mybatis 3.5.0/mybatis plus 3.x中dao层与xml参数绑定的案例分析

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方式1（不推荐） 单个参数方式

@Mapperpublic interface UserDao extends BaseMapper {   User selectList1(String username, String phone);}

   select * from user where username= #{arg0} and phone=#{arg1}

注意：与网上所说的select * from user where username= #{0} and phone=#{1}在新版本中是不对的，会报错误：

nested exception is org.apache.ibatis.binding.BindingException: Parameter '0' not found. Available parameters are [arg1, arg0, param1, param2]

查看报错报错信息可以看出还可以这样做

   select * from user where username= #{param1} and phone=#{param2}

方式2（推荐） 实体类对象方式

该方法和之前版本是兼容的，没有变化

@Mapperpublic interface UserDao extends BaseMapper {    User selectList1(@Param("username") String username,@Param("phone") String phone);}

   select * from user where username= #{username} and phone=#{phone}

或者

     select * from user where username= #{username} and phone=#{phone} 

这两种方式都可以的

方式3 使用bean工具类转成map，map类型参数（推荐）

bean工具类

import com.alibaba.fastjson.JSONObject;import java.beans.BeanInfo;import java.beans.Introspector;import java.beans.PropertyDescriptor;import java.lang.reflect.Field;import java.lang.reflect.Method;import java.util.ArrayList;import java.util.HashMap;import java.util.List;import java.util.Map;import java.util.regex.Matcher;import java.util.regex.Pattern;public class QueryEntityTools {        public static Map objectToMap(Object obj) {                if (obj == null) {                        return null;                }                Map map = new HashMap();                try {                        Field[] declaredFields = obj.getClass().getDeclaredFields();                        for (Field field : declaredFields) {                                field.setAccessible(true);                                map.put(field.getName(), field.get(obj));                        }                } catch (Exception e) {                }                return map;        }        /**         * 将实体转换成Map         *          * @param bean         * @return         */        public static Map beanToMap(Object bean) {                Class type = bean.getClass();                Map returnMap = new HashMap();                try {                        BeanInfo beanInfo = Introspector.getBeanInfo(type);                        PropertyDescriptor[] propertyDescriptors = beanInfo.getPropertyDescriptors();                        for (int i = 0; i < propertyDescriptors.length; i++) {                                PropertyDescriptor descriptor = propertyDescriptors[i];                                String propertyName = descriptor.getName();                                if (!propertyName.equals("class")) {                                        Method readMethod = descriptor.getReadMethod();                                        if (readMethod != null) {                                                Object result = readMethod.invoke(bean, new Object[0]);                                                if (result != null) {                                                        returnMap.put(propertyName, result);                                                } else {                                                        returnMap.put(propertyName, "");                                                }                                        }                                }                        }                } catch (Exception e) {                        returnMap.put("error", e.getMessage());                }                return returnMap;        }        /**         * 将实体转换成Json         *          * @param bean         * @return         */        public static JSONObject beanToJson(Object bean) {                Class type = bean.getClass();                JSONObject json = new JSONObject();                try {                        BeanInfo beanInfo = Introspector.getBeanInfo(type);                        PropertyDescriptor[] propertyDescriptors = beanInfo.getPropertyDescriptors();                        for (int i = 0; i < propertyDescriptors.length; i++) {                                PropertyDescriptor descriptor = propertyDescriptors[i];                                String propertyName = descriptor.getName();                                if (!propertyName.equals("class")) {                                        Method readMethod = descriptor.getReadMethod();                                        if (readMethod != null) {                                                Object result = readMethod.invoke(bean, new Object[0]);                                                if (result != null) {                                                        json.put(propertyName, result);                                                } else {                                                        json.put(propertyName, "");                                                }                                        }                                }                        }                } catch (Exception e) {                        json.put("error", e.getMessage());                }                return json;        }        /**         * 将map转换成Json         */        public static JSONObject mapToJson(Map map) {                JSONObject json = new JSONObject();                for (String key : map.keySet()) {                        json.put(key, map.get(key));                }                return json;        }        /**         * 将map转换成实体         *          * @param map         * @param bean         * @return         */        public static  T mapToBean(Map map, Class bean) {                T t = null;                try {                        BeanInfo beanInfo = Introspector.getBeanInfo(bean);                        PropertyDescriptor[] propertyDescriptors = beanInfo.getPropertyDescriptors();                        t = bean.newInstance();                        for (PropertyDescriptor property : propertyDescriptors) {                                String key = property.getName();                                if (map.containsKey(key)) {                                        Object value = map.get(key);                                        Method setter = property.getWriteMethod();                                        if (checkType(value, property.getPropertyType())) {                                                setter.invoke(t, value);                                        }                                }                        }                } catch (Exception e) {                        e.printStackTrace();                }                return t;        }        private static boolean checkType(Object a, Class b) {                Class oc = a.getClass();                if (oc == b || oc.getSuperclass() == b || checkInterfaces(oc.getInterfaces(), b)) {                        return true;                } else {                        return false;                }        }        private static boolean checkInterfaces(Class[] cArray, Class b) {                boolean tag = false;                for (Class c : cArray) {                        if (c == b) {                                tag = true;                                break;                        }                }                return tag;        }        /**         * Map List To Bean List         * @param bean         * @return         */        public static  List mapListToBeanList(List> listMap, Class bean) {                List beanList = new ArrayList(listMap.size());                for (Map map : listMap) {                        T t = null;                        try {                                BeanInfo beanInfo = Introspector.getBeanInfo(bean);                                PropertyDescriptor[] propertyDescriptors = beanInfo.getPropertyDescriptors();                                t = bean.newInstance();                                for (PropertyDescriptor property : propertyDescriptors) {                                        String key = property.getName();                                        if (map.containsKey(key)) {                                                Object value = map.get(key);                                                Method setter = property.getWriteMethod();                                                setter.invoke(t, value);                                        }                                }                        } catch (Exception e) {                                e.printStackTrace();                        }                        beanList.add(t);                }                return beanList;        }        /**         * 将实体转换成Map         * 将key按驼峰规则转换成下划线分隔(字母大写)         * @param bean         * @return         */        public static Map beanToColumnMap(Object bean) {                Class type = bean.getClass();                Map returnMap = new HashMap();                try {                        BeanInfo beanInfo = Introspector.getBeanInfo(type);                        PropertyDescriptor[] propertyDescriptors = beanInfo.getPropertyDescriptors();                        for (int i = 0; i < propertyDescriptors.length; i++) {                                PropertyDescriptor descriptor = propertyDescriptors[i];                                String propertyName = descriptor.getName();                                if (!propertyName.equals("class")) {                                        Method readMethod = descriptor.getReadMethod();                                        Object result = readMethod.invoke(bean, new Object[0]);                                        if (result != null && !result.equals("")) {                                                returnMap.put(camelToUnderline(propertyName), result);                                        }                                }                        }                } catch (Exception e) {                        e.getMessage();                        // returnMap.put("error", e.getMessage());                        // returnMap = null;                }                return returnMap;        }        /**         * 将camel Map转成Column Map         *          * @param bean         * @return         */        public static Map camelMapToColumnMap(Map beanMap) {                Map returnMap = new HashMap();                try {                        for (String key : beanMap.keySet()) {                                returnMap.put(camelToUnderline(key), beanMap.get(key));                        }                } catch (Exception e) {                        e.printStackTrace();                }                return returnMap;        }        /**         * 字符串下划线转驼峰         *          * @param line         * @return         */        public static String underlineToCamel(String line) {                if (line == null || "".equals(line)) {                        return "";                }                StringBuffer sb = new StringBuffer();                Pattern pattern = Pattern.compile("([A-Za-z\\d]+)(_)?");                Matcher matcher = pattern.matcher(line);                while (matcher.find()) {                        String word = matcher.group();                        Character c = word.charAt(0);                        sb.append(matcher.start() == 0 ? Character.toLowerCase(c) : Character.toUpperCase(c));                        int index = word.lastIndexOf('_');                        if (index > 0) {                                sb.append(word.substring(1, index).toLowerCase());                        } else {                                sb.append(word.substring(1).toLowerCase());                        }                }                return sb.toString();        }        /**         * 字符串驼峰转下划线         *          * @param line         * @return         */        public static String camelToUnderline(String line) {                if (line == null || "".equals(line)) {                        return "";                }                Character c = line.charAt(0);                String f = line.substring(1);                line = String.valueOf(c).toUpperCase().concat(f);                StringBuffer sb = new StringBuffer();                Pattern pattern = Pattern.compile("[A-Z]([a-z\\d]+)?");                Matcher matcher = pattern.matcher(line);                while (matcher.find()) {                        String word = matcher.group();                        sb.append(word.toUpperCase());                        sb.append(matcher.end() == line.length() ? "" : "_");                }                return sb.toString();        }}

impl代码

 @Override    public User selectList1(User user) {        Map map = QueryEntityTools.beanToMap(user);        return baseMapper.selectList1(map); }

mappper

@Mapperpublic interface UserDao extends BaseMapper {    User selectList1(Map map);}

xml

     select * from user where username= #{username} and phone=#{phone} 

或者

   select * from user where username= #{username} and phone=#{phone}

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