初学JDBC

内容概要：

一、JDBC简介

二、使用详解

1、JDBC常用的接口

2、JDBC编程的步骤

3、执行SQL语句

一、JDBC是什么？

JDBC全称Java Data Base Connectivity（java数据库连接），可以为多种数据库提供统一的访问。

JDBC像一座桥梁，连接着java和数据库。有了JDBC，java才可以从数据库读取和存储数据。



二、JDBC使用详解

2、JDBC编程步骤

加载驱动程序：Class.forName(driverClass);

加载Mysql驱动：Class.forName(“com.mysql.jdbc.Driver”);

加载Oracle驱动：Class.forName(“oracle.jdbc.driver.OracleDriver”);

获得数据库连接：DriverManager.getConnection(“jdbc:mysql://127.0.0.1:3306/imooc”,”root”,”root”);

创建Statement对象：conn.createStatement();

Java连接数据库例子

// 必须要加入 mysql-connector-java-5.0.8.jar

package com.example.db;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

public class DButil {

private static final String URL = "jdbc:mysql://192.168.191.1:3306/jdbctest";
private static final String USER = "root";
private static final String PASSWORD = "root";

public static void main(String[] args) throws ClassNotFoundException, SQLException {
// 1.加载驱动程序
Class.forName("com.mysql.jdbc.Driver");
// 2. 获得数据库的连接
Connection conn = DriverManager.getConnection(URL, USER, PASSWORD);
// 3.通过数据库的连接操作数据库，实现增删改查
Statement stmt = conn.createStatement();
ResultSet rs = stmt.executeQuery("select * from man");
//有数据才会执行,可以循环获取全部数据
while(rs.next()) {
//根据列名得到数据
System.out.println(rs.getString("name")+":"+rs.getString("age"));
}
}
}

MVC模型



架构



util工具类 用于获得connction

package com.example.db;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;

public class DButil {

private static final String URL = "jdbc:mysql://192.168.191.1:3306/jdbctest?useUnicode=true&characterEncoding=utf-8";
private static final String USER = "root";
private static final String PASSWORD = "root";

public static Connection conn = null;
static {
try {
// 1.加载驱动程序
Class.forName("com.mysql.jdbc.Driver");
// 2. 获得数据库的连接
conn = DriverManager.getConnection(URL, USER, PASSWORD);
} catch (ClassNotFoundException e) {
e.printStackTrace();
} catch (SQLException e) {
e.printStackTrace();
}

}

public static Connection getConnection() {
return conn;
}

}

View层 调用 Action

package com.example.view;

import com.example.action.ManAction;
import com.example.model.Man;

public class MainView {
public static void main(String[] args) {

ManAction action = new ManAction();
Man man = new Man();
man.setName("YoYo");
man.setAge(19);
action.DeleteMan(man);

}

}

action层

package com.example.action;

import java.util.HashMap;
import java.util.List;

import com.example.dao.ManDao;
import com.example.model.Man;

public class ManAction {

// 增
public void addMan(Man man) {
ManDao dao = new ManDao();
dao.AddMan(man);
}

// 删
public void DeleteMan(Man man) {
ManDao dao = new ManDao();
dao.DeleteMan(man);
}

// 改
public void AlterMan(Man man) {
ManDao dao = new ManDao();
dao.AlterMan(man);

}

// 查
public List<Man> queryMans() {
ManDao dao = new ManDao();
List<Man> list = dao.queryMans();
return list;
}

// 查单个
public Man getMan(String name) {
ManDao dao = new ManDao();
Man man = dao.getMan(name);
return man;
}

// 带条件查
public List<Man> queryMans(List<HashMap<String, String>> params) {
// 在外部初始化params
// List<HashMap<String, String>> params = new ArrayList<HashMap<String,
// String>>();
// HashMap<String, String> map1 = new HashMap<String,String>();
// map1.put("name", "name");
// map1.put("rela", "like");
// map1.put("value", "%冬眠%");
// params.add(map1);
//
// HashMap<String, String> map2 = new HashMap<String,String>();
// map2.put("name", "age");
// map2.put("rela", "=");
// map2.put("value", "23");
// params.add(map2);

// 以这种方式可以不需要频繁的修改DAO方法, 只需要添加对应的HashMap
ManDao dao = new ManDao();
List<Man> list = dao.queryMans(params);
return list;
}

}

DAO 连接数据库

package com.example.dao;

import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;

import com.example.db.DButil;
import com.example.model.Man;
import com.mysql.jdbc.PreparedStatement;

public class ManDao {

//增
public void AddMan(Man man)  {
Connection conn = DButil.getConnection();
try {
String sql = "INSERT INTO man (name,age) values (?,?)";
PreparedStatement ptmt =  (PreparedStatement) conn.prepareStatement(sql);
ptmt.setString(1, man.getName());
ptmt.setInt(2, man.getAge());
ptmt.execute();
} catch (SQLException e) {
e.printStackTrace();
}
}
//删
public void DeleteMan(Man man) {
Connection conn = DButil.getConnection();
try {
String sql = "DELETE from man where name = ?";// set age = ? , city = ?//逗号隔开
PreparedStatement ptmt =  (PreparedStatement) conn.prepareStatement(sql);
ptmt.setString(1, man.getName());
ptmt.execute();
} catch (SQLException e) {
e.printStackTrace();
}

}
//改
public void AlterMan(Man man) {
Connection conn = DButil.getConnection();
try {
String sql = "UPDATE  man set age = ? where name = ?";// set age = ? , city = ?//逗号隔开
PreparedStatement ptmt =  (PreparedStatement) conn.prepareStatement(sql);
ptmt.setInt(1, man.getAge());
ptmt.setString(2, man.getName());
ptmt.execute();
} catch (SQLException e) {
e.printStackTrace();
}
}
//查
public List<Man> queryMans() {
List<Man> list = new ArrayList<Man>();
Connection conn = DButil.getConnection();
try {
String sql = "select * from man";
PreparedStatement ptmt = (PreparedStatement) conn.prepareStatement(sql);
ResultSet rs = ptmt.executeQuery();
Man man = null;
while(rs.next()) {
man = new Man();
man.setName(rs.getString("name"));
man.setAge(rs.getInt("age"));
list.add(man);
}
} catch (SQLException e) {
e.printStackTrace();
}
return list;
}

//带条件查
public List<Man> queryMans(List<HashMap<String,String>> params) {
List<Man> list = new ArrayList<Man>();
Connection conn = DButil.getConnection();
try {
StringBuffer sql = new StringBuffer();
sql.append( "select * from man where 1 = 1");
for (HashMap<String, String> map : params) {
sql.append(" and "+map.get("name")+" "+map.get("rela")+" '"+map.get("value")+"'");
}
PreparedStatement ptmt = (PreparedStatement) conn.prepareStatement(sql.toString());
ResultSet rs = ptmt.executeQuery();
Man man = null;
while(rs.next()) {
man = new Man();
man.setName(rs.getString("name"));
man.setAge(rs.getInt("age"));
list.add(man);
}
} catch (SQLException e) {
e.printStackTrace();
}
return list;
}
//查单个
public Man getMan(String name) {
Connection conn = DButil.getConnection();
Man man = null;
try {
String sql = "select * from man where name = ?";
PreparedStatement ptmt = (PreparedStatement) conn.prepareStatement(sql);
ptmt.setString(1, name);
ResultSet rs = ptmt.executeQuery();
if (rs.next()) {
man = new Man();
man.setName(rs.getString("name"));
man.setAge(rs.getInt("age"));
}
} catch (SQLException e) {
e.printStackTrace();
}
return man;
}

}

model层 实体类

package com.example.model;

public class Man {

private String name ;
private Integer age ;

public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Integer getAge() {
return age;
}
public void setAge(Integer age) {
this.age = age;
}

}

转载于：http://www.imooc.com/learn/157