package cn.rt.util;
import java.io.IOException;
import java.io.InputStream;
import java.lang.reflect.InvocationTargetException;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.ArrayList;
import java.util.List;
import java.util.Properties;
import org.apache.commons.beanutils.BeanUtils;
/**
* jdbc工具类
*/
public final class JdbcUtils {
private static String driver;
private static String url;
private static String user;
private static String password;
static {
try {
Properties ps = new Properties();
InputStream instream = jdbcUtils.class.getResourceAsStream("/jdbc.properties");
//jdbc.properties中包含连接数据库的信息
ps.load(instream); // 加载属性文件
driver = ps.getProperty("driver");
url = ps.getProperty("url");
user = ps.getProperty("user");
password = ps.getProperty("password");
} catch (IOException e) {
e.printStackTrace();
}
try {
Class.forName(driver);// 加载驱动
} catch (ClassNotFoundException e) {
e.printStackTrace();
}
}
/**
* 获取数据库连接对象
*
* @return 连接对象
*/
public static Connection getConn() {
Connection conn = null;
try {
conn = DriverManager.getConnection(url, user, password);
} catch (SQLException e) {
e.printStackTrace();
}
return conn;
}
/**
* 查询多个对象
*
* @param clazz
* 要查询的对象类型
* @param sql
* 查询语句
* @return 查询出的对象组成的集合
*/
public static List getList(Class clazz, String sql) {
List list = new ArrayList();
Connection conn = getConn();
PreparedStatement st = null;
ResultSet rs = null;
try {
st = conn.prepareStatement(sql);
rs = st.executeQuery();// 执行查询
ResultSetMetaData metaData = rs.getMetaData();
while (rs.next()) { // 遍历查询出的每个结果 并封装对象
Object obj = clazz.newInstance();
for (int i = 1; i <= metaData.getColumnCount(); i++) {
BeanUtils.copyProperty(obj, metaData.getColumnName(i), rs.getObject(i));
}
list.add(obj); // 将对象添加到集合
}
} catch (SQLException e) {
e.printStackTrace();
} catch (InstantiationException e) {
e.printStackTrace();
} catch (IllegalAccessException e) {
e.printStackTrace();
} catch (InvocationTargetException e) {
e.printStackTrace();
} finally {// 关闭
close(rs, st, conn);
}
return list;
}
/**
* 根据标识查询出唯一一个对象
*
* @param clazz
* 要查询的类型
* @param sql
* 查询语句
* @return 查询出的对象 where id=?
*/
public static Object getObjectById(Class clazz, String sql,Object id) {
Connection conn = getConn();
PreparedStatement st = null;
ResultSet rs = null;
Object obj = null;
try {
st = conn.prepareStatement(sql);
st.setObject(1,id);
rs = st.executeQuery();
ResultSetMetaData metaData = rs.getMetaData();
if (rs.next()) { // 如果可以查询出数据
obj = clazz.newInstance(); // 实例化对象
for (int i = 1; i <= metaData.getColumnCount(); i++) {
// 使用工具类设置各个列的值到对象 注意：列名和属性名要一致
BeanUtils.copyProperty(obj, metaData.getColumnName(i), rs.getObject(i));
}
}
} catch (InstantiationException e) {
e.printStackTrace();
} catch (IllegalAccessException e) {
e.printStackTrace();
} catch (SQLException e) {
e.printStackTrace();
} catch (InvocationTargetException e) {
e.printStackTrace();
} finally {
close(rs, st, conn);
}
return obj;
}
/**
* 获取行数
*
* @param sql
* 查询行数的sql语句
* @return 查询的结果
*/
public static int getListCount(String sql) {
int result = 0;
Connection conn = getConn();
PreparedStatement st = null;
ResultSet rs = null;
try {
st = conn.prepareStatement(sql);
rs = st.executeQuery();// 执行查询
ResultSetMetaData metaData = rs.getMetaData();
if (rs.next()) {
result = rs.getInt(1);// 记录查询出的结果
}
} catch (SQLException e) {
e.printStackTrace();
} finally {
close(rs, st, conn);
}
return result;
}
/**
* 执行增删改的方法
*
* @param sql
* 增删改的语句
* @param ps
* 动态数组 语句中的参数
* @return 影响的行数
*/
public static int executeSQL(String sql, Object... ps) {
Connection conn = getConn();
int executeUpdate = 0;
PreparedStatement prepareStatement = null;
try {
prepareStatement = conn.prepareStatement(sql);
for (int i = 1; i <= ps.length; i++) {// 设置参数
prepareStatement.setObject(i, ps[i - 1]);
}
executeUpdate = prepareStatement.executeUpdate();
} catch (SQLException e) {
e.printStackTrace();
} finally {
close(null, prepareStatement, conn);
}
return executeUpdate;
}
/**
* 事务管理
*
* @param sqlArray
* 需要在同一个事务中处理的Sql语句
*/
public static void executeTran(String... sqlArray) {
Connection conn = getConn();
PreparedStatement prepareStatement = null;
try {
conn.setAutoCommit(false);// 关闭自动提交
if (sqlArray.length > 0) {
for (String sql : sqlArray) {
prepareStatement = conn.prepareStatement(sql);
prepareStatement.execute();
}
}
conn.commit();// 所有操作执行结束 提交事务
conn.setAutoCommit(true);// 打开自动事务提交
} catch (SQLException e) {// 如果出现异常
try {
conn.rollback();// 回滚
} catch (SQLException e1) {
e1.printStackTrace();
}
e.printStackTrace();
} finally {
close(null, prepareStatement, conn);
}
}
/**
*关闭资源
* @param rs 结果集
* @param st 命令行对象
* @param conn 数据库连接
*/
private static void close(ResultSet rs, Statement st, Connection conn) {
try {
if (rs != null) {
rs.close();
}
if (st != null) {
st.close();
}
if (conn != null) {
conn.close();
}
} catch (SQLException e) {
e.printStackTrace();
}
}
}
jdbc.properties文件内容：
driver=com.mysql.jdbc.Driver ///连接到MySQL的数据库
url=jdbc\:mysql\://127.0.0.1\:3306/students //连接到本地students数据库
user=root //连接数据库用户名
password=123456 //连接数据库密码