spring JdbcTemplate 的若干问题

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 = 2
null result: select max(salary) from user where 1 = 2 返回就是null
0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10.1.0.20
getObject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.Date
System.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("CREATETABLEUSER(user_idinteger,namevarchar(100))");

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("INSERTINTOUSERVALUES('"
 +user.getId()+"','"
 +user.getName()+"','"
 +user.getSex()+"','"
 +user.getAge()+"')");

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

3、带参数的更新

jdbcTemplate.update("UPDATEUSERSETname=?WHEREuser_id=?",newObject[]{name,id});

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

jdbcTemplate.update("INSERTINTOUSERVALUES(?,?,?,?)",newObject[]{user.getId(),user.getName(),user.getSex(),user.getAge()});

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

intcount=jdbcTemplate.queryForInt("SELECTCOUNT(*)FROMUSER");

int count = jdbcTemplate.queryForInt("SELECT COUNT(*) FROM USER");

Stringname=(String)jdbcTemplate.queryForObject("SELECTnameFROMUSERWHEREuser_id=?",newObject[]{id},java.lang.String.class);

String name = (String) jdbcTemplate.queryForObject("SELECT name FROM USER WHERE user_id = ?", new Object[] {id}, java.lang.String.class);

Listrows=jdbcTemplate.queryForList("SELECT*FROMUSER");

List rows = jdbcTemplate.queryForList("SELECT * FROM USER");

Listrows=jdbcTemplate.queryForList("SELECT*FROMUSER");
Iteratorit=rows.iterator();
 while(it.hasNext()){
MapuserMap=(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");
}

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

finalStringid=user.getId();
 finalStringname=user.getName();
 finalStringsex=user.getSex()+"";
 finalintage=user.getAge();

 jdbcTemplate.update("INSERTINTOUSERVALUES(?,?,?,?)",
 newPreparedStatementSetter(){
 publicvoidsetValues(PreparedStatementps)throwsSQLException{
 ps.setString(1,id);
 ps.setString(2,name);
 ps.setString(3,sex);
 ps.setInt(4,age);
}
});

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);
                         }
                     });

finalUseruser=newUser();
 jdbcTemplate.query("SELECT*FROMUSERWHEREuser_id=?",
 newObject[]{id},
 newRowCallbackHandler(){
 publicvoidprocessRow(ResultSetrs)throwsSQLException{
 user.setId(rs.getString("user_id"));
 user.setName(rs.getString("name"));
 user.setSex(rs.getString("sex").charAt(0));
 user.setAge(rs.getInt("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"));
                        }
                    });

classUserRowMapperimplementsRowMapper{
 publicObjectmapRow(ResultSetrs,intindex)throwsSQLException{
 Useruser=newUser();

 user.setId(rs.getString("user_id"));
 user.setName(rs.getString("name"));
 user.setSex(rs.getString("sex").charAt(0));
 user.setAge(rs.getInt("age"));

 returnuser;
}
}

 publicListfindAllByRowMapperResultReader(){
 Stringsql="SELECT*FROMUSER";
 returnjdbcTemplate.query(sql,newRowMapperResultReader(newUserRowMapper()));
}

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

publicUsergetUser(finalStringid)throwsDataAccessException{
 Stringsql="SELECT*FROMUSERWHEREuser_id=?";
 finalObject[]params=newObject[]{id};
 Listlist=jdbcTemplate.query(sql,params,newRowMapperResultReader(newUserRowMapper()));

 return(User)list.get(0);
}

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

publicPreparedStatementcreatePreparedStatement(Connectioncon)throwsSQLException{
 returncon.prepareStatement(sql);
}

 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("insertintoweb_personvalues(?,?,?)",Object[]);

 template.update("insert into web_person values(?,?,?)",Object[]);

或

template.update("insertintoweb_personvalues(?,?,?)",newPreparedStatementSetter(){匿名内部类只能访问外部最终局部变量

 publicvoidsetValues(PreparedStatementps)throwsSQLException{
 ps.setInt(index++,3);
});

 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

publicvoidsetValues(PreparedStatementps)throwsSQLException{
 ps.setInt(index++,3);
}

 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

publicObjectmapRow(ResultSetrs,intarg1)throwsSQLException{int表当前行数
 person.setId(rs.getInt("id"));
}
 Listtemplate.query("select*fromweb_personwhereid=?",Object[],RowMapper);

 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*fromweb_personwhereid=?",Object[],newRowCallbackHandler(){
 publicvoidprocessRow(ResultSetrs)throwsSQLException{
 person.setId(rs.getInt("id"));
});

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