spring之jdbcTemplate
Posted fjk
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spring的另一个功能模块data access对于数据库的支持
spring data access第一个helloword案例:
使用java程序实现访问配置
1.导包
2.测试案例
@Test
public void test01(){
DriverManagerDataSource dataSource=new DriverManagerDataSource();
dataSource.setDriverClassName("com.mysql.jdbc.Driver");
dataSource.setUrl("jdbc:mysql:///springtest");
dataSource.setUsername("root");
dataSource.setPassword("123");
JdbcTemplate jdbcTemplate=new JdbcTemplate();
jdbcTemplate.setDataSource(dataSource);
String sql="insert into t_user values(1,\'张三\',123,\'男\')";
jdbcTemplate.execute(sql);
}
把创建对象交给spring来控制,这样就需要在applicationContext.xml文件中配置数据访问
applicationContext.xml
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:c="http://www.springframework.org/schema/c"
xmlns:p="http://www.springframework.org/schema/p"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:context="http://www.springframework.org/schema/context"
xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context.xsd
http://www.springframework.org/schema/aop
http://www.springframework.org/schema/aop/spring-aop.xsd
http://www.springframework.org/schema/tx
http://www.springframework.org/schema/tx/spring-tx.xsd">
<!-- 创建数据源 -->
<bean id="driverManagerDataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource">
<!-- 配置数据库驱动 -->
<property name="driverClassName" value="com.mysql.jdbc.Driver"></property>
<property name="url" value="jdbc:mysql:///springtest"></property>
<property name="username" value="root"></property>
<property name="password" value="123"></property>
</bean>
<bean id="jdbcTemplate" class="org.springframework.jdbc.core.JdbcTemplate">
<!-- 注入数据源 -->
<property name="dataSource" ref="driverManagerDataSource"></property>
</bean>
</beans>
测试方法;
@RunWith(SpringJUnit4ClassRunner.class) //整合junit4
@ContextConfiguration(locations="classpath:applicationContext.xml")//使用注解加载配置文件
public class SpringJDBCTest {
@Autowired
private JdbcTemplate jdbcTemplate;
@Test
public void test01(){
String sql="insert into t_user values(2,\'张三\',123,\'男\')";
jdbcTemplate.execute(sql);
}
}
CRUD操作
创建表
CREATE DATABASE springtest; USE springtest; CREATE TABLE t_user( id INT PRIMARY KEY AUTO_INCREMENT, NAME VARCHAR(20), age INT, sex VARCHAR(20) ) INSERT INTO t_user VALUES(NULL,\'tom\',20,\'男\'); INSERT INTO t_user VALUES(NULL,\'fox\',30,\'男\'); INSERT INTO t_user VALUES(NULL,\'tony\',40,\'男\');
cud操作
@RunWith(SpringJUnit4ClassRunner.class) //整合junit4 @ContextConfiguration(locations="classpath:applicationContext.xml")//使用注解加载配置文件 public class SpringJDBCTest { @Autowired private JdbcTemplate jdbcTemplate; @Test //添加数据 public void insertData(){ //String sql="insert into t_user values(4,\'张三\',123,\'男\')"; //jdbcTemplate.execute(sql); String sql="insert into t_user values(?,?,?,?)"; jdbcTemplate.update(sql,5,"王五",66,"女"); } @Test //删除数据 public void deleteData(){ //String sql="delete from t_user where id=4 "; //jdbcTemplate.execute(sql); String sql="delete from t_user where id=? "; jdbcTemplate.update(sql,5); } @Test //修改数据 public void updateData(){ /*String sql="update t_user set name=\'李四\' where id=3 "; jdbcTemplate.execute(sql);*/ String sql="update t_user set name=? where id=? "; jdbcTemplate.update(sql,"jj",1); } }
查询操作
对没有封装的数据进行查询
@Test //查询简单的一格数据 public void seachOne3(){ List<Map<String, Object>> list = jdbcTemplate.queryForObject("select * from t_user",new RowMapper<List<Map<String,Object>>>() { List<Map<String,Object>> list=new ArrayList<Map<String,Object>>(); @Override public List<Map<String,Object>> mapRow(ResultSet rs, int rowNum) throws SQLException { System.out.println(rowNum); System.out.println("------"); Map<String,Object> map=null; while(rs.next()){ map=new HashMap<String,Object>(); map.put("id",rs.getInt("id")); map.put("name",rs.getString("name")); map.put("age",rs.getInt("age")); map.put("sex",rs.getString("sex")); list.add(map); } return list; } }); System.out.println(list); }
@Test //查询简单的一格数据 public void seachOne3(){ List<Map<String, Object>> list = jdbcTemplate.query("select * from t_user",new RowMapper<Map<String,Object>>() { List<Map<String,Object>> list=new ArrayList<Map<String,Object>>(); @Override public Map<String,Object> mapRow(ResultSet rs, int rowNum) throws SQLException { Map<String,Object> map=new HashMap<String,Object>(); map.put("id",rs.getInt("id")); map.put("name",rs.getString("name")); map.put("age",rs.getInt("age")); map.put("sex",rs.getString("sex")); return map; } }); System.out.println(list); }
对封装的数据进行查询
@Test //查询简单的一格数据 public void seachOne2(){ List<User> list = jdbcTemplate.queryForObject("select * from t_user",new RowMapper<List<User>>() { List<User> list=new ArrayList<User>(); @Override public List<User> mapRow(ResultSet rs, int rowNum) throws SQLException { //System.out.println(rs.getRow()); //do { User u=new User(); u.setId(rs.getInt("id")); u.setName(rs.getString("name")); u.setAge(rs.getInt("age")); u.setSex(rs.getString("sex")); list.add(u); //} while (rs.next()); return list; } }); System.out.println(list); }
@Test //查询简单的一格数据 public void seachOne4(){ List<User> list = jdbcTemplate.query("select * from t_user",new RowMapper<User>() { List<User> list=new ArrayList<User>(); @Override public User mapRow(ResultSet rs, int rowNum) throws SQLException { User u=new User(); u.setId(rs.getInt("id")); u.setName(rs.getString("name")); u.setAge(rs.getInt("age")); u.setSex(rs.getString("sex")); return u; } }); System.out.println(list); }
query 和queryForObject的区别
query是底层会对查询出来的数据进行处理,比如查询结果为空会返回为空,并不会抛异常;query的返回值会根据第二个参数来对返回进行区分
@Override
public void query(String sql, RowCallbackHandler rch) throws DataAccessException {
query(sql, new RowCallbackHandlerResultSetExtractor(rch));
}
@Override
public <T> List<T> query(String sql, RowMapper<T> rowMapper) throws DataAccessException { 返回值为T的集合
return query(sql, new RowMapperResultSetExtractor<T>(rowMapper));
}
@Override
public List<T> extractData(ResultSet rs) throws SQLException {
List<T> results = (this.rowsExpected > 0 ? new ArrayList<T>(this.rowsExpected) : new ArrayList<T>());
int rowNum = 0;//设置为第零行开始
while (rs.next()) {//没有数据 并不会报错 只是会返回为null
results.add(this.rowMapper.mapRow(rs, rowNum++));
}
return results;
}
queryForObject在查询时候如果没有查询出数据则会抛出异常 因为会对results进行判断 如果为空则会抛出异常.
public static <T> T requiredSingleResult(Collection<T> results) throws IncorrectResultSizeDataAccessException {
int size = (results != null ? results.size() : 0);
if (size == 0) {
throw new EmptyResultDataAccessException(1);
}
if (results.size() > 1) {
throw new IncorrectResultSizeDataAccessException(1, size);
}
return results.iterator().next();
}
Bean查询 类似于beanUtils对于javabean类进行数据赋值
public class BeanPropertyRowMapper<T> implements RowMapper<T>
@Test //使用bean来进行查询数据
public void seachBean(){
List<User> list = jdbcTemplate.query("select * from t_user",new BeanPropertyRowMapper<User>(User.class));
System.out.println(list);
}
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