09-JDBC高级

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1 自定义JDBC的框架

    1.1 UserDao的CRUD的编写已经总结出规律

// 进行增删改查
    // 增
    public void insert(User user) throws SQLException {
        Connection conn = ConnectionUtil.getConnection();
        String sql = "insert into user(username,psw) values(?,?)";
        PreparedStatement psmt = conn.prepareStatement(sql);
        psmt.setString(1, user.getUserName());
        psmt.setString(2, user.getPassword());
        psmt.executeUpdate();
        ConnectionUtil.close(conn, psmt, null);
    }

    // 删除
    public void delete(int id) throws SQLException {
        Connection conn = ConnectionUtil.getConnection();
        String sql = "delete from user where id=?";
        PreparedStatement psmt = conn.prepareStatement(sql);
        psmt.setInt(1, id);
        psmt.executeUpdate();
        ConnectionUtil.close(conn, psmt, null);
    }
    // 总结增删改：
    // 一样地方获取连接，释放资源，获得PreparedStatement，执行executeUpdate
    // 不一样的地方，sql语句不一样，设置参数也不一样
    // 更新
    public void update(int id, String name) throws SQLException {
        Connection conn = ConnectionUtil.getConnection();
        String sql = "update user set username=? where id=?";
        PreparedStatement psmt = conn.prepareStatement(sql);
        psmt.setString(1, name);
        psmt.setInt(2, id);
        psmt.executeUpdate();
        ConnectionUtil.close(conn, psmt, null);
    }
    
    // 总结查询单个：一样地方获取连接，释放资源，获得PreparedStatement，executeQuery
    // 不一样的地方，sql语句不一样，设置参数也不一样,返回值不一样
    // 查询
    public User query(int id) throws SQLException {
        Connection conn = ConnectionUtil.getConnection();
        String sql = "select * from user where id=?";
        PreparedStatement psmt = conn.prepareStatement(sql);
        psmt.setInt(1, id);
        ResultSet rs = psmt.executeQuery();
        User user = new User();
        if (rs.next()) {
            String username = rs.getString(2);
            String psw = rs.getString(3);
            user.setId(id);
            user.setUserName(username);
            user.setPassword(psw);
        }
        ConnectionUtil.close(conn, psmt, rs);
        return user;
    }

    
    // 总结查询列表：一样地方获取连接，释放资源，获得PreparedStatement，executeQuery
    // 不一样的地方，sql语句不一样，设置参数也不一样,返回值列表不一样
    // 查询
    public List<User> getAllUser() throws SQLException {
        Connection conn = ConnectionUtil.getConnection();
        String sql = "select * from user";
        PreparedStatement psmt = conn.prepareStatement(sql);
        ResultSet rs = psmt.executeQuery();
        List<User> users=new ArrayList<User>();
        while (rs.next()) {
            User user = new User();
            String username = rs.getString(2);
            String psw = rs.getString(3);
            user.setId(rs.getInt(1));
            user.setUserName(username);
            user.setPassword(psw);
            users.add(user);
        }
        ConnectionUtil.close(conn, psmt, rs);
        return users;
    }

 1.2 总结增删改

        1.2.1  一样地方获取连接，释放资源，获得PreparedStatement，执行executeUpdate

        1.2.2 不一样的地方，sql语句不一样，设置参数也不一样

   1.3 总结查询单个

        1.3.1 一样地方获取连接，释放资源，获得PreparedStatement，executeQuery

        1.3.2 不一样的地方，sql语句不一样，设置参数也不一样,返回值不一样

    1.4 总结查询列表

        1.4.1 一样地方获取连接，释放资源，获得PreparedStatement，executeQuery

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       1.4.2 不一样的地方，sql语句不一样，设置参数也不一样,返回值列表不一样

     1.5 元数据的学习

        * DataBaseMetaData

@Test
	public void test1() throws Exception {
		//DatabaseMetaData
		Connection conn = ConnectionUtils.getConnection();
		DatabaseMetaData metaData = conn.getMetaData();
		String productName=metaData.getDatabaseProductName();
		String productVersion=metaData.getDatabaseProductVersion();
		String driverName=metaData.getDriverName();
		String driverVersion=metaData.getDriverVersion();
		String url=metaData.getURL();
		String username=metaData.getUserName();
		System.out.println(productName);
		System.out.println(productVersion);
		System.out.println(driverName);
		System.out.println(driverVersion);
		System.out.println(url);
		System.out.println(username);
		ConnectionUtils.close(conn, null);
	}

 * ParameterMetaData

/ 测试元数据(ParameterMetaData)
    @Test
    public void test16() throws SQLException {
        Connection conn = ConnectionUtil.getConnection();
        // 1 获得ParameterMetaData
        String sql="select * from user where id=?";
        PreparedStatement psmt = conn.prepareStatement(sql);
        psmt.setInt(1, 5);
        ParameterMetaData parameterMetaData = psmt.getParameterMetaData();
        int parameterCount = parameterMetaData.getParameterCount();
        System.out.println(parameterCount);
        // 这个Mysql驱动不支持
        //java.sql.SQLException: Parameter metadata not available for the given statement
//      int parameterType = parameterMetaData.getParameterType(1);
//      String parameterClassName = parameterMetaData.getParameterClassName(1);
//      String parameterTypeName = parameterMetaData.getParameterTypeName(1);
//      System.out.println(parameterType);
//      System.out.println(parameterClassName);
//      System.out.println(parameterTypeName);
        ConnectionUtil.close(conn, psmt, null);
    }

 

#将db.properties文件放在任意资源管理文件夹下，程序编译的时候会自动放入项目的类路径下(classpath),方便查找
#key=value格式编写  不要多余的符号
#oracle
#driver=oracle.jdbc.OracleDriver
#url=jdbc:oracle:thin:@127.0.0.1:1521:xe
#username=scott
#pwd=tiger
#mysql
#早期的数据库版本需要指定设置发送连接数据时候的编码
driver=com.mysql.jdbc.Driver
url=jdbc:mysql://127.0.0.1:3306/etc0102?useUnicode=true&characterEncoding=utf-8&generateSimpleParameterMetadata=true
username=root
pwd=root

 * ResultSetMetaData

 // 测试元数据(ResultSetMetaData)
    @Test
    public void test17() throws SQLException {
        Connection conn = ConnectionUtil.getConnection();
        // 1 获得ParameterMetaData
        String sql="select * from user where id=?";
        PreparedStatement psmt = conn.prepareStatement(sql);
        psmt.setInt(1, 3);
        ResultSet rs = psmt.executeQuery();
        ResultSetMetaData metaData = rs.getMetaData();
        int columnCount = metaData.getColumnCount();
        System.out.println("columnCount:"+columnCount);
        for(int i=0;i<columnCount;i++) {
            String columnName = metaData.getColumnName(i+1);
            String columnTypeName = metaData.getColumnTypeName(i+1);
            System.out.println("columnName:"+columnName);
            System.out.println("columnTypeName:"+columnTypeName);
        }
        ConnectionUtil.close(conn, psmt, null);
    }

1.6 封装JDBC框架

        * JdbcUtils

        * public static void update(String sql,Object[] params)

        * public static Object query(String sql,Object[] params,ResultSetHandler rsh)

        * 定义ResultSetHandler接口

            * public Object handler(ResultSet rs) 

        * BeanResultSetHandler

        * ListResultSetHandler(作业)

        * Map....

// CUD:封装
    public static void update(String sql, Object[] params) {
        Connection conn = null;
        PreparedStatement stmt = null;
        try {
            conn = ConnectionUtil.getConnection();
            stmt = conn.prepareStatement(sql);
            ParameterMetaData parameterMetaData = stmt.getParameterMetaData();
            int paramCount = parameterMetaData.getParameterCount();
            if (params != null && paramCount != params.length) {
                throw new IllegalAnnotationException("参数的个数不对");
            }
            for (int i = 0; i < paramCount; i++) {
                stmt.setObject(i + 1, params[i]);
            }
            stmt.executeUpdate();
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            ConnectionUtil.close(conn, stmt, null);
        }
    }
    

// 进行增删改查
    // 增
    public void insert(User user) throws SQLException {
        String sql = "insert into user(username,psw) values(?,?)";
        Object[] params = { user.getUsername(), user.getPsw() };
        JdbcUtils.update(sql, params);
    }

    // 删除
    public void delete(int id) throws SQLException {
        String sql = "delete from user where id=?";
        Object[] params = { id };
        JdbcUtils.update(sql, params);
    }

    // 总结增删改：
    // 一样地方获取连接，释放资源，获得PreparedStatement，执行executeUpdate
    // 不一样的地方，sql语句不一样，设置参数也不一样
    // 更新
    public void update(int id, String name) throws SQLException {
        String sql = "update user set username=? where id=?";
        Object[] params = { name, id };
        JdbcUtils.update(sql, params);
    }

 // Q:查询
    public static Object query(String sql, Object[] params, ResultSetHandler rsh) {
        Connection conn = null;
        PreparedStatement stmt = null;
        ResultSet rs=null;
        try {
            conn = ConnectionUtil.getConnection();
            stmt = conn.prepareStatement(sql);
            ParameterMetaData parameterMetaData = stmt.getParameterMetaData();
            int paramCount = parameterMetaData.getParameterCount();
            if (params != null && paramCount != params.length) {
                throw new IllegalAnnotationException("参数的个数不对");
            }
            for (int i = 0; i < paramCount; i++) {
                stmt.setObject(i + 1, params[i]);
            }
             rs = stmt.executeQuery();
            return rsh.handler(rs);
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            ConnectionUtil.close(conn, stmt, rs);
        }
        return null;
    }

import java.sql.ResultSet;

public interface ResultSetHandler {
    public Object handler(ResultSet rs);
}

import java.lang.reflect.Field;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;

// BeanResultSetHandler
    public class BeanResultSetHandler implements ResultSetHandler {
        Class<?> clss;

        public BeanResultSetHandler(Class<?> clss) {
            this.clss = clss;
        }
        @Override
        public Object handler(ResultSet rs) {
            try {
                if (!rs.next()) {
                    return null;
                }
                ResultSetMetaData metaData = rs.getMetaData();
                Object obj = clss.newInstance();
                // 获得由多少列
                int columnCount = metaData.getColumnCount();
                for (int i = 0; i < columnCount; i++) {
                    // 获得列的名字
                    String columnName = metaData.getColumnName(i+1);
                    // 获得值
                    Object value = rs.getObject(columnName);
                    Field field = clss.getDeclaredField(columnName);
                    // 暴力反射打开私有
                    field.setAccessible(true);
                    field.set(obj, value);
                }
                return obj;
            } catch (Exception e) {
                e.printStackTrace();
            } finally {
                ConnectionUtil.close(null, null, rs);
            }
            return null;
        }
    }

备注：

* http://www.cnblogs.com/xdp-gacl/p/4006830.html

2 使用ApacheJDBC的框架（DBUtils）

    2.1 下载jar和源码（ https://commons.apache.org/proper/commons-dbutils/）

  2.2 导入jar

  2.3 CRUD 测试

        2.3.1 测试CUD

 // 测试插入
    @Test
    public void test1() throws SQLException {
        // 没有传递数据库连接池
        QueryRunner queryRunner = new QueryRunner();
        Connection conn = ConnectionUtil.getConnection();
        String sql = "insert into user(username,psw) values(?,?)";
        Object[] params = { "xiaobai", "123" };
        queryRunner.update(conn, sql, params);
    }

    // 测试删除
    @Test
    public void test2() throws SQLException {
        QueryRunner queryRunner = new QueryRunner();
        Connection conn = ConnectionUtil.getConnection();
        String sql = "delete from user where id=?";
        Object id = 4;
        queryRunner.update(conn, sql, id);
    }

    @Test
    public void test3() throws SQLException {
        QueryRunner queryRunner = new QueryRunner();
        Connection conn = ConnectionUtil.getConnection();
        String sql = "update user set username=? where id=?";
        Object[] params = { "xiaoxiao", 5 };
        queryRunner.update(conn, sql, params);
    }

 2.3.2 源码的解析

         *  QueryRunner

            构造器

 批处理

查询

 

  CUD

 

 

2.3.3 查询

        * 单个查询

@Test
    public void test4() throws SQLException {
        QueryRunner queryRunner = new QueryRunner();
        Connection conn = ConnectionUtil.getConnection();
        String sql = "select * from user where id=?";
        User user = queryRunner.query(conn, sql, new BeanHandler<User>(User.class), 6);
        System.out.println(user);
    }

   * 列表查询

 

// 列表的查询
    @Test
    public void test5() throws SQLException {
        QueryRunner queryRunner = new QueryRunner();
        Connection conn = ConnectionUtil.getConnection();
        String sql = "select * from user";
        List<User> users = queryRunner.query(conn, sql, new BeanListHandler<User>(User.class));
        System.out.println(users);
    }

     2.3.4 批处理

// 测试批处理
    @Test
    public void test6() throws SQLException {
        QueryRunner queryRunner = new QueryRunner();
        Connection conn = ConnectionUtil.getConnection();
        String sql = "insert into user(username,psw) values(?,?)";
        Object[][] params = new Object[10][];
        for (int i = 0; i < 10; i++) {
            params[i]=new Object[] {"xiaochengyan"+i,"123"};
        }
        queryRunner.batch(conn, sql, params);
    }

2.4 ResultSetHandler的子类的测试    

    2.4.1 子类分析

• ArrayHandler：
• ArrayListHandler：
• BeanHandler：
• BeanListHandler：
• ColumnListHandler：
• KeyedHandler(name)：
• MapHandler：
• MapListHandler：

• BeanMapHandler：
• ScalarHandler：

  2.4.2 子类源码的分析

     * ArrayHandler

 总结;数组的长度，就是列个数，数组值，列的值，适应查询出一条数据

  *  ArrayListHandler

       父类：AbstractListHandler

 

 总结;列表装了（数组的长度，就是列个数，数组值，列的值）适应查询出多条数据 

  2.4.3 测试这个子类的用
 

  // ArrayHandler
    @Test
    public void test7() throws SQLException {
        QueryRunner qr = new QueryRunner();
        Connection conn = ConnectionUtil.getConnection();
        String sql = "select * from user where id=?";
        Object result[] = (Object[]) qr.query(conn, sql, new ArrayHandler(), 5);
        System.out.println(Arrays.asList(result)); // list toString()
    }

    // ArrayListHandler
    @Test
    public void test8() throws SQLException {
        QueryRunner qr = new QueryRunner();
        Connection conn = ConnectionUtil.getConnection();
        String sql = "select * from user";
        List<Object[]> list = (List<Object[]>) qr.query(conn, sql, new ArrayListHandler());
        for (Object[] objs : list) {
            System.out.println(Arrays.asList(objs));
        }
    }
    // BeanHandler
    // BeanListHandler
    
    //ColumnListHandler
    @Test
    public void test9() throws SQLException {
        QueryRunner qr = new QueryRunner();
        Connection conn = ConnectionUtil.getConnection();
        String sql = "select * from user";
        List list = (List) qr.query(conn,sql, new ColumnListHandler("username"));
        System.out.println(list);
    }

备注：

* http://www.cnblogs.com/xdp-gacl/p/4007225.html

* https://commons.apache.org/proper/commons-dbutils/