使用java反射將結(jié)果集封裝成為對(duì)象和對(duì)象集合的案例

package coral.base.util;

import java.beans.IntrospectionException;
import java.beans.PropertyDescriptor;
import java.lang.reflect.Field;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.Date;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import wfc.service.database.RecordSet;

public class ReflectUtils {
  /**
   * 將一個(gè)map集合封裝成為bean對(duì)象
   * 
   * @param param
   * @param clazz
   * @return
   */
  public static <T> T MapToBean(Map<String, Object> param, Class<&#63;> clazz) {
    Object value = null;

    Class[] paramTypes = new Class[1];

    Object obj = null;

    try {
      obj = clazz.newInstance();

      // 獲取類的屬性
      Field[] declaredFields = clazz.getDeclaredFields();
      // 獲取父類或接口的公有屬性
      Field[] superFields = clazz.getSuperclass().getFields();

      List<Field[]> list = new ArrayList<Field[]>();
      if (declaredFields != null) {
        list.add(declaredFields);
      }
      if (superFields != null) {
        list.add(superFields);
      }
      for (Field[] fields : list) {
        for (Field field : fields) {
          String fieldName = field.getName();
          // 獲取屬性對(duì)應(yīng)的值&#1461;
          value = param.get(fieldName);
          // 把值設(shè)置進(jìn)入對(duì)象屬性中 這里可能是有屬性但是沒有相應(yīng)的set方法，所以要做異常處理
          try {
            PropertyDescriptor pd = new PropertyDescriptor(
                fieldName, clazz);
            Method method = pd.getWriteMethod();
            method.invoke(obj, new Object[] { value });
          } catch (Exception e1) {
          }
        }
      }
    } catch (Exception e1) {
    }
    return (T) obj;
  }
  /**
   * 獲取類的所有屬性，包括父類和接口
   * @param clazz
   * @return
   */
  public static List<Field[]> getBeanFields(Class<&#63;> clazz) {
    List<Field[]> list = new ArrayList<Field[]>();
    Field[] declaredFields = clazz.getDeclaredFields();

    Field[] superFields = clazz.getSuperclass().getFields();
    if (declaredFields != null) {
      list.add(declaredFields);

    }
    if (superFields != null) {
      list.add(superFields);
    }
    return list;
  }
  /**
   * 從結(jié)果集中獲取出值
   * @param fieldName
   * @param rs
   * @return
   */
  public static Object getFieldValue(String fieldName, ResultSet rs) {
    Object value = null;
    try {
      //捕獲值不存在的異常
      value = rs.getObject(fieldName);
      return value;
    } catch (SQLException e) {
      //oracle數(shù)據(jù)庫的列都是大寫，所以才查找一次
      fieldName = fieldName.toLowerCase();
      try {

        value = rs.getObject(fieldName);
        return value;
      } catch (SQLException e1) {
        //結(jié)果集中沒有對(duì)應(yīng)的值，返回為空
        return null;
      }

    }
  }
  /**
   * 方法重載，
   * @param fieldName
   * @param rs 這個(gè)是封裝過的結(jié)果集
   * @return
   */
  public static Object getFieldValue(String fieldName, RecordSet rs) {
    Object value = null;
    value = rs.getObject(fieldName);
    return value;
  }

  /**
   * 方法重載
   * @param rs 封裝過的結(jié)果集
   * @param clazz
   * @return
   */
  public static <T> T RSToBean(RecordSet rs, Class<&#63;> clazz) {
    Object obj = null;
    List<Field[]> list = getBeanFields(clazz);
    try {
      obj = clazz.newInstance();

      for (Field[] fields : list) {
        for (Field field : fields) {
          String fieldName = field.getName();
          // String fieldName = field.getName();&#1461;
          Object value = getFieldValue(fieldName, rs);
          try {
            PropertyDescriptor pd = new PropertyDescriptor(
                fieldName, clazz);
            Method method = pd.getWriteMethod();
            method.invoke(obj, new Object[] { value });
          } catch (Exception e1) {

          }
        }
      }
    } catch (Exception e) {
      // TODO Auto-generated catch block
      e.printStackTrace();
    }
    return (T) obj;
  }
  /**
   * 把結(jié)果集封裝成為bean對(duì)象
   * @param rs
   * @param clazz
   * @return
   */
  public static <T> T RSToBean(ResultSet rs, Class<&#63;> clazz) {
    Object obj = null;
    List<Field[]> list = getBeanFields(clazz);
    try {
      while (rs.next()) {
        obj = clazz.newInstance();

        for (Field[] fields : list) {
          for (Field field : fields) {
            String fieldName = field.getName();
            // String fieldName = field.getName();&#1461;
            Object value = getFieldValue(fieldName, rs);
            PropertyDescriptor pd = new PropertyDescriptor(
                fieldName, clazz);
            Method method = pd.getWriteMethod();
            method.invoke(obj, new Object[] { value });
          }
        }
      }
    } catch (Exception e) {
      // TODO Auto-generated catch block
      e.printStackTrace();
    }
    return (T) obj;
  }

  /**
   * 把結(jié)果集封裝成為L(zhǎng)ist
   * 
   * @param rs
   * @param clazz
   * @return
   */
  public static <T> List<T> RsToList(ResultSet rs, Class<&#63;> clazz) {
    ArrayList<T> objList = new ArrayList<T>();
    // 獲取所有的屬性
    List<Field[]> list = getBeanFields(clazz);
    try {
      while (rs.next()) {
        // 定義臨時(shí)變量
        Object tempObeject = clazz.newInstance();

        // 添加到屬性中
        for (Field[] fields : list) {
          for (Field field : fields) {
            String fieldName = field.getName();
            // 獲取屬性值&#1461;
            Object value = getFieldValue(fieldName, rs);
            PropertyDescriptor pd = new PropertyDescriptor(
                fieldName, clazz);
            Method method = pd.getWriteMethod();
            method.invoke(tempObeject, new Object[] { value });
          }
        }
        objList.add((T) tempObeject);
      }
    } catch (Exception e) {
      // TODO Auto-generated catch block
      e.printStackTrace();
    }
    return objList;
  }
}

package com.util;

import com.entity.Student;
import javax.servlet.ServletRequest;
import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.text.SimpleDateFormat;
import java.util.Enumeration;

/**
 * Created by wq on 2017/8/30.
 */
public class BeanOperateTools {

  /*
  利用反射進(jìn)行所以請(qǐng)求參數(shù)的設(shè)置，要求參數(shù)名與屬性名一致
   */

  /**
   *
   * @param obj
   * @param req
   * @param datePatern 將字符串變?yōu)槿掌跁r(shí)間格式化的字符串
   * @throws Exception
   */
  public static void setValue(Object obj, ServletRequest req,String datePatern)
      throws Exception {//設(shè)置屬性的內(nèi)容
    {
      System.out.println("進(jìn)了setValue方法.....");
      //取得class對(duì)象
      Class<&#63;> cls = obj.getClass();
      //取得輸入的全部參數(shù)名稱
      Enumeration<String> enu = req.getParameterNames();
      //循環(huán)輸入的全部參數(shù)名稱
      while (enu.hasMoreElements()) {
        String paramName = enu.nextElement();//取得參數(shù)名稱
        String paramValue = req.getParameter(paramName);
      //取得屬性的類型是為了取得參數(shù)的類型，以確定method方法和是否轉(zhuǎn)型

        Field field = cls.getDeclaredField(paramName); //取得指定名稱的屬性 (實(shí)體類里面
        //取得指定的操作方法，以滿足反射調(diào)用
        Method method = cls.getMethod("set"+StringTools.initcap(paramName),field.getType());
        //根據(jù)類型進(jìn)行數(shù)據(jù)的轉(zhuǎn)換，同時(shí)調(diào)用setter設(shè)置數(shù)據(jù)
        //取得類型
        String fieldType=field.getType().getSimpleName();
        if ("string".equalsIgnoreCase(fieldType)) {
          method.invoke(obj,paramValue);
        }else if ("integer".equalsIgnoreCase(fieldType)||"int".equalsIgnoreCase(fieldType)){
          method.invoke(obj,Integer.parseInt(paramValue));
        }else if ("double".equalsIgnoreCase(fieldType)){
          method.invoke(obj,Double.parseDouble(paramValue));
        }else if ("date".equalsIgnoreCase(fieldType)){
          method.invoke(obj,new SimpleDateFormat(datePatern).parse(paramValue));
        }
      }
    }
  }
}

package com.servlet;

import com.entity.Student;
import com.sun.xml.internal.bind.v2.runtime.reflect.opt.FieldAccessor_Double;
import com.util.BeanOperateTools;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.lang.reflect.Field;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Enumeration;

/**
 * Created by wq on 2017/8/22.
 */
@WebServlet(name = "studentServlet", urlPatterns = {"/StudentServlet"})
public class StudentServlet extends HttpServlet {
  //private Student stu = new Student();
  private Student student=new Student();
  public Student getStudent() {
    return student;
  }

  public void setStudent(Student student) {
    this.student = student;
  }

-------此處模仿依賴注入
  @Override
  protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
    req.setCharacterEncoding("UTF-8");
    try {
      BeanOperateTools.setValue(this.getStudent(),req,"yyyy-MM-dd");
    } catch (Exception e) {
      e.printStackTrace();
    }
    req.setAttribute("student",this.student);
    req.getRequestDispatcher("student_insert_do.jsp").forward(req,resp);
    // Class<&#63;> cls= this.stu.getClass();
  }

  @Override
  protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
    this.doGet(req, resp);
  }
  public String initcap(String str) {//首字母大寫
    return str.substring(0, 1).toUpperCase().concat(str.substring(1).toLowerCase());
  }
}

<%--
 Created by IntelliJ IDEA.
 User: wq
 Date: 2017/8/21
 Time: 23:25
 To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
  <title>Title</title>
</head>
<body>
<form action="StudentServlet" method="post">
  姓名:<input type="text" name="name"><br>
  年齡:<input type="text" name="age"><br>
  成績(jī):<input type="text" name="score"><br>
  <input type="submit" value="輸入">
  <input type="reset" value="重置">
</form>
</body>
</html>

<%--
 Created by IntelliJ IDEA.
 User: wq
 Date: 2017/8/21
 Time: 23:25
 To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
  <title>Title</title>
</head>
<body>
 <h2>姓名：${student.name}</h2>
 <h2>年齡：${student.age}</h2>
 <h2>成績(jī)：${student.score}</h2>

</body>
</html>