利用jdbc写的一个类似DBUtils的框架
package com.jdbc.orm.dbutils; import java.io.IOException;
import java.io.InputStream;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.Properties; import com.jdbc.orm.handler.ResultsetHand; /**
*
* 功能描述：基于jdbc自己封装的orm小框架
*
*/
public class DBUtils {
public static String username;
public static String password;
public static String driverClass;
public static String url; public static Connection connection;
public static PreparedStatement statement;
public static ResultSet rs; static {
Properties properties = new Properties();
InputStream in = DBUtils.class.getClassLoader().getResourceAsStream("db.properties");
try {
properties.load(in);// 加载数据库的配置文件
driverClass = properties.get("jdbc.driverclass").toString();
username = properties.get("jdbc.username").toString();
password = properties.get("jdbc.password").toString();
url = properties.get("jdbc.url").toString();
} catch (IOException e) {
e.printStackTrace();
try {
Class.forName(driverClass);// 加载数据库的驱动程序
} catch (ClassNotFoundException e1) {
e1.printStackTrace();
}
}
} /**
*
* 功能 ：为SQL语句设置参数
*
* @param sql
* 输入的sql语句
* @param params
* 需要的参数
* @throws SQLException
*/
public static void setParams(String sql, Object... params) throws SQLException {
connection = DriverManager.getConnection(url, username, password);
statement = connection.prepareStatement(sql);
if ( params != null && params.length > 0) {
for (int i = 0; i < params.length; i++) {
statement.setObject(i + 1, params[i]);
}
}
} /**
*
* @功能 ：根据ID查询实体
* @param sql
* @param id
* @return 返回结果集
* @throws Exception
*/
public static ResultSet queryBeanById(String sql, int id) throws Exception {
setParams(sql, id);
return statement.executeQuery();
} /**
*
* @功能 ：查询功能
* @param sql
* @param params
* @return 将查询到的结果映射到一个实体中返回
* @throws SQLException
*/
public static Object query(String sql, ResultsetHand rsh, Object... params) throws SQLException {
setParams(sql, params);
ResultSet rs = statement.executeQuery();
return rsh.handler(rs);
} /**
*
* @功能 ：增删改功能
* @param sql
* @param params
* @throws SQLException
*/
public static int update(String sql, Object... params) throws SQLException {
setParams(sql, params);
return statement.executeUpdate();
} }
package com.jdbc.orm.handler; import java.lang.reflect.Field;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.util.ArrayList;
import java.util.List; /**
* @描述 : 将查询到的结果映射到集合中
* @author 作者 jjkang
* @version 创建时间：2017年10月6日 下午8:04:46
*/
@SuppressWarnings("rawtypes")
public class BeanListHandler implements ResultsetHand {
private Class clazz; public BeanListHandler(Class clazz) {
this.clazz = clazz;
} @SuppressWarnings("unchecked")
@Override
public Object handler(ResultSet rs) {
List list = new ArrayList();
try { ResultSetMetaData metaData = rs.getMetaData();
int columnCount = metaData.getColumnCount();
while (rs.next()) {
Object bean = clazz.newInstance();
for (int i = 0; i < columnCount; i++) {
Object object = rs.getObject(i + 1);
String name = metaData.getColumnName(i + 1);
Field field = clazz.getDeclaredField(name);
field.setAccessible(true);
field.set(bean, object);
}
list.add(bean);
}
return list;
} catch (Exception e) {
throw new RuntimeException(e);
}
} }
package com.jdbc.orm.handler; import java.lang.reflect.Field;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData; /**
* @描述 :将查询的结果映射到实体中
* @author 作者 E-mail: jiajunkang@outlook.com
* @version 创建时间：2017年10月6日 下午5:45:04
*/
public class BeanHandler implements ResultsetHand { private Class clazz;// 将结果映射到的实体 public BeanHandler(Class clazz) {
this.clazz = clazz;
} @Override
public Object handler(ResultSet rs) {
try {
if (!rs.next()) {
return null;
}
Object bean = clazz.newInstance();
ResultSetMetaData metaData = rs.getMetaData();
int columnCount = metaData.getColumnCount();
for (int i = 0; i < columnCount; i++) {
String name = metaData.getColumnName(i + 1);// 得出每一列的列名
Object value = rs.getObject(i + 1);// 得到每一列的值
Field field = clazz.getDeclaredField(name);// 利用反射，根据列名得到属性对象
field.setAccessible(true);
field.set(bean, value);
}
return bean;
} catch (Exception e) {
throw new RuntimeException(e);
}
}
}
package com.jdbc.orm.junit; import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List; import org.junit.Test; import com.jdbc.orm.bean.Student;
import com.jdbc.orm.dbutils.DBUtils;
import com.jdbc.orm.handler.BeanHandler;
import com.jdbc.orm.handler.BeanListHandler; /**
* 描述 : 测试DBUtils
* @version 创建时间：2017年10月6日 下午2:40:45
*/
public class TestDBUtils {
DBUtils dbUtils = new DBUtils();
@Test
public void test(){
System.out.println(dbUtils.driverClass);
System.out.println(dbUtils.password);
System.out.println(dbUtils.url);
System.out.println(dbUtils.username);
} @Test
public void testSetParams() throws SQLException{
String sql = "select name from student where id = ?";
Object params[] = {1};
DBUtils.setParams(sql, params);
}
@Test
public void testQueryBeanById() throws Exception{
String sql = "select id,name,chinese,english,math from student where id = ?";
ResultSet rs=dbUtils.queryBeanById(sql, 1);
Student student = new Student(); while(rs.next()){
student.setId(rs.getInt(1));
student.setName(rs.getString(2));
student.setChinese(rs.getDouble(3));
student.setEnglish(rs.getDouble(4));
student.setMath(rs.getDouble(5));
}
System.out.println(student);
} @Test
public void testUpdate() throws SQLException{
String sql = "update student set name=? where id =?";
Object[] params = {"李晓明",1};
int rows = dbUtils.update(sql, params);
System.out.println(rows);
} @Test
public void testQuery() throws Exception{
String sql = "select id,name,chinese,english,math from student where id = ?";
Student student = new Student();
student = (Student) dbUtils.query(sql,new BeanHandler(Student.class), 1);
System.out.println(student);
}
@Test
public void testQuery1() throws Exception{
String sql = "select id,name,chinese,english,math from student";
List<Student> list = new ArrayList<>();
list = (List<Student>) dbUtils.query(sql,new BeanListHandler(Student.class), null);
System.out.println(list.size());
System.out.println(list);
}
}