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自定义简单版ORMapping框架：

1、在mysql中创建相应的表

create table t_user(id int not null auto_increment,name varchar(10) not null,age int not null,birth_day date,primary key(id)
);

我的mysql版本：

2、框架代码

HuiqBean.java:

package com.xiaoqiang.interview.framework.annotation;import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;/*** Created by Huiq on 2021/4/11.*/
@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.TYPE)
public @interface HuiqBean {String value();
}

HuiqField.java:

package com.xiaoqiang.interview.framework.annotation;import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;/*** Created by Huiq on 2021/4/11.*/
@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.FIELD)
public @interface HuiqField {String value();
}

BaseDAOImpl.java:

package com.xiaoqiang.interview.framework.dao.impl;import com.xiaoqiang.interview.framework.dao.BaseDAO;
import com.xiaoqiang.interview.framework.utils.DBUtils;
import com.xiaoqiang.interview.framework.utils.Tools;import java.io.Serializable;
import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;/*** Created by Huiq on 2021/4/11.*/
public class BaseDAOImpl implements BaseDAO {/*** 入参是T：User** insert into t_user(name,age,birth_day) values(?,?,?);*/@Overridepublic <T> Serializable save(T t) {StringBuilder builder = new StringBuilder("insert into ");String table = Tools.getTable(t.getClass());builder.append(table).append("(");Class<?> clazz = t.getClass();Field[] fields = clazz.getDeclaredFields();for (Field field : fields) {if (!field.getName().equals("id")) {String colum = Tools.getColum(field);builder.append(colum).append(",");}}builder.deleteCharAt(builder.toString().length()-1).append(") values (");for (Field field : fields) {if (!field.getName().equals("id")) {builder.append("?,");}}builder.deleteCharAt(builder.toString().length()-1).append(")");System.out.println(builder.toString());Connection connection = null;PreparedStatement pstmt = null;ResultSet rs = null;int index = 1;try {connection = DBUtils.getConnection();pstmt = connection.prepareStatement(builder.toString(), new String[]{"id"});for (Field field : fields) {if (!field.getName().equals("id")) {String getMethod = Tools.getMethod(field);Method method = clazz.getDeclaredMethod(getMethod);Object obj = method.invoke(t);pstmt.setObject(index++, obj);}}int rowCount = pstmt.executeUpdate();System.out.println("rowCount: " + rowCount);if (rowCount > 0) {rs = pstmt.getGeneratedKeys();rs.next();return (Serializable)rs.getObject(1);}} catch (Exception e) {e.printStackTrace();}return null;}
}

BaseDAO.java:

package com.xiaoqiang.interview.framework.dao;import java.io.Serializable;/*** Created by Huiq on 2021/4/11.*/
public interface BaseDAO {/*** insert into xxx(col1,col2,col3...) values(?,?,?...)*/<T> Serializable save(T t);
}

User.java:

package com.xiaoqiang.interview.framework.domain;import com.xiaoqiang.interview.framework.annotation.HuiqBean;
import com.xiaoqiang.interview.framework.annotation.HuiqField;import java.util.Date;/*** Created by Huiq on 2021/4/11.*/
@HuiqBean("t_user")
public class User {private Integer id;private String name;private Integer age;@HuiqField("birth_day")private Date birthday;@Overridepublic String toString() {return "User{" +"id=" + id +", name='" + name + '\'' +", age=" + age +", birthday=" + birthday +'}';}public User(String name, Integer age, Date birthday) {this.name = name;this.age = age;this.birthday = birthday;}public User() {}public Integer getId() {return id;}public void setId(Integer id) {this.id = id;}public String getName() {return name;}public void setName(String name) {this.name = name;}public Integer getAge() {return age;}public void setAge(Integer age) {this.age = age;}public Date getBirthday() {return birthday;}public void setBirthday(Date birthday) {this.birthday = birthday;}
}

DBUtils.java:

package com.xiaoqiang.interview.framework.utils;import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;/*** Created by Huiq on 2021/4/12.*/
public class DBUtils {public static Connection getConnection() {String url = "jdbc:mysql://localhost:3306/database1?useSSL=false";String user = "root";String password = "123456";Connection connection = null;try {Class.forName("com.mysql.jdbc.Driver");connection = DriverManager.getConnection(url, user, password);} catch (Exception e) {e.printStackTrace();}return connection;}public static void close(Connection connection) {if (connection != null) {try {connection.close();} catch (SQLException e) {e.printStackTrace();}}}
}

Tools.java:

package com.xiaoqiang.interview.framework.utils;import com.xiaoqiang.interview.framework.annotation.HuiqBean;
import com.xiaoqiang.interview.framework.annotation.HuiqField;import java.lang.reflect.Field;/*** Created by Huiq on 2021/4/11.*/
public class Tools {/*** 根据注解获取表名*/public static String getTable(Class<?> clazz) {String tableName = "";HuiqBean huiqBean = clazz.getAnnotation(HuiqBean.class);if (huiqBean != null) {tableName = huiqBean.value();} else {tableName = clazz.getSimpleName();}return tableName;}/*** 根据注解获取属性名称*/public static String getColum(Field field) {String colum = "";HuiqField huiqField = field.getAnnotation(HuiqField.class);if (huiqField != null) {colum = huiqField.value();} else {colum = field.getName();}return colum;}public static String getMethod(Field field) {String fieldName = field.getName();// id==>getId  name==>getNameString name = fieldName.substring(0,1).toUpperCase() + fieldName.substring(1);return "get" + name;}
}

3、测试代码

BaseDAOImplTest.java:

package com.xiaoqiang.interview.framework.dao.impl;import com.xiaoqiang.interview.framework.dao.BaseDAO;
import com.xiaoqiang.interview.framework.domain.User;
import org.junit.Test;import java.io.Serializable;
import java.util.Date;/*** Created by Huiq on 2021/4/12.*/
public class BaseDAOImplTest {@Testpublic void test02() {BaseDAO dao = new BaseDAOImpl();for (int i=0; i<10; i++) {User user = new User("xiaoqiang" + i, 18+i, new Date());Serializable id = dao.save(user);System.out.println("id: " + id);}}@Testpublic void test01() {BaseDAO dao = new BaseDAOImpl();User user = new User("xiaoqiang", 18, new Date());Serializable id = dao.save(user);System.out.println("id: " + id);}
}

DBUtilsTest.java:

package com.xiaoqiang.interview.framework.utils;import org.junit.Test;/*** Created by Huiq on 2021/4/12.*/
public class DBUtilsTest {@Testpublic void test01() {System.out.println(DBUtils.getConnection());}
}

ToolsTest.java:

package com.xiaoqiang.interview.framework.utils;import com.xiaoqiang.interview.framework.domain.User;
import org.junit.Test;import javax.tools.Tool;
import java.lang.reflect.Field;/*** Created by Huiq on 2021/4/11.*/
public class ToolsTest {@Testpublic void test03() throws Exception {Class<?> clazz = Class.forName("com.xiaoqiang.interview.framework.domain.User");Field field = clazz.getDeclaredField("name");System.out.println(Tools.getMethod(field));field = clazz.getDeclaredField("birthday");System.out.println(Tools.getMethod(field));}@Testpublic void test02() throws Exception {Class<?> clazz = Class.forName("com.xiaoqiang.interview.framework.domain.User");Field field = clazz.getDeclaredField("birthday");System.out.println(Tools.getColum(field));}@Testpublic void test01() throws Exception {System.out.println(Tools.getTable(User.class));}
}

4、插入数据