c3p0连接池连接数据库 并增删改查

使用c3p0连接池连接数据库

示例（mvc模式）

1.mysql.properties （连接数据库的）文件：

driver=com.mysql.jdbc.Driver
url=jdbc:mysql://localhost:3306/test?useSSL=false&serverTimezone=UTC&characterEncoding=utf8&useUnicode=true
user=root
password=root

2.c3p0-config.xml 文件（配置在src根目录下）：

  
     com.mysql.jdbc.Driver 
     jdbc:mysql:///test 
     root 
     root 
     5 
     10 
  
  
    com.mysql.jdbc.Driver 
     jdbc:mysql:///test 
     root 
     root 
     5 
     10 
   

3.util 类：

public class JDBCUtils {
	// 初始化连接池
	private static DataSource dataSource;
	static {
		dataSource=new ComboPooledDataSource();
	}
	public static DataSource getDataSource() {
		return dataSource;
	}
	/**
	 * 创建DbUtils常用工具类对象
	 */
	public static QueryRunner getQuerrRunner() {
		return new QueryRunner(dataSource);	
	}
}

注意：区别

4.dao 层：

/**
 * 2. 菜系模块，dao接口设计
 */
public interface StudentTypeDao {
	
	public void save(StudentType studentType);//添加
	
	public void update(StudentType studentType);//更新
	
	public void delete(int id);//删除
	
	public StudentType findById(int id);//根据主键查询
	
	public List getAll();//查询全部
	
	public List getAllForName(String sName);//根据名称查询
}

5.dao 的实现：

/**
 * 2. 学生系模块dao实现
 */
public class StudentTypeDaoimpl implements StudentTypeDao{

	@Override
	public void save(StudentType studentType) {//增加
	//SQL语句
		String sql="insert into student_list(id,sName,sex,major,nianji) values(?,?,?,?,?)";
		try {//抛异常
		//把得到的值放入一个数组
			Object params[]= {studentType.getId(),studentType.getsName(),
					studentType.getSex(),studentType.getMajor(),studentType.getNianji()};
					//调用util类的getQuerrRunner()方法
			JDBCUtils.getQuerrRunner().update(sql,params);
		} catch (Exception e) {
			throw new RuntimeException(e);
		}
	}

	@Override
	public void update(StudentType studentType) {//更新
		String sql="update student_list set sName=?,major=?,nianji=? where id=?";
		try {
			Object params[]={studentType.getsName(),
					studentType.getMajor(),studentType.getNianji(),studentType.getId()};
			JDBCUtils.getQuerrRunner().update(sql,params);
		} catch (Exception e) {
			throw new RuntimeException(e);
		}
	}

	@Override
	public void delete(int id) {
		String sql="delete from student_list where id=?";
		try {
			JDBCUtils.getQuerrRunner().update(sql, id);
		} catch (Exception e) {
			throw new RuntimeException(e);
		}
	}

	@Override
	public StudentType findById(int id) {
		String sql="select * from student_list where id=?";	
		try {
			return JDBCUtils.getQuerrRunner().query(sql, new BeanHandler(StudentType.class), id);
		} catch (Exception e) {
			throw new RuntimeException(e);
		}
	}

	@Override
	public List getAll() {
		String sql="select * from student_list";
		try {
List list = JDBCUtils.getQuerrRunner().query(sql, new BeanListHandler(StudentType.class));
			return list;
		} catch (Exception e) {
			throw new RuntimeException(e);
		}
	}

	@Override
	public List getAllForName(String sName) {
		String sql="select * from student_list where sName like ?";
		try {
			return JDBCUtils.getQuerrRunner().query(sql, new BeanListHandler(StudentType.class), "%"+sName+"%");
		} catch (Exception e) {;
			throw new RuntimeException(e);
		}
	}
}

用到的jar包：
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