OrmLite 一对多

项目中要用到一对多，所以就稍作了解了一下，测试成功的代码，记录一下。

一个User对应一个Department，一个Department对应多个User。

package com.example.aandroidtest;

import com.j256.ormlite.field.DatabaseField;
import com.j256.ormlite.table.DatabaseTable;

@DatabaseTable
public class User {
	@DatabaseField(generatedId=true)//自增长的主键
	private int id;
	@DatabaseField
	private String userName;
	@DatabaseField
	private String password;
	
	/**
	 * 这个是一个普通的字段@DatabaseField，只是在后面加了个foreign
	 * 在数据库中的名称默认为 depa_id
	 * 查询到的User对象中可以直接获取到对应的Department
	 * 删除User，并不会同时删除Department
	 */
	@DatabaseField(foreign=true,foreignAutoRefresh=true)
	private Department depa;
	
	//必须有一个无参的构造函数
	public User() {
		super();
	}
	
	public int getId() {
		return id;
	}
	public void setId(int id) {
		this.id = id;
	}
	public String getUserName() {
		return userName;
	}
	public void setUserName(String userName) {
		this.userName = userName;
	}
	public String getPassword() {
		return password;
	}
	public void setPassword(String password) {
		this.password = password;
	}

	public Department getDepa() {
		return depa;
	}

	public void setDepa(Department depa) {
		this.depa = depa;
	}
}

package com.example.aandroidtest;

import com.j256.ormlite.dao.ForeignCollection;
import com.j256.ormlite.field.DatabaseField;
import com.j256.ormlite.field.ForeignCollectionField;
import com.j256.ormlite.table.DatabaseTable;

/**
 * 部门
 * @author LinZhiquan
 *
 */
@DatabaseTable
public class Department {
	@DatabaseField(generatedId=true)
	private int id;
	@DatabaseField
	private String name;
	
	/**
	 * 在数据库中不会生成对应的字段
	 * 获取到Department的时候同时会获取Department下面的User
	 * 
	 * **要注意的是：删除Department的时候，并不会自动删除对应的User
	 * 这个还没搞清楚哪里出的问题，待究
	 */
	@ForeignCollectionField
	private ForeignCollection<User> users;
	
	public Department() {
		super();
	}
	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 ForeignCollection<User> getUsers() {
		return users;
	}
	public void setUsers(ForeignCollection<User> users) {
		this.users = users;
	}
}

package com.example.aandroidtest;

import java.sql.SQLException;

import android.content.Context;
import android.database.sqlite.SQLiteDatabase;

import com.j256.ormlite.android.apptools.OrmLiteSqliteOpenHelper;
import com.j256.ormlite.dao.Dao;
import com.j256.ormlite.support.ConnectionSource;
import com.j256.ormlite.table.TableUtils;

public class DBHelper extends OrmLiteSqliteOpenHelper {
	/*一张表对应一个dao*/
	private Dao<User, Integer> userDao;
	private Dao<Department, Integer> departmentDao;
	
	private final static int DB_VERSION = 1;  
    private static final String DB_NAME = "orm";  
	
	/**构造函数，貌似是必须有的
	 * @param context
	 */
	public DBHelper(Context context) {
		super(context, DB_NAME, null, DB_VERSION);
	}
	
	@Override
	public void onCreate(SQLiteDatabase arg0, ConnectionSource arg1) {
		try {
			TableUtils.createTable(arg1, User.class);
			TableUtils.createTable(arg1, Department.class);
		} catch (SQLException e) {
			e.printStackTrace();
		}
	}

	@Override
	public void onUpgrade(SQLiteDatabase arg0, ConnectionSource arg1, int arg2,
			int arg3) {
		try {
			TableUtils.dropTable(arg1, User.class, true);
			TableUtils.dropTable(arg1, Department.class, true);
			this.onCreate(arg0, arg1);
		} catch (SQLException e) {
			e.printStackTrace();
		}
	}

	public Dao<User, Integer> getUserDao() throws SQLException {
		if(userDao == null) {
			userDao = getDao(User.class);
		}
		return userDao;
	}
	
	public Dao<Department, Integer> getDepartmentDao() throws SQLException {
		if(departmentDao == null) {
			departmentDao = getDao(Department.class);
		}
		return departmentDao;
	}
}