package com.powernode.javassist; import com.powernode.bank.dao.AccountDao; import javassist.ClassPool; import javassist.CtClass; import javassist.CtMethod; import org.junit.Test; import java.lang.reflect.Constructor; import java.lang.reflect.Method; import java.util.Arrays; public class JavassistTest { @Test public void TestGenerateAccountDaoImpl() throws Exception { //获取类池 ClassPool pool = ClassPool.getDefault(); //制造类 CtClass ctClass = pool.makeClass("com.powernode.bank.dao.impl.AccountDaoImpl"); //制造接口 CtClass Interface = pool.makeInterface("com.powernode.bank.dao.AccountDao"); //实现接口 ctClass.addInterface(Interface); //获取所有的方法,获取接口中所有的方法 Method[] methods = AccountDao.class.getDeclaredMethods(); Arrays.stream(methods).forEach(method -> { //method是接口的抽象方法,我们现在需要实现这些方法 try { //"public void insert(){System.out.println(123);}"我们要拼接出来的结果 StringBuilder methodCode = new StringBuilder(); methodCode.append("public ");//追加修饰符列表 methodCode.append(method.getReturnType().getName());//最佳返回值类型 methodCode.append(" "); methodCode.append(method.getName());//追加方法名字 methodCode.append("("); //拼接参数,并用逗号隔开 Class<?>[] parameterTypes = method.getParameterTypes(); for (int i = 0; i < parameterTypes.length; i++) { Class<?> parameterType = parameterTypes[i]; methodCode.append(parameterType.getName()); methodCode.append(" "); // methodCode.append(parameterType.getName().toLowerCase().charAt(0) + parameterType.getName().substring(1)); methodCode.append("arg" + i); if(i != parameterTypes.length - 1) { methodCode.append(","); } } methodCode.append("){"); methodCode.append("System.out.println(123);"); //添加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\";"); } else if("double".equals(simpleName)) { methodCode.append("return 1;"); } methodCode.append("}"); System.out.println(methodCode); CtMethod ctMethod = CtMethod.make(methodCode.toString(),ctClass); ctClass.addMethod(ctMethod); } catch (Exception e) { e.printStackTrace(); } }); //实现接口中所有的方法 //在内存中生成class,并加载到JVM中 Class<?> aClass = ctClass.toClass(); // //创建对象 Constructor<?> declaredConstructor = aClass.getDeclaredConstructor(); AccountDao accountDao = (AccountDao) declaredConstructor.newInstance(); //调用方法 accountDao.insert("aaaa"); accountDao.update("aaaa",1000.0); accountDao.selectByActno("aaaa"); accountDao.delete(); } @Test public void TestGenerateFirstClass() throws Exception { //获取类池,用于生成Class ClassPool pool = ClassPool.getDefault(); //需要完整全类名 CtClass ctClass = pool.makeClass("com.powernode.bank.dao.impl.AccountDaoImpl"); //制造方法 String methodCode = "public void insert(){System.out.println(123);}"; CtMethod ctMethod = CtMethod.make(methodCode,ctClass); //将方法添加到类中 ctClass.addMethod(ctMethod); //生成类(在内存中生成class) ctClass.toClass(); //类加载返回AccountDaoImpl的字节码 //这里内存里就有这个类了,所以可以使用Class.forName创建class对象 Class<?> aClass = Class.forName("com.powernode.bank.dao.impl.AccountDaoImpl"); //创建对象 Constructor<?> declaredConstructor = aClass.getDeclaredConstructor(); Object o = declaredConstructor.newInstance(); //获取AccountDaoImpl的Insert方法 Method insert = aClass.getDeclaredMethod("insert"); insert.invoke(o); } @Test public void TestGenerateImpl() throws Exception { //获取类池 ClassPool pool = ClassPool.getDefault(); //制造类 CtClass ctClass = pool.makeClass("com.powernode.bank.dao.impl.AccountDaoImpl"); //制造接口 CtClass ctInterface = pool.makeInterface("com.powernode.bank.dao.AccountDao"); //添加接口到类中 ctClass.addInterface(ctInterface);//相当于AccountDaoImpl去implements接口AccountDao //实现接口的方法(制造方法先) //制造方法 CtMethod ctMethod = CtMethod.make("public void delete(){System.out.println(\"hello delete!\");}", ctClass); ctClass.addMethod(ctMethod); //在内存中生成类(同时将生成的类加载到JVM中) Class<?> aClass = ctClass.toClass(); Constructor<?> declaredConstructor = aClass.getDeclaredConstructor(); AccountDao accountDao = (AccountDao)declaredConstructor.newInstance(); accountDao.delete(); } }package com.powernode.javassist; import com.powernode.bank.dao.AccountDao; import javassist.ClassPool; import javassist.CtClass; import javassist.CtMethod; import org.junit.Test; import java.lang.reflect.Constructor; import java.lang.reflect.Method; import java.util.Arrays; public class JavassistTest { @Test public void TestGenerateAccountDaoImpl() throws Exception { //获取类池 ClassPool pool = ClassPool.getDefault(); //制造类 CtClass ctClass = pool.makeClass("com.powernode.bank.dao.impl.AccountDaoImpl"); //制造接口 CtClass Interface = pool.makeInterface("com.powernode.bank.dao.AccountDao"); //实现接口 ctClass.addInterface(Interface); //获取所有的方法,获取接口中所有的方法 Method[] methods = AccountDao.class.getDeclaredMethods(); Arrays.stream(methods).forEach(method -> { //method是接口的抽象方法,我们现在需要实现这些方法 try { //"public void insert(){System.out.println(123);}"我们要拼接出来的结果 StringBuilder methodCode = new StringBuilder(); methodCode.append("public ");//追加修饰符列表 methodCode.append(method.getReturnType().getName());//最佳返回值类型 methodCode.append(" "); methodCode.append(method.getName());//追加方法名字 methodCode.append("("); //拼接参数,并用逗号隔开 Class<?>[] parameterTypes = method.getParameterTypes(); for (int i = 0; i < parameterTypes.length; i++) { Class<?> parameterType = parameterTypes[i]; methodCode.append(parameterType.getName()); methodCode.append(" "); // methodCode.append(parameterType.getName().toLowerCase().charAt(0) + parameterType.getName().substring(1)); methodCode.append("arg" + i); if(i != parameterTypes.length - 1) { methodCode.append(","); } } methodCode.append("){"); methodCode.append("System.out.println(123);"); //添加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\";"); } else if("double".equals(simpleName)) { methodCode.append("return 1;"); } methodCode.append("}"); System.out.println(methodCode); CtMethod ctMethod = CtMethod.make(methodCode.toString(),ctClass); ctClass.addMethod(ctMethod); } catch (Exception e) { e.printStackTrace(); } }); //实现接口中所有的方法 //在内存中生成class,并加载到JVM中 Class<?> aClass = ctClass.toClass(); // //创建对象 Constructor<?> declaredConstructor = aClass.getDeclaredConstructor(); AccountDao accountDao = (AccountDao) declaredConstructor.newInstance(); //调用方法 accountDao.insert("aaaa"); accountDao.update("aaaa",1000.0); accountDao.selectByActno("aaaa"); accountDao.delete(); } @Test public void TestGenerateFirstClass() throws Exception { //获取类池,用于生成Class ClassPool pool = ClassPool.getDefault(); //需要完整全类名 CtClass ctClass = pool.makeClass("com.powernode.bank.dao.impl.AccountDaoImpl"); //制造方法 String methodCode = "public void insert(){System.out.println(123);}"; CtMethod ctMethod = CtMethod.make(methodCode,ctClass); //将方法添加到类中 ctClass.addMethod(ctMethod); //生成类(在内存中生成class) ctClass.toClass(); //类加载返回AccountDaoImpl的字节码 //这里内存里就有这个类了,所以可以使用Class.forName创建class对象 Class<?> aClass = Class.forName("com.powernode.bank.dao.impl.AccountDaoImpl"); //创建对象 Constructor<?> declaredConstructor = aClass.getDeclaredConstructor(); Object o = declaredConstructor.newInstance(); //获取AccountDaoImpl的Insert方法 Method insert = aClass.getDeclaredMethod("insert"); insert.invoke(o); } @Test public void TestGenerateImpl() throws Exception { //获取类池 ClassPool pool = ClassPool.getDefault(); //制造类 CtClass ctClass = pool.makeClass("com.powernode.bank.dao.impl.AccountDaoImpl"); //制造接口 CtClass ctInterface = pool.makeInterface("com.powernode.bank.dao.AccountDao"); //添加接口到类中 ctClass.addInterface(ctInterface);//相当于AccountDaoImpl去implements接口AccountDao //实现接口的方法(制造方法先) //制造方法 CtMethod ctMethod = CtMethod.make("public void delete(){System.out.println(\"hello delete!\");}", ctClass); ctClass.addMethod(ctMethod); //在内存中生成类(同时将生成的类加载到JVM中) Class<?> aClass = ctClass.toClass(); Constructor<?> declaredConstructor = aClass.getDeclaredConstructor(); AccountDao accountDao = (AccountDao)declaredConstructor.newInstance(); accountDao.delete(); } }
package com.powernode.bank.dao; public interface AccountDao { void delete(); int insert(String actno); int update(String actno,Double balance); String selectByActno(String actno); }package com.powernode.bank.dao; public interface AccountDao { void delete(); int insert(String actno); int update(String actno,Double balance); String selectByActno(String actno); }
<?xml version="1.0" encoding="UTF-8"?> <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"> <modelVersion>4.0.0</modelVersion> <groupId>com.powernode</groupId> <artifactId>javassist-Test</artifactId> <version>1.0-SNAPSHOT</version> <packaging>jar</packaging> <dependencies> <dependency> <groupId>org.javassist</groupId> <artifactId>javassist</artifactId> <version>3.29.1-GA</version> </dependency> <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <version>4.13.2</version> <scope>test</scope> </dependency> </dependencies> <properties> <maven.compiler.source>17</maven.compiler.source> <maven.compiler.target>17</maven.compiler.target> <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding> </properties> </project><?xml version="1.0" encoding="UTF-8"?> <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"> <modelVersion>4.0.0</modelVersion> <groupId>com.powernode</groupId> <artifactId>javassist-Test</artifactId> <version>1.0-SNAPSHOT</version> <packaging>jar</packaging> <dependencies> <dependency> <groupId>org.javassist</groupId> <artifactId>javassist</artifactId> <version>3.29.1-GA</version> </dependency> <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <version>4.13.2</version> <scope>test</scope> </dependency> </dependencies> <properties> <maven.compiler.source>17</maven.compiler.source> <maven.compiler.target>17</maven.compiler.target> <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding> </properties> </project>
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