JdbcTemplate学习笔记

小灰灰 2022-09-29 04:30 152阅读 0赞

1、使用JdbcTemplate的execute()方法执行SQL语句

jdbcTemplate.execute("CREATE TABLE USER (user\_id integer, name varchar(100))");

2、如果是UPDATE或INSERT,可以用update()方法。

jdbcTemplate.update("INSERT INTO USER VALUES('" + user.getId() + "', '" + user.getName() + "', '" + user.getSex() + "', '" + user.getAge() + "')");

3、带参数的更新

jdbcTemplate.update("UPDATE USER SET name = ? WHERE user\_id = ?", new Object\[\] \{name, id\});

jdbcTemplate.update("INSERT INTO USER VALUES(?, ?, ?, ?)", new Object\[\] \{user.getId(), user.getName(), user.getSex(), user.getAge()\});

4、使用JdbcTemplate进行查询时，使用queryForXXX()等方法

int count = jdbcTemplate.queryForInt("SELECT COUNT(\*) FROM USER");String name = (String) jdbcTemplate.queryForObject("SELECT name FROM USER WHERE user\_id = ?", new Object\[\] \{id\}, java.lang.String.class);List rows = jdbcTemplate.queryForList("SELECT \* FROM USER");List rows = jdbcTemplate.queryForList("SELECT \* FROM USER"); Iterator it = rows.iterator(); while(it.hasNext()) \{ Map userMap = (Map) it.next(); System.out.print(userMap.get("user\_id") + "/t"); System.out.print(userMap.get("name") + "/t"); System.out.print(userMap.get("sex") + "/t"); System.out.println(userMap.get("age") + "/t"); \}

JdbcTemplate将我们使用的JDBC的流程封装起来，包括了异常的捕捉、SQL的执行、查询结果的转换等等。spring大量使用Template Method模式来封装固定流程的动作，XXXTemplate等类别都是基于这种方式的实现。  
除了大量使用Template Method来封装一些底层的操作细节，spring也大量使用callback方式类回调相关类别的方法以提供JDBC相关类别的功能，使传统的JDBC的使用者也能清楚了解spring所提供的相关封装类别方法的使用。

JDBC的PreparedStatement  
final String id = user.getId(); final String name = user.getName(); final String sex = user.getSex() + ""; final int age = user.getAge(); jdbcTemplate.update("INSERT INTO USER VALUES(?, ?, ?, ?)", new PreparedStatementSetter() \{ public void setValues(PreparedStatement ps) throws SQLException \{ ps.setString(1, id); ps.setString(2, name); ps.setString(3, sex); ps.setInt(4, age); \} \}); final User user = new User(); jdbcTemplate.query("SELECT \* FROM USER WHERE user\_id = ?", new Object\[\] \{id\}, new RowCallbackHandler() \{ public void processRow(ResultSet rs) throws SQLException \{ user.setId(rs.getString("user\_id")); user.setName(rs.getString("name")); user.setSex(rs.getString("sex").charAt(0)); user.setAge(rs.getInt("age")); \} \});

class UserRowMapper implements RowMapper \{ public Object mapRow(ResultSet rs, int index) throws SQLException \{ User user = new User(); user.setId(rs.getString("user\_id")); user.setName(rs.getString("name")); user.setSex(rs.getString("sex").charAt(0)); user.setAge(rs.getInt("age")); return user; \} \} public List findAllByRowMapperResultReader() \{ String sql = "SELECT \* FROM USER"; return jdbcTemplate.query(sql, new RowMapperResultReader(new UserRowMapper())); \}

在getUser(id)里面使用UserRowMapper

public User getUser(final String id) throws DataAccessException \{ String sql = "SELECT \* FROM USER WHERE user\_id=?"; final Object\[\] params = new Object\[\] \{ id \}; List list = jdbcTemplate.query(sql, params, new RowMapperResultReader(new UserRowMapper())); return (User) list.get(0); \}

网上收集  
org.springframework.jdbc.core.PreparedStatementCreator 返回预编译SQL 不能于Object\[\]一起用

public PreparedStatement createPreparedStatement(Connection con) throws SQLException \{ return con.prepareStatement(sql); \}

1.增删改  
org.springframework.jdbc.core.JdbcTemplate 类(必须指定数据源dataSource)

template.update("insert into web\_person values(?,?,?)",Object\[\]);

或

template.update("insert into web\_person values(?,?,?)",new PreparedStatementSetter()\{ 匿名内部类 只能访问外部最终局部变量 public void setValues(PreparedStatement ps) throws SQLException \{ ps.setInt(index++,3); \});

org.springframework.jdbc.core.PreparedStatementSetter 接口 处理预编译SQL  
public void setValues(PreparedStatement ps) throws SQLException \{ ps.setInt(index++,3); \}

2.查询JdbcTemplate.query(String,\[Object\[\]/PreparedStatementSetter\],RowMapper/RowCallbackHandler)  
org.springframework.jdbc.core.RowMapper 记录映射接口 处理结果集

public Object mapRow(ResultSet rs, int arg1) throws SQLException \{ int表当前行数 person.setId(rs.getInt("id")); \} List template.query("select \* from web\_person where id=?",Object\[\],RowMapper);

org.springframework.jdbc.core.RowCallbackHandler 记录回调管理器接口 处理结果集

template.query("select \* from web\_person where id=?",Object\[\],new RowCallbackHandler()\{ public void processRow(ResultSet rs) throws SQLException \{ person.setId(rs.getInt("id")); \});