Spring -JdbcTemplate 总结
? Spring-JdbcTemplate 总结
1． 查询单个对象:
a)????? 基本类型
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下面两个方法主要适用于静态sql
◆???? public Object queryForObject(String sql, RowMapper rowMapper)
◆???? public Object queryForObject(String sql, Class requiredType)
注意：requiredType 只能是基本类型的class,只针对基本类型有效
◆???? public Object queryForObject(String sql, Object[] args, Class requiredType)
◆???? public Object queryForObject(String sql, Object[] args, RowMapper rowMapper)
◆???? public Object queryForObject(String sql, Object[] args, int[] argTypes, Class requiredType)
注：其中argTypes 可以使用java.sql.Types常量类中的常量值
◆???? public Object queryForObject(String sql, Object[] args, int[] argTypes, RowMapper rowMapper)
注： rowMapper是一个回调接口
以下主要用于查询数值对象
◆???? public int queryForInt(String sql, Object[] args)
◆???? public long queryForLong(String sql, Object[] args)
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下面的方法将返回的各个列封装成map对象，key为列名，value为列值.只能一行数据，不能返回多行数据.
◆???? public Map queryForMap(String sql, Object[] args)
b)????? 引用类型
◆???? public Object queryForObject(String sql, RowMapper rowMapper)
◆???? public Object queryForObject(String sql, Object[] args, RowMapper rowMapper)
◆???? public Map queryForMap(String sql, Object[] args)
2． 查询多个对象
a)????? 基本类型:
◆???? public List queryForList(String sql, Object[] args)
注：返回的list的每个元素都是一个map对象,该map对象封装了一行数据且只有一行数据，包括要查询的列字段
b)????? 引用类型:???
◆???? public List queryForList(String sql, Object[] args)
??????? Iterator iter =? this.jdbcTemplate.queryForList(sql,new Object[]{}).iterator();
??????? List list = new ArrayList();
??????? while(iter.hasNext()){
??????????? User user = new User();
??????????? Map map = (Map) iter.next();
??????????? Set<Entry<String, String>> set = map.entrySet();
??????????? Iterator<Entry<String, String>> iter2 = set.iterator();
??????????? Entry<String, String> entry = iter2.next();
??????????? user.setUsername(entry.getValue());
??????????? entry = iter2.next();
??????????? user.setPassword(entry.getValue());
??????????? list.add(user);
?????? }
◆???? public List query(String sql, Object[] args, RowMapper rowMapper)
注：返回的list 中的元素可以是引用类型的对象.
◆???? ??public Object execute(ConnectionCallback action)
注：使用回调接口.将各个字段值封装成引用类型的对象，然后以list方式返回.
3． ?修改操作.适用于增、删、改
◆???? public int update(String sql, Object[] args)
4.? 批处理
?String sql = "insert into user(username,password) values(?,?)";
?????? final List list = new ArrayList();
?????? for(int i = 0;i < 5 ; i++){
?????????? User user = new User();
?????????? user.setPassword("dog" + i);
?????????? user.setUsername("dog" + i);
?????????? list.add(user);
?????? }
?????? int [] rst = this.jdbcTemplate.batchUpdate(sql, new BatchPreparedStatementSetter(){
?????????? public int getBatchSize() {
????????????? return list.size();
?????????? }
?????????? public void setValues(PreparedStatement ps, int i)
????????????????? throws SQLException {
????????????? User user = (User) list.get(i);
????????????? ps.setString(1, user.getUsername());
????????????? ps.setString(2, user.getPassword());
?????????? }
????? });
