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【转】JdbcTemplate学习札记

2012-10-08 
【转】JdbcTemplate学习笔记本文转载自：http://it.oyksoft.com/post/234/?JdbcTemplate学习笔记1、使用JdbcTe

【转】JdbcTemplate学习笔记

本文转载自：http://it.oyksoft.com/post/234/

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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))");???? 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('"?????? + user.getId() + "', '"??????
  2. + user.getName() + "', '"?????? + user.getSex() + "', '"??????
  3. + user.getAge() + "')");?????? jdbcTemplate.update("INSERT INTO USER VALUES('"??????
  4. + user.getId() + "', '"?????? + user.getName() + "', '"??????
  5. + user.getSex() + "', '"?????? + 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");?????? Iterator it = rows.iterator();??????
  2. while(it.hasNext()) {?????? Map userMap = (Map) it.next();??????
  3. System.out.print(userMap.get("user_id") + "\t");?????? System.out.print(userMap.get("name") + "\t");??????
  4. System.out.print(userMap.get("sex") + "\t");?????? System.out.println(userMap.get("age") + "\t");??????
  5. }?????? ??????
  6. List rows = jdbcTemplate.queryForList("SELECT * FROM USER");?????? ??????
  7. Iterator it = rows.iterator();?????? while(it.hasNext()) {??????
  8. Map userMap = (Map) it.next();?????? System.out.print(userMap.get("user_id") + "\t");??????
  9. System.out.print(userMap.get("name") + "\t");?????? System.out.print(userMap.get("sex") + "\t");??????
  10. System.out.println(userMap.get("age") + "\t");
    ????????
  11. }??

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);?????? ps.setString(2, name);??????
  9. ps.setString(3, sex);?????? ps.setInt(4, age);??????
  10. }??????
  11. });?????? ??????
  12. final String id = user.getId();?????? final String name = user.getName();??????
  13. final String sex = user.getSex() + "";?????? final int age = user.getAge();??????
  14. ????????
  15. jdbcTemplate.update("INSERT INTO USER VALUES(?, ?, ?, ?)",?????? ???????? new PreparedStatementSetter() {??????????
  16. public void setValues(PreparedStatement ps) throws SQLException {????????
  17. ps.setString(1, id);????????
  18. ps.setString(2, name);?????????? ps.setString(3, sex);???????? ps.setInt(4, age);??????????
  19. }????????
  20. });????????
Java代码
    ????
  1. 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"));??????
  2. user.setName(rs.getString("name"));?????? user.setSex(rs.getString("sex").charAt(0));???????? user.setAge(rs.getInt("age"));???????? }??????
  3. });?????? ??????
  4. final User user = new User();?????? ???????? jdbcTemplate.query("SELECT * FROM USER WHERE user_id = ?",???????? new Object[] {id},??????????
  5. new RowCallbackHandler() {?????? ??????
  6. ?????? 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"));???????? }???????? });??
Java代码
    ????
  1. class UserRowMapper implements RowMapper {?????? ??????
  2. public Object mapRow(ResultSet rs, int index) throws SQLException {?????? ??????
  3. User user = new User();?????? user.setId(rs.getString("user_id"));??????????
  4. user.setName(rs.getString("name"));????????
  5. user.setSex(rs.getString("sex").charAt(0));?????????? user.setAge(rs.getInt("age"));??????????
  6. return user;?????? ??????
  7. }?????? ??????
  8. }?????? ???????? public List findAllByRowMapperResultReader() {?????? ????
  9. ?????? String sql = "SELECT * FROM USER";??????
  10. ?????? return jdbcTemplate.query(sql, new RowMapperResultReader(new UserRowMapper()));??????
  11. ?????? }??????
  12. ?????? class UserRowMapper implements RowMapper {??????
  13. ?????? public Object mapRow(ResultSet rs, int index) throws SQLException {??????
  14. User user = new User();????????
  15. user.setId(rs.getString("user_id"));????????
  16. user.setName(rs.getString("name"));????????
  17. user.setSex(rs.getString("sex").charAt(0));????????
  18. user.setAge(rs.getInt("age"));????????
  19. return user;????????
  20. }????????
  21. }?????? ??????
  22. public List findAllByRowMapperResultReader() {?????????? String sql = "SELECT * FROM USER";???????? return jdbcTemplate.query(sql, new RowMapperResultReader(new UserRowMapper()));?????? }??

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()));?????????? return (User) list.get(0);???????? }???? ??????
  5. public User getUser(final String id) throws DataAccessException {?????? String sql = "SELECT * FROM USER WHERE user_id=?";??????????
  6. final Object[] params = new Object[] { id };?????????? List list = jdbcTemplate.query(sql, params, new RowMapperResultReader(new UserRowMapper()));??????????
  7. 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

Java代码
    ????
  1. public PreparedStatement createPreparedStatement(Connection con) throws SQLException {????????
  2. return con.prepareStatement(sql);????????
  3. }?????? ??????
  4. public PreparedStatement createPreparedStatement(Connection con) throws SQLException {????????
  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. });??

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