JdbcTemplate学习笔记

JdbcTemplate学习笔记

1、使用JdbcTemplate的execute()方法执行SQL语句

Java 代码

1. jdbcTemplate.execute("CREATE TABLE USER (user_id integer, name varchar(100))");    
2. jdbcTemplate.execute("CREATE TABLE USER (user_id integer, name varchar(100))");  

2、如果是UPDATE或INSERT,可以用update()方法。

1. jdbcTemplate.update("INSERT INTO USER VALUES('"      
2. + user.getId() + "', '"      
3. + user.getName() + "', '"      
4. + user.getSex() + "', '"      
5. + user.getAge() + "')");      
10. + user.getAge() + "')");  

3、带参数的更新

Java代码

1. jdbcTemplate.update("UPDATE USER SET name = ? WHERE user_id = ?", new Object[]

   {name, id});        

2. {name, id});  

1. jdbcTemplate.update("INSERT INTO USER VALUES(?, ?, ?, ?)", new Object[]

   {user.getId(), user.getName(), user.getSex(), user.getAge()});        

2. {user.getId(), user.getName(), user.getSex(), user.getAge()});  

4、使用JdbcTemplate进行查询时，使用queryForXXX()等方法

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

1. String name = (String) jdbcTemplate.queryForObject("SELECT name FROM USER WHERE user_id = ?", new Object[]

   {id}, java.lang.String.class);        

2. {id}, java.lang.String.class);  

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

1. List rows = jdbcTemplate.queryForList("SELECT * FROM USER");      
2. Iterator it = rows.iterator();      
3. while(it.hasNext()) {      
4. Map userMap = (Map) it.next();      
5. System.out.print(userMap.get("user_id") + "\t");      
6. System.out.print(userMap.get("name") + "\t");      
7. System.out.print(userMap.get("sex") + "\t");      
8. System.out.println(userMap.get("age") + "\t");      
9. }      
17. System.out.println(userMap.get("age") + "\t"); 
18. }  

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

1. final String id = user.getId();        
2. final String name = user.getName();        
3. final String sex = user.getSex() + "";        
4. final int age = user.getAge();      
5. jdbcTemplate.update("INSERT INTO USER VALUES(?, ?, ?, ?)",      
6. new PreparedStatementSetter() {        

7. public void setValues(PreparedStatement

   ps) throws SQLException {        

8. ps.setString(1, id);      
9. ps.setString(2, name);      
10. ps.setString(3, sex);      
11. ps.setInt(4, age);      
13. });      
14. final String id = user.getId();      
15. final String name = user.getName();      
16. final String sex = user.getSex() + "";      
19. new PreparedStatementSetter() {          
21. ps.setString(1, id);        
22. ps.setString(2, name);          
23. ps.setString(3, sex);        
24. ps.setInt(4, age);          
25. }        
26. });        

1. final User user = new User();          
2. jdbcTemplate.query("SELECT * FROM USER WHERE user_id = ?",        
3. new Object[] {id},        
4. new RowCallbackHandler() {        

5. public void processRow(ResultSet rs) throws SQLException

   {        

6. user.setId(rs.getString("user_id"));      
7. user.setName(rs.getString("name"));      
8. user.setSex(rs.getString("sex").charAt(0));        
9. user.setAge(rs.getInt("age"));        
12. final User user = new User();      
14. new Object[] {id},          
15. new RowCallbackHandler() {      
17. user.setId(rs.getString("user_id"));        
18. user.setName(rs.getString("name"));        
22. });  

1. class UserRowMapper implements RowMapper

   {      

2. public Object mapRow(ResultSet rs, int index) throws SQLException
3. User user = new User();      
4. user.setId(rs.getString("user_id"));          
6. user.setSex(rs.getString("sex").charAt(0));          
7. user.setAge(rs.getInt("age"));          
8. return user;             
9. }             
11. public List findAllByRowMapperResultReader() {          
12. String sql = "SELECT * FROM USER";      
13. return jdbcTemplate.query(sql, new RowMapperResultReader(new UserRowMapper()));      
15. class UserRowMapper implements RowMapper {      
17. User user = new User();        
22. return user;        
26. String sql = "SELECT * FROM USER";        

在getUser(id)里面使用UserRowMapper

1. public User getUser(final String id) throws DataAccessException
2. String sql = "SELECT * FROM USER WHERE user_id=?";        

3. final Object[] params = new Object[]

   { id };        

4. List list = jdbcTemplate.query(sql, params, new RowMapperResultReader(new UserRowMapper()));          
5. return (User) list.get(0);        
6. }    
8. String sql = "SELECT * FROM USER WHERE user_id=?";          
9. { id };          
11. return (User) list.get(0);          
12. }

网上收集

org.springframework.jdbc.core.PreparedStatementCreator 返回预编译SQL 不能于Object[]一起用

1. public PreparedStatement createPreparedStatement(Connection con) throwsSQLException
2. return con.prepareStatement(sql);        

1.增删改

org.springframework.jdbc.core.JdbcTemplate 类(必须指定数据源dataSource)

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

或

1. 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        

3. ps.setInt(index++,3);        
5. 只能访问外部最终局部变量      
9. org.springframework.jdbc.core.PreparedStatementSetter //接口 处理预编译SQL            

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

1. public Object mapRow(ResultSet rs, int arg1) throws SQLException

   { //int表当前行数        

2. person.setId(rs.getInt("id"));        
4. List template.query("select * from web_person where id=?",Object[],RowMapper);        
8. 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

1. template.query("select * from web_person where id=?",Object[],new RowCallbackHandler(){        
4. });