学步园

就是说，如果你已经有了数据库表，那么你又不想手工书写jpa或hibernate实体（要谁都不想，还要自己写那么一大堆的注解），myeclipse能够帮助你自动生成。

1、首先你需要创建一个jpa项目：

如图在普通项目上点右键添加

2、打开生成工作环境

3、创建数据库连接

因为，myeclipse也要连接数据库获取表结构

4、填写连接信息

5、打开表列表，选择导出模式

6、保存导出实体工程选择

（这一步需要第1步的操作，否则，没有可选工程）

现在就生成了entity，如：

package com.partner4java.entity;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import static javax.persistence.GenerationType.IDENTITY;
import javax.persistence.Id;
import javax.persistence.Table;

/**
 * User entity. @author MyEclipse Persistence Tools
 */
@Entity
@Table(name = "user", catalog = "hello_world")
public class User implements java.io.Serializable {

	// Fields

	private Integer id;
	private String username;
	private String password;
	private String address;

	// Constructors

	/** default constructor */
	public User() {
	}

	/** minimal constructor */
	public User(String username, String password) {
		this.username = username;
		this.password = password;
	}

	/** full constructor */
	public User(String username, String password, String address) {
		this.username = username;
		this.password = password;
		this.address = address;
	}

	// Property accessors
	@Id
	@GeneratedValue(strategy = IDENTITY)
	@Column(name = "id", unique = true, nullable = false)
	public Integer getId() {
		return this.id;
	}

	public void setId(Integer id) {
		this.id = id;
	}

	@Column(name = "username", nullable = false, length = 20)
	public String getUsername() {
		return this.username;
	}

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

	@Column(name = "password", nullable = false, length = 20)
	public String getPassword() {
		return this.password;
	}

	public void setPassword(String password) {
		this.password = password;
	}

	@Column(name = "address", length = 20)
	public String getAddress() {
		return this.address;
	}

	public void setAddress(String address) {
		this.address = address;
	}

}