDBC连接
*/
public static Connection makeConnection() {
Connection conn = null;
try {
Class.forName(driverClassName);
conn = DriverManager.getConnection(url, user, password);
} catch (ClassNotFoundException e) {
e.printStackTrace();
} catch (SQLException e) {
e.printStackTrace();
}
return conn;
}
public static void close(Connection conn) {
if (conn != null)
try {
conn.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
public static void close(ResultSet rs) {
if (rs != null)
try {
rs.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
public static void close(Statement stmt) {
if (stmt != null)
try {
stmt.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
/**
* 关闭所有可关闭资源
*
* @param objs 可关闭的资源对象有Connection、Statement、ResultSet,别的类型资源自动忽略
*/
public static void closeAll(Object... objs) {
for (Object obj : objs) {
if (obj instanceof Connection) close((Connection) obj);
if (obj instanceof Statement) close((Statement) obj);
if (obj instanceof ResultSet) close((ResultSet) obj);
}
}
public static void main(String[] args) {
DataSourceMetaData dbmd = MySQLDataSourceMetaData.instatnce();
List<Table> tableList = dbmd.getAllTableMetaData(DBTools.makeConnection());
for (Table table : tableList) {
System.out.println(table);
}
}
}