JDBC工具类
1、log4j.properties
在src目录下创建log4j.properties文件
内容如下：
# DEBUG设置输出日志级别，由于为DEBUG，所以ERROR、WARN和INFO 级别日志信息也会显示出来
log4j.rootLogger=DEBUG,Console,RollingFile
#将日志信息输出到控制台
log4j.appender.Console=org.apache.log4j.ConsoleAppender
log4j.appender.Console.layout=org.apache.log4j.PatternLayout
log4j.appender.Console.layout.ConversionPattern= [%-5p]-[%d{yyyy-MM-dd HH:mm:ss}] -%l -%m%n
#将日志信息输出到操作系统D盘根目录下的log.log文件中
log4j.appender.RollingFile=org.apache.log4j.DailyRollingFileAppender
log4j.appender.RollingFile.File=D://log.log
log4j.appender.RollingFile.layout=org.apache.log4j.PatternLayout
log4j.appender.RollingFile.layout.ConversionPattern=%d [%t] %-5p %-40.40c %X{traceId}-%m%n
再次在src根目录下创建db.properties（名字不固定）
其内容为连接信息,修改时只需要修改等式右边的内容，用户名、密码以及URL
db.username=root
db.password=root
db.url=jdbc:mysql://localhost:3306/date_base?serverTimezone=UTC
创建读取连接信息工具：PropertiesTool
import java.io.IOException;
import java.io.InputStream;
import java.util.Properties;
public class PropertiesTool {
private static Properties properties = new Properties();
static {
InputStream inputStream = PropertiesTool.class.getClassLoader().getResourceAsStream("db.properties");//将db.properties变为javaIO流对象
try {
properties.load(inputStream);
} catch (IOException e) {
e.printStackTrace();
}
}
public static String getValue(String key){
return properties.getProperty(key);
}
}
查询方法抽象类 IRowMapper：
import java.sql.ResultSet;
public interface IRowMapper {
void rowMapper(ResultSet resultSet);
}
连接代码：Linked
import com.zzu.tool.PropertiesTool;
import org.apache.log4j.Logger;
import java.sql.*;
public class Linked {
private static Logger logger = Logger.getLogger(Linked.class);
//更新数据
public static boolean update(String sql,Object ...params){
Connection connection = null;
PreparedStatement prepareStatement =null;
try {
connection = getConnection();
prepareStatement = connection.prepareStatement(sql);
for (int i = 0; i < params.length; i++) {
prepareStatement.setObject(i + 1, params[i]);
}
if (prepareStatement.executeUpdate()>0){
return true;
}else return false;
}catch (SQLException e) {
logger.debug(e.getMessage(),e);
} finally {
close(prepareStatement,connection);
}
return false;
}
/* public static void login(String sql) {
Connection connection = null;
PreparedStatement pstmt = null;
ResultSet resultSet = null;
try {
*//*Class.forName("com.mysql.jdbc.Driver");
connection = DriverManager.getConnection("jdbc:mysql://localhost:3306/date_base?serverTimezone=UTC", "root", "root");*//*
connection = getConnection();
System.out.println("连接成功");
*//*String sql = "select id,name,mobile,address from test";*//*
Statement statement = connection.createStatement();
ResultSet re = statement.executeQuery(sql);
if (re.next()) {
String id = re.getString("id");
String name = re.getString("name");
String mobile = re.getString("mobile");
String address = re.getString("address");
System.out.println(id + "," + name + "," + mobile + "," + address);
}
} catch ( SQLException e) {
logger.debug(e.getMessage(),e);
} finally {
//7.释放资源
if (resultSet != null) {
try {
resultSet.close();
} catch (SQLException e) {
logger.debug(e.getMessage(),e);
}
}
//避免空指针异常
if (pstmt != null) {
try {
pstmt.close();
} catch (SQLException e) {
logger.debug(e.getMessage(),e);
}
}
if (connection != null) {
try {
connection.close();
} catch (SQLException e) {
logger.debug(e.getMessage(),e);
}
}
}
}*/
//查询封装，借助实现类
public static void select(String sql, IRowMapper rowMapper) {//接口无法创建对象，所以rowMapper参数一定指向IRowMapper接口实现类对象
Connection connection = null;
Statement statement =null;
ResultSet resultSet=null;
try {
/* Class.forName("com.mysql.jdbc.Driver");//加载驱动
String url = "jdbc:mysql://localhost:3306/date_base?serverTimezone=UTC";*/
connection = getConnection();//DriverManager.getConnection(url, "root", "root");//获取连接
statement = connection.createStatement();
resultSet= statement.executeQuery(sql);//执行sql,将查询的数据存到ResultSet类型的变量中
rowMapper.rowMapper(resultSet);//因为rowMapper参数指向IRowMapper接口实现类对象，所以此处将调用接口实现类中所实现的rowMapper方法 多态
} catch (Exception e) {
e.printStackTrace();
}finally {
close(resultSet,statement,connection);
}
}
public static void select(String sql, IRowMapper rowMapper,Object ...params) {//接口无法创建对象，所以rowMapper参数一定指向IRowMapper接口实现类对象
Connection connection = null;
PreparedStatement prepareStatement =null;
ResultSet resultSet=null;
try{
connection = getConnection();
prepareStatement = connection.prepareStatement(sql);
for (int i = 0; i < params.length; i++) {
prepareStatement.setObject(i+1,params[i]);
}
resultSet = prepareStatement.executeQuery();
/* Class.forName("com.mysql.jdbc.Driver");//加载驱动
String url = "jdbc:mysql://localhost:3306/date_base?serverTimezone=UTC";*//*
connection = getConnection();//DriverManager.getConnection(url, "root", "root");//获取连接
statement = connection.createStatement();*/
//resultSet= statement.executeQuery(sql);//执行sql,将查询的数据存到ResultSet类型的变量中
rowMapper.rowMapper(resultSet);//因为rowMapper参数指向IRowMapper接口实现类对象，所以此处将调用接口实现类中所实现的rowMapper方法 多态
} catch (Exception e) {
logger.debug(e.getMessage(),e);
}finally {
close(resultSet,prepareStatement,connection);
}
}
public static void close(ResultSet resultSet,Statement statement,Connection connection){
try {
if(resultSet!=null) {
resultSet.close();
}
} catch (SQLException e) {
logger.debug(e.getMessage(),e);
}
try {
if(statement!=null) {
statement.close();
}
} catch (SQLException e) {
logger.debug(e.getMessage(),e);
}
try {
if(connection!=null) {
connection.close();
}
} catch (SQLException e) {
logger.debug(e.getMessage(),e);
}
}
public static void close(Statement statement,Connection connection){
try {
if(statement!=null) {
statement.close();
}
} catch (SQLException e) {
logger.debug(e.getMessage(),e);
}
try {
if(connection!=null) {
connection.close();
}
} catch (SQLException e) {
logger.debug(e.getMessage(),e);
}
}
//连接
public static Connection getConnection(){
try {
Class.forName("com.mysql.jdbc.Driver");//加载驱动
String userName = PropertiesTool.getValue("db.username");
String password = PropertiesTool.getValue("db.password");
String url = PropertiesTool.getValue("db.url");
/*
String url = "jdbc:mysql://localhost:3306/test?serverTimezone=UTC";*/
return DriverManager.getConnection(url, userName, password);//获取连接
} catch (Exception e) {
logger.debug(e.getMessage(),e);
}
return null;
}
//判断是否存在
public static boolean exist(String sql){
Connection connection = null;
Statement statement =null;
ResultSet resultSet=null;
try{
connection = getConnection();
statement = connection.createStatement();
resultSet = statement.executeQuery(sql);
return resultSet.next();
}catch (Exception e) {
logger.debug(e.getMessage(),e);
}finally {
close(resultSet,statement,connection);
}
return false;
}
public static boolean exist(String sql,Object ...params){
Connection connection = null;
PreparedStatement prepareStatement =null;
ResultSet resultSet=null;
try{
connection = getConnection();
prepareStatement = connection.prepareStatement(sql);
for (int i = 0; i < params.length; i++) {
prepareStatement.setObject(i+1,params[i]);
}
resultSet = prepareStatement.executeQuery();
return resultSet.next();
}catch (Exception e) {
logger.debug(e.getMessage(),e);
}finally {
close(resultSet,prepareStatement,connection);
}
return false;
}
}
测试类 Test:
public class test {
public static void main(String[] args) {
}
}