package com.xc.sap.util;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;

import cnblogs.com.ooo0.oracle.OperateOracle;

public class Test {

    public static void main(String[] args) {
        try {
            // oracle Database connection
            OperateOracle oo = new OperateOracle();//https://www.cnblogs.com/ooo0/p/10225374.html
            Connection connection = oo.getConnection();

            String mainSql = "select * from users";
            PreparedStatement pstm = connection.prepareStatement(mainSql);
            ResultSet rs = pstm.executeQuery();

            ArrayList<Users> putResult = ResultSetPropertiesSimplifyHelps.putResult(rs, Users.class);

            for (int i = 0; i < putResult.size(); i++) {
                System.out.println(putResult.get(i).toString());
            }
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

    }
}

package com.xc.sap.util;

import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.math.BigDecimal;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.Date;

/**
 * java jdbc ResultSet The result is assigned to a Java object through java reflection
 * 
 * @author xc
 */
public class ResultSetPropertiesSimplifyHelps {

    /**
     * Put the result of ResultSet into java object
     * 
     * @param <T>
     * @param rs
     *            ResultSet
     * @param obj
     *            java Class of class
     * @return
     */
    public static <T> ArrayList<T> putResult(ResultSet rs, Class<T> obj) {
        try {
            ArrayList<T> arrayList = new ArrayList<T>();
            ResultSetMetaData metaData = rs.getMetaData();
            /**
             * Get total columns
             */
            int count = metaData.getColumnCount();
            while (rs.next()) {
                /**
                 * Create an object instance
                 */
                T newInstance = obj.newInstance();
                for (int i = 1; i <= count; i++) {
                    /**
                     * Assign a value to an attribute of an object
                     */
                    String name = metaData.getColumnName(i).toLowerCase();
                    name = toJavaField(name);// Change column name format to java Naming format
                    String substring = name.substring(0, 1);// title case
                    String replace = name.replaceFirst(substring, substring.toUpperCase());
                    Class<?> type = null;
                    try {
                        type = obj.getDeclaredField(name).getType();// Get field type
                    } catch (NoSuchFieldException e) { // Class When the field is not defined by the object,skip
                        continue;
                    }

                    Method method = obj.getMethod("set" + replace, type);
                    /**
                     * Determine the type of data read
                     */
                    if (type.isAssignableFrom(String.class)) {
                        method.invoke(newInstance, rs.getString(i));
                    } else if (type.isAssignableFrom(byte.class) || type.isAssignableFrom(Byte.class)) {
                        method.invoke(newInstance, rs.getByte(i));// byte The data type is an 8-bit signed integer represented by a binary complement
                    } else if (type.isAssignableFrom(short.class) || type.isAssignableFrom(Short.class)) {
                        method.invoke(newInstance, rs.getShort(i));// short The data type is a 16 bit signed integer represented by a binary complement
                    } else if (type.isAssignableFrom(int.class) || type.isAssignableFrom(Integer.class)) {
                        method.invoke(newInstance, rs.getInt(i));// int The data type is a 32-bit signed integer represented by a binary complement
                    } else if (type.isAssignableFrom(long.class) || type.isAssignableFrom(Long.class)) {
                        method.invoke(newInstance, rs.getLong(i));// long The data type is a 64 bit signed integer represented by a binary complement
                    } else if (type.isAssignableFrom(float.class) || type.isAssignableFrom(Float.class)) {
                        method.invoke(newInstance, rs.getFloat(i));// float Data type is single precision, 32-bit, compliant IEEE 754 Standard floating point number
                    } else if (type.isAssignableFrom(double.class) || type.isAssignableFrom(Double.class)) {
                        method.invoke(newInstance, rs.getDouble(i));// double Data type is double, 64 bit, compliant IEEE 754 Standard floating point number
                    } else if (type.isAssignableFrom(BigDecimal.class)) {
                        method.invoke(newInstance, rs.getBigDecimal(i));
                    } else if (type.isAssignableFrom(boolean.class) || type.isAssignableFrom(Boolean.class)) {
                        method.invoke(newInstance, rs.getBoolean(i));// boolean Data type represents one bit of information
                    } else if (type.isAssignableFrom(Date.class)) {
                        method.invoke(newInstance, rs.getDate(i));
                    }
                }
                arrayList.add(newInstance);
            }
            return arrayList;

        } catch (InstantiationException | IllegalAccessException | SQLException | SecurityException | NoSuchMethodException | IllegalArgumentException
                | InvocationTargetException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

        return null;
    }

    /**
     * Database naming format to java Naming format
     * 
     * @param str
     *            Database field name
     * @return java Field name
     */
    public static String toJavaField(String str) {

        String[] split = str.split("_");
        StringBuilder builder = new StringBuilder();
        builder.append(split[0]);// Concatenate first character

        // If the array has more than one word
        if (split.length > 1) {
            for (int i = 1; i < split.length; i++) {
                // Remove underscores and capitalize initial
                String string = split[i];
                String substring = string.substring(0, 1);
                split[i] = string.replaceFirst(substring, substring.toUpperCase());
                builder.append(split[i]);
            }
        }

        return builder.toString();
    }

}