JdbcTemplate學習筆記

1、使用JdbcTemplate的execute()方法執行SQL語句

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

3、帶參數的更新

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

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

4、使用JdbcTemplate進行查詢時，使用queryForXXX()等方法

int count = jdbcTemplate.queryForInt("SELECT COUNT(*) FROM USER");String name = (String) jdbcTemplate.queryForObject("SELECT name FROM USER WHERE user_id = ?", new Object[] {id}, java.lang.String.class);List rows = jdbcTemplate.queryForList("SELECT * FROM USER");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將我們使用的JDBC的流程封裝起來，包括了異常的捕捉、SQL的執行、查詢結果的轉換等等。spring大量使用Template Method模式來封裝固定流程的動作，XXXTemplate等類別都是基於這種方式的實現。
    除了大量使用Template Method來封裝一些底層的操作細節，spring也大量使用callback方式類回調相關類別的方法以提供JDBC相關類別的功能，使傳統的JDBC的使用者也能清楚瞭解spring所提供的相關封裝類別方法的使用。

 

JDBC的PreparedStatement
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); } });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")); } });

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)裏面使用UserRowMapper

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); }

網上收集
org.springframework.jdbc.core.PreparedStatementCreator 返回預編譯SQL   不能於Object[]一起用

public PreparedStatement createPreparedStatement(Connection con) throws SQLException { return con.prepareStatement(sql); }

1.增刪改
org.springframework.jdbc.core.JdbcTemplate   類(必須指定數據源dataSource)

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

或

template.update("insert into web_person values(?,?,?)",new PreparedStatementSetter(){ 匿名內部類 只能訪問外部最終局部變量 public void setValues(PreparedStatement ps) throws SQLException { ps.setInt(index++,3); });

org.springframework.jdbc.core.PreparedStatementSetter 接口 處理預編譯SQL
public void setValues(PreparedStatement ps) throws SQLException { ps.setInt(index++,3); }

2.查詢JdbcTemplate.query(String,[Object[]/PreparedStatementSetter],RowMapper/RowCallbackHandler)
org.springframework.jdbc.core.RowMapper   記錄映射接口  處理結果集

public Object mapRow(ResultSet rs, int arg1) throws SQLException { int表當前行數 person.setId(rs.getInt("id")); } List template.query("select * from web_person where id=?",Object[],RowMapper);

org.springframework.jdbc.core.RowCallbackHandler  記錄回調管理器接口 處理結果集

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