【SSM_Spring】学习笔记05
spring与jdbc
一、用Spring中的JdbcTemplate操作数据库
1、创建web动态项目，导入基本包、c3p0连接池包、数据库包、事务包（jdbc\tx）
2、创建User对象，属性与数据库一一对应
public class User {
private Integer u_id;
private String u_username;
private String u_password;
}3、创建UserDao接口，以及实现其接口，在接口中使用JdbcTemplete.
public interface UserDao {
//根据id查找用户
User selectUserById(Integer id);
}
public class UserDaoImpl implements UserDao {
private static ComboPooledDataSource dataSource;
static {
try {
//配置c3p0数据库
dataSource = new ComboPooledDataSource();
dataSource.setDriverClass("com.mysql.jdbc.Driver");
dataSource.setJdbcUrl("jdbc:mysql://localhost:3306/ssm_spring");
dataSource.setUser("root");
dataSource.setPassword("root");
} catch (PropertyVetoException e) {
e.printStackTrace();
}
}
@Override
public User selectUserById(Integer id) {
JdbcTemplate jTemplate = new JdbcTemplate(dataSource);
String sql = "select * from user where u_id=?";
User user = jTemplate.queryForObject(sql,
new RowMapper() {
@Override
public User mapRow(ResultSet rSet, int index) throws SQLException {
User user = new User();
user.setU_id(rSet.getInt("u_id"));
user.setU_username(rSet.getString("u_username"));
user.setU_password(rSet.getString("u_password"));
return user;
}
}, id);
return user;
}
}
4、创建测试类
public class test {
@Test
public void test1() {
UserDao uDao = new UserDaoImpl();
User user = uDao.selectUserById(0);
System.out.println(user);
}
}5、总结：简单的spring中的jdbcTemplate测试例子就写好了，总体其实跟spring_servlet有点相似，所以理解起来也不算困难。
二、JdbcTemplate的增删改查操作
1、修改UserDao接口；
public interface UserDao {
//增
void saveUser(User user);
//删
void deleteUserById(Integer id);
//改
void updateUser(User user);
//查
//根据id查找用户
User selectUserById(Integer id);
//查询所有用户列表
List selectAllUser();
//查询用户数量
Integer selectUserCount();
}
2、实现UserDaoImpl
public class UserDaoImpl implements UserDao {
private static ComboPooledDataSource dataSource;
JdbcTemplate jTemplate = new JdbcTemplate(dataSource);
static {
try {
//配置c3p0数据库
dataSource = new ComboPooledDataSource();
dataSource.setDriverClass("com.mysql.jdbc.Driver");
dataSource.setJdbcUrl("jdbc:mysql://localhost:3306/ssm_spring");
dataSource.setUser("root");
dataSource.setPassword("root");
} catch (PropertyVetoException e) {
e.printStackTrace();
}
}
@Override
public User selectUserById(Integer id) {
String sql = "select * from user where u_id=?";
User user = jTemplate.queryForObject(sql,
new RowMapper() {
@Override
public User mapRow(ResultSet rSet, int index) throws SQLException {
User user = new User();
user.setU_id(rSet.getInt("u_id"));
user.setU_username(rSet.getString("u_username"));
user.setU_password(rSet.getString("u_password"));
return user;
}
}, id);
return user;
}
//保存用户
@Override
public void saveUser(User user) {
String sql = "insert into user values(null,?,?)";
jTemplate.update(sql, user.getU_username(),user.getU_password());
}
//根据id删除用户
@Override
public void deleteUserById(Integer id) {
String sql = "delete from user where u_id=?";
jTemplate.update(sql, id);
}
//修改用户信息
@Override
public void updateUser(User user) {
String sql = "update user set u_username=?,u_password=? where u_id=?";
jTemplate.update(sql, user.getU_username(),user.getU_password(),user.getU_id());
}
//查询所有用户列表
@Override
public List selectAllUser() {
String sql = "select * from user";
return jTemplate.query(sql, new RowMapper() {
@Override
public User mapRow(ResultSet rSet, int index) throws SQLException {
User user = new User();
user.setU_id(rSet.getInt("u_id"));
user.setU_username(rSet.getString("u_username"));
user.setU_password(rSet.getString("u_password"));
return user;
}
});
}
//查询用户数量
@Override
public Integer selectUserCount() {
String sql = "select count(*) from user";
Integer count = jTemplate.queryForObject(sql, Integer.class);
return count;
}
}
3、测试
@Test
public void test2() {
UserDao uDao = new UserDaoImpl();
User user = new User();
user.setU_username("dunka97");
user.setU_password("abcd");
uDao.saveUser(user);
}
@Test
public void test3() {
UserDao uDao = new UserDaoImpl();
uDao.deleteUserById(1);
}
@Test
public void test4() {
UserDao uDao = new UserDaoImpl();
User user = new User();
user.setU_id(0);
user.setU_username("dunka");
user.setU_password("1212");
uDao.updateUser(user );
}
@Test
public void test5() {
UserDao uDao = new UserDaoImpl();
uDao.selectAllUser();
}
@Test
public void test6() {
UserDao uDao = new UserDaoImpl();
Integer count = uDao.selectUserCount();
System.out.println(count);
}4、注意，其中出现了一个错误
org.springframework.dao.DataIntegrityViolationException: PreparedStatementCallback; SQL [insert into user values(null,?,?)Column 'u_id' cannot be null; nested exception is com.mysql.jdbc.exceptions.MySQLIntegrityConstraintViolationException: Column 'u_id' cannot be null
at
从其中意思可以知道，我把一个不能为空的字段保存了一个null值属性，经过检查发现是我的数据表没有设计好，u_id没有设置自增，所以在主键上保存一个空值就会报错，把其修正就OK了。
三、使用spring容器管理jdbcTemplate
1、创建spring配置文件applicationContext.xml
其中，要分清楚其中的依赖关系是dao - > jdbcTemplate -> dataSource
2、修改UserDaoImpl中的jdbcTemplate,改为set方法，以及去掉自己连接数据库的部分
public class UserDaoImpl implements UserDao {
JdbcTemplate jTemplate;
public void setjTemplate(JdbcTemplate jTemplate) {
this.jTemplate = jTemplate;
}
@Override
public User selectUserById(Integer id) {
String sql = "select * from user where u_id=?";
User user = jTemplate.queryForObject(sql,
new RowMapper() {
@Override
public User mapRow(ResultSet rSet, int index) throws SQLException {
User user = new User();
user.setU_id(rSet.getInt("u_id"));
user.setU_username(rSet.getString("u_username"));
user.setU_password(rSet.getString("u_password"));
return user;
}
}, id);
return user;
}
//保存用户
@Override
public void saveUser(User user) {
String sql = "insert into user values(null,?,?)";
jTemplate.update(sql, user.getU_username(),user.getU_password());
}
//根据id删除用户
@Override
public void deleteUserById(Integer id) {
String sql = "delete from user where u_id=?";
jTemplate.update(sql, id);
}
//修改用户信息
@Override
public void updateUser(User user) {
String sql = "update user set u_username=?,u_password=? where u_id=?";
jTemplate.update(sql, user.getU_username(),user.getU_password(),user.getU_id());
}
//查询所有用户列表
@Override
public List selectAllUser() {
String sql = "select * from user";
return jTemplate.query(sql, new RowMapper() {
@Override
public User mapRow(ResultSet rSet, int index) throws SQLException {
User user = new User();
user.setU_id(rSet.getInt("u_id"));
user.setU_username(rSet.getString("u_username"));
user.setU_password(rSet.getString("u_password"));
return user;
}
});
}
//查询用户数量
@Override
public Integer selectUserCount() {
String sql = "select count(*) from user";
Integer count = jTemplate.queryForObject(sql, Integer.class);
return count;
}
}
3、测试类，使用注解
@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration("classpath:applicationContext.xml")
public class test {
@Resource(name="userDao")
UserDao uDao;
@Test
public void test1() {
User user = uDao.selectUserById(1);
System.out.println(user);
}
@Test
public void test2() {
User user = new User();
user.setU_username("dunka111");
user.setU_password("abcd");
uDao.saveUser(user);
}
@Test
public void test3() {
uDao.deleteUserById(1);
}
@Test
public void test4() {
User user = new User();
user.setU_id(2);
user.setU_username("dunka");
user.setU_password("666");
uDao.updateUser(user );
}
@Test
public void test5() {
List list = uDao.selectAllUser();
for (User user : list) {
System.out.println(user);
}
}
@Test
public void test6() {
Integer count = uDao.selectUserCount();
System.out.println(count);
}
}
四、使用JdbcDaoSupport修改Dao和Spring读取配置文件
1、使用JdbcDaoSupport修改Dao
（1）使UserDaoImpl继承JdbcDaoSupport,把jdbcTemplate修改为getJdbcTemplate(),使用父类封装好的方法
public class UserDaoImpl extends JdbcDaoSupport implements UserDao {
@Override
public User selectUserById(Integer id) {
String sql = "select * from user where u_id=?";
User user = getJdbcTemplate().queryForObject(sql,
new RowMapper() {
@Override
public User mapRow(ResultSet rSet, int index) throws SQLException {
User user = new User();
user.setU_id(rSet.getInt("u_id"));
user.setU_username(rSet.getString("u_username"));
user.setU_password(rSet.getString("u_password"));
return user;
}
}, id);
return user;
}
} （2）配置文件中依赖关系就变成dao->datasourece
2、spring读取配置文件
（1）以数据库连接信息作为例子：db.properties
jdbc.driverClass=com.mysql.jdbc.Driver
jdbc.jdbcUrl=jdbc:mysql://localhost:3306/ssm_spring
jdbc.user=root
jdbc.password=123456(2)给spring配置文件添加spring-context约束，使用标签
3、测试