Spring 中的JdbcTemplate使用（转）
2009-04-27 13:20
1.JdbcTemplate的execute()方法执行SQL DDL语句,例如：
jdbcTemplate.execute("CREATE TABLE USER (user_id integer, name varchar(100))");
使用JdbcTemplate进行查询时,可以使用queryForXXX()等方法,例如使用queryForInt()方法传回user表格中的数据数目： jdbcTemplate.quertForInt("select count(*) from user"); 也可以使用queryForObject()传回一个查询后的对象,例如传回一个String对象：
String name=(String)jdbcTemplate.queryForObject("selcet name from user where id=?",new Object[]{id},java.lang.String.class);)
单独查询某个数据并赋值给特定对象时：
??? public BaseObj getBaseObj(final int ID) {
??????? String sql = "select * from " + DB_TABLE_NAME + " where NewsId=" + ID;
??????? BaseObj obj =(BaseObj) getJdbcTemplate().query(sql,new ResultSetExtractor(){
??????????? public Object extractData(ResultSet rs) throws SQLException,DataAccessException {
??????????????? if (rs.next()) {
??????????????????? NewsObj news = new NewsObj();
??????????????????? news.setID(rs.getInt("NewsID"));
??????????????????? news.setTitle(rs.getString("NewsTitle"));
??????????????????? news.setBigClass(rs.getInt("BigClassId"));
??????????????????? news.setNewsContent(rs.getString("NewsContent"));
??????????????????? news.setNewsKey(rs.getString("NewsKey"));
??????????????????? news.setNewsAuthor(rs.getString("NewsAuthor"));
??????????????????? news.setImg(rs.getBoolean("isImg"));
??????????????????? news.setNewsFrom(rs.getString("NewsFrom"));
??????????????????? return news;
??????????????? }
??????????????? return null;
??????????? }
??????? });
?????? return obj;
??? }
上面两个例子都是传回单独一笔数据,如果要传回多笔数据,则可以使用queryForList()方法
例如：
List rows=jdbcTemplate().queryForList("select * from user where id="+id.intValue()); 传回的list中包括的是map对象,每个map对象代表查询结果中的一笔数据,每笔数据包括多个字段,要取得字段中的值,就要使用字段名作为key,
例如：
??? Iterator it=rows.iterator();
??? while(it.hasNext()){
??????? Map result=(Map)it.next();
??????? System.out.println(userMap.get("id"));
??????? System.out.println(userMap.get("name"));
??????? System.out.println(userMap.get("age"));
???? }
在查询的同时,你可以在返回结果之前先进行一些处理,这就要实现RowCallbackHandler接口
public User find(Integer id){
??? final User user=new User();
??? jdbcTemplate.query("select * from user where id=?",new Object[]{id},
???????????????????????????????????? new RowCallBackHandler(){
?????????????????????????????????????????? public void proccessRow(ResultSet rs){?
???????????????????????????????????????????????? user.setId(new Integer(rs.getInt("id")));
???????????????????????????????????????????????? uset.setName(rs.getString("name"));????
??????????????????????????????????????????? }});
??? return user;
}
如果一次要返回多个查询结果对象,则可以实现RowMapper接口
public class UserRowMapper implements RowMapper{
??????? public Object MapRow(ResultSet rsmint rowNum) throws SQLException{
??????????????? User user=new User();
??????????????? user.setId(new Integer(rs.getInt("id")));
??????????????? user.setName(rs.getString("name"));
??????????????? return user;
?????? }?
}
使用RowMapper查询单笔数据
public User find(Integer id){
???????? User user=(User)jdbcTemplate.queryForObject("select * from user where id=?",new Object[]{id},new UserRowMapper());
????????? return user;
}
使用RowMapper查询多笔数据
class UserRowMapper implements RowMapper {
???????? public Object mapRow(ResultSet rs,int index) throws SQLException?
???????? {
???????????? User u = new User();
???????????? u.setId(rs.getString(”ID”));
???????????? u.setName(rs.getString(”Name”));
???????????? u.setPassword(rs.getString(”Password”));
???????????? return u;
???????? }
???? }
public List select(String where)
??? {
??????? List list;????????
??????? String sql = "select * from admin "+where;????????
??????? list = jdbcTemplate.query(sql,new RowMapperResultReader(new UserRowMapper()));
??????? return list;
??? }
传回的users对象中,包括了从数据库查询出来的结果,并已经封装成user对象
JdbcTemplate语句使用:
1、使用JdbcTemplate的execute()方法执行SQL语句
代码
jdbcTemplate.execute("CREATE TABLE USER (user_id integer, name varchar(100))");
2、如果是UPDATE或INSERT,可以用update()方法。
代码
jdbcTemplate.update("INSERT INTO USER VALUES('"???
??????????? + user.getId() + "', '"???
??????????? + user.getName() + "', '"???
??????????? + user.getSex() + "', '"???
??????????? + user.getAge() + "')");??
3、带参数的更新
代码
jdbcTemplate.update("UPDATE USER SET name = ? WHERE user_id = ?", new Object[] {name, id});
代码
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
代码
int count = jdbcTemplate.queryForInt("SELECT COUNT(*) FROM USER");
代码
String name = (String) jdbcTemplate.queryForObject("SELECT name FROM USER WHERE user_id = ?", new Object[] {id}, java.lang.String.class);
代码
List rows = jdbcTemplate.queryForList("SELECT * FROM USER");
代码
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
代码
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);????
???????????????????????? }????
???????????????????? });???
代码
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"));????
??????????????????????? }????
??????????????????? });???
代码
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
代码
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
代码
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)
代码
template.update("insert into web_person values(?,?,?)",Object[]);??
或
代码
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
代码
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
代码
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
代码
template.query("select * from web_person where id=?",Object[],new RowCallbackHandler(){????
public void processRow(ResultSet rs) throws SQLException {????
person.setId(rs.getInt("id"));????
}); ?
