Mybatis实现接口自动生成代理类对接口中抽象方法的重写并实现增删改查-----Mybatis框架

曾经终败给现在 2024-03-04 06:26 61阅读 0赞

>     package com.powernode.bank.utils;
>     
>     import org.apache.ibatis.javassist.ClassPool;
>     import org.apache.ibatis.javassist.CtClass;
>     import org.apache.ibatis.javassist.CtMethod;
>     import org.apache.ibatis.mapping.SqlCommandType;
>     import org.apache.ibatis.session.SqlSession;
>     
>     import java.lang.reflect.Constructor;
>     import java.lang.reflect.Method;
>     import java.util.Arrays;
>     
>     public class GenerateDaoProxy
>     {
>         //看作Mybatis提供的
>         //传一个Dao接口的Class传过来,就返回一个接口的实现类对象
>         public static Object generate(SqlSession sqlSession, Class daoInterface)
>         {
>             //类池
>             ClassPool classPool = ClassPool.getDefault();
>             //制造类
>             CtClass ctClass = classPool.makeClass(daoInterface.getName() + "Proxy");
>             //制造接口
>             CtClass ctInterface = classPool.makeInterface(daoInterface.getName());
>             //实现接口
>             ctClass.addInterface(ctInterface);
>             Method[] declaredMethods = daoInterface.getDeclaredMethods();
>             Arrays.stream(declaredMethods).forEach(declaredMethod -> {
>                 //取出抽象方法
>                 try
>                 {
>                     StringBuilder methodCode = new StringBuilder();
>                     methodCode.append("public ");
>                     methodCode.append(declaredMethod.getReturnType().getName());
>                     methodCode.append(" ");
>                     methodCode.append(declaredMethod.getName());
>                     methodCode.append("(");
>                     //需要形参代码
>                     Class<?>[] ParameterTypes = declaredMethod.getParameterTypes();
>                     for(int i = 0; i < ParameterTypes.length; i++)
>                     {
>                         Class<?> genericParameterType = ParameterTypes[i];
>                         methodCode.append(genericParameterType.getName());
>                         methodCode.append(" ");
>                         methodCode.append("arg" + i);
>                         if(i != ParameterTypes.length - 1)
>                         {
>                             methodCode.append(",");
>                         }
>                     }
>                     methodCode.append(")");
>                     methodCode.append("{");
>                     //需要方法代码
>                     methodCode.append("org.apache.ibatis.session.SqlSession sqlSession = com.powernode.bank.utils.SqlSessionUtil.openSession();");
>                     //需要知道是什么类型的Sql语句
>                     //sql语句的ID是框架使用者提供的,对于我框架的开发人员来说,我不知道
>                     //既然我不知道,于是规定如下,凡是使用GenerateDaoProxy机制的
>                     //sqlId都不能随便写,namespace必须是dao接口全限定类名,id必须是dao接口方法名
>                     String sqlId = daoInterface.getName() + "." + declaredMethod.getName();
>                     SqlCommandType sqlCommandType = sqlSession.getConfiguration().getMappedStatement(sqlId).getSqlCommandType();
>                     if(sqlCommandType == SqlCommandType.INSERT)
>                     {
>                         methodCode.append("return sqlSesssion.insert(\"" + sqlId + "\",arg0);");
>                     }
>                     if(sqlCommandType == SqlCommandType.UPDATE)
>                     {
>                         methodCode.append("return sqlSession.update(\"" + sqlId + "\",arg0);");
>                     }
>                     if(sqlCommandType == SqlCommandType.DELETE)
>                     {
>                         methodCode.append("return sqlSesssion.delete(\"" + sqlId + "\",arg0);");
>                     }
>                     if(sqlCommandType == SqlCommandType.SELECT)
>                     {
>                         methodCode.append("return ("+ declaredMethod.getReturnType().getName() + ")sqlSession.selectOne(\"" + sqlId + "\",arg0);");
>                     }
>                     methodCode.append("}");
>                     String code = methodCode.toString();
>                     CtMethod make = CtMethod.make(code,ctClass);
>                     //实现抽象方法
>                     ctClass.addMethod(make);
>                 }
>                 catch (Exception e)
>                 {
>                     e.printStackTrace();
>                 }
>             });
>             //创建对象
>             Object o = null;
>             try
>             {
>                 Class<?> aClass = ctClass.toClass();
>                 Method[] declaredMethods1 = aClass.getDeclaredMethods();
>                 Constructor<?> declaredConstructor = aClass.getDeclaredConstructor();
>                 o = declaredConstructor.newInstance();
>             }
>             catch (Exception e)
>             {
>                 throw new RuntimeException(e);
>             }
>             //mybatis已经集成了javassist的依赖
>             return o;
>         }
>     }
> 
>     package com.powernode.bank.utils;
>     
>     import org.apache.ibatis.javassist.ClassPool;
>     import org.apache.ibatis.javassist.CtClass;
>     import org.apache.ibatis.javassist.CtMethod;
>     import org.apache.ibatis.mapping.SqlCommandType;
>     import org.apache.ibatis.session.SqlSession;
>     
>     import java.lang.reflect.Constructor;
>     import java.lang.reflect.Method;
>     import java.util.Arrays;
>     
>     public class GenerateDaoProxy
>     {
>         //看作Mybatis提供的
>         //传一个Dao接口的Class传过来,就返回一个接口的实现类对象
>         public static Object generate(SqlSession sqlSession, Class daoInterface)
>         {
>             //类池
>             ClassPool classPool = ClassPool.getDefault();
>             //制造类
>             CtClass ctClass = classPool.makeClass(daoInterface.getName() + "Proxy");
>             //制造接口
>             CtClass ctInterface = classPool.makeInterface(daoInterface.getName());
>             //实现接口
>             ctClass.addInterface(ctInterface);
>             Method[] declaredMethods = daoInterface.getDeclaredMethods();
>             Arrays.stream(declaredMethods).forEach(declaredMethod -> {
>                 //取出抽象方法
>                 try
>                 {
>                     StringBuilder methodCode = new StringBuilder();
>                     methodCode.append("public ");
>                     methodCode.append(declaredMethod.getReturnType().getName());
>                     methodCode.append(" ");
>                     methodCode.append(declaredMethod.getName());
>                     methodCode.append("(");
>                     //需要形参代码
>                     Class<?>[] ParameterTypes = declaredMethod.getParameterTypes();
>                     for(int i = 0; i < ParameterTypes.length; i++)
>                     {
>                         Class<?> genericParameterType = ParameterTypes[i];
>                         methodCode.append(genericParameterType.getName());
>                         methodCode.append(" ");
>                         methodCode.append("arg" + i);
>                         if(i != ParameterTypes.length - 1)
>                         {
>                             methodCode.append(",");
>                         }
>                     }
>                     methodCode.append(")");
>                     methodCode.append("{");
>                     //需要方法代码
>                     methodCode.append("org.apache.ibatis.session.SqlSession sqlSession = com.powernode.bank.utils.SqlSessionUtil.openSession();");
>                     //需要知道是什么类型的Sql语句
>                     //sql语句的ID是框架使用者提供的,对于我框架的开发人员来说,我不知道
>                     //既然我不知道,于是规定如下,凡是使用GenerateDaoProxy机制的
>                     //sqlId都不能随便写,namespace必须是dao接口全限定类名,id必须是dao接口方法名
>                     String sqlId = daoInterface.getName() + "." + declaredMethod.getName();
>                     SqlCommandType sqlCommandType = sqlSession.getConfiguration().getMappedStatement(sqlId).getSqlCommandType();
>                     if(sqlCommandType == SqlCommandType.INSERT)
>                     {
>                         methodCode.append("return sqlSesssion.insert(\"" + sqlId + "\",arg0);");
>                     }
>                     if(sqlCommandType == SqlCommandType.UPDATE)
>                     {
>                         methodCode.append("return sqlSession.update(\"" + sqlId + "\",arg0);");
>                     }
>                     if(sqlCommandType == SqlCommandType.DELETE)
>                     {
>                         methodCode.append("return sqlSesssion.delete(\"" + sqlId + "\",arg0);");
>                     }
>                     if(sqlCommandType == SqlCommandType.SELECT)
>                     {
>                         methodCode.append("return ("+ declaredMethod.getReturnType().getName() + ")sqlSession.selectOne(\"" + sqlId + "\",arg0);");
>                     }
>                     methodCode.append("}");
>                     String code = methodCode.toString();
>                     CtMethod make = CtMethod.make(code,ctClass);
>                     //实现抽象方法
>                     ctClass.addMethod(make);
>                 }
>                 catch (Exception e)
>                 {
>                     e.printStackTrace();
>                 }
>             });
>             //创建对象
>             Object o = null;
>             try
>             {
>                 Class<?> aClass = ctClass.toClass();
>                 Method[] declaredMethods1 = aClass.getDeclaredMethods();
>                 Constructor<?> declaredConstructor = aClass.getDeclaredConstructor();
>                 o = declaredConstructor.newInstance();
>             }
>             catch (Exception e)
>             {
>                 throw new RuntimeException(e);
>             }
>             //mybatis已经集成了javassist的依赖
>             return o;
>         }
>     }