Java中JDBC工具类
一、项目结构：
二、工具类：
1、log4j.properties：
# 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,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
2、db.properties:
db.username = root
db.password = root
db.url = jdbc:mysql://127.0.0.1:3306/test3、PropertiesTool.java:
package com.jd.tool;
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inputStream
try {
properties.load(inputStream);
} catch (IOException e) {
e.printStackTrace();
}
}
public static String getValue(String string) {
return properties.getProperty(string);
}
}
4、IRowMapper.java:
package com.jd.tool.db;
import java.sql.ResultSet;
public interface IRowMapper {
void rowMapper(ResultSet rs);
}
5、DBLink.java:
package com.jd.tool.db;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import org.apache.log4j.Logger;
import com.jd.tool.PropertiesTool;
public class DBLink {
private Logger logger = Logger.getLogger(DBLink.class);
/**
* 获取数据连接
*
* @author 样光伊
*/
private Connection getConnection() {
try {
Class.forName("com.mysql.jdbc.Driver");
String userName = PropertiesTool.getValue("db.username");
String password = PropertiesTool.getValue("db.password");
String url = PropertiesTool.getValue("db.url");
return DriverManager.getConnection(url,userName,password);
}catch (Exception e) {
//e.printStackTrace(); //将异常显示在控制台上
logger.debug(e.getMessage(), e);//异常将不再显示在控制台上
}
return null;
}
/**
* 判断数据是否存在
*
* @author 样光伊
*/
public 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;
}
/**
* 判断数据是否存在（避免了SQL注入）
*
* @author 样光伊
*/
public boolean exist(String sql,Object ...params) {
Connection connection = null;
PreparedStatement preparedStatement = null;
ResultSet resultSet = null;
try {
connection = getConnection();
preparedStatement = connection.prepareStatement(sql);
for (int i = 0; i < params.length; i++) {
preparedStatement.setObject(i+1, params[i]);
}
resultSet = preparedStatement.executeQuery();
return resultSet.next();
} catch (Exception e) {
logger.debug(e.getMessage(), e);
} finally {
close(resultSet,preparedStatement,connection);
}
return false;
}
/**
* 修改（insert、delete、update）数据
*
* @author 样光伊
*/
public boolean update(String sql) {
Connection connection = null;
Statement statement = null;
try {
connection = getConnection();
statement = connection.createStatement();
int affect = statement.executeUpdate(sql);
return affect>0;
} catch (Exception e) {
logger.debug(e.getMessage(), e);
}finally {
close(statement,connection);
}
return false;
}
/**
* 修改（insert、delete、update）数据（避免了SQL注入）
*
* @author 样光伊
*/
public boolean update(String sql,Object ...params) {//Object ...params是动态参数，只能放在参数列表的最后面
Connection connection = null;
PreparedStatement preparedStatement = null;
try {
connection = getConnection();
preparedStatement = connection.prepareStatement(sql);
for (int i = 0; i < params.length; i++) {
preparedStatement.setObject(i+1, params[i]);
}
return preparedStatement.executeUpdate()>0;
} catch (Exception e) {
logger.debug(e.getMessage(), e);
} finally {
close(preparedStatement,connection);
}
return false;
}
/**
* 查询数据
*
* @author 样光伊
*/
public void select(String sql,IRowMapper rowMapper) { //为什么去掉static:因为静态方法里不能直接调用非静态方法，
Connection connection = null; //而getConnection() close(resultSet,statement,connection)都是非静态方法
Statement statement = null;
ResultSet resultSet = null;
try {
connection = getConnection();
statement = connection.createStatement();
resultSet = statement.executeQuery(sql);
rowMapper.rowMapper(resultSet);
} catch (Exception e) {
logger.debug(e.getMessage(), e);
} finally {
close(resultSet,statement,connection);
}
}
/**
* 查询数据（避免了SQL注入）
*
* @author 样光伊
*/
public void select(String sql,IRowMapper rowMapper,Object ...params) {
Connection connection = null;
PreparedStatement preparedStatement = null;
ResultSet resultSet = null;
try {
connection = getConnection();
preparedStatement = connection.prepareStatement(sql);
for (int i = 0; i < params.length; i++) {
preparedStatement.setObject(i+1,params[i]);
}
resultSet = preparedStatement.executeQuery();
rowMapper.rowMapper(resultSet);
} catch (Exception e) {
e.printStackTrace();
} finally {
close(resultSet,preparedStatement,connection);
}
}
/**
* 关闭资源
*
* @author 样光伊
*/
private 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);
}
}
/**
* 关闭资源
*
* @author 样光伊
*/
private void close(ResultSet resultSet,Statement statement,Connection connection) {
try {
if(resultSet!=null) {
resultSet.close();
}
} catch (SQLException e) {
logger.debug(e.getMessage(), e);
}
close(statement,connection);
}
}
三、Test.java:
package com.jd.test;
public class Test{
public static void main(String [] args){
}
}