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java通过cglib动态生成实体bean的操作

转载 作者：qq735679552 更新时间：2022-09-29 22:32:09 24 4
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maven依赖：

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< 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：

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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;
/**
  * @author: zhaoxu
  * @description:
  */
public class DynamicBeanEntity {
   Object dynamicBean;
   Class clazz;
   public DynamicBeanEntity(Map dynAttrMap) {
     this .dynamicBean = generateBean(dynAttrMap);
     clazz = dynamicBean.getClass();
   }
   /**
    * 获取所有属性值
    *
    * @return
    * @throws IllegalAccessException
    */
   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;
   }
   /**
    * 获取动态bean所有方法信息
    *
    * @return
    */
   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;
   }
   /**
    * 执行某个方法
    *
    * @param methodName
    * @param parameters
    * @return
    * @throws InvocationTargetException
    * @throws IllegalAccessException
    * @throws NoSuchMethodException
    */
   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;
   }
   /**
    * 设置属性值
    *
    * @param property
    * @param value
    * @throws NoSuchFieldException
    * @throws IllegalAccessException
    */
   public void setValue(String property, Object value) throws NoSuchFieldException, IllegalAccessException {
     Field declaredField = clazz.getDeclaredField( "$cglib_prop_" + property);
     declaredField.setAccessible( true );
     declaredField.set(dynamicBean, value);
   }
   /**
    * 获取属性值
    *
    * @param property
    * @return
    * @throws NoSuchFieldException
    * @throws IllegalAccessException
    */
   public Object getValue(String property) throws NoSuchFieldException, IllegalAccessException {
     Field declaredField = clazz.getDeclaredField( "$cglib_prop_" + property);
     declaredField.setAccessible( true );
     Object value = declaredField.get(dynamicBean);
     return value;
   }
   public Object getEntity() {
     return this .dynamicBean;
   }
   /**
    * 利用cglib的BeanGenerator创建对象
    *
    * @param dynAttrMap
    * @return
    */
   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

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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;
/**
  * @author: zhaoxu
  * @description:
  */
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

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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;
/**
  * @author: zhaoxu
  * @description:
  */
@Component
public 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:

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package com.dym.util;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
/**
  * @author: zhaoxu
  * @description:
  */
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 ;
   /**
    *
    *@Title:DBUtil
    *@Description:
    */
   public DBUtil(){
   }
   /**
    *
    * @Tiltle getConn
    * @return Connection
    * @Description:返回连接
    */
   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~ 。

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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;
     }
 
     @Override
     public String toString() {
         return "Student [name=" + name + ", age=" + age + ", address=" + address + "]" ;
     }
    
     public void sayHello(Book book){
         System.out.println(book.getName());    
     }
}
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package test.refect;
public class Book {
     private String name;
     public String getName() {
         return name;
     }
 
     public void setName(String name) {
         this .name = name;
     }  
}
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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JSONOBJECT
         String 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);      
     }
}

以上为个人经验，希望能给大家一个参考，也希望大家多多支持我。如有错误或未考虑完全的地方，望不吝赐教.

原文链接：https://blog.csdn.net/qq_39898191/article/details/112366508 。

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