Hibernate模拟实现

最新推荐文章于 2025-08-22 13:45:39 发布

转载最新推荐文章于 2025-08-22 13:45:39 发布 · 378 阅读

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#java #hibernate

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本文介绍了如何通过Hibernate框架实现Java对象与数据库之间的映射，包括持久化类的设计、模拟Session类的创建以及具体的测试过程。

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1：持久化类 Student.java

2：Hibernate的模拟类 Session.java

3：测试类

com.tang.model.Student.java

package com.tang.model;

public class Student {
	private int id;
	private String name;
	private int age;
	public int 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;
	}

}

com.tang.hibernate.Session.java

package com.tang.hibernate;

import java.lang.reflect.Method;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.util.HashMap;
import java.util.Map;

import com.tang.model.Student;

public class Session {
	//假设表名和字段名都已经从配置文件取到了
	String tableName = "_student"; 
	Map<String,String> cfs = new HashMap<String,String>();
	String[] methodNames;
	
	public Session(){
		cfs.put("_id", "id");
		cfs.put("_name", "name");
		cfs.put("_age", "age");
		methodNames = new String[cfs.size()];
	}

	public void save(Student s) { 
		String sql = createSQL();
		try {
			Class.forName("com.mysql.jdbc.Driver");
			Connection conn = DriverManager.getConnection("jdbc:mysql://localhost/hibernate","root","123456");
			PreparedStatement ps = conn.prepareStatement(sql);
			 
			// 用反射机制实现
			for(int i=0;i<methodNames.length;i++){
//				Method m = s.getClass().getMethod(methodNames[i]);
				Method m = Class.forName("com.tang.model.Student").getMethod(methodNames[i]);
				Class c = m.getReturnType();
				if(c.getName().equals("java.lang.String")){
					String returnValue = (String)m.invoke(s);
					ps.setString(i+1, returnValue);
				}
				if(c.getName().equals("int")){
					Integer returnValue = (Integer)m.invoke(s);
					ps.setInt(i+1, returnValue);
				}
				
			}
			
			ps.executeUpdate();
			ps.close();
			conn.close();
		} catch (Exception e) {
			e.printStackTrace();
		}
	}

	private String createSQL() {
		String keyStr = "";
		int index = 0;
		for(String s : cfs.keySet()){
			String v = cfs.get(s);
			v = Character.toUpperCase(v.charAt(0)) + v.substring(1);
			methodNames[index++] = "get" + v;
			keyStr += "," + s;
		}
		keyStr = keyStr.substring(1);
		
		String valStr = "";
		for(int i=0; i<cfs.size();i++){
			valStr += ",?"; 
		}
		valStr = valStr.substring(1);
		
		String sql = "insert into " + tableName + "(" + keyStr +") values (" + valStr +")";
		System.out.println(sql);
		return sql;
	}

}

StudentTest.java

package com.tang.model;

import com.tang.hibernate.Session;

public class StudentTest {
	
	public static void main(String args[]){
		Student s= new Student();
		s.setId(2);
		s.setName("tang");
		s.setAge(19);
		Session session = new Session();
		session.save(s);
	}

}