数据库dbutils

common-dbutils.jar

QueryRunner

update方法:
* int update(String sql, Object... params) -->  可执行增、删、改语句
* int update(Connection con, String sql, Object... parmas) --> 需要调用者提供Connection,这说明本方法不再管理Connection了。支持事务!

query方法:
* T query(String sql, ResultSetHandler rsh, Object... params) --> 可执行查询
 > 它会先得到ResultSet,然后调用rsh的handle()把rs转换成需要的类型!
* T query(Connection con, String sql, ResultSetHadler rsh, Object... params),支持事务

ResultSetHandler接口:
* BeanHandler(单行) --> 构造器需要一个Class类型的参数,用来把一行结果转换成指定类型的javaBean对象
* BeanListHandler(多行) --> 构造器也是需要一个Class类型的参数,用来把一行结果集转换成一个javabean,那么多行就是转换成List对象,一堆javabean
* MapHandler(单行) --> 把一行结果集转换Map对象
  > 一行记录:
    sid  sname  age  gender
    1001 zs     99   male
  > 一个Map:
    {sid:1001, sname:zs, age:99, gender:male}
* MapListHandler(多行) --> 把一行记录转换成一个Map,多行就是多个Map,即List<Map>!
* ScalarHandler(单行单列) --> 通常用与select count(*) from t_stu语句!结果集是单行单列的!它返回一个Object
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代码:

 

public void fun1() throws SQLException {
        QueryRunner qr = new QueryRunner(JdbcUtils.getDataSource());
        String sql = "insert into t_stu values(?,?,?,?)";
        Object[] params = {1002, "liSi", 88, "female"};
        
        qr.update(sql, params);
    }
    
    @Test
    public void fun2() throws SQLException {
        // 创建QueryRunner,需要提供数据库连接池对象
        QueryRunner qr = new QueryRunner(JdbcUtils.getDataSource());
        // 给出sql模板
        String sql = "select * from t_stu where sid=?";
        // 给出参数
        Object[] params = {1001};
// 执行query()方法,需要给出结果集处理器,即ResultSetHandler的实现类对象
        // 我们给的是BeanHandler,它实现了ResultSetHandler
        // 它需要一个类型,然后它会把rs中的数据封装到指定类型的javabean对象中,然后返回javabean
        Stu stu = qr.query(sql, new BeanHandler<Stu>(Stu.class), params);
        System.out.println(stu);
    }
    
    /**
     * BeanListHandler的应用,它是多行处理器
     * 每行对象一个Stu对象!
     * @throws Exception
     */
    @Test
    public void fun3() throws Exception {
        QueryRunner qr = new QueryRunner(JdbcUtils.getDataSource());
        String sql = "select * from t_stu";
        List<Stu> stuList = qr.query(sql, new BeanListHandler<Stu>(Stu.class));
        
        System.out.println(stuList);
    }
    
    /**
     * MapHandler的应用,它是单行处理器,把一行转换成一个Map对象
     * @throws SQLException 
     */
    @Test
    public void fun4() throws SQLException  {
        QueryRunner qr = new QueryRunner(JdbcUtils.getDataSource());
        String sql = "select * from t_stu where sid=?";
        Object[] params = {1001};
        Map map = qr.query(sql, new MapHandler(), params);
        
        System.out.println(map);
    }
    
    /**
     * MapListHandler,它是多行处理器,把每行都转换成一个Map,即List<Map>
     * @throws SQLException
     */
    @Test
    public void fun5() throws SQLException  {
        QueryRunner qr = new QueryRunner(JdbcUtils.getDataSource());
        String sql = "select * from t_stu";
        List<Map<String,Object>> mapList = qr.query(sql, new MapListHandler());
        
        System.out.println(mapList);
    }
    
    /**
     * ScalarHandler,它是单行单列时使用,最为合适!
     * @throws SQLException
     */
    @Test
    public void fun6() throws SQLException {
        QueryRunner qr = new QueryRunner(JdbcUtils.getDataSource());
        String sql = "select count(*) from t_stu";
        /*
         * Integer、Long、BigInteger
         */
        Number cnt = (Number)qr.query(sql, new ScalarHandler());
        
        long c = cnt.longValue();
        System.out.println(c);
    }
}

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增、删、改

public void fun1() throws SQLException {
 QueryRunner qr = new QueryRunner();
 String sql = "insert into user values(?,?,?)";
 qr.update(JdbcUtils.getConnection(), sql, "u1", "zhangSan", "123");
}

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DataSource ds = JdbcUtils.getDataSource();
QueryRunner qr = new QueryRunner(ds);
String sql = "select * from tab_student";

// 把结果集转换成Bean
Student stu = qr.query(sql, new BeanHandler<Student>(Student.class));

// 把结果集转换成Bean的List
List<Student> list = qr.query(sql, new BeanListHandler<Student>(Student.class));

// 把结果集转换成Map
Map<String,Object> map = qr.query(sql, new MapHandler());

// 把结果集转换成List<Map>
List<Map<String,Object>> list = qr.query(sql, new MapListHandler() );

// 把结果集转换成一列的List
List<Object> list = qr.query(sql, new ColumnListHandler("name")) ;

// 把结果转换成单行单列的值
Number number = (Number)qr.query(sql, new ScalarHandler());

 

批处理

 DataSource ds = JdbcUtils.getDataSource();
 QueryRunner qr = new QueryRunner(ds);
 String sql = "insert into tab_student values(?,?,?,?)";
 Object[][] params = new Object[10][]; //表示 要插入10行记录
 for(int i = 0; i < params.length; i++) {
  params[i] = new Object[]{"S_300" + i, "name" + i, 30 + i, i%2==0?"男":"女"};
 }
 qr.batch (sql, params);

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posted @ 2017-03-30 20:54  晓梦蝶  阅读(235)  评论(0编辑  收藏  举报