JDBCTest

package com.atguigu.spring.jdbc;

import java.sql.SQLException;

import java.util.ArrayList;

import java.util.HashMap;

import java.util.List;

import java.util.Map;

import javax.sql.DataSource;

import org.junit.Test;

import org.springframework.context.ApplicationContext;

import org.springframework.context.support.ClassPathXmlApplicationContext;

import org.springframework.jdbc.core.BeanPropertyRowMapper;

import org.springframework.jdbc.core.JdbcTemplate;

import org.springframework.jdbc.core.RowMapper;

import org.springframework.jdbc.core.namedparam.BeanPropertySqlParameterSource;

import org.springframework.jdbc.core.namedparam.NamedParameterJdbcTemplate;

import org.springframework.jdbc.core.namedparam.SqlParameterSource;

public class JDBCTest {

    private ApplicationContext ctx = null;

    private JdbcTemplate jdbcTemplate;

    private EmployeeDao employeeDao;

    private DepartmentDao departmentDao;

    private NamedParameterJdbcTemplate namedParameterJdbcTemplate;

    {

        ctx = new ClassPathXmlApplicationContext("applicationContext.xml");

        jdbcTemplate = (JdbcTemplate) ctx.getBean("jdbcTemplate");

        employeeDao = ctx.getBean(EmployeeDao.class);

        departmentDao = ctx.getBean(DepartmentDao.class);

        namedParameterJdbcTemplate = ctx.getBean(NamedParameterJdbcTemplate.class);

    }

    /**

     * 使用具名参数时, 可以使用 update(String sql, SqlParameterSource paramSource) 方法进行更新操作

     * 1. SQL 语句中的参数名和类的属性一致!

     * 2. 使用 SqlParameterSource 的 BeanPropertySqlParameterSource 实现类作为参数.

     */

    @Test

    public void testNamedParameterJdbcTemplate2(){

        String sql = "INSERT INTO employees(last_name, email, dept_id) "

                + "VALUES(:lastName,:email,:dpetId)";

        Employee employee = new Employee();

        employee.setLastName("XYZ");

        employee.setEmail("[email protected]");

        employee.setDpetId(3);

        SqlParameterSource paramSource = new BeanPropertySqlParameterSource(employee);

        namedParameterJdbcTemplate.update(sql, paramSource);

    }

    /**

     * 可以为参数起名字.

     * 1. 好处: 若有多个参数, 则不用再去对应位置, 直接对应参数名, 便于维护

     * 2. 缺点: 较为麻烦.

     */

    @Test

    public void testNamedParameterJdbcTemplate(){

        String sql = "INSERT INTO employees(last_name, email, dept_id) VALUES(:ln,:email,:deptid)";

        Map<String, Object> paramMap = new HashMap<>();

        paramMap.put("ln", "FF");

        paramMap.put("email", "[email protected]");

        paramMap.put("deptid", 2);

        namedParameterJdbcTemplate.update(sql, paramMap);

    }

    @Test

    public void testDepartmentDao(){

        System.out.println(departmentDao.get(1));

    }

    @Test

    public void testEmployeeDao(){

        System.out.println(employeeDao.get(1));

    }

    /**

     * 获取单个列的值, 或做统计查询

     * 使用 queryForObject(String sql, Class<Long> requiredType)

     */

    @Test

    public void testQueryForObject2(){

        String sql = "SELECT count(id) FROM employees";

        long count = jdbcTemplate.queryForObject(sql, Long.class);

        System.out.println(count);

    }

    /**

     * 查到实体类的集合

     * 注意调用的不是 queryForList 方法

     */

    @Test

    public void testQueryForList(){

        String sql = "SELECT id, last_name lastName, email FROM employees WHERE id > ?";

        RowMapper<Employee> rowMapper = new BeanPropertyRowMapper<>(Employee.class);

        List<Employee> employees = jdbcTemplate.query(sql, rowMapper,5);

        System.out.println(employees);

    }

    /**

     * 从数据库中获取一条记录, 实际得到对应的一个对象

     * 注意不是调用 queryForObject(String sql, Class<Employee> requiredType, Object... args) 方法!

     * 而需要调用 queryForObject(String sql, RowMapper<Employee> rowMapper, Object... args)

     * 1. 其中的 RowMapper 指定如何去映射结果集的行, 常用的实现类为 BeanPropertyRowMapper

     * 2. 使用 SQL 中列的别名完成列名和类的属性名的映射. 例如 last_name lastName

     * 3. 不支持级联属性. JdbcTemplate 到底是一个 JDBC 的小工具, 而不是 ORM 框架

     */

    @Test

    public void testQueryForObject(){

        String sql = "SELECT id, last_name lastName, email, dept_id as \"department.id\" FROM employees WHERE id = ?";

        RowMapper<Employee> rowMapper = new BeanPropertyRowMapper<>(Employee.class);

        Employee employee = jdbcTemplate.queryForObject(sql, rowMapper, 1);

        System.out.println(employee);

    }

    /**

     * 执行批量更新: 批量的 INSERT, UPDATE, DELETE

     * 最后一个参数是 Object[] 的 List 类型: 因为修改一条记录需要一个 Object 的数组, 那么多条不就需要多个 Object 的数组吗

     */

    @Test

    public void testBatchUpdate(){

        String sql = "INSERT INTO employees(last_name, email, dept_id) VALUES(?,?,?)";

        List<Object[]> batchArgs = new ArrayList<>();

        batchArgs.add(new Object[]{"AA", "[email protected]", 1});

        batchArgs.add(new Object[]{"BB", "[email protected]", 2});

        batchArgs.add(new Object[]{"CC", "[email protected]", 3});

        batchArgs.add(new Object[]{"DD", "[email protected]", 3});

        batchArgs.add(new Object[]{"EE", "[email protected]", 2});

        jdbcTemplate.batchUpdate(sql, batchArgs);

    }

    /**

     * 执行 INSERT, UPDATE, DELETE

     */

    @Test

    public void testUpdate(){

        String sql = "UPDATE employees SET last_name = ? WHERE id = ?";

        jdbcTemplate.update(sql, "Jack", 5);

    }

    @Test

    public void testDataSource() throws SQLException {

        DataSource dataSource = ctx.getBean(DataSource.class);

        System.out.println(dataSource.getConnection());

    }

}