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spring的javadoc上讲getObject(String, Object[], Class) will return NULL if the result of the query is NUL

这里有0行和nullresult的区别0行: select salary from user where 1 = 2null result: select max(salary) from user where 1 = 2 返回就是null0行一定抛出IncorrectResultSizeDataAccessException异常原因如下ResultSetMetaData rsmd = rs.getMetaData();int nrOfColumns = rsmd.getColumnCount();这里返回ResultSet的列数  if (nrOfColumns != 1) {    throw new IncorrectResultSizeDataAccessException(     "Expected single column but found " + nrOfColumns, 1, nrOfColumns);  }0行,多于1行,就抛异常了 最好还是用QueryForList,返回的list的size为0,就是0行 还有oracle 10g的问题,jdbc驱动版本10.1.0.20getObject返回一个日期类型为java.util.Date但是这个日期只有年-月-日,没有时-分-秒,因为10g对于DATE类型的列,getObject().getClass().getName()得到 java.sql.DateSystem.out.println(rs.getObject("date_created") + " " + rs.getObject("date_created").getClass());得到 2005-10-06 class java.sql.Date要得到全部日期,必须使用oracle.sql.TIMESTAMP但是使用queryForObject("sql", Timestamp.class) 得到org.springframework.dao.TypeMismatchDataAccessException异常java.sql.Timestamp] and could not be converted to required type [java.sql.Timestamp] 很是莫名其妙只好使用java -Doracle.jdbc.V8Compatibility="true" MyApp解决

 

 

 

以下是对JdbcTemplate 常规用法总结:

 

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")); });

 

 

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