1.创建 Maven 工程
log4j
log4j
1.2.12
dom4j
dom4j
1.6.1
mysql
mysql-connector-java
5.1.6
jaxen
jaxen
1.1.6
junit
junit
4.10
org.projectlombok
lombok
RELEASE
compile
public class Resources {
/**
* 根据传入的参数,获取一个字节输入流
* @param filePath
* @return
*/
public static InputStream getResourceAsStream(String filePath){
return Resources.class.getClassLoader().getResourceAsStream(filePath);
}
}
/**
* 用于封装执行的SQL语句和结果类型的全限定类名
*/
public class Mapper {
private String queryString;//SQL
private String resultType;//实体类的全限定类名
public String getQueryString() {
return queryString;
}
public void setQueryString(String queryString) {
this.queryString = queryString;
}
public String getResultType() {
return resultType;
}
public void setResultType(String resultType) {
this.resultType = resultType;
}
}
/**
* 自定义mybatis的配置类
*/
public class Configuration {
private String driver;
private String url;
private String username;
private String password;
private Map mappers = new HashMap();
public Map getMappers() {
return mappers;
}
public void setMappers(Map mappers) {
this.mappers.putAll(mappers);//此处需要使用追加的方式
}
public String getDriver() {
return driver;
}
public void setDriver(String driver) {
this.driver = driver;
}
public String getUrl() {
return url;
}
public void setUrl(String url) {
this.url = url;
}
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;
}
}
@Data
public class User {
private Integer id;
private String username;
private Date birthday;
private String sex;
private String address;
}
/**
* 用户的持久层接口
*/
public interface IUserDao {
/**
* 查询所有操作
* @return
*/
//@Select("select * from user")
List findAll();
}
/**
* 用于创建一个SqlSessionFactory对象
*/
public class SqlSessionFactoryBuilder {
/**
* 根据参数的字节输入流来构建一个SqlSessionFactory工厂
* @param config
* @return
*/
public SqlSessionFactory build(InputStream config){
Configuration cfg = XMLConfigBuilder.loadConfiguration(config);
return new DefaultSqlSessionFactory(cfg);
}
}
public interface SqlSessionFactory {
/**
* 用于打开一个新的SqlSession对象
* @return
*/
SqlSession openSession();
}
public class DefaultSqlSessionFactory implements SqlSessionFactory {
private Configuration cfg;
public DefaultSqlSessionFactory(Configuration cfg){
this.cfg = cfg;
}
/**
* 用于创建一个新的操作数据库对象
* @return
*/
@Override
public SqlSession openSession() {
return new DefaultSqlSession(cfg);
}
}
/**
* 自定义Mybatis中和数据库交互的核心类
* 它里面可以创建dao接口的代理对象
*/
public interface SqlSession {
/**
* 根据参数创建一个代理对象
* @param daoInterfaceClass dao的接口字节码
* @param
* @return
*/
T getMapper(Class daoInterfaceClass);
/**
* 释放资源
*/
void close();
}
/**
* SqlSession接口的实现类
*/
public class DefaultSqlSession implements SqlSession {
private Configuration cfg;
private Connection connection;
public DefaultSqlSession(Configuration cfg){
this.cfg = cfg;
connection = DataSourceUtil.getConnection(cfg);
}
/**
* 用于创建代理对象
* @param daoInterfaceClass dao的接口字节码
* @param
* @return
*/
@Override
public T getMapper(Class daoInterfaceClass) {
return (T) Proxy.newProxyInstance(daoInterfaceClass.getClassLoader(),
new Class[]{daoInterfaceClass},new MapperProxy(cfg.getMappers(),connection));
}
/**
* 用于释放资源
*/
@Override
public void close() {
if(connection != null) {
try {
connection.close();
} catch (Exception e) {
e.printStackTrace();
}
}
}
}
public class MapperProxy implements InvocationHandler {
//map的key是全限定类名+方法名
private Map mappers;
private Connection conn;
public MapperProxy(Map mappers,Connection conn){
this.mappers = mappers;
this.conn = conn;
}
/**
* 用于对方法进行增强的,我们的增强其实就是调用selectList方法
* @param proxy
* @param method
* @param args
* @return
* @throws Throwable
*/
@Override
public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
//1.获取方法名
String methodName = method.getName();
//2.获取方法所在类的名称
String className = method.getDeclaringClass().getName();
//3.组合key
String key = className+"."+methodName;
//4.获取mappers中的Mapper对象
Mapper mapper = mappers.get(key);
//5.判断是否有mapper
if(mapper == null){
throw new IllegalArgumentException("传入的参数有误");
}
//6.调用工具类执行查询所有
return new Executor().selectList(mapper,conn);
}
}
public class UserDaoTest {
@Test
public void findAllTest() throws Exception{
//1.读取配置文件
InputStream in= Resources.getResourceAsStream("SqlMapConfig.xml");
// 2.创建SqlSessionFactory的构建者对象
SqlSessionFactoryBuilder builder= new SqlSessionFactoryBuilder();
//3.使用构建者创建工厂对象SqlSessionFactory
SqlSessionFactory factory= builder.build(in);
// 4.使用SqlSessionFactory生产SqlSession对象
SqlSession session= factory.openSession();
// 5.使用SqlSession创建dao接口的代理对象
IUserDao userDao= session.getMapper(IUserDao.class);
//6.使用代理对象执行查询所有方法
List users= userDao.findAll();for(User user: users) {System.out.println(user);}
//7.释放资源
session.close();
in.close();
}
}
/**
* 查询的注解
*/
@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.METHOD)
public @interface Select {
/**
* 配置SQL语句的
* @return
*/
String value();
}
public interface IUserDao {
/**
* 查询所有操作
* @return
*/
@Select("select * from user")
List findAll();
}
删除原来的mappers标签,添加下面的