简易版Mybatis框架
自己的Mybatis框架设计图
- 依照Mybatis的框架执行原理，实现简易版的Mybatis框架
数据库建User表：
- 建立如下的实体表，用于增删改查
CREATE TABLE `NewTable` (
`id` int(20) NOT NULL AUTO_INCREMENT ,
`username` varchar(100) CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT NULL ,
`password` varchar(100) CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT NULL ,
`gender` int(1) NULL DEFAULT NULL ,
`age` int(2) NULL DEFAULT NULL ,
`idcard` int(20) NULL DEFAULT NULL ,
`phone` int(15) NULL DEFAULT NULL ,
PRIMARY KEY (`id`)
);
新建Maven项目引入需要的依赖
- 引入Mysql驱动依赖、Dom4j（解析Xml）、FastJson（Json工具）
<dependencies>
<!-- Mysql 驱动-->
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>5.1.47</version>
</dependency>
<!-- xml解析工具包 -->
<dependency>
<groupId>dom4j</groupId>
<artifactId>dom4j</artifactId>
<version>1.1</version>
</dependency>
<!-- Json工具-->
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>fastjson</artifactId>
<version>1.2.62</version>
</dependency>
</dependencies>
数据源配置文件：mysqlconfig.xml
<?xml version="1.0" encoding="UTF-8" ?>
<database>
<property name="driverClassName">com.mysql.jdbc.Driver</property>
<property name="url">jdbc:mysql://localhost:3306/test</property>
<property name="username">root</property>
<property name="password">root</property>
</database>
连接数据库和解析Mapper的工具类：MyConfiguration
public class MyConfiguration {
private ClassLoader classLoader=ClassLoader.getSystemClassLoader();
private Logger logger= LoggerFactory.getLogger(MyConfiguration.class);
/**
* 读取数据库的Xml信息
*/
public Connection getDataSourceInfo(){
try{
InputStream inputStream=classLoader.getResourceAsStream("mysqlconfig.xml");
SAXReader reader=new SAXReader();
Document document=reader.read(inputStream);
Element element=document.getRootElement();
logger.info("==========数据库配置信息读取成功！");
return getConnection(element);
}catch (Exception e){
logger.error(e.getMessage());
return null;
}
}
/**
* 得到XMl中的数据库的配置信息返回连接
*/
private Connection getConnection(Element element) {
String driverClassName=null;
String url=null;
String username=null;
String password=null;
if(!"database".equals(element.getName())){
throw new RuntimeException("数据库xml配置读取错误!");
}
List<Object> property = element.elements("property");
for (Object o : property) {
Element el= (Element) o;
String name = el.attribute(0).getValue();
String value= (String) el.getData();
if(name==null || value==null){
throw new RuntimeException("property信息读取失败！");
}
switch (name){
case "driverClassName":
driverClassName=value;
break;
case "url":
url=value;
break;
case "username":
username=value;
break;
case "password":
password=value;
break;
default:
throw new RuntimeException("==========数据库信息有错误！");
}
}
try {
Connection connection=null;
Class.forName(driverClassName);
logger.info("==========连接数据库获取驱动成功！");
connection= DriverManager.getConnection(url,username,password);
logger.info("==========连接数据库成功！");
return connection;
}catch (Exception e){
logger.error(e.getMessage());
return null;
}
}
/**
* 读取Mapper和xml中的配置信息
*/
public MapperBean readMapper(String path){
MapperBean mapperBean=new MapperBean();
try{
InputStream inputStream=classLoader.getResourceAsStream(path);
SAXReader saxReader=new SAXReader();
Document document=saxReader.read(inputStream);
Element root=document.getRootElement();
// 存储xml文件中namespace的值
mapperBean.setInterfaceName(root.attributeValue("namespace").trim());
// 存储方法
List<Function> list=new ArrayList<>();
for(Iterator iterator=root.elementIterator();iterator.hasNext();){
Function function=new Function();
Element element= (Element) iterator.next();
String sqlType=element.getName().trim();
String functionNam=element.attributeValue("id").trim();
String sql=element.getText().trim();
String resultType=null;
Object newinstance=null;
if(null!=element.attributeValue("resultType")){
resultType=element.attributeValue("resultType");
try{
newinstance=Class.forName(resultType).newInstance();
}catch (Exception e){
logger.error(e.getMessage());
}
function.setResultType(resultType);
}
function.setFunctionName(functionNam);
function.setSqlType(sqlType);
function.setSql(sql);
list.add(function);
}
// 所有的mapper.xml文件解析后保存
mapperBean.setList(list);
}catch (Exception e){
return null;
}
return mapperBean;
}
}
存放Mapper类信息的实体类：MapperBean、省略setget方法
public class MapperBean {
// 接口名
private String interfaceName;
// 接口下的所有方法
private List<Function> list;
public MapperBean(){
}
public MapperBean(String interfaceName, List<Function> list) {
this.interfaceName = interfaceName;
this.list = list;
}
@Override
public String toString() {
return "MapperBean{" +
"interfaceName='" + interfaceName + '\'' +
", list=" + list +
'}';
}
}
存放Mapper.xml的信息的实体类：Function
public class Function {
private String sqlType;
private String functionName;
private String sql;
private String resultType;
private String parameterType;
public Function(){
}
public Function(String sqlType, String functionName, String sql, String resultType, String parameterType) {
this.sqlType = sqlType;
this.functionName = functionName;
this.sql = sql;
this.resultType = resultType;
this.parameterType = parameterType;
}
}
MyMapperProxy代理类完成读取的UserMapper.xml中方法与真实方法校验，并调用执行对应的方法
public class MyMapperProxy implements InvocationHandler {
private MysqlSession mysqlSession;
private MyConfiguration myConfiguration;
public MyMapperProxy(MysqlSession mysqlSession, MyConfiguration myConfiguration) {
this.mysqlSession = mysqlSession;
this.myConfiguration = myConfiguration;
}
@Override
public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
MapperBean mapperBean = myConfiguration.readMapper("UserMapper.xml");
// 判断是否是xml文件对应的接口
if (!method.getDeclaringClass().getName().equals(mapperBean.getInterfaceName())) {
return null;
}
List<Function> list = mapperBean.getList();
if (!CollectionUtils.isEmpty(list)) {
for (Function x : list) {
if (judge(method, x, "selectById")) {
return mysqlSession.selectOne(x.getSql(), String.valueOf(args[0]));
}
if (judge(method, x, "deleteById")) {
mysqlSession.deleteOne(x.getSql(), String.valueOf(args[0]));
}
if (judge(method, x, "insert")) {
mysqlSession.insertOne(x.getSql(), String.valueOf(args[0]));
}
if (judge(method, x, "updateById")) {
mysqlSession.updateOne(x.getSql(), String.valueOf(args[0]));
}
}
}
return null;
}
/**
* 判断Mapper文件中id是否一致
*/
private boolean judge(Method method, Function x, String methodId) {
return method.getName().equals(x.getFunctionName()) && x.getFunctionName().equals(methodId);
}
}
MysqlSession类，其中getMapper()动态代理的方式获取对象
public class MysqlSession {
private Logger logger= LoggerFactory.getLogger(MysqlSession.class);
private MyConfiguration myConfiguration=new MyConfiguration();
private Excutor excutor=new ExcutorImpl();
public <T> T selectOne(String statment,Object parameter){
logger.info("我是query的SqlSession!");
return excutor.query(statment,parameter);
}
public void insertOne(String statment,Object parmeter){
logger.info("我是save的SqlSession!");
excutor.save(statment,parmeter);
}
public void updateOne(String statment,Object parmeter){
logger.info("我是modify的SqlSession!");
excutor.modify(statment,parmeter);
}
public void deleteOne(String statment,Object parmeter){
logger.info("我是remove的SqlSession!");
excutor.remove(statment,parmeter);
}
public <T> T getMapper(Class<T> clazz){
logger.info("已经通过代理获取对象！");
// 动态代理
return (T) Proxy.newProxyInstance(clazz.getClassLoader(), new Class[]{
clazz}, new MyMapperProxy(this, myConfiguration));
}
}
增删改查底层接口：Excutor
public interface Excutor {
<T> T query(String statement,Object parameter);
void save(String statement,Object parameter);
void modify(String statement,Object parameter);
void remove(String statement,Object parameter);
}
增删改查底层接口实现：ExcutorImpl
- 连接数据库，Jdbc方式进行怎删改查操作
public class ExcutorImpl implements Excutor {
private Logger logger= LoggerFactory.getLogger(ExcutorImpl.class);
private MyConfiguration myConfiguration=new MyConfiguration();
Connection connection = myConfiguration.getDataSourceInfo();
@Override
public <T> T query(String statement, Object parameter) {
try{
PreparedStatement preparedStatement = connection.prepareStatement(statement);
preparedStatement.setString(1,parameter.toString());
ResultSet resultSet = preparedStatement.executeQuery();
User user=new User();
while (resultSet.next()){
user.setId(resultSet.getInt("id"));
user.setUsername(resultSet.getString("username"));
user.setPassword(resultSet.getString("password"));
user.setGender(resultSet.getInt("gender"));
user.setAge(resultSet.getInt("age"));
user.setIdcard(resultSet.getInt("idcard"));
user.setPhone(resultSet.getInt("phone"));
}
logger.info("遍历结果集完成！");
return (T)user;
}catch (Exception e){
logger.error("查询结果报错"+e.getMessage());
return null;
}
}
@Override
public void save(String statement, Object parameter) {
try {
connection.setAutoCommit(false);
PreparedStatement preparedStatement = connection.prepareStatement(statement);
User user = JSON.parseObject(String.valueOf(parameter),User.class);
preparedStatement.setInt(1,user.getId());
preparedStatement.setString(2,user.getUsername());
preparedStatement.setString(3,user.getPassword());
preparedStatement.setInt(4,user.getGender());
preparedStatement.setInt(5,user.getAge());
preparedStatement.setInt(6,user.getIdcard());
preparedStatement.setInt(7,user.getPhone());
preparedStatement.execute();
comit(connection);
logger.info("保存成功！");
} catch (Exception e ) {
logger.error("保存失败"+e.getMessage());
rollBack(connection);
}
}
@Override
public void modify(String statement, Object parameter) {
try {
PreparedStatement preparedStatement = connection.prepareStatement(statement);
User user = JSON.parseObject(String.valueOf(parameter),User.class);
preparedStatement.setInt(3,user.getId());
preparedStatement.setString(1,user.getUsername());
preparedStatement.setString(2,user.getPassword());
preparedStatement.execute();
comit(connection);
logger.info("修改成功！");
} catch (SQLException e) {
logger.error("修改失败"+e.getMessage());
rollBack(connection);
}
}
@Override
public void remove(String statement, Object parameter) {
try {
PreparedStatement preparedStatement = connection.prepareStatement(statement);
preparedStatement.setString(1,parameter.toString());
preparedStatement.execute();
logger.info("删除成功！");
} catch (SQLException throwables) {
throwables.printStackTrace();
}
}
/**
* 事物提交
*/
private void comit(Connection connection){
try {
connection.commit();
logger.error("事物提交成功！");
}catch (Exception e){
logger.error("事物提交失败！"+e.getMessage());
}
}
/**
* 事物回滚
*/
private void rollBack(Connection connection){
try{
connection.rollback();
logger.info("事物回滚成功！");
} catch (Exception e){
logger.info("事物回滚失败！"+e.getMessage());
}
}
}
User实体类
public class User {
private int id;
private String username;
private String password;
private int gender;
private int age;
private int idcard;
private int phone;
@Override
public String toString() {
return "User{" +
"id=" + id +
", username='" + username + '\'' +
", password='" + password + '\'' +
", gender=" + gender +
", age=" + age +
", idcard=" + idcard +
", phone=" + phone +
'}';
}
}
UserMapper类
public interface UserMapper {
User selectById(String id);
void insert(Object user);
void updateById(Object user);
void deleteById(String id);
}
UserMapper.xml
<?xml version="1.0" encoding="UTF-8" ?>
<mapper namespace="com.li.mybatisconfig.mapper.UserMapper">
<select id="selectById" resultType="com.li.mybatisconfig.entity.User">
select * from user where id=?
</select>
<delete id="deleteById" >
delete from user where id=?
</delete>
<insert id="insert">
insert into user (id,username,password,gender,age,idcard,phone) values(?,?,?,?,?,?,?)
</insert>
<update id="updateById">
update user set username=?,password=? where id=?
</update>
</mapper>
增删改查测试类：MybatisTestRunner
public class MybatisTestRunner {
MysqlSession mysqlSession=new MysqlSession();
UserMapper mapper=mysqlSession.getMapper(UserMapper.class);
@Test
public void findById(){
User user = mapper.selectById("1");
System.out.println(user);
}
@Test
public void insert(){
User user=new User();
user.setId(2);
user.setUsername("test1");
user.setPassword("test1");
mapper.insert(JSON.toJSON(user));
}
@Test
public void deleteById(){
mapper.deleteById("1");
}
@Test
public void update(){
User user=new User();
user.setId(2);
user.setUsername("test2");
user.setPassword("test2");
mapper.updateById(JSON.toJSON(user));
}
}
- 查询接口方法运行日志打印如下
很Nice 感觉Mybatis 不是那么难 哈哈 哈哈！