Apache-DBUtils实现mysql数据库的CRUD操作-白红宇

Apache-DBUtils实现mysql数据库的CRUD操作

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发布时间：2019-03-15

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Apache-DBUtils是Apache组织提供的一个开源JDBC工具库，旨在简化数据库操作，提供标准化的数据访问接口。它支持CRUD（Create, Read, Update, Delete）操作，并通过多种Handler实现对ResultSet的处理。

QueryRunner的基本使用

QueryRunner 是DBUtils中的核心类，用于执行数据库操作。以下是通过QueryRunner实现插入操作的示例：

public void testInsert() throws Exception {    Connection conn = JDBCUtils.getConnection1();    QueryRunner runner = new QueryRunner();    String sql = "insert into customers(name,email,birth) values(?,?,?)";    runner.update(conn, sql, "古德", "gude@126.com", "1987-08-08");}

ResultSet处理器（ResultSetHandler）

DBUtils提供了多种ResultSetHandler，用于将数据库查询结果转换为Java对象或集合。以下是常见Handler的使用示例：

BeanHandler（处理单条记录）

public void testInsert1() {    Connection conn = null;    try {        conn = JDBCUtils.getConnection1();        QueryRunner runner = new QueryRunner();        String sql = "select id,name,email,birth from customers where id = ?";        BeanHandler
   
     handle = new BeanHandler
    
     (Customer.class);        Customer cust = runner.query(conn, sql, handle, 20);        System.out.println(cust);    } catch (Exception e) {        e.printStackTrace();    } finally {        JDBCUtils.closeResource(conn, null);    }}

BeanListHandler（处理多条记录）

public void testInsert2() {    Connection conn = null;    try {        conn = JDBCUtils.getConnection1();        QueryRunner runner = new QueryRunner();        String sql = "select id,name,email,birth from customers where id < ?";        BeanListHandler
   
     handle = new BeanListHandler
    
     (Customer.class);        List
     
       list = runner.query(conn, sql, handle, 20);        list.forEach(System.out::println);    } catch (Exception e) {        e.printStackTrace();    } finally {        JDBCUtils.closeResource(conn, null);    }}

MapHandler（处理单条记录为Map）

public void testInsert3() {    Connection conn = null;    try {        conn = JDBCUtils.getConnection1();        QueryRunner runner = new QueryRunner();        String sql = "select id,name,email,birth from customers where id = ?";        MapHandler handler = new MapHandler();        Map
   
     map = runner.query(conn, sql, handler, 20);        System.out.println(map);    } catch (Exception e) {        e.printStackTrace();    } finally {        JDBCUtils.closeResource(conn, null);    }}

MapListHandler（处理多条记录为Map集合）

public void testInsert4() {    Connection conn = null;    try {        conn = JDBCUtils.getConnection1();        QueryRunner runner = new QueryRunner();        String sql = "select id,name,email,birth from customers where id < ?";        MapListHandler handler = new MapListHandler();        List
    
     > list = runner.query(conn, sql, handler, 20);        list.forEach(System.out::println);    } catch (Exception e) {        e.printStackTrace();    } finally {        JDBCUtils.closeResource(conn, null);    }}

ScalarHandler（处理单值查询）

DBUtils的ScalarHandler专门用于处理只返回一个标量值的查询，常用于统计查询或获取单值结果。例如：

public void testquery() {    Connection conn = null;    try {        conn = JDBCUtils.getConnection1();        QueryRunner runner = new QueryRunner();        String sql = "select count(*) from customers";        ScalarHandler handler = new ScalarHandler();        Long count = (Long) runner.query(conn, sql, handler);        System.out.println(count);    } catch (Exception e) {        e.printStackTrace();    } finally {        JDBCUtils.closeResource(conn, null);    }}

通过这些示例可以看出，Apache-DBUtils通过提供统一的API接口，显著简化了数据库操作，降低了代码冗余，提高了开发效率。

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