ResultMapUtil.java

package com.huazhu.user.utils;

import java.lang.reflect.Field;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

/**
 * @author ruanruan
 * @since 2018-12-04
 */
public class ResultMapUtil {
    private static Pattern humpPattern = Pattern.compile("[A-Z]");

    /**
     * 获取属性
     * @param clazz
     * @return
     */
    public static String getProp(Class<?> clazz) {
        Object obj = null;
        try {
            obj = clazz.newInstance();
        } catch (Exception e) {
            return "#Exception.反射生成实体异常#";
        }

        StringBuilder resultMap = new StringBuilder();


        Field[] fields = clazz.getDeclaredFields();
        for (Field f : fields) {
            String property = f.getName();
            String javaType = f.getType().getName();
            if ("serialVersionUID".equals(property)) {
            }
            resultMap.append("#{");
            resultMap.append(property);
            resultMap.append("}");
            resultMap.append(",");
            resultMap.append("\n");
        }
        return resultMap.toString();
    }

    /**
     * 获取column
     * @param clazz
     * @return
     */
    public static String getColumn(Class<?> clazz) {
        Object obj = null;
        try {
            obj = clazz.newInstance();
        } catch (Exception e) {
            return "#Exception.反射生成实体异常#";
        }

        StringBuilder resultMap = new StringBuilder();


        Field[] fields = clazz.getDeclaredFields();
        for (Field f : fields) {
            String property = f.getName();
            String javaType = f.getType().getName();
            if ("serialVersionUID".equals(property)) {
            }

            resultMap.append(property2Column(property));
            resultMap.append(",");
            resultMap.append("\n");
        }
        return resultMap.toString();
    }


    /**
     *      * 获取ResultMap
     *      * @param clazz 实体类的Class
     *      * @return String
     *      
     */
    public static String getResultMap(Class<?> clazz) {

        Object obj = null;
        try {
            obj = clazz.newInstance();
        } catch (Exception e) {
            return "#Exception.反射生成实体异常#";
        }

        String clazzName = clazz.getSimpleName();
        String resultMapId = Character.toLowerCase(clazzName.charAt(0)) + clazzName.substring(1) + "Map";
        String pkgName = clazz.getName();

        StringBuilder resultMap = new StringBuilder();
        resultMap.append("<resultMap id=\"");
        resultMap.append(resultMapId);
        resultMap.append("\" type=\"");
        resultMap.append(pkgName);
        resultMap.append("\">\n");

        Field[] fields = clazz.getDeclaredFields();
        for (Field f : fields) {
            String property = f.getName();
            String javaType = f.getType().getName();
            if ("serialVersionUID".equals(property)) {
            }
            resultMap.append("<result column=\"");
            resultMap.append(property2Column(property));
            resultMap.append("\" jdbcType=\"");
            resultMap.append(javaType2jdbcType(javaType.toLowerCase()));
            resultMap.append("\" property=\"");
            resultMap.append(property);
            resultMap.append("\" />\n");
        }
        resultMap.append("</resultMap>");
        return resultMap.toString();
    }


    private static String property2Column(String property) {
        Matcher matcher = humpPattern.matcher(property);
        StringBuffer sb = new StringBuffer();
        while (matcher.find()) {
            matcher.appendReplacement(sb, "_" + matcher.group(0).toLowerCase());
        }
        matcher.appendTail(sb);
        return sb.toString();
    }


    private static String javaType2jdbcType(String javaType) {
        if (javaType.contains("string")) {
            return "VARCHAR";
        } else if (javaType.contains("boolean")) {
            return "BIT";
        } else if (javaType.contains("byte")) {
            return "TINYINT";
        } else if (javaType.contains("short")) {
            return "SMALLINT";
        } else if (javaType.contains("int")) {
            return "INTEGER";
        } else if (javaType.contains("long")) {
            return "BIGINT";
        } else if (javaType.contains("double")) {
            return "DOUBLE";
        } else if (javaType.contains("float")) {
            return "REAL";
        } else if (javaType.contains("date")) {
            return "DATE";
        } else if (javaType.contains("timestamp")) {
            return "TIMESTAMP";
        } else if (javaType.contains("time")) {
            return "TIME";
        } else if (javaType.contains("bigdecimal")) {
            return "DECIMAL";
        } else {
            return "未知类型";
        }
    }

}