Apache-DBUtils实现mysql数据库的CRUD操作
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Apache-DBUtils实现CRUD操作
commons-dbutils是Apache组织提供的一个开源JDBC工具库类,封装了针对于数据库的增删改查操作
QueryRunner测试插入数据
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");
}
QueryRunner测试插入数据
BeanHandler:是ResultSetHandler接口的实现类,用于封装表中的一条记录
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<Customer> 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:是ResultSetHandler接口的实现类,用于封装表中的多条记录构成的集合
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<Customer> handle = new BeanListHandler<>(Customer.class);
List<Customer> list = runner.query(conn, sql, handle, 20);
list.forEach(System.out::println);
} catch (Exception e) {
e.printStackTrace();
} finally {
JDBCUtils.closeResource(conn,null);
}
}
MapHandler:是ResultSetHandler接口的实现类,对应表中的一条记录,将字段及相应字段的值作为map中的key和value
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<String, Object> map = runner.query(conn, sql, handler, 20);
System.out.println(map);
} catch (Exception e) {
e.printStackTrace();
} finally {
JDBCUtils.closeResource(conn,null);
}
}
MapListHandler:是ResultSetHandler接口的实现类,对应表中的多条记录,将字段及相应字段的值作为map中的key和value
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<Map<String, Object>> list = runner.query(conn, sql, handler, 20);
list.forEach(System.out::println);
} catch (Exception e) {
e.printStackTrace();
} finally {
JDBCUtils.closeResource(conn,null);
}
}
用于查询特殊值,使用ScalarHandler
比如总数,平均数,最大数,最小数等
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);
}
}
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