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<!-- https://mvnrepository.com/artifact/commons-dbutils/commons-dbutils --><dependency>    <groupId>commons-dbutils</groupId>    <artifactId>commons-dbutils</artifactId>    <version>1.6</version></dependency>  <!-- https://mvnrepository.com/artifact/mysql/mysql-connector-java --><dependency>    <groupId>mysql</groupId>    <artifactId>mysql-connector-java</artifactId>    <version>5.1.38</version></dependency>

/** * 获取jdbc连接 * @return */ public static Connection getConnection() { Connection connection = null; try { connection = DriverManager.getConnection(Constants.JDBC_URL,  Constants.USERNAME, Constants.PASSWORD); } catch (SQLException e) { e.printStackTrace(); } return connection;  }

/** * 关闭数据库连接 * @param con */ public static void closeConnection(Connection connection) { try { if(connection != null) { connection.close(); } } catch (SQLException e) { e.printStackTrace(); } }

public static void main(String[] args) throws SQLException{ //QueryRunner 中提供了对sql语句操作的api，    //update()执行install update delete //query(),执行select操作 QueryRunner runner = new QueryRunner(); String sql = "select id from member t WHERE t.mobile_phone = '13927427493';"; Connection conn = getConnection(); //ResultSetHandler接口，用于定义select操作后，对结果集进行封装 //ResultSetHandler结果集处理类 //ScalarHandler 处理单个字段 例如：select id from member t WHERE t.mobile_phone = '13927427493';  //DbUtils类是一个工具类，定义了关闭资源和处理事务的方法    //ScalarHandler可以不指定泛型 Integer query = runner.query(conn, sql, new ScalarHandler<Integer>()); System.out.println(query); closeConnection(conn);  }

public static void main(String[] args) throws SQLException{ //QueryRunner 中提供了对sql语句操作的api，update()执行install update delete //query(),执行select操作    QueryRunner runner = new QueryRunner(); String sql3 = "select mobile_phone from member;";    Connection conn = getConnection();    //DbUtils类是一个工具类，定义了关闭资源和处理事务的方法    //ColumnListHandler对象将结果集中的某一列字段值封装到List集合中 List<Object> query2 = runner.query(conn, sql3, new ColumnListHandler<Object>()); for (Object obj : query2) { System.out.println(obj);    }     closeConnection(conn); }

package com.lemon.pojo;import java.math.BigDecimal;public class UserInfo { private int id; private String reg_name; private String pwd; private String moblie_phone; private BigDecimal leave_amount;   public UserInfo() { super(); // TODO Auto-generated constructor stub }
 public UserInfo(int id, String reg_name, String pwd, String moblie_phone, BigDecimal leave_amount) { super(); this.id = id; this.reg_name = reg_name; this.pwd = pwd; this.moblie_phone = moblie_phone; this.leave_amount = leave_amount; }
 public int getId() { return id; }
 public void setId(int id) { this.id = id; }
 public String getReg_name() { return reg_name; }
 public void setReg_name(String reg_name) { this.reg_name = reg_name; }
 public String getPwd() { return pwd; }
 public void setPwd(String pwd) { this.pwd = pwd; }
 public String getMoblie_phone() { return moblie_phone; }
 public void setMoblie_phone(String moblie_phone) { this.moblie_phone = moblie_phone; }
 public BigDecimal getLeave_amount() { return leave_amount; }
 public void setLeave_amount(BigDecimal leave_amount) { this.leave_amount = leave_amount; }
 @Override public String toString() { return "UserInfo [id=" + id + ", reg_name=" + reg_name + ", pwd=" + pwd + ", moblie_phone=" + moblie_phone + ", leave_amount=" + leave_amount + "]"; }  }

public static void main(String[] args) throws SQLException{ //QueryRunner 中提供了对sql语句操作的api，update()执行install update delete //query(),执行select操作    QueryRunner runner = new QueryRunner(); String sql4 = "select id,reg_name,pwd,mobile_phone,leave_amount from member t LIMIT 5;";    Connection conn = getConnection(); //将结果集中的每一条记录封装到指定的javabean中，将这些javabean再封装到List中 List<UserInfo> userInfo = runner.query(conn, sql4,  new BeanListHandler<UserInfo>(UserInfo.class)); for(UserInfo element :userInfo) { System.out.print(element); System.out.println(); }     closeConnection(conn); }