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NamedParameterJdbcTemplate类拓展了JdbcTemplate类,对JdbcTemplate类进行了封装从而支持命名参数特性。 NamedParameterJdbcTemplate主要提供以下三类方法:execute方法、query及queryForXXX方法、update及batchUpdate方法。数据库结构
1.支持类SqlParameterSource 简介可以使用SqlParameterSource实现作为来实现为命名参数设值,默认实现有 :MapSqlParameterSource实现非常简单,只是封装了java.util.Map;
BeanPropertySqlParameterSource封装了一个JavaBean对象,通过JavaBean对象属性来决定命名参数的值。
EmptySqlParameterSource 一个空的SqlParameterSource ,常用来占位使用
RowMapper简介
这个接口为了实现sql查询结果和对象间的转换,可以自己实现,也可以使用系统实现,主要实现类有:SingleColumnRowMapper ,sql结果为一个单列的数据,如List<String> , List<Integer>,String,Integer等
BeanPropertyRowMapper, sql结果匹配到对象 List< XxxVO> , XxxVO
2.插入/修改/删除数据,使用updateXXX方法
使用Map作为参数API: int update(String sql, Map<String, ?> paramMap)示例:
Map<String, Object> paramMap = new HashMap<>();
paramMap.put("id", UUID.randomUUID().toString());paramMap.put("name", "小明");paramMap.put("age", 33);paramMap.put("homeAddress", "乐山");paramMap.put("birthday", new Date());template.update( "insert into student(id,name,age,home_address,birthday) values (:id,:name,:age,:homeAddress,:birthday)", paramMap);12345678910使用BeanPropertySqlParameterSource作为参数API: int update(String sql, SqlParameterSource paramSource)使用 BeanPropertySqlParameterSource作为参数
public class StudentDTO{
private String id; private String name; private String homeAddress;//getter,setter
}1234567StudentDTO dto=new StudentDTO();//这个DTO为传入数据dto.setId(UUID.randomUUID().toString());dto.setName("小红");dto.setHomeAddress("成都");//------------------------------template.update("insert into student(id,name,home_address) values (:id,:name,:homeAddress)", new BeanPropertySqlParameterSource(dto));1234567使用MapSqlParameterSource 作为参数API: int update(String sql, SqlParameterSource paramSource)//使用 MapSqlParameterSource 作为参数
MapSqlParameterSource mapSqlParameterSource = new MapSqlParameterSource()
.addValue("id", UUID.randomUUID().toString()) .addValue("name", "小王") .addValue("homeAddress", "美国");template.update("insert into student(id,name,home_address) values (:id,:name,:homeAddress)",mapSqlParameterSource);123456或者Map<String, Object> paramMap = new HashMap<>();
paramMap.put("id", UUID.randomUUID().toString());paramMap.put("name", "小明");paramMap.put("homeAddress", "乐山");//---------------MapSqlParameterSource mapSqlParameterSource = new MapSqlParameterSource(paramMap);1234563.查询返回单行单列数据API: public < T > T queryForObject(String sql, Map<String, ?> paramMap, Class<T> requiredType)API: public < T > T queryForObject(String sql, SqlParameterSource paramSource, Class<T> requiredType)
示例(注意EmptySqlParameterSource的使用):
Integer count = template.queryForObject(
"select count(*) from student", new HashMap<>(), Integer.class);12String name = template.queryForObject( "select name from student where home_address limit 1 ", EmptySqlParameterSource.INSTANCE, String.class); 1返回 (多行)单列 数据API: public < T> List< T> queryForList(String sql, Map<String, ?> paramMap, Class< T > elementType)API: public < T> List< T> queryForList(String sql, SqlParameterSource paramSource, Class< T> elementType)
示例:List< String> namelist = template.queryForList("select name from student", new HashMap<>(), String.class);
1返回单行数据API: public < T> T queryForObject(String sql, Map< String, ?> paramMap, RowMapper< T>rowMapper)API: public < T> T queryForObject(String sql, SqlParameterSource paramSource, RowMapper< T> rowMapper)
示例:Student stu = template.queryForObject(
"select * from student limit 1", new HashMap<>(), new BeanPropertyRowMapper<Student>(Student.class));//BeanPropertyRowMapper会把下划线转化为驼峰属性//结果对象可比实际返回字段多或者少1234注意:这两个API也可以使用SingleColumnRowMapper返回单行单列数据String name = template.queryForObject(
"select name from student limit 1", EmptySqlParameterSource.INSTANCE, new SingleColumnRowMapper<>(String.class));122.4 返回Map形式的单行数据API: public Map< String, Object> queryForMap(String sql, Map< String, ?> paramMap)API: public Map< String, Object> queryForMap(String sql, SqlParameterSource paramSource)
示例:Map< String, Object> studentMap = template.queryForMap("select * from student limit 1", new HashMap<>());
12.5 返回多行数据API: public < T> List< T> query(String sql, Map< String, ?> paramMap, RowMapper< T> rowMapper) API: public < T> List< T> query(String sql, SqlParameterSource paramSource, RowMapper< T> rowMapper) API: public < T> List< T> query(String sql, RowMapper< T> rowMapper) 示例:List< Student> studentList = template.query(
"select * from student", new BeanPropertyRowMapper<>(Student.class)); 1234同理,也可以使用SingleColumnRowMapper返回单行列表List< String>,List< Integer>等2.6 返回多行数据(Map)
API: public List< Map< String, Object>> queryForList(String sql, Map< String, ?> paramMap) API: public List< Map< String, Object>> queryForList(String sql, SqlParameterSource paramSource)示例:
List<Map<String, Object>> mapList = template.queryForList(
"select * from student", new HashMap<>());12总结开发中尽量使用NamedParameterJdbcTemplate代替JdbcTemplate,如果想使用JdbcTemplate,也可以通过NamedParameterJdbcTemplate#getJdbcOperations()获取不建议使用查询结构为Map的API--------------------- 作者:chenjazz 来源:CSDN 原文:https://blog.csdn.net/u011179993/article/details/74791304 版权声明:本文为博主原创文章,转载请附上博文链接!