文章目錄
JdbcTemplate
參考文章:https://my.oschina.net/u/218421/blog/38598
配置JdbcTemplatet
配置JdbcTemplate有很多種方法
- 使用JdbcTemplate空參構造器創建,
setDataSource()
方法注入DataSource - 或者使用有參構造器傳入DataSource
- Spring當中配置到IoC容器
Spring當中配置jdbcTemplate
db.properties
jdbc.user=root
jdbc.password=hhh123
jdbc.driverClass=com.mysql.cj.jdbc.Driver
jdbc.jdbcUrl=jdbc:mysql://localhost:3306/spring_jdbc?useSSL=true&serverTimezone=GMT&useUnicode=true&characterEncoding=UTF8
jdbc.initialPoolSize=5
jdbc.maxPoolSize=20
ApplicationContext.xml
<!--引入db.properties-->
<context:property-placeholder location="classpath:db.properties"/>
<bean name="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource">
<property name="user" value="${jdbc.user}"></property>
<property name="password" value="${jdbc.password}"></property>
<property name="driverClass" value="${jdbc.driverClass}"></property>
<property name="jdbcUrl" value="${jdbc.jdbcUrl}"></property>
<property name="initialPoolSize" value="${jdbc.initialPoolSize}"></property>
<property name="maxPoolSize" value="${jdbc.maxPoolSize}"></property>
</bean>
配置jdbcTemple bean
ApplicatonContext.xml
<bean id="jdbcTemplate"
class="org.springframework.jdbc.core.JdbcTemplate">
<property name="dataSource" ref="dataSource"></property>
</bean>
數據庫操作
假設有數據庫表
department:
Field | Type | Null | Key | Default | Extra |
---|---|---|---|---|---|
id | int(11) | NO | PRI | NULL | auto_increment |
name | varchar(20) | YES | NULL | ||
department_id | int(11) | YES | MUL | NULL |
employee:
Field | Type | Null | Key | Default | Extra |
---|---|---|---|---|---|
id | int(11) | NO | PRI | NULL | auto_increment |
department_name | varchar(20) | YES | NULL |
更新操作
更新操作統一使用update(String sql,Object args...)
相應的更新批處理使用batcdUpdate(String sql, List<T> args)
刪除數據
@Test
public void func01() throws SQLException{
String sql = "delete from department where department_name=?;";
jdbcTemplate.update(sql,"銷售部");
}
插入數據
@Test
public void fun01() throws SQLException{
String sql = "insert into department(department_name) values(?)";
jdbcTemplate.update(sql,"事業部");
}
修改數據
@Test
public void fun01() throws SQLException{
String sql = "update department set department_name=? where department_name =?;
jdbcTemplate.update(sql,"銷售部","事業部");
}
批處理
public void fun01() throws SQLException{
String sql = "insert into employee(name,department_id) values(?,?)";
List<Object[]> argList = new LinkedList<Object[]>();
argList.add(new Object[] {"Mari",1});
argList.add(new Object[] {"Lari",1});
argList.add(new Object[] {"Kari",1});
argList.add(new Object[] {"Rari",1});
argList.add(new Object[] {"Wari",1});
argList.add(new Object[] {"Dari",1});
jdbcTemplate.batchUpdate(sql, argList);
}
查詢操作
對於簡單的查詢操作,如提供sql語句和參數然後返回一個結果的查詢,可以使用一下一組JdbcTemplate提供的模板方法
public int queryForInt(String sql)
public int queryForInt(String sql, Object[] args)
public int queryForInt(String sql, Object[] args)
public long queryForLong(String sql)
public long queryForLong(String sql, Object[] args)
public long queryForLong(String sql, Object[] args, int[] argTypes)
public Object queryForObject(String sql, Class requiredType)
public Object queryForObject(String sql, Object[] args, int[] argTypes, Class requiredType)
public Object queryForObject(String sql, Object[] args, int[] argTypes, RowMapper rowMapper)
public Object queryForObject(String sql, Object[] args, Class requiredType)
public Object queryForObject(String sql, Object[] args, RowMapper rowMapper)
public Object queryForObject(String sql, RowMapper rowMapper)
對於其中ForInt,ForLong查詢不作演示
查詢結果多行
查詢返回有映射關係的對象實體
使用JdbcTemplate.queryForObject(String sql, RowMapper<Class<T>> rowMapper, Object... args)
其中RowMapper爲數據庫表與bean的映射
即列名稱與bean對象屬性名稱映射,可以給查詢列指定別名進行映射
如
列–>employee:id,name,department_id
類–>Employee:id,username,departmentId
查詢語句使用別名select id,name username,derpartment_id departmentId from employee where=?
創建RowMapper對象使用BeanPropertyRowMapper實現類
例RowMapper<Employee> rowMapper = new BeanPropertyRowMapper(Employee.clas);
使用queryForObject方法的查詢結果爲表對應的列,但是JdbcTemplate無法爲級聯屬性創建對象
即無法直接創建外鍵關聯列所在表的對象
用例
@Test
public void fun01() throws SQLException{
String sql = "select id,name username,department_id departmentId from employee where id=?";
RowMapper<Employee> rowMapper = new BeanPropertyRowMapper(Employee.class);
Employee e1 = jdbcTemplate.queryForObject(sql, rowMapper,1);
System.out.println(e1);
}
如果查詢到的結果是多行的,那麼可以使用以下方法較爲便捷的把多行結果的對象實體存儲到List對象當中
使用``JdbcTemplate.query(String sql, RowMapper<Class> rowMapper, Object… args)`
用例
@Test
public void fun01() throws SQLException{
String sql = "select id,name username,department_id departmentId from employee where department_id=?";
RowMapper<Employee> rowMapper = new BeanPropertyRowMapper<Employee>(Employee.class);
List<Employee> employees = jdbcTemplate.query(sql, rowMapper, 1);
for(Employee e:employees) {
System.out.println(e);
}
}
查詢結果多行但列數不足以裝配實體對象
有時候查詢返回的結果爲多行,但是列數不足以構建一個有映射關係的實體對象時,我們可以queryForList()
方法
public List queryForList(String sql)
public List queryForList(String sql, Object[] args)
public List queryForList(String sql, Object[] args, int[] argTypes)
使用這種方法返回的結果類型是List<Map<String,Object>>
其中List對象中的成員Map的key爲列名稱、value爲查詢的結果
用例:
@Test
public void fun01() throws SQLException{
String sql = "select id,name username,department_id departmentId from employee where department_id=?";
List<Map<String, Object>> resultList = null;
resultList = jdbcTemplate.queryForList(sql, 1);
int i=1;
for(Map<String, Object> m:resultList) {
System.out.println("Row:"+i++);
for(Entry e:m.entrySet()) {
System.out.println("Key:"+e.getKey()+" Value:"+e.getValue());
}
System.out.println();
}
}
自定義結果集處理器查詢
可以定製一下三種接口對結果集處理進行定製,其中ResultSetExtractor功能性最強
-
org.springframework.jdbc.core.ResultSetExtractor
重寫
public Object extractData(ResultSet rs)
方法 -
org.springframework.jdbc.core.RowCallbackHandler
重寫
public void processRow(ResultSet rs)
方法 -
org.springframework.jdbc.core.RowMapper
重寫
public Object mapRow(ResultSet rs, int rowNum)
方法
實現處理方法後的接口傳入到
-
query(String sql,ResultSetExtractor interface,Object args...)
-
query(String sql,RowCallbackHandler interface,Object args...)
-
query(String sql,RowMapper interface,Object args...)