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。

Java 代码

1. jdbcTemplate.update("INSERT INTO USER VALUES('"
2. + user.getId() + "', '"
3. + user.getName() + "', '"
4. + user.getSex() + "', '"
5. + user.getAge() + "')");
6. jdbcTemplate.update("INSERT INTO USER VALUES('"
7. + user.getId() + "', '"
8. + user.getName() + "', '"
9. + user.getSex() + "', '"
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. jdbcTemplate.update("UPDATE USER SET name = ? WHERE user_id = ?", new Object[] {name, id});

Java代码

1. jdbcTemplate.update("INSERT INTO USER VALUES(?, ?, ?, ?)", new Object[] {user.getId(), user.getName(), user.getSex(), user.getAge()});
2. 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

Java代码

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

Java代码

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

Java代码

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

Java代码

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. }
10. List rows = jdbcTemplate.queryForList("SELECT * FROM USER");
11. Iterator it = rows.iterator();
12. while(it.hasNext()) {
13. Map userMap = (Map) it.next();
14. System.out.print(userMap.get("user_id") + "\t");
15. System.out.print(userMap.get("name") + "\t");
16. System.out.print(userMap.get("sex") + "\t");
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

Java代码

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);
12. }
13. });
14. final String id = user.getId();
15. final String name = user.getName();
16. final String sex = user.getSex() + "";
17. final int age = user.getAge();
18. jdbcTemplate.update("INSERT INTO USER VALUES(?, ?, ?, ?)",
19. new PreparedStatementSetter() {
20. public void setValues(PreparedStatement ps) throws SQLException {
21. ps.setString(1, id);
22. ps.setString(2, name);
23. ps.setString(3, sex);
24. ps.setInt(4, age);
25. }
26. });

Java代码

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"));
10. }
11. });
12. final User user = new User();
13. jdbcTemplate.query("SELECT * FROM USER WHERE user_id = ?",
14. new Object[] {id},
15. new RowCallbackHandler() {
16. public void processRow(ResultSet rs) throws SQLException {
17. user.setId(rs.getString("user_id"));
18. user.setName(rs.getString("name"));
19. user.setSex(rs.getString("sex").charAt(0));
20. user.setAge(rs.getInt("age"));
21. }
22. });

Java代码

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"));
5. user.setName(rs.getString("name"));
6. user.setSex(rs.getString("sex").charAt(0));
7. user.setAge(rs.getInt("age"));
8. return user;
9. }
10. }
11. public List findAllByRowMapperResultReader() {
12. String sql = "SELECT * FROM USER";
13. return jdbcTemplate.query(sql, new RowMapperResultReader(new UserRowMapper()));
14. }
15. class UserRowMapper implements RowMapper {
16. public Object mapRow(ResultSet rs, int index) throws SQLException {
17. User user = new User();
18. user.setId(rs.getString("user_id"));
19. user.setName(rs.getString("name"));
20. user.setSex(rs.getString("sex").charAt(0));
21. user.setAge(rs.getInt("age"));
22. return user;
23. }
24. }
25. public List findAllByRowMapperResultReader() {
26. String sql = "SELECT * FROM USER";
27. return jdbcTemplate.query(sql, new RowMapperResultReader(new UserRowMapper()));
28. }

在getUser(id)里面使用UserRowMapper

Java代码

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. }
7. public User getUser(final String id) throws DataAccessException {
8. String sql = "SELECT * FROM USER WHERE user_id=?";
9. final Object[] params = new Object[] { id };
10. List list = jdbcTemplate.query(sql, params, new RowMapperResultReader(new UserRowMapper()));
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

Java代码

1. public PreparedStatement createPreparedStatement(Connection con) throwsSQLException {
2. return con.prepareStatement(sql);
3. }
4. public PreparedStatement createPreparedStatement(Connection con) throwsSQLException {
5. return con.prepareStatement(sql);
6. }

1.增删改

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

Java代码

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

或

Java代码

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
2. public void setValues(PreparedStatement ps) throws SQLException {
3. ps.setInt(index++,3);
4. });
5. 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
6. public void setValues(PreparedStatement ps) throws SQLException {
7. ps.setInt(index++,3);
8. });
9. org.springframework.jdbc.core.PreparedStatementSetter //接口 处理预编译SQL
10. public void setValues(PreparedStatement ps) throws SQLException {
11. ps.setInt(index++,3);
12. }
13. public void setValues(PreparedStatement ps) throws SQLException {
14. ps.setInt(index++,3);
15. }

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

Java代码

1. public Object mapRow(ResultSet rs, int arg1) throws SQLException { //int表当前行数
2. person.setId(rs.getInt("id"));
3. }
4. List template.query("select * from web_person where id=?",Object[],RowMapper);
5. public Object mapRow(ResultSet rs, int arg1) throws SQLException { //int表当前行数
6. person.setId(rs.getInt("id"));
7. }
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

Java代码

1. template.query("select * from web_person where id=?",Object[],new RowCallbackHandler(){
2. public void processRow(ResultSet rs) throws SQLException {
3. person.setId(rs.getInt("id"));
4. });