代码路径：https://github.com/m2492565210/java_orm自行下载
框架的类结构如下，anno包下注解和MODEL类结合用于定义数据库结构。MyORM类是工具类，获取工厂SESSIONFACTORY，工厂资源采用单例模式，目前没有考虑线程安全。使用工厂获取SESSION，利用SESSION类是数据库直接执行者，通过传入MODEL完成数据库读写。时间有限，SESSION方法中只是完成写数据库语句，并没有真正进行数据库操作。
测试类中有SESSION的使用方法，如下。
@Test
public void test() throws ClassNotFoundException, SQLException, IOException, NoSuchMethodException, SecurityException, IllegalAccessException, IllegalArgumentException, InvocationTargetException
{
Session ss = MyORM.getSessionFactory("db.properties").openConnection();／／db.properties是数据库URL，密码等信息， ss.save(new Student(1001, "A", 27));
ss.update(new Student(1001, "A", 27));
ss.delete(new Student(1001, "A", 27));
ss.query(new Student(1001, "A", 27)); ss.close();
}
MyORM:
package m.cnblogs.com.orm; import m.cnblogs.com.orm.conn.Factory;
import m.cnblogs.com.orm.conn.Session; public final class MyORM
{
private static Factory sin = null; private static class SessionFactory implements Factory
{
private SessionFactory(String path) throws ClassNotFoundException
{
System.out.println("use the file path provided to init factory");
} public Session openConnection()
{
return new Session();
} } public static Factory getSessionFactory(String path) throws ClassNotFoundException
{
if (null == sin)
{
sin = new SessionFactory(path);
}
return sin;
}
}
Student类对应数据表，定义如下：
@Table(name = "STUDENT")
public class Student
{
@ID //框架中定义的注解
@Property(name = "ID", type = "int")
private int id;
@Property(name = "NAME", type = "varchar")
private String name;
@Property(name = "AGE", type = "int")
private int age; public Student(int id, String name, int age)
{
super();
this.id = id;
this.name = name;
this.age = age;
}
public Integer getId()
{
return id;
}
public void setId(int id)
{
this.id = id;
}
public String getName()
{
return name;
}
public void setName(String name)
{
this.name = name;
}
public int getAge()
{
return age;
}
public void setAge(int age)
{
this.age = age;
}
}
session.java
package m.cnblogs.com.orm.conn; import java.lang.reflect.Field;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method; import m.cnblogs.com.orm.anno.ID;
import m.cnblogs.com.orm.anno.Property;
import m.cnblogs.com.orm.anno.Table; public class Session
{ public Session()
{
System.out.println("SESSION INIT");
} public <T> void save(T obj) throws NoSuchMethodException, SecurityException, IllegalAccessException,
IllegalArgumentException, InvocationTargetException
{
Class<? extends Object> cls = obj.getClass(); StringBuffer sql = new StringBuffer(); sql.append("INSERT INTO "); Table tbl = (Table) cls.getAnnotation(Table.class); if (null != tbl)
{
sql.append(tbl.name());
}
else
{
sql.append(cls.getName().substring(cls.getName().lastIndexOf(".") + 1));
} sql.append("( "); Field[] fields = cls.getDeclaredFields();
StringBuffer valueSql = new StringBuffer(); for (Field field : fields)
{ Property proper = field.getAnnotation(Property.class); // 获得字段第一个字母大写
String methodFirstLetter = field.getName().substring(0, 1).toUpperCase();
// 转换成字段的get方法
String getterName = "get" + methodFirstLetter + field.getName().substring(1); Method getMethod = cls.getMethod(getterName, new Class[]
{});
// 这个对象字段get方法的值
Object value = getMethod.invoke(obj, new Object[]
{}); if (field.getType().getName().equals(java.lang.String.class.getName()))
{
valueSql.append("'" + value + "'").append(",");
}
else
{
valueSql.append(value).append(",");
} if (null != proper)
{
sql.append(proper.name()).append(",");
}
else
{
sql.append(field.getName()).append(",");
}
} valueSql.deleteCharAt(valueSql.length() - 1);
sql.deleteCharAt(sql.length() - 1);
sql.append(" ) VALUES( ");
sql.append(valueSql);
sql.append(" )"); System.out.println(sql.toString());
} public <T> void query(T obj) throws NoSuchMethodException, SecurityException, IllegalAccessException, IllegalArgumentException, InvocationTargetException
{
Class<? extends Object> cls = obj.getClass(); StringBuffer sql = new StringBuffer(); sql.append("SELETE FROM "); Table tbl = (Table)cls.getAnnotation(Table.class); if (null != tbl) {
sql.append(tbl.name());
} else {
sql.append(cls.getName().substring(cls.getName().lastIndexOf(".")+1));
} Field[] fields = cls.getDeclaredFields(); for (Field field : fields) { if (null != field.getAnnotation(ID.class))
{
//获得字段第一个字母大写
String methodFirstLetter = field.getName().substring(0,1).toUpperCase();
//转换成字段的get方法
String getterName = "get" + methodFirstLetter + field.getName().substring(1); Method getMethod = cls.getMethod(getterName, new Class[] {});
//这个对象字段get方法的值
Object value = getMethod.invoke(obj, new Object[] {});
sql.append(" WHERE ").append(field.getName()).append("=");
if (field.getType().getName().equals(java.lang.String.class.getName())) {
sql.append("'" + value + "'");
} else {
sql.append(value);
}
} } System.out.println(sql.toString()); } public <T> void update(T obj) throws NoSuchMethodException, SecurityException, IllegalAccessException,
IllegalArgumentException, InvocationTargetException
{
Class<? extends Object> cls = obj.getClass(); StringBuffer sql = new StringBuffer();
StringBuffer condition = new StringBuffer(); sql.append("UPDATE "); Table tbl = (Table) cls.getAnnotation(Table.class); if (null != tbl)
{
sql.append(tbl.name());
}
else
{
sql.append(cls.getName().substring(cls.getName().lastIndexOf(".") + 1));
} sql.append(" SET "); Field[] fields = cls.getDeclaredFields(); for (Field field : fields)
{ Property proper = field.getAnnotation(Property.class); // 获得字段第一个字母大写
String methodFirstLetter = field.getName().substring(0, 1).toUpperCase();
// 转换成字段的get方法
String getterName = "get" + methodFirstLetter + field.getName().substring(1); Method getMethod = cls.getMethod(getterName, new Class[]
{});
// 这个对象字段get方法的值
Object value = getMethod.invoke(obj, new Object[]
{}); if (null != field.getAnnotation(ID.class))
{
condition.append(" WHERE ").append(field.getName()).append("=");
if (field.getType().getName().equals(java.lang.String.class.getName()))
{
condition.append("'" + value + "'");
}
else
{
condition.append(value);
}
}
else
{
String tmp = ""; if (field.getType().getName().equals(java.lang.String.class.getName()))
{
tmp = "'" + value + "'";
}
else
{
tmp = value + "";
} if (null != proper)
{
sql.append(proper.name()).append("=").append(tmp).append(",");
}
else
{
sql.append(field.getName()).append("=").append(tmp).append(",");
}
} } sql.deleteCharAt(sql.length() - 1); sql.append(condition); System.out.println(sql.toString());
} public <T> void delete(T obj) throws NoSuchMethodException, SecurityException, IllegalAccessException,
IllegalArgumentException, InvocationTargetException
{
Class<? extends Object> cls = obj.getClass(); StringBuffer sql = new StringBuffer(); sql.append("DELETE FROM "); Table tbl = (Table) cls.getAnnotation(Table.class); if (null != tbl)
{
sql.append(tbl.name());
}
else
{
sql.append(cls.getName().substring(cls.getName().lastIndexOf(".") + 1));
} Field[] fields = cls.getDeclaredFields(); for (Field field : fields)
{ if (null != field.getAnnotation(ID.class))
{
// 获得字段第一个字母大写
String methodFirstLetter = field.getName().substring(0, 1).toUpperCase();
// 转换成字段的get方法
String getterName = "get" + methodFirstLetter + field.getName().substring(1); Method getMethod = cls.getMethod(getterName, new Class[]
{});
// 这个对象字段get方法的值
Object value = getMethod.invoke(obj, new Object[]
{});
sql.append(" WHERE ").append(field.getName()).append("=");
if (field.getType().getName().equals(java.lang.String.class.getName()))
{
sql.append("'" + value + "'");
}
else
{
sql.append(value);
}
} } System.out.println(sql.toString());
} public void close()
{
System.out.println("SESSION CLOSE");
}
}
简易框架模仿hibernate，运算后的结果如下：
