JdbcTemplate主要提供以下五类方法:
execute方法:可以用于执行任何SQL语句,一般用于执行DDL语句;
update方法及batchUpdate方法:update方法用于执行新增、修改、删除等语句;batchUpdate方法用于执行批处理相关语句;
query方法及queryForXXX方法:用于执行查询相关语句;
call方法:用于执行存储过程、函数相关语句。
JdbcTemplate类支持的回调类:
预编译语句及存储过程创建回调:用于根据JdbcTemplate提供的连接创建相应的语句;
PreparedStatementCreator:通过回调获取JdbcTemplate提供的Connection,由用户使用该Conncetion创建相关的PreparedStatement;
CallableStatementCreator:通过回调获取JdbcTemplate提供的Connection,由用户使用该Conncetion创建相关的CallableStatement;
预编译语句设值回调:用于给预编译语句相应参数设值;
PreparedStatementSetter:通过回调获取JdbcTemplate提供的PreparedStatement,由用户来对相应的预编译语句相应参数设值;
BatchPreparedStatementSetter:;类似于PreparedStatementSetter,但用于批处理,需要指定批处理大小;
自定义功能回调:提供给用户一个扩展点,用户可以在指定类型的扩展点执行任何数量需要的操作;
ConnectionCallback:通过回调获取JdbcTemplate提供的Connection,用户可在该Connection执行任何数量的操作;
StatementCallback:通过回调获取JdbcTemplate提供的Statement,用户可以在该Statement执行任何数量的操作;
PreparedStatementCallback:通过回调获取JdbcTemplate提供的PreparedStatement,用户可以在该PreparedStatement执行任何数量的操作;
CallableStatementCallback:通过回调获取JdbcTemplate提供的CallableStatement,用户可以在该CallableStatement执行任何数量的操作;
结果集处理回调:通过回调处理ResultSet或将ResultSet转换为需要的形式;
RowMapper:用于将结果集每行数据转换为需要的类型,用户需实现方法mapRow(ResultSet rs, int rowNum)来完成将每行数据转换为相应的类型。
RowCallbackHandler:用于处理ResultSet的每一行结果,用户需实现方法processRow(ResultSet rs)来完成处理,在该回调方法中无需执行rs.next(),该操作由JdbcTemplate来执行,用户只需按行获取数据然后处理即可。
ResultSetExtractor:用于结果集数据提取,用户需实现方法extractData(ResultSet rs)来处理结果集,用户必须处理整个结果集;
1: JdbcTemplate
1.1 query
单个对象
/**
* 处理单个对象
*/
@Test
public void test_1() {
JdbcTemplate jdbcTemplate = new JdbcTemplate(JDBCUtils.getDataSource());
String sql = "select * from student where id=1";
Student student = jdbcTemplate.query(sql, new ResultSetExtractor<Student>() {
@Override
public Student extractData(ResultSet res) throws SQLException, DataAccessException {
Student student = null;
while (res.next()) {
int id = res.getInt("id");
String name = res.getString("name");
boolean gender = res.getBoolean("gender");
Date birthday = res.getDate("birthday");
student = new Student(id, name, gender, birthday);
}
return student;
}
});
System.out.println(student);
}
@Test
public void test_2() {
JdbcTemplate jdbcTemplate = new JdbcTemplate(JDBCUtils.getDataSource());
String sql = "select * from student where id=1";
// 这里演示RowCallbackHandler 上面也可以使用函数式写法 不能返回
jdbcTemplate.query(sql, (res)-> {
String name = res.getString("name");
System.out.println(name);
});
}
@Test
public void test_3() {
JdbcTemplate jdbcTemplate = new JdbcTemplate(JDBCUtils.getDataSource());
String sql = "select * from student where id=1";
Student stu = jdbcTemplate.query(sql, (res)->{
Student student = null;
while (res.next()) {
int id = res.getInt("id");
String name = res.getString("name");
boolean gender = res.getBoolean("gender");
Date birthday = res.getDate("birthday");
student = new Student(id, name, gender, birthday);
}
return student;
});
System.out.println(stu);
}
//聚集函数
@Test
public void test_4() {
JdbcTemplate jdbcTemplate = new JdbcTemplate(JDBCUtils.getDataSource());
String sql = "select count(*) from student";
Integer inx = jdbcTemplate.queryForObject(sql, Integer.class);
System.out.println(inx);
}
@Test
public void test_5() {
JdbcTemplate jdbcTemplate = new JdbcTemplate(JDBCUtils.getDataSource());
String sql = "select id from student";
List<Integer> list = jdbcTemplate.queryForList(sql, Integer.class);
}
List Map
/**
* 处理单个对象
*/
@Test
public void test_1() {
JdbcTemplate jdbcTemplate = new JdbcTemplate(JDBCUtils.getDataSource());
String sql = "select * from student where id=1";
Student student = jdbcTemplate.query(sql, new ResultSetExtractor<Student>() {
@Override
public Student extractData(ResultSet res) throws SQLException, DataAccessException {
Student student = null;
while (res.next()) {
int id = res.getInt("id");
String name = res.getString("name");
boolean gender = res.getBoolean("gender");
Date birthday = res.getDate("birthday");
student = new Student(id, name, gender, birthday);
}
return student;
}
});
System.out.println(student);
}
@Test
public void test_2() {
JdbcTemplate jdbcTemplate = new JdbcTemplate(JDBCUtils.getDataSource());
String sql = "select * from student where id=1";
// 这里演示RowCallbackHandler 上面也可以使用函数式写法 不能返回
jdbcTemplate.query(sql, (res)-> {
String name = res.getString("name");
System.out.println(name);
});
}
@Test
public void test_3() {
JdbcTemplate jdbcTemplate = new JdbcTemplate(JDBCUtils.getDataSource());
String sql = "select * from student where id=1";
Student stu = jdbcTemplate.query(sql, (res)->{
Student student = null;
while (res.next()) {
int id = res.getInt("id");
String name = res.getString("name");
boolean gender = res.getBoolean("gender");
Date birthday = res.getDate("birthday");
student = new Student(id, name, gender, birthday);
}
return student;
});
System.out.println(stu);
}
//聚集函数
@Test
public void test_4() {
JdbcTemplate jdbcTemplate = new JdbcTemplate(JDBCUtils.getDataSource());
String sql = "select count(*) from student";
Integer inx = jdbcTemplate.queryForObject(sql, Integer.class);
System.out.println(inx);
}
@Test
public void test_5() {
JdbcTemplate jdbcTemplate = new JdbcTemplate(JDBCUtils.getDataSource());
String sql = "select id from student";
List<Integer> list = jdbcTemplate.queryForList(sql, Integer.class);
}
1.2 upadte
@Test
public int insertUser(Student stu) {
JdbcTemplate jdbcTemplate = new JdbcTemplate(JDBCUtils.getDataSource());
String sql = "insert into student values(null,?,?,?)";
return jdbcTemplate.update(sql, new Object[] { stu.getName(), stu.isGender(), stu.getBirthday() });
}
@Test
public int delete(int id) {
JdbcTemplate jdbcTemplate = new JdbcTemplate(JDBCUtils.getDataSource());
String sql = "delete from student where id=?";
return jdbcTemplate.update(sql, 1);
}
2:NamedParameterJdbcTemplate
使用与JdbcTemplate 最大的区别就是 使用命名符号来代表占位符? 使SQl 容易理解 但是 代码量增加了,取舍在于个人
@Test
public void findById() {
NamedParameterJdbcTemplate template = new NamedParameterJdbcTemplate(JDBCUtils.getDataSource());
String sql="select * FROM student where name like (:regxp)";
/*
* jdbctemplate 用?站位
* NamedParameterJdbcTemplate : 使用:xxx 站位 通过hashmap 写入参数
* map:
* String:参数名称
* Object:参数值
*/
HashMap<String, Object> paMap = new HashMap<>();
paMap.put("regxp", "%");
BeanPropertyRowMapper<Student> rowMapper = new BeanPropertyRowMapper<>(Student.class);
List<Student> list = template.query(sql,paMap, rowMapper);
System.out.println(list);
}
@Test
public void insert_Stu() {
NamedParameterJdbcTemplate template = new NamedParameterJdbcTemplate(JDBCUtils.getDataSource());
String sql="insert into student(name,gender,birthday) values(:name,:gender,:birthday)";
HashMap<String, Object> paramMap = new HashMap<>();
paramMap.put("name", "如来佛祖");
paramMap.put("gender", "1");
paramMap.put("birthday", "2019-2-2");
if(template.update(sql, paramMap)>0) {
System.out.println("true");
}
}