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"));
 });

评论

4 楼 lgn21st 2007-03-13  

dzgwt2004 写道

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);
}

是Spring-1.2.x么？
在Spring-2.0.x里面，ResultReader接口以及实现类RowMapperResultReader()都取消了吧

3 楼 xuehongliang 2007-02-12  

总结的很好,收藏了!

2 楼 IvanLi 2007-02-09  

seairy 写道

用过一段，queryForList如果是0行就会throw exception，有点奇怪

queryForList返回0行是不会有异常的，queryForInt, queryForMap, queryForObject会抛

1 楼 seairy 2007-02-09  

用过一段，queryForList如果是0行就会throw exception，有点奇怪