JdbcTemplate是Spring提供的⼀个JDBC模板类,是对JDBC的封装,简化JDBC代码。 当然,你也可以不⽤,可以让Spring集成其它的ORM框架,例如:MyBatis、Hibernate等。
第一步:引入依赖
org.springframework
spring-context
6.0.2
junit
junit
4.13.2
test
mysql
mysql-connector-java
8.0.30
org.springframework
spring-jdbc
6.0.2
第二步:编写Spring配置⽂件
JdbcTemplate是Spring提供好的类,这类的完整类名是: org.springframework.jdbc.core.JdbcTemplate 我们怎么使⽤这个类呢?new对象就可以了。怎么new对象,Spring最在⾏了。直接将这个类配置到 Spring配置⽂件中,纳⼊Bean管理即可。
可以看到JdbcTemplate中有⼀个DataSource属性,这个属性是数据源,我们都知道连接数据库需要 Connection对象,⽽⽣成Connection对象是数据源负责的。
所以我们需要给JdbcTemplate设置数据源 属性。 所有的数据源都是要实现javax.sql.DataSource接⼝的。这个数据源可以⾃⼰写⼀个,也可以⽤写好的, ⽐如:阿⾥巴巴的德鲁伊连接池,c3p0,dbcp等。我们这⾥⾃⼰先⼿写⼀个数据源。
public class MyDataSource implements DataSource {
// 添加4个属性
private String driver;
private String url;
private String username;
private String password;
// 提供4个setter⽅法
public void setDriver(String driver) {
this.driver = driver;
}
public void setUrl(String url) {
this.url = url;
}
public void setUsername(String username) {
this.username = username;
}
public void setPassword(String password) {
this.password = password;
}
// 重点写怎么获取Connection对象就⾏。其他⽅法不⽤管。
@Override
public Connection getConnection() throws SQLException {
try {
Class.forName(driver);
Connection conn = DriverManager.getConnection(url, username, password);
return conn;
} catch (Exception e) {
e.printStackTrace();
}
return null;
}
@Override
public Connection getConnection(String username, String password) throws SQLException {
return null;
}
@Override
public PrintWriter getLogWriter() throws SQLException {
return null;
}
@Override
public void setLogWriter(PrintWriter out) throws SQLException {
}
@Override
public void setLoginTimeout(int seconds) throws SQLException {
}
@Override
public int getLoginTimeout() throws SQLException {
return 0;
}
@Override
public Logger getParentLogger() throws SQLFeatureNotSupportedException {
return null;
}
@Override
public T unwrap(Class iface) throws SQLException {
return null;
}
@Override
public boolean isWrapperFor(Class iface) throws SQLException {
return false;
}
}
写完数据源,我们需要把这个数据源传递给JdbcTemplate。因为JdbcTemplate中有⼀个DataSource属 性:
public class SpringTest {
@Test
public void test(){
// 获取JdbcTemplate对象
ApplicationContext applicationContext = new ClassPathXmlApplicationContext("spring.xml");
JdbcTemplate jdbcTemplate = applicationContext.getBean("jdbcTemplate", JdbcTemplate.class);
/*注意:insert delete update的sql语句,都是执⾏update⽅法。update⽅法有两个参数:
第⼀个参数:要执⾏的SQL语句。(SQL语句中可能会有占位符 ? )
第⼆个参数:可变⻓参数,参数的个数可以是0个,也可以是多个。⼀般是SQL语句中有⼏个问号,
则对应⼏个参数。*/
String sql = "insert into t_user(id,real_name,age) values(?,?,?)";
int count = jdbcTemplate.update(sql, null, "张三", 30);
System.out.println("插⼊的记录条数:" + count);
}
}
public class SpringTest {
@Test
public void test(){
ApplicationContext applicationContext = new ClassPathXmlApplicationContext("spring.xml");
JdbcTemplate jdbcTemplate = applicationContext.getBean("jdbcTemplate", JdbcTemplate.class);
// 执⾏更新操作
String sql = "update t_user set real_name = ?, age = ? where id = ?";
int count = jdbcTemplate.update(sql, "张三丰", 55, 1);
System.out.println("更新的记录条数:" + count);
}
}
public class SpringTest {
@Test
public void test(){
ApplicationContext applicationContext = new ClassPathXmlApplicationContext("spring.xml");
JdbcTemplate jdbcTemplate = applicationContext.getBean("jdbcTemplate", JdbcTemplate.class);
// 执⾏delete
String sql = "delete from t_user where id = ?";
int count = jdbcTemplate.update(sql, 1);
System.out.println("删除了⼏条记录:" + count);
}
}
public class SpringTest {
@Test
public void test(){
ApplicationContext applicationContext = new ClassPathXmlApplicationContext("spring.xml");
JdbcTemplate jdbcTemplate = applicationContext.getBean("jdbcTemplate", JdbcTemplate.class);
// 执⾏select
String sql = "select id, real_name, age from t_user where id = ?";
/*
queryForObject⽅法三个参数:
第⼀个参数:sql语句
第⼆个参数:Bean属性值和数据库记录⾏的映射对象。在构造⽅法中指定映射的对象类型。
第三个参数:可变⻓参数,给sql语句的占位符问号传值。
*/
User user = jdbcTemplate.queryForObject(sql, new BeanPropertyRowMapper<>(User.class), 2);
System.out.println(user);
}
}
public class SpringTest {
@Test
public void test(){
ApplicationContext applicationContext = new ClassPathXmlApplicationContext("spring.xml");
JdbcTemplate jdbcTemplate = applicationContext.getBean("jdbcTemplate", JdbcTemplate.class);
// 执⾏select
String sql = "select id, real_name, age from t_user";
List users = jdbcTemplate.query(sql, new BeanPropertyRowMapper<>(User.class));
System.out.println(users);
}
}
public class SpringTest {
@Test
public void test(){
ApplicationContext applicationContext = new ClassPathXmlApplicationContext("spring.xml");
JdbcTemplate jdbcTemplate = applicationContext.getBean("jdbcTemplate", JdbcTemplate.class);
// 执⾏select
String sql = "select count(1) from t_user";
Integer count = jdbcTemplate.queryForObject(sql, int.class); // 这⾥⽤Integer.class也可以
System.out.println("总记录条数:" + count);
}
}
public class SpringTest {
@Test
public void test(){
ApplicationContext applicationContext = new ClassPathXmlApplicationContext("spring.xml");
JdbcTemplate jdbcTemplate = applicationContext.getBean("jdbcTemplate", JdbcTemplate.class);
// 批量添加
String sql = "insert into t_user(id,real_name,age) values(?,?,?)";
Object[] objs1 = {null, "⼩花", 20};
Object[] objs2 = {null, "⼩明", 21};
Object[] objs3 = {null, "⼩刚", 22};
List
public class SpringTest {
@Test
public void test(){
ApplicationContext applicationContext = new ClassPathXmlApplicationContext("spring.xml");
JdbcTemplate jdbcTemplate = applicationContext.getBean("jdbcTemplate", JdbcTemplate.class);
// 批量修改
String sql = "update t_user set real_name = ?, age = ? where id = ?";
Object[] objs1 = {"⼩花11", 10, 2};
Object[] objs2 = {"⼩明22", 12, 3};
Object[] objs3 = {"⼩刚33", 9, 4};
List
public class SpringTest {
@Test
public void test(){
ApplicationContext applicationContext = new ClassPathXmlApplicationContext("spring.xml");
JdbcTemplate jdbcTemplate = applicationContext.getBean("jdbcTemplate", JdbcTemplate.class);
// 批量删除
String sql = "delete from t_user where id = ?";
Object[] objs1 = {2};
Object[] objs2 = {3};
Object[] objs3 = {4};
List
public class SpringTest {
@Test
public void test(){
ApplicationContext applicationContext = new ClassPathXmlApplicationContext("spring.xml");
JdbcTemplate jdbcTemplate = applicationContext.getBean("jdbcTemplate", JdbcTemplate.class);
String sql = "select id, real_name, age from t_user where id = ?";
User user = jdbcTemplate.execute(sql, new PreparedStatementCallback() {
@Override
public User doInPreparedStatement(PreparedStatement ps) throws SQLException, DataAccessException {
User user = null;
ps.setInt(1, 5);
ResultSet rs = ps.executeQuery();
if (rs.next()) {
user = new User();
user.setId(rs.getInt("id"));
user.setRealName(rs.getString("real_name"));
user.setAge(rs.getInt("age"));
}
return user;
}
});
System.out.println(user);
}
}
上面数据源是⽤我们⾃⼰写的。也可以使⽤别⼈写好的。例如⽐较⽜的德鲁伊连接池。
第⼀步:引⼊德鲁伊连接池的依赖。
com.alibaba
druid
1.1.8
第⼆步:将德鲁伊中的数据源配置到spring配置⽂件中。和配置我们⾃⼰写的⼀样。
测试
public class SpringTest {
@Test
public void test(){
// 获取JdbcTemplate对象
ApplicationContext applicationContext = new ClassPathXmlApplicationContext("spring.xml");
JdbcTemplate jdbcTemplate = applicationContext.getBean("jdbcTemplate", JdbcTemplate.class);
String sql = "insert into t_user(id,real_name,age) values(?,?,?)";
int count = jdbcTemplate.update(sql, null, "张三", 30);
System.out.println("插⼊的记录条数:" + count);
}
}