Simple handwritten ORM framework

Simple handwriting ORM frame
Project structure

1. introduce jar package
<dependencies> <dependency> <groupId>mysql</groupId> <artifactId>mysql-connector-java</artifactId> <version>8.0.27</version> </dependency> <dependency> <groupId>com.alibaba</groupId> <artifactId>druid</artifactId> <version>1.2.7</version> </dependency> <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <version>4.12</version> <scope>test</scope> </dependency> <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <version>4.12</version> <scope>test</scope> </dependency> </dependencies>

AnMyTableFieldId annotation

// Mark the primary key used 
// Use 
@Target(ElementType.FIELD)
@Retention(RetentionPolicy.RUNTIME)
public @interface AnMyTableFieldId {
    String value();
}

AnMyTableFiled

// Mark different field names 
public @interface AnMyTableFiled {
    String value();
}

AnMyTableName

// Custom annotation 
// Can only be used on classes 
@Target(ElementType.TYPE)
// Runtime annotations are still in scope 
@Retention(RetentionPolicy.RUNTIME)
public @interface AnMyTableName {
    String value();
}

AccountDao

public class AccountDao  extends BaseDao<Account> {
}

Account

@AnMyTableName("account")
public class Account {
    @AnMyTableFieldId("username")
    private String username;
    @AnMyTableFiled("balance")
    private Integer balance;


    @Override
    public String toString() {
        return "Account{" +
                "username='" + username + '\'' +
                ", balance=" + balance +
                '}';
    }

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public Integer getBalance() {
        return balance;
    }

    public void setBalance(Integer balance) {
        this.balance = balance;
    }
}

DbUtil

package com.ccr.util;

import com.alibaba.druid.pool.DruidDataSourceFactory;

import javax.sql.DataSource;
import java.io.IOException;
import java.io.InputStream;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.Properties;

@SuppressWarnings("all")
public class DbUtil {
//     Declare the data source object 
  private  static DataSource dataSource;

    static {
        try {
            InputStream inputStream = DbUtil.class.getClassLoader().getResourceAsStream("db.properties");
            Properties properties = new Properties();
//           Read configuration file 
            properties.load(inputStream);
//             According to the content in the configuration file datasourcse To configure 
            dataSource = DruidDataSourceFactory.createDataSource(properties);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
//     Get connection pool object 
    public  static Connection getConn(){
//  Get the connection object from the connection pool 
        try {
            Connection connection = dataSource.getConnection();
            return connection;
        } catch (SQLException throwables) {
            throwables.printStackTrace();
        }
        return null;
    }
//     close resource 
    public static void close(ResultSet r, PreparedStatement ps, Connection c) {

        if (r != null) {
            try {
                r.close();

                if (ps != null) {
                    ps.close();
                }
                if (c != null) {
                    c.close();
                }

            } catch (SQLException throwables) {
                throwables.printStackTrace();
            }
        }
    }
}

BaseDao

package com.ccr.util;


import com.ccr.annotation.AnMyTableFieldId;
import com.ccr.annotation.AnMyTableFiled;
import com.ccr.annotation.AnMyTableName;

import java.lang.reflect.Field;
import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Type;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;

// Table plus data 
public class BaseDao<T> {
    public PreparedStatement ps;
    public Connection conn;
    public ResultSet rs;
    private Class<?> aClass;

    public BaseDao() {
//         Of the direct superclass of the current object Type
// To obtain a subclass Dao Reflection class object 
        Class<? extends BaseDao> aClazz = this.getClass();
//         Get subclass objects and subclass object generics 
        ParameterizedType genericSuperclass = (ParameterizedType) aClazz.getGenericSuperclass();
//    Get generic objects in subclasses 
        Type[] actualTypeArguments = genericSuperclass.getActualTypeArguments();
//        Get the reflection object 
        aClass = (Class<?>) actualTypeArguments[0];
//        System.out.println(aClass);

    }

    //     Query all 
    public List<T> findAll() {

//         The query method is to use an array 
        List<T> list = new ArrayList<T>();
        StringBuffer sql = new StringBuffer("select * from ");
//         Get table name 
        String tableName = aClass.getAnnotation(AnMyTableName.class).value();
//        sql Add table name 
        sql.append(tableName);

//         perform sql sentence 
        try {
//         Connect to database 
            conn = DbUtil.getConn();
            ps = conn.prepareStatement(sql.toString());
            rs = ps.executeQuery();
//             Get all field names 
            while (rs.next()){
//                 Create entity class objects 
                Object o = aClass.newInstance();
// Get the property name 
                Field[] declaredFields = aClass.getDeclaredFields();
                for (Field f: declaredFields) {
//                     Set attribute courseware 
                    f.setAccessible(true);
//                     Loop to get the attributes in the table , But not rigorous , The data in the entity class may not be compared with the data in the data group 
//                    f.set(o,rs.getObject(f.getName()));
                    AnMyTableFieldId annotationid = f.getAnnotation(AnMyTableFieldId.class);
//
                    if (annotationid!=null){
                        f.set(o,rs.getObject(annotationid.value()));
                    }
                    AnMyTableFiled annotationname = f.getAnnotation(AnMyTableFiled.class);
                    if (annotationname!=null){
                        f.set(o,rs.getObject(annotationname.value()));
                    }else {
                        f.set(o,rs.getObject(f.getName()));
                    }
                }
                list.add((T) o);

            }

        } catch (Exception throwables) {
            throwables.printStackTrace();
        } finally {
            DbUtil.close(null, ps, conn);
        }
        return list;

    }

    //      according to id Inquire about 
    public T findById(Object id){
        StringBuffer sql = new StringBuffer("select * from ");
//         Get table name 
        String tableName = aClass.getAnnotation(AnMyTableName.class).value();
        sql.append(tableName+" where ");
//         Get primary key id
//         Get all first 
        Field[] declaredFields = aClass.getDeclaredFields();
        for (Field f: declaredFields){
            AnMyTableFieldId annotationid = f.getAnnotation(AnMyTableFieldId.class);
                if (annotationid!=null){
                    String valueid = annotationid.value();
//                     Add to data 
                    sql.append(valueid+"='"+id+"'");
                    break;
                }

        }
        try {
//         Connect to database 
            conn = DbUtil.getConn();
            ps = conn.prepareStatement(sql.toString());
            rs = ps.executeQuery();
            //                 Create entity class objects 

            Object o = aClass.newInstance();
//             Get all field names 
            if (rs.next()){

                for (Field f: declaredFields) {
//                     Set attribute courseware 
                    f.setAccessible(true);
//                     Loop to get the attributes in the table , But not rigorous , The data in the entity class may not be compared with the data in the data group 
//                    f.set(o,rs.getObject(f.getName()));
                    AnMyTableFieldId annotationid = f.getAnnotation(AnMyTableFieldId.class);
//
                    if (annotationid!=null){
                        f.set(o,rs.getObject(annotationid.value()));
                    }
                    AnMyTableFiled annotationname = f.getAnnotation(AnMyTableFiled.class);
                    if (annotationname!=null){
                        f.set(o,rs.getObject(annotationname.value()));
                    }else {
                        f.set(o,rs.getObject(f.getName()));
                    }
                }
              return (T) o;


            }

        } catch (Exception throwables) {
            throwables.printStackTrace();
        }finally {
            DbUtil.close(null, ps, conn);
        }
//        System.out.println(sql);
        return null;
    }

    // Add function add function of all tables . insert into  surface （） values（）
    public int insert(T t) {


        try {
//         Declare a string sql sentence 
            StringBuffer sql = new StringBuffer("insert into ");
//         Get reflection class objects through generics 
            Class<?> aClass = t.getClass();
//         Get the class name by annotation 
            AnMyTableName anMyTableName = aClass.getAnnotation(AnMyTableName.class);
//         Get table name 
            String tableName = anMyTableName.value();
//         Splice the obtained table names sql On 
            sql.append(tableName);
//         Declare two sets   Store column names separately   The column value 
//         The column value 
            ArrayList<Object> values = new ArrayList<Object>();
//         Name 
            ArrayList<String> columns = new ArrayList<String>();


//         Get the column name of the added field through the reflection class 
            Field[] declaredFields = aClass.getDeclaredFields();
            for (Field f : declaredFields) {
// Set the current class property value to visibility 
                f.setAccessible(true);
//             Determine the properties of the current class id Is it empty 
                if (f.getAnnotation(AnMyTableFieldId.class) == null || f.get(t) != null) {
//                 When id When the value is equal to null, add 
                    String name = f.getName();
//                     Add values through generics 
                    Object value = f.get(t);
//                     Save the name in the defined class name array 
                    columns.add(name);
//                     Values are stored in column values   It is uncertain whether the value is the string column value plus ‘’
                    values.add("'" + value + "'");
                }
            }
//             Get the column name and column value   The data is   The array situation appears, so we should put [] Replace （）
            sql.append(columns.toString().replace("[", "(").replace("]", ")"));
            sql.append("values ");
            sql.append(values.toString().replace("[", "(").replace("]", ")"));

            System.out.println(sql);
//           Database connection 
            conn = DbUtil.getConn();
            ps = conn.prepareStatement(sql.toString());
            int i = ps.executeUpdate();
            return i;
        } catch (Exception e) {
            DbUtil.close(null, ps, conn);
        }
        return 0;

    }

    //     modify  update   Table name  set  Field = value  where id=id;
    public int update(T t) {
        try {
            StringBuffer sql = new StringBuffer("update ");
//      1.   Get table name ,
            Class<?> aClass = t.getClass();
//         Get the corresponding table name in the database through annotations 
            AnMyTableName tableNamean = aClass.getAnnotation(AnMyTableName.class);
            String tablename = tableNamean.value();
            sql.append(tablename + " set ");
//         obtain values value 
            Field[] declaredFields = aClass.getDeclaredFields();
//         Acquisition conditions 
            String where = " where ";
            for (Field f : declaredFields) {
//             Set visibility 
                f.setAccessible(true);
//             Get id  Modify the data through judgment 
                AnMyTableFieldId annotation = f.getAnnotation(AnMyTableFieldId.class);
//             Get data 
                String name = f.getName();
                Object value = f.get(t);
                /*if (annotation.equals("")||annotation!=null)*/
                if (annotation == null || annotation.equals("")) {
                    sql.append(name + "='" + value + "',");
                } else {
                    where += name + "='" + value + "'";
                }
            }
//             Intercept where Before , Number 
            String s = sql.substring(0, sql.lastIndexOf(",")) + where;


            Connection conn = DbUtil.getConn();
            ps = conn.prepareStatement(s);
//            System.out.println(s);
            int i = ps.executeUpdate();
            return i;

        } catch (Exception e) {

        } finally {
            DbUtil.close(null, ps, conn);
        }
        return 0;
    }

    //     Delete  delete from  Table name 
    public int delete(Object id) {
        try {
            StringBuffer sql = new StringBuffer("delete from ");
//         Get the reflection object of the entity class     Table name 
            String tableName = aClass.getAnnotation(AnMyTableName.class).value();
            sql.append(tableName + " where ");
//         Get primary key 
            Field[] declaredFields = aClass.getDeclaredFields();
//         Cycle to get id
            for (Field f : declaredFields) {
//             Set field visibility 
                f.setAccessible(true);
//             obtain id value 
                AnMyTableFieldId annotation = f.getAnnotation(AnMyTableFieldId.class);
//             Judge id Is it empty to delete 
                if (annotation != null) {
//                 To get the column name 
                    String vaid = annotation.value();
//               Joining together to SQL in 
                    sql.append(vaid + "='" + id + "'");
//                 Get to stop and delete 
                    break;
                }

            }
//         Get data link object 
            conn = DbUtil.getConn();
            ps = conn.prepareStatement(sql.toString());
            int i = ps.executeUpdate();
            return i;
        } catch (SQLException throwables) {
            throwables.printStackTrace();
        } finally {
            DbUtil.close(null, ps, conn);
        }


        return 0;
    }
}

db.properties

# druid.properties Configuration of files 
driverClassName=com.mysql.cj.jdbc.Driver
url=jdbc:mysql://localhost:3306/tranbook?serverTimezone=Asia/Shanghai
username=root
password=root
#  Initialize the number of connections 
initialSize=5
#  maximum connection 
maxActive=10
#  Maximum timeout 
maxWait=3000

Test

public class Test01 {

    @Test
//     according to id check 
    public void Test11(){

            AccountDao accountDao = new AccountDao();
            Account a = accountDao.findById(" Ha ha ha 21");
            System.out.println(a);
        }

@Test
// add to 
public void Test12(){
    AccountDao accountDao = new AccountDao();
    Account account = new Account();
    account.setUsername(" Ha ha ha ");
    account.setBalance(12);
    int insert = accountDao.insert(account);
    System.out.println(" Add success "+insert);
}
    @Test
// modify 
    public void Test13(){
        AccountDao accountDao = new AccountDao();
        Account account = new Account();
        account.setUsername(" Ha ha ha ");
        account.setBalance(15);
        int update = accountDao.update(account);
        System.out.println(" Modification successful "+update);
    }
    @Test
//    Delete id
    public void Test14(){

        AccountDao accountDao = new AccountDao();
        int a = accountDao.delete(" Ha ha ha ");
        System.out.println(a);
    }
    @Test
//     according to id check 
    public void Test15(){

        AccountDao accountDao = new AccountDao();
        List<Account> all = accountDao.findAll();
        System.out.println(all);
    }
}