JdbcTemplate学习笔记

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"));   
});