如何在java中利用cglib动态生成一个实体bean？很多新手对此不是很清楚，为了帮助大家解决这个难题，下面小编将为大家详细讲解，有这方面需求的人可以来学习下，希望你能有所收获。
maven依赖：
<dependency> <groupId>commons-beanutils</groupId> <artifactId>commons-beanutils</artifactId> <version>1.9.3</version> </dependency> <dependency> <groupId>cglib</groupId> <artifactId>cglib-nodep</artifactId> <version>3.2.4</version> </dependency>DynamicBeanEntity.class动态bean类：
package com.dym.entity;import net.sf.cglib.beans.BeanGenerator;import org.apache.commons.collections.map.MultiValueMap;import java.lang.reflect.*;import java.util.ArrayList;import java.util.HashMap;import java.util.Iterator;import java.util.Map;public class DynamicBeanEntity { Object dynamicBean; Class clazz; public DynamicBeanEntity(Map dynAttrMap) { this.dynamicBean = generateBean(dynAttrMap); clazz = dynamicBean.getClass(); } public Map<String, Object> getValues() throws IllegalAccessException { Map<String, Object> fieldValuesMap = new HashMap(16); Field[] fields = clazz.getDeclaredFields(); for (Field field : fields) { field.setAccessible(true); Object fieldValue = field.get(dynamicBean); fieldValuesMap.put(field.getName().split("\\$cglib_prop_")[1], fieldValue); } return fieldValuesMap; } public MultiValueMap getMethods() { MultiValueMap map = new MultiValueMap(); Method[] methods = clazz.getMethods(); for (Method method : methods) { Type[] genericParameterTypes = method.getGenericParameterTypes(); if (genericParameterTypes.length > 0) { for (Type type : genericParameterTypes) { map.put(method.getName(), type); } } else { map.put(method.getName(), null); } } return map; } public Object executeMethod(String methodName, Object... parameters) throws InvocationTargetException, IllegalAccessException, NoSuchMethodException { ArrayList<Class> paramTypeList = new ArrayList(); for (Object paramType : parameters) { paramTypeList.add(paramType.getClass()); } Class[] classArray = new Class[paramTypeList.size()]; Method method = clazz.getMethod(methodName, paramTypeList.toArray(classArray)); Object invoke = method.invoke(dynamicBean, parameters); return invoke; } public void setValue(String property, Object value) throws NoSuchFieldException, IllegalAccessException { Field declaredField = clazz.getDeclaredField("$cglib_prop_" + property); declaredField.setAccessible(true); declaredField.set(dynamicBean, value); } public Object getValue(String property) throws NoSuchFieldException, IllegalAccessException { Field declaredField = clazz.getDeclaredField("$cglib_prop_" + property); declaredField.setAccessible(true); Object value = declaredField.get(dynamicBean); return value; } public Object getEntity() { return this.dynamicBean; } private Object generateBean(Map dynAttrMap) { BeanGenerator generator = new BeanGenerator(); Iterator iterator = dynAttrMap.keySet().iterator(); while (iterator.hasNext()) { String key = iterator.next().toString(); generator.addProperty(key, (Class) dynAttrMap.get(key)); } return generator.create(); }}test.class测试类测试动态生成bean
package com.dym.attr;import com.dym.entity.DynamicBeanEntity;import org.apache.commons.collections.map.MultiValueMap;import java.lang.reflect.InvocationTargetException;import java.util.HashMap;import java.util.Map;public class test { public static void main(String[] args) throws NoSuchFieldException, IllegalAccessException, NoSuchMethodException, InvocationTargetException { // 设置属性们，默认16 HashMap propertyMap = new HashMap(16); propertyMap.put("name", String.class); propertyMap.put("age", Integer.class); propertyMap.put("height", Double.class); // 生成动态 Entity DynamicBeanEntity bean = new DynamicBeanEntity(propertyMap); //设置属性值 bean.setValue("name", "zx"); bean.setValue("age", 22); bean.setValue("height", 175.0); //获取属性值 Map<String, Object> values = bean.getValues(); //获取可执行的方法 MultiValueMap methods = bean.getMethods(); //执行某个方法 bean.executeMethod("setAge", 23); System.out.println("动态bean的age属性："+bean.getValue("age")); }}test.class测试类测试链接数据库动态生成bean
package com.dym.test;import com.dym.util.DBUtil;import com.dym.util.DynmicEntity;import org.springframework.stereotype.Component;import java.sql.Connection;import java.sql.PreparedStatement;import java.sql.ResultSet;import java.sql.SQLException;import java.util.ArrayList;import java.util.HashMap;import java.util.Map;@Componentpublic class test { public static void main(String[] args) { ArrayList<DynmicEntity> beans = new ArrayList<>(); Connection conn = null; PreparedStatement prst = null; String sql = ""; sql = "select table_name from information_schema.tables where table_schema=\'public\'"; conn = DBUtil.getConn(); try { prst = conn.prepareStatement(sql); ResultSet rs = prst.executeQuery(); while (rs.next()) { String tableName = rs.getString(1); Map attrMap = new HashMap<>(); String findFieldSql = "SELECT format_type(a.atttypid,a.atttypmod) as type,a.attname as name, a.attnotnull as notnull \n" + "FROM pg_class as c,pg_attribute as a where c.relname = \'" + tableName + "\' and a.attrelid = c.oid and a.attnum>0"; PreparedStatement fieldsPrst = conn.prepareStatement(findFieldSql); ResultSet fieldsRs = fieldsPrst.executeQuery(); while (fieldsRs.next()) { String fieldType = fieldsRs.getString(1); String fieldName = fieldsRs.getString(2); attrMap.put(fieldName, Object.class); } DynmicEntity bean = new DynmicEntity(attrMap); beans.add(bean); } } catch (SQLException e) { e.printStackTrace(); } DBUtil.close(prst, conn); }}DBUtil.class:
package com.dym.util;import java.sql.Connection;import java.sql.DriverManager;import java.sql.PreparedStatement;import java.sql.ResultSet;import java.sql.SQLException;public class DBUtil { private final static String URL="jdbc:postgresql://localhost:5432/dynmic"; private final static String NAME="postgres"; private final static String PASS="123456"; private static Connection conn=null; public DBUtil(){ } public static Connection getConn(){ //告诉jvm使用mysql try { //加载驱动，string为驱动名字 Class.forName("org.postgresql.Driver"); //连接数据库，得到Connection连接 conn=DriverManager.getConnection(URL,NAME,PASS); //System.out.println("连接数据库： "+conn); }catch(ClassNotFoundException e) { // TODO Auto-generated catch block e.printStackTrace(); }catch(SQLException e){ e.printStackTrace(); } return conn; } //关闭结果对象集 public static void close(ResultSet rs){ if(rs!=null){ try{ rs.close(); }catch(SQLException e){ e.printStackTrace(); } } } //关闭编译语句对象 public static void close(PreparedStatement prst){ if(prst!=null){ try{ prst.close(); }catch(SQLException e){ e.printStackTrace(); } } } //关闭结果对象集 public static void close(Connection conn){ if(conn!=null){ try{ conn.close(); }catch(SQLException e){ e.printStackTrace(); } } } //对于更新操作关闭资源 public static void close(PreparedStatement prst,Connection conn){ close(prst); close(conn); } //关闭所有 public static void close(ResultSet rs,PreparedStatement prst,Connection conn){ close(rs); close(prst); close(conn); }}补充：java 反射 json动态转实体类
我就废话不多说了，大家还是直接看代码吧~
package test.refect; public class Student {// 姓名private String name;// 年龄private String age;// 住址private String address; public String getName() {return name;} public void setName(String name) {this.name = name;} public String getAge() {return age;} public void setAge(String age) {this.age = age;} public String getAddress() {return address;} public void setAddress(String address) {this.address = address;} @Overridepublic String toString() {return "Student [name=" + name + ", age=" + age + ", address=" + address + "]";}public void sayHello(Book book){System.out.println(book.getName());}}package test.refect; public class Book {private String name; public String getName() {return name;} public void setName(String name) {this.name = name;}}package test.refect; import java.lang.reflect.Field;import java.lang.reflect.Method;import java.net.URLDecoder;import java.util.Iterator; import net.sf.json.JSONObject; public class Main {public static void main(String[] args) throws Exception {//Student str --> Student 主类String str = "test.refect.Student";Class<?> clazz = Class.forName(str);//Book实体 str --> Book 参数类String bookStr = "test.refect.Book";Class<?> bookClazz = Class.forName(bookStr);//json --> Book 将参数类转为JSONOBJECTString bookJson ="{\"name\":\"Java\"}"; JSONObject jsonObject=JSONObject.fromObject(bookJson);//实例化参数类Object bookInStance = bookClazz.newInstance();// 通过JSONOBJECT 为参数类赋值Iterator<?> keys = jsonObject.keys(); while (keys.hasNext()) { Object key = keys.next(); Object value = jsonObject.get(key); // 替换非法字符 String _key = String.valueOf(key).replaceFirst("\\W", ""); Field field = bookClazz.getDeclaredField(_key); field.setAccessible(true); field.set(bookInStance, URLDecoder.decode(String.valueOf(value), "UTF-8")); field.setAccessible(false); } //将参数类注入到主类 Method method = clazz.getDeclaredMethod("sayHello", bookClazz); //执行主类 method.invoke(clazz.newInstance(), bookInStance); } }看完上述内容是否对您有帮助呢？如果还想对相关知识有进一步的了解或阅读更多相关文章，请关注编程网行业资讯频道，感谢您对编程网的支持。
