package com.at221.jdbc;

 import java.io.IOException;

 import java.io.InputStream;

 import java.sql.*;

 import java.util.Properties;

 import com.mysql.jdbc.Connection;

 public class JDBCTools {

     public static void release(Statement sta,java.sql.Connection con,ResultSet rs){

         if(sta != null){

             try{

                 sta.close();

             }catch(Exception e){

                 e.getStackTrace();

             }

         }

         if(con != null){

             try{

                 con.close();

             }catch(Exception e){

                 e.getStackTrace();

             }

         }

         if(rs != null){

             try {

                 rs.close();

             } catch (SQLException e) {

                 // TODO Auto-generated catch block

                 e.printStackTrace();

             }

         }

     }

     public static void release(Statement sta,java.sql.Connection con){

         if(sta != null){

             try{

                 sta.close();

             }catch(Exception e){

                 e.getStackTrace();

             }

         }

         if(con != null){

             try{

                 con.close();

             }catch(Exception e){

                 e.getStackTrace();

             }

         }

     }

     public static Connection getConnec() throws SQLException, IOException, ClassNotFoundException,

     InstantiationException, IllegalAccessException{

         String driverClass = null;

         String jdbcUrl = null;

         String user = null;

         String password = null;

         //利用配置文件，来更改数据库的配置

         InputStream is = JDBCTools.class.getClassLoader().getResourceAsStream("jdbc.properties");

         Properties p = new Properties();

         p.load(is);

         driverClass = p.getProperty("driver");

 //        System.out.println(driverClass);

         jdbcUrl = p.getProperty("jdbcUrl");

 //        System.out.println(jdbcUrl);

         user = p.getProperty("user");

 //        System.out.println(driverClass);

         password = p.getProperty("password");

 //        System.out.println(password);

         Properties info = new Properties();

         info.put("user", user);

         info.put("password", password);

         DriverManager.registerDriver((Driver)Class.forName(driverClass).newInstance());

         Connection connec = (Connection)DriverManager.getConnection(jdbcUrl, user, password);

 //        System.out.println(connec);

         return connec;

     }

 }

 package com.at221.jdbc;

 import java.sql.Connection;

 import java.sql.PreparedStatement;

 import java.sql.ResultSet;

 import java.util.HashMap;

 import java.util.Map;

 import org.junit.Test;

 import com.mysql.jdbc.ResultSetMetaData;

 public class TestReflection {

     @Test

     public void test(){

         String sql = "SELECT id Id,name Name,birth Birth,email Email from student where id = ?";

         Student s = (Student)getStudent(Student.class,sql,3);

         System.out.println(s);

     }

     public <T> Object getStudent(Class<T> clazz,String sql,Object ... args ){

         Connection conn = null;

         PreparedStatement ps = null;

         ResultSet rs = null;

         ResultSetMetaData rsmd = null;

         T entity = null;

         try {

             //1.SQL语句进行配置

             conn = JDBCTools.getConnec();

             ps = conn.prepareStatement(sql);

             //①给SQL语句中的通配符赋值

             for(int i = 0; i < args.length; i++){

                 ps.setObject(i+1, args[i]);

             }

             //②利用SQL进行查询得到结果集

             rs = ps.executeQuery();

             //2.创建类的对象

             entity = clazz.newInstance();

             //3.利用jdbc元数据来获得列的别名,为map中的键值对进行赋值

             rsmd = (ResultSetMetaData)rs.getMetaData();

             Map<String, Object> value = new HashMap<String, Object>();

             if(rs.next()){

                 for(int i = 0; i < rsmd.getColumnCount(); i++){

                     String key = rsmd.getColumnLabel(i+1);

                     Object obj = rs.getObject(i+1);

                     value.put(key, obj);

                 }

             }

             //4.利用得到的map进行对创建的对象进行赋值

             if(value.size() > 0){

                 for(Map.Entry<String, Object> entry : value.entrySet()){

                     String column = entry.getKey();

                     Object columnValue = entry.getValue();

                     RecflectionUtils.setFieldValue(entity, column, columnValue);

                 }

             }

         } catch(Exception e){

             e.printStackTrace();

         }finally {

             JDBCTools.release(ps, conn);

         }

         return entity;

     }

 }

 package com.at221.jdbc;

 import java.sql.Date;

 public class Student {

     private int id;

     private String name = null;

     private Date birth = null;

     private String email = null;

     public Student(int id, String name, Date birth, String email) {

         super();

         this.id = id;

         this.name = name;

         this.birth = birth;

         this.email = email;

     }

     public Student() {

         super();

     }

     public int getId() {

         return id;

     }

     public void setId(Integer id) {

         this.id = id.intValue();

     }

     public String getName() {

         return name;

     }

     public void setName(String name) {

         this.name = name;

     }

     public Date getBirth() {

         return birth;

     }

     public void setBirth(Date birth) {

         this.birth = birth;

     }

     public String getEmail() {

         return email;

     }

     public void setEmail(String email) {

         this.email = email;

     }

     @Override

     public String toString() {

         return "Student [id=" + id + ", name=" + name

                 + ", birth=" + birth + ", email=" + email + "]";

     }

 }