前言
java JDBC工具类
1、pom文件加入mysql依赖
<!-- mysql -->
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>8.0.25</version>
</dependency>
2、resources目录下编写config.properties配置文件 :
gjSass.jdbc.driverClassName = com.mysql.cj.jdbc.Driver
gjSass.jdbc.url = jdbc:mysql://172.0.0.1:3306/data_18_ind_poscal?useSSL=false&useUnicode=true&characterEncoding=utf-8&zeroDateTimeBehavior=convertToNull&transformedBitIsBoolean=true&serverTimezone=GMT%2B8&nullCatalogMeansCurrent=true&allowPublicKeyRetrieval=true
gjSass.jdbc.username = root
gjSass.jdbc.password = root@123
3、编写 GJMGJdbcTemplate 类
package com.springblade.positionCalculate.utils;
import lombok.extern.slf4j.Slf4j;
import java.io.IOException;
import java.io.InputStream;
import java.sql.*;
import java.util.*;
/**
* mysql-jdbc连接工具
*
*/
@Slf4j
public class GJMGJdbcTemplate {
private static String url;
private static String username;
private static String password;
private static String driver;
static {
// 加载配置文件
InputStream is = GJMGJdbcTemplate.class.getClassLoader().getResourceAsStream("config.properties");
Properties pro = new Properties();
try {
pro.load(is);
url = pro.getProperty("gjSass.jdbc.url");
username = pro.getProperty("gjSass.jdbc.username");
password = pro.getProperty("gjSass.jdbc.password");
driver = pro.getProperty("gjSass.jdbc.driverClassName");
} catch (IOException e) {
e.printStackTrace();
}
// 注册驱动
try {
Class.forName(driver);
} catch (ClassNotFoundException e) {
e.printStackTrace();
log.info(e.getMessage(), e);
}
}
public static Connection getConnection() {
Connection conn = null;
try {
conn = DriverManager.getConnection(url, username, password);
// 把jdbc 链接 设置成 非自动提交
conn.setAutoCommit(false);
} catch (SQLException e) {
e.printStackTrace();
log.info(e.getMessage(), e);
log.info("获得链接失败!");
}
return conn;
}
public static void closeAll(Statement stmt, Connection conn) {
if (stmt != null) {
try {
stmt.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
if (conn != null) {
try {
conn.close();// 关闭
} catch (SQLException e) {
e.printStackTrace();
}
}
}
public static void closeResAll(ResultSet rs, Statement stmt, Connection conn) {
if (rs != null) {
try {
rs.close();// 关闭
} catch (SQLException e) {
e.printStackTrace();
}
}
if (stmt != null) {
try {
stmt.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
if (conn != null) {
try {
conn.close();// 关闭
} catch (SQLException e) {
e.printStackTrace();
}
}
}
public static List<Map<String, Object>> selectAll(String querysql) {
List<Map<String, Object>> list = new ArrayList<>();
long starttime = System.currentTimeMillis();
Connection conn = getConnection();
Statement statement = null;
ResultSet rs = null;
try {
statement = conn.createStatement();
rs = statement.executeQuery(querysql);
ResultSetMetaData data = rs.getMetaData();
int columnCount = data.getColumnCount();
while (rs.next()) {
int i = 1;
Map<String, Object> map = new HashMap<String, Object>();
while (i <= columnCount) {
String name = data.getColumnName(i);
// System.out.println(name + " : " + rs.getObject(i));
if (rs.getObject(i) == null || "".equals(rs.getObject(i))) {
map.put(name, "");
} else {
map.put(name, rs.getObject(i));
}
i++;
}
list.add(map);
}
log.info(" 执行成功一次,总使用时间：" + (System.currentTimeMillis() - starttime) + "ms");
} catch (SQLException e) {
e.printStackTrace();
log.info(e.getMessage(), e);
} finally {
closeResAll(rs, statement, conn);
}
return list;
}
public static void main(String[] args) {
String sql = "select * from table";
List<Map<String, Object>> maps = selectAll(sql);
JSONArray jsonArray = new JSONArray();
jsonArray.addAll(maps);
List<xxx> xxx = jsonArray.toJavaList(xxx.class);
}
/*public static void batchUpdate(String sql) {
Connection conn = null;
Statement ps = null;
try {
conn = getConnection();
ps = conn.createStatement();
int executeUpdate = ps.executeUpdate(sql);
conn.commit();
} catch (SQLException e) {
e.printStackTrace();
log.error(e.getMessage(), e);
try {
conn.rollback();
} catch (SQLException e1) {
log.error(e1.getMessage(), e1);
}
} finally {
try {
ps.close();
} catch (SQLException e) {
log.error(e.getMessage(), e);
}
try {
conn.close();
} catch (SQLException e) {
log.error(e.getMessage(), e);
}
}
}*/
}
总结
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