mybatis--javassist 11.26
有没有自动生成接口的实现类的方式？？？先自己实现
（如下自动生成AccountDao实现类的方式）
1.AcountDao
package com.jiang.dao.impl;
public interface AccountDao {
void delete();
int update(String actno,Double balance);
int insert(String actno);
String selectByActno(String actno);
}
2.TestGenerate
- 获取类池
- 制造类
- 制造方法
- 添加方法至类中
- 内存中生成类
- 类加载到JVM 返回类的字节码
- 创建对象
- 获取方法
- 使用方法
@org.junit.Test
public void testGenerate() throws CannotCompileException, ClassNotFoundException, IllegalAccessException, InstantiationException, NoSuchMethodException, InvocationTargetException {
//获取类池
ClassPool classPool=ClassPool.getDefault();
//制造类 类名
CtClass ctClass = classPool.makeClass("com.jiang.dao.impl.AccountDapImpl");
//制造方法
String src=" public void insert(){\n" +
" System.out.println(\"hello javassist\");\n" +
" }";
CtMethod ctMethod = CtMethod.make(src, ctClass);
//添加方法
ctClass.addMethod(ctMethod);
//在内存中生成类
ctClass.toClass();
//类加载到JVM当中 返回类的字节码
Class aClass = Class.forName("com.jiang.dao.impl.AccountDapImpl");
//创建对象
Object o = aClass.newInstance();
//获取其方法
Method insert = aClass.getDeclaredMethod("insert");
//调用方法insert
insert.invoke(o);
}实现接口
知道有哪些方法存在
@org.junit.Test
//实现接口
//知道有哪些方法名存在
public void Testinterface() throws CannotCompileException, IllegalAccessException, InstantiationException {
//获取类池
ClassPool classPool = ClassPool.getDefault();
//创建类
CtClass ctClass = classPool.makeClass("com.jiang.dao.impl.AccountDaopImpl");
//创接口
CtClass anInterface = classPool.makeInterface("com.jiang.dao.impl.AccountDao");
//将接口添加到类中
ctClass.addInterface(anInterface);
//实现方法：
//创造方法：
String src=" public void delete(){\n" +
" System.out.println(\" delete-ing\");\n" +
" }";
CtMethod ctMethod = CtMethod.make(src, ctClass);
//将方法添加到类中
ctClass.addMethod(ctMethod);
//内存中生成类，同时将生成的类加载到JVM中
Class aClass = ctClass.toClass();
AccountDao accountDa = (AccountDao) aClass.newInstance();
accountDa.delete();
}实现接口，不知道有哪些方法
实现方法模样如下
public void delete() {
}
public int update(String actno, Double balance) {
return 0;
}
public int insert(String actno) {
return 0;
}
public String selectByActno(String actno) {
return null;
}动态拼接StringBuilder：
- append public
- void/int/String method.getReturnType().getName()
- delete/update/insert/... 方法名 method.getName() java.lang.String getSimplename string
- ()
- ()里面的参数 （）、（String actno,Double balance）....
两个参数方法：
method.getParameterCount() 参数个数
parameterType.getName() 参数类型- 加逗号
if (i!=parameterTypes.length-1){ methodCode.append(","); } - return语句
String simpleName = method.getReturnType().getSimpleName(); if ("void".equals(simpleName)) { }else if ("int".equals(simpleName)) { methodCode.append("return 1;"); }else if ("String".equals(simpleName)) { methodCode.append("return \"hello\";"); } methodCode.append("}");
@org.junit.Test
//动态实现接口方法（不知道方法名等）
public void TestInterface() throws CannotCompileException, IllegalAccessException, InstantiationException {
//获取类池
ClassPool pool = ClassPool.getDefault();
//创建类
CtClass ctClass = pool.makeClass("com.jiang.dao.impl.AccountDaoImpl");
//创建接口
CtClass anInterface = pool.makeInterface("com.jiang.dao.impl.AccountDao");
//implement接口
ctClass.addInterface(anInterface);
//实现方法：
//获取方法：
Method[] methods = AccountDao.class.getDeclaredMethods();
//System.out.println(methods.length); 4
Arrays.stream(methods).forEach(method -> {
try {
//接口中的方法如下：
//int update(String actno,Double balance);
//void delete();
//int insert(String actno);
//String selectByActno(String actno);
StringBuilder methodCode = new StringBuilder();
methodCode.append("public");//修饰符号
methodCode.append(" ");
methodCode.append(method.getReturnType().getName());//返回值类型
methodCode.append(" ");
methodCode.append(method.getName());
methodCode.append("(");
//参数:
//System.out.println(method.getParameterCount()); 2 0 1 1
//System.out.println(method.getParameterTypes());
//System.out.println(method.getAnnotatedReturnType().getType()); int void int String
Class[] parameterTypes = method.getParameterTypes();
for (int i = 0; i < parameterTypes.length; i++) {
Class parameterType = parameterTypes[i];
methodCode.append(parameterType.getName());
methodCode.append(" ");
methodCode.append("arg"+i);
//加上逗号
if (i!=parameterTypes.length-1){
methodCode.append(",");
}
}
methodCode.append(")");
methodCode.append("{System.out.println(1111);");
//添加return语句
//System.out.println(method.getReturnType().getName()); java.lang.String
//System.out.println(method.getReturnType().getSimpleName()); String
String simpleName = method.getReturnType().getSimpleName();
if ("void".equals(simpleName)) {
}else if ("int".equals(simpleName)) {
methodCode.append("return 1;");
}else if ("String".equals(simpleName)) {
methodCode.append("return \"hello\";");
}
methodCode.append("}");
System.out.println(methodCode);
CtMethod ctMethod = CtMethod.make(methodCode.toString(),ctClass);
ctClass.addMethod(ctMethod);
} catch (Exception e) {
e.printStackTrace();
}
});
Class aClass = ctClass.toClass();
AccountDao accountDao = (AccountDao) aClass.newInstance();
accountDao.insert("aaa");
accountDao.delete();
accountDao.update("aaa",1000.00);
accountDao.selectByActno("aaa");
}
获取方法
1.无接口
Object o = aClass.newInstance();
//获取其方法
Method insert = aClass.getDeclaredMethod("insert");
//调用方法insert
insert.invoke(o);2. 有接口，直接接口调方法
Class aClass = ctClass.toClass();
AccountDao accountDa = (AccountDao) aClass.newInstance();
accountDa.delete();Mybatis自带的自动生成接口实现类方法
SqlSession sqlSession = MybatisTool.getSession(); CarMapper carMapper =sqlSession.getMapper(CarMapper.class);
使用mybatis自带方法
结构
1.CarMapper
package com.jiang.mapper;
import com.jiang.pojo.T_Car;
import java.util.List;
//一般使用mybatis来生产的话，不叫Dao 而是Mapper
public interface CarMapper {
//持久化层 专门做增删改查
int insert(T_Car car);
//Long 防止null异常
int deleteByid(Long id);
int update(T_Car car);
T_Car selectByid(Long id);
List selectAll();
}
2.T_Car
package com.jiang.pojo;
import java.util.Objects;
public class T_Car {
//如果你认为这个属性不能为null,那么就用long，因为它默认初值为0，如果这个字段可以为null，那么就应该选择Long。
private Long id;
private String car_num;
private String brand;
private Double guide_price;
private String produce_time;
private String car_type;
@Override
public String toString() {
return "T_Car{" +
"id=" + id +
", car_num='" + car_num + '\'' +
", brand='" + brand + '\'' +
", guide_price='" + guide_price + '\'' +
", produce_time='" + produce_time + '\'' +
", car_type='" + car_type + '\'' +
'}';
}
@Override
public boolean equals(Object o) {
if (this == o) return true;
if (o == null || getClass() != o.getClass()) return false;
T_Car t_car = (T_Car) o;
return Objects.equals(id, t_car.id) && Objects.equals(car_num, t_car.car_num) && Objects.equals(brand, t_car.brand) && Objects.equals(guide_price, t_car.guide_price) && Objects.equals(produce_time, t_car.produce_time) && Objects.equals(car_type, t_car.car_type);
}
@Override
public int hashCode() {
return Objects.hash(id, car_num, brand, guide_price, produce_time, car_type);
}
public Long getId() {
return id;
}
public void setId(Long id) {
this.id = id;
}
public String getcar_num() {
return car_num;
}
public void setcar_num(String car_num) {
this.car_num = car_num;
}
public String getBrand() {
return brand;
}
public void setBrand(String brand) {
this.brand = brand;
}
public Double getGuide_price() {
return guide_price;
}
public void setGuide_price(Double guide_price) {
this.guide_price = guide_price;
}
public String getProduce_time() {
return produce_time;
}
public void setProduce_time(String produce_time) {
this.produce_time = produce_time;
}
public String getCar_type() {
return car_type;
}
public void setCar_type(String car_type) {
this.car_type = car_type;
}
public T_Car() {
}
public T_Car(Long id, String car_num, String brand, Double guide_price, String produce_time, String car_type) {
this.id = id;
this.car_num = car_num;
this.brand = brand;
this.guide_price = guide_price;
this.produce_time = produce_time;
this.car_type = car_type;
}
}
3.MybatisTool(获取sqlsession)
package com.jiang.utils;
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
import java.io.IOException;
public class MybatisTool {
public static ThreadLocal local = new ThreadLocal();
private MybatisTool(){}
private static SqlSessionFactory sessionFactory;
static {
try {
//该处容易出错，记得指定环境 ****
sessionFactory = new SqlSessionFactoryBuilder().build(Resources.getResourceAsStream("Config.xml"),"one");
} catch (IOException e) {
e.printStackTrace();
}
}
public static SqlSession getSession(){
SqlSession session = local.get();
if (session==null) {
SqlSession sqlSession = sessionFactory.openSession();
session=sqlSession;
local.set(session);
}
return session;
}
public static void close(SqlSession session){
if (session!=null) {
session.close();
local.remove();
}
}
}
4.Mapper.xml
insert into t_car values(null,#{num},#{brand},#{guide_price},#{produce_time},#{car_type})
delete from t_car where id=#{id}
update t_car set car_num=#{num},brand=#{brand},guide_price=#{guide_price},produce_time=#{produce_time},car_type=#{car_type} where id=#{id}
测试
关键几个点：
- sqlsession是用来获取Mapper.xml中的sql语句和其返回值类型（参照自己写的）
- sqlsession.getMapper(传入想实现的接口)
package com.jiang.Test;
import com.jiang.mapper.CarMapper;
import com.jiang.pojo.T_Car;
import com.jiang.utils.MybatisTool;
import org.apache.ibatis.session.SqlSession;
import java.util.List;
public class Test {
@org.junit.Test
public void TestInsert(){
SqlSession sqlSession = MybatisTool.getSession();
CarMapper carMapper =sqlSession.getMapper(CarMapper.class);
T_Car car=new T_Car(null,"1000","宝马",1010.00,"2022-11-22","motuo");
int i = carMapper.insert(car);
sqlSession.commit();
MybatisTool.close(sqlSession);
System.out.println(i);
}
@org.junit.Test
public void TestDeleteByid(){
//实现持久化接口：
SqlSession sqlSession=MybatisTool.getSession();
CarMapper carMapper=MybatisTool.getSession().getMapper(CarMapper.class);
int i = carMapper.deleteByid(37L);
sqlSession.commit();
MybatisTool.close(sqlSession);
}
@org.junit.Test
public void TestUpdate(){
SqlSession sqlSession=MybatisTool.getSession();
T_Car car=new T_Car(1L,"1000","宝马",1010.00,"2022-11-22","motuo");
CarMapper carMapper = sqlSession.getMapper(CarMapper.class);
carMapper.update(car);
sqlSession.commit();
MybatisTool.close(sqlSession);
}
@org.junit.Test
public void TestSelectById(){
SqlSession sqlSession=MybatisTool.getSession();
CarMapper carMapper = sqlSession.getMapper(CarMapper.class);
T_Car t_car = carMapper.selectByid(1L);
System.out.println(t_car);
MybatisTool.close(sqlSession);
}
@org.junit.Test
public void TestSelectAll(){
SqlSession sqlSession=MybatisTool.getSession();
CarMapper carMapper=sqlSession.getMapper(CarMapper.class);
List t_carList = carMapper.selectAll();
for (T_Car t_car : t_carList) {
System.out.println(t_car);
}
MybatisTool.close(sqlSession);
}
}