mybatis plus 中 EntityWrapper源码解读

mybatis plus内置了好多CRUD,其中 EntityWrapper这个类就是。
这个类是mybatis plus帮我们写好的好多接口,就如同我们在dao层写好方法在xml中实现一样。
那么这个友好的类给我们实现了哪些方法呐,今天我们来通过看看源码,来具体说说,

/**
 * Copyright (c) 2011-2014, hubin (jobob@qq.com).
 * <p>
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not
 * use this file except in compliance with the License. You may obtain a copy of
 * the License at
 * <p>
 * http://www.apache.org/licenses/LICENSE-2.0
 * <p>
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations under
 * the License.
 */
package com.baomidou.mybatisplus.mapper;

import java.io.Serializable;
import java.util.Arrays;
import java.util.Collection;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.concurrent.atomic.AtomicInteger;

import com.baomidou.mybatisplus.enums.SqlLike;
import com.baomidou.mybatisplus.exceptions.MybatisPlusException;
import com.baomidou.mybatisplus.toolkit.ArrayUtils;
import com.baomidou.mybatisplus.toolkit.CollectionUtils;
import com.baomidou.mybatisplus.toolkit.MapUtils;
import com.baomidou.mybatisplus.toolkit.SqlUtils;
import com.baomidou.mybatisplus.toolkit.StringUtils;

/**
 * <p>
 * 条件构造抽象类,定义T-SQL语法
 * </p>
 *
 * @author hubin , yanghu , Dyang , Caratacus
 * @Date 2016-11-7
 */
@SuppressWarnings("serial")
public abstract class Wrapper<T> implements Serializable {

    /**
     * 占位符
     */
    private static final String PLACE_HOLDER = "{%s}";

    private static final String MYBATIS_PLUS_TOKEN = "#{%s.paramNameValuePairs.%s}";

    private static final String MP_GENERAL_PARAMNAME = "MPGENVAL";

    private static final String DEFAULT_PARAM_ALIAS = "ew";
    protected String paramAlias = null;
    /**
     * SQL 查询字段内容,例如:id,name,age
     */
    protected String sqlSelect = null;
    /**
     * 实现了TSQL语法的SQL实体
     */
    protected SqlPlus sql = new SqlPlus();
    /**
     * 自定义是否输出sql为 WHERE OR AND OR OR
     */
    protected Boolean isWhere;
    /**
     * 拼接WHERE后应该是AND还是OR
     */
    protected String AND_OR = "AND";
    private Map<String, Object> paramNameValuePairs = new HashMap<>(4);
    private AtomicInteger paramNameSeq = new AtomicInteger(0);

    /**
     * 兼容EntityWrapper
     *
     * @return
     */
    public T getEntity() {
        return null;
    }

    public String getSqlSelect() {
        if (StringUtils.isEmpty(sqlSelect)) {
            return null;
        }
        return stripSqlInjection(sqlSelect);
    }

    public Wrapper<T> setSqlSelect(String sqlSelect) {
        if (StringUtils.isNotEmpty(sqlSelect)) {
            this.sqlSelect = sqlSelect;
        }
        return this;
    }

    /**
     * SQL 片段 (子类实现)
     */
    public abstract String getSqlSegment();

    public String toString() {
        String sqlSegment = getSqlSegment();
        if (StringUtils.isNotEmpty(sqlSegment)) {
            sqlSegment = sqlSegment.replaceAll("#\\{" + getParamAlias() + ".paramNameValuePairs.MPGENVAL[0-9]+}", "\\?");
        }
        return sqlSegment;
    }

    /**
     * <p>
     * SQL中WHERE关键字跟的条件语句
     * </p>
     * <p>
     * eg: ew.where("name='zhangsan'").where("id={0}","123");
     * <p>
     * 输出: WHERE (NAME='zhangsan' AND id=123)
     * </p>
     *
     * @param sqlWhere where语句
     * @param params   参数集
     * @return this
     */
    public Wrapper<T> where(String sqlWhere, Object... params) {
        sql.WHERE(formatSql(sqlWhere, params));
        return this;
    }

    /**
     * <p>
     * 等同于SQL的"field=value"表达式
     * </p>
     *
     * @param column
     * @param params
     * @return
     */
    public Wrapper<T> eq(String column, Object params) {
        sql.WHERE(formatSql(String.format("%s = {0}", column), params));
        return this;
    }

    /**
     * <p>
     * 等同于SQL的"field <> value"表达式
     * </p>
     *
     * @param column
     * @param params
     * @return
     */
    public Wrapper<T> ne(String column, Object params) {
        sql.WHERE(formatSql(String.format("%s <> {0}", column), params));
        return this;
    }

    /**
     * <p>
     * 等同于SQL的"field=value"表达式
     * </p>
     *
     * @param params
     * @return
     */
    @SuppressWarnings({"rawtypes", "unchecked"})
    public Wrapper<T> allEq(Map<String, Object> params) {
        if (MapUtils.isNotEmpty(params)) {
            Iterator iterator = params.entrySet().iterator();
            while (iterator.hasNext()) {
                Map.Entry<String, Object> entry = (Map.Entry<String, Object>) iterator.next();
                Object value = entry.getValue();
                if (StringUtils.checkValNotNull(value)) {
                    sql.WHERE(formatSql(String.format("%s = {0}", entry.getKey()), entry.getValue()));
                }

            }

        }
        return this;
    }

    /**
     * <p>
     * 等同于SQL的"field>value"表达式
     * </p>
     *
     * @param column
     * @param params
     * @return
     */
    public Wrapper<T> gt(String column, Object params) {
        sql.WHERE(formatSql(String.format("%s > {0}", column), params));
        return this;
    }

    /**
     * <p>
     * 等同于SQL的"field>=value"表达式
     * </p>
     *
     * @param column
     * @param params
     * @return
     */
    public Wrapper<T> ge(String column, Object params) {
        sql.WHERE(formatSql(String.format("%s >= {0}", column), params));
        return this;
    }

    /**
     * <p>
     * 等同于SQL的"field<value"表达式
     * </p>
     *
     * @param column
     * @param params
     * @return
     */
    public Wrapper<T> lt(String column, Object params) {
        sql.WHERE(formatSql(String.format("%s < {0}", column), params));
        return this;
    }

    /**
     * <p>
     * 等同于SQL的"field<=value"表达式
     * </p>
     *
     * @param column
     * @param params
     * @return
     */
    public Wrapper<T> le(String column, Object params) {
        sql.WHERE(formatSql(String.format("%s <= {0}", column), params));
        return this;
    }

    /**
     * <p>
     * AND 连接后续条件
     * </p>
     *
     * @param sqlAnd and条件语句
     * @param params 参数集
     * @return this
     */
    public Wrapper<T> and(String sqlAnd, Object... params) {
        sql.AND().WHERE(formatSql(sqlAnd, params));
        return this;
    }

    /**
     * <p>
     * 使用AND连接并换行
     * </p>
     * <p>
     * eg: ew.where("name='zhangsan'").and("id=11").andNew("statu=1"); 输出: WHERE
     * (name='zhangsan' AND id=11) AND (statu=1)
     * </p>
     *
     * @param sqlAnd AND 条件语句
     * @param params 参数值
     * @return this
     */
    public Wrapper<T> andNew(String sqlAnd, Object... params) {
        sql.AND_NEW().WHERE(formatSql(sqlAnd, params));
        return this;
    }

    /**
     * <p>
     * 使用AND连接并换行
     * </p>
     * <p>
     *
     * @return this
     */
    public Wrapper<T> and() {
        sql.AND_NEW();
        return this;
    }

    /**
     * <p>
     * 使用OR连接并换行
     * </p>
     *
     * @return this
     */
    public Wrapper<T> or() {
        sql.OR_NEW();
        return this;
    }

    /**
     * <p>
     * 添加OR条件
     * </p>
     *
     * @param sqlOr  or 条件语句
     * @param params 参数集
     * @return this
     */
    public Wrapper<T> or(String sqlOr, Object... params) {
        if (StringUtils.isEmpty(sql.toString())) {
            AND_OR = "OR";
        }
        sql.OR().WHERE(formatSql(sqlOr, params));
        return this;
    }

    /**
     * <p>
     * 使用OR换行,并添加一个带()的新的条件
     * </p>
     * <p>
     * eg: ew.where("name='zhangsan'").and("id=11").orNew("statu=1"); 输出: WHERE
     * (name='zhangsan' AND id=11) OR (statu=1)
     * </p>
     *
     * @param sqlOr  AND 条件语句
     * @param params 参数值
     * @return this
     */
    public Wrapper<T> orNew(String sqlOr, Object... params) {
        if (StringUtils.isEmpty(sql.toString())) {
            AND_OR = "OR";
        }
        sql.OR_NEW().WHERE(formatSql(sqlOr, params));
        return this;
    }

    /**
     * <p>
     * SQL中groupBy关键字跟的条件语句
     * </p>
     * <p>
     * eg: ew.where("name='zhangsan'").groupBy("id,name")
     * </p>
     *
     * @param columns SQL 中的 Group by 语句,无需输入 Group By 关键字
     * @return this
     */
    public Wrapper<T> groupBy(String columns) {
        sql.GROUP_BY(columns);
        return this;
    }

    /**
     * <p>
     * SQL中having关键字跟的条件语句
     * </p>
     * <p>
     * eg: ew.groupBy("id,name").having("id={0}",22).and("password is not null")
     * </p>
     *
     * @param sqlHaving having关键字后面跟随的语句
     * @param params    参数集
     * @return EntityWrapper<T>
     */
    public Wrapper<T> having(String sqlHaving, Object... params) {
        sql.HAVING(formatSql(sqlHaving, params));
        return this;
    }

    /**
     * <p>
     * SQL中orderby关键字跟的条件语句
     * </p>
     * <p>
     * eg: ew.groupBy("id,name").having("id={0}",22).and("password is not null"
     * ).orderBy("id,name")
     * </p>
     *
     * @param columns SQL 中的 order by 语句,无需输入 Order By 关键字
     * @return this
     */
    public Wrapper<T> orderBy(String columns) {
        sql.ORDER_BY(columns);
        return this;
    }

    /**
     * <p>
     * SQL中orderby关键字跟的条件语句,可根据变更动态排序
     * </p>
     *
     * @param columns SQL 中的 order by 语句,无需输入 Order By 关键字
     * @param isAsc   是否为升序
     * @return this
     */
    public Wrapper<T> orderBy(String columns, boolean isAsc) {
        if (StringUtils.isNotEmpty(columns)) {
            sql.ORDER_BY(columns + (isAsc ? " ASC" : " DESC"));
        }
        return this;
    }

    /**
     * LIKE条件语句,value中无需前后%
     *
     * @param column 字段名称
     * @param value  匹配值
     * @return this
     */
    public Wrapper<T> like(String column, String value) {
        handerLike(column, value, SqlLike.DEFAULT, false);
        return this;
    }

    /**
     * NOT LIKE条件语句,value中无需前后%
     *
     * @param column 字段名称
     * @param value  匹配值
     * @return this
     */
    public Wrapper<T> notLike(String column, String value) {
        handerLike(column, value, SqlLike.DEFAULT, true);
        return this;
    }

    /**
     * 处理LIKE操作
     *
     * @param column 字段名称
     * @param value  like匹配值
     * @param isNot  是否为NOT LIKE操作
     */
    private void handerLike(String column, String value, SqlLike type, boolean isNot) {
        if (StringUtils.isNotEmpty(column) && StringUtils.isNotEmpty(value)) {
            StringBuilder inSql = new StringBuilder();
            inSql.append(column);
            if (isNot) {
                inSql.append(" NOT");
            }
            inSql.append(" LIKE {0}");
            sql.WHERE(formatSql(inSql.toString(), SqlUtils.concatLike(value, type)));
        }
    }

    /**
     * LIKE条件语句,value中无需前后%
     *
     * @param column 字段名称
     * @param value  匹配值
     * @param type
     * @return this
     */
    public Wrapper<T> like(String column, String value, SqlLike type) {
        handerLike(column, value, type, false);
        return this;
    }

    /**
     * NOT LIKE条件语句,value中无需前后%
     *
     * @param column 字段名称
     * @param value  匹配值
     * @param type
     * @return this
     */
    public Wrapper<T> notLike(String column, String value, SqlLike type) {
        handerLike(column, value, type, true);
        return this;
    }

    /**
     * is not null 条件
     *
     * @param columns 字段名称。多个字段以逗号分隔。
     * @return this
     */
    public Wrapper<T> isNotNull(String columns) {
        sql.IS_NOT_NULL(columns);
        return this;
    }

    /**
     * is not null 条件
     *
     * @param columns 字段名称。多个字段以逗号分隔。
     * @return this
     */
    public Wrapper<T> isNull(String columns) {
        sql.IS_NULL(columns);
        return this;
    }

    /**
     * EXISTS 条件语句,目前适配mysql及oracle
     *
     * @param value 匹配值
     * @return this
     */
    public Wrapper<T> exists(String value) {
        sql.EXISTS(value);
        return this;
    }

    /**
     * NOT EXISTS条件语句
     *
     * @param value 匹配值
     * @return this
     */
    public Wrapper<T> notExists(String value) {
        sql.NOT_EXISTS(value);
        return this;
    }

    /**
     * IN 条件语句,目前适配mysql及oracle
     *
     * @param column 字段名称
     * @param value  逗号拼接的字符串
     * @return this
     */
    public Wrapper<T> in(String column, String value) {
        if (StringUtils.isNotEmpty(value)) {
            in(column, StringUtils.splitWorker(value, ",", -1, false));
        }
        return this;
    }

    /**
     * NOT IN条件语句
     *
     * @param column 字段名称
     * @param value  逗号拼接的字符串
     * @return this
     */
    public Wrapper<T> notIn(String column, String value) {
        if (StringUtils.isNotEmpty(value)) {
            notIn(column, StringUtils.splitWorker(value, ",", -1, false));
        }
        return this;
    }

    /**
     * IN 条件语句,目前适配mysql及oracle
     *
     * @param column 字段名称
     * @param value  匹配值 List集合
     * @return this
     */
    public Wrapper<T> in(String column, Collection<?> value) {
        if (CollectionUtils.isNotEmpty(value))
            sql.WHERE(formatSql(inExpression(column, value, false), value.toArray()));
        return this;
    }

    /**
     * NOT IN 条件语句,目前适配mysql及oracle
     *
     * @param column 字段名称
     * @param value  匹配值 List集合
     * @return this
     */
    public Wrapper<T> notIn(String column, Collection<?> value) {
        if (CollectionUtils.isNotEmpty(value))
            sql.WHERE(formatSql(inExpression(column, value, true), value.toArray()));
        return this;
    }

    /**
     * IN 条件语句,目前适配mysql及oracle
     *
     * @param column 字段名称
     * @param value  匹配值 object数组
     * @return this
     */
    public Wrapper<T> in(String column, Object[] value) {
        if (ArrayUtils.isNotEmpty(value))
            sql.WHERE(formatSql(inExpression(column, Arrays.asList(value), false), value));
        return this;
    }

    /**
     * NOT IN 条件语句,目前适配mysql及oracle
     *
     * @param column 字段名称
     * @param value  匹配值 object数组
     * @return this
     */
    public Wrapper<T> notIn(String column, Object... value) {
        if (ArrayUtils.isNotEmpty(value))
            sql.WHERE(formatSql(inExpression(column, Arrays.asList(value), true), value));
        return this;
    }

    /**
     * 获取in表达式
     *
     * @param column 字段名称
     * @param value  集合List
     * @param isNot  是否为NOT IN操作
     */
    private String inExpression(String column, Collection<?> value, boolean isNot) {
        if (StringUtils.isNotEmpty(column) && CollectionUtils.isNotEmpty(value)) {
            StringBuilder inSql = new StringBuilder();
            inSql.append(column);
            if (isNot) {
                inSql.append(" NOT");
            }
            inSql.append(" IN ");
            inSql.append("(");
            int size = value.size();
            for (int i = 0; i < size; i++) {
                inSql.append(String.format(PLACE_HOLDER, i));
                if (i + 1 < size) {
                    inSql.append(",");
                }
            }
            inSql.append(")");
            return inSql.toString();
        }
        return null;
    }

    /**
     * betwwee 条件语句
     *
     * @param column 字段名称
     * @param val1
     * @param val2
     * @return this
     */
    public Wrapper<T> between(String column, Object val1, Object val2) {
        sql.WHERE(formatSql(String.format("%s BETWEEN {0} AND {1}", column), val1, val2));
        return this;
    }

    /**
     * NOT betwwee 条件语句
     *
     * @param column 字段名称
     * @param val1
     * @param val2
     * @return this
     */
    public Wrapper<T> notBetween(String column, Object val1, Object val2) {
        sql.WHERE(formatSql(String.format("%s NOT BETWEEN {0} AND {1}", column), val1, val2));
        return this;
    }

    /**
     * 为了兼容之前的版本,可使用where()或and()替代
     *
     * @param sqlWhere where sql部分
     * @param params   参数集
     * @return this
     */
    public Wrapper<T> addFilter(String sqlWhere, Object... params) {
        return and(sqlWhere, params);
    }

    /**
     * <p>
     * 根据判断条件来添加条件语句部分 使用 andIf() 替代
     * </p>
     * <p>
     * eg: ew.filterIfNeed(false,"name='zhangsan'").where("name='zhangsan'")
     * .filterIfNeed(true,"id={0}",22)
     * <p>
     * 输出: WHERE (name='zhangsan' AND id=22)
     * </p>
     *
     * @param need     是否需要添加该条件
     * @param sqlWhere 条件语句
     * @param params   参数集
     * @return this
     */
    public Wrapper<T> addFilterIfNeed(boolean need, String sqlWhere, Object... params) {
        return need ? where(sqlWhere, params) : this;
    }

    /**
     * <p>
     * SQL注入内容剥离
     * </p>
     *
     * @param value 待处理内容
     * @return this
     */
    protected String stripSqlInjection(String value) {
        return value.replaceAll("('.+--)|(--)|(\\|)|(%7C)", "");
    }

    /**
     * <p>
     * 格式化SQL
     * </p>
     *
     * @param sqlStr SQL语句部分
     * @param params 参数集
     * @return this
     */
    protected String formatSql(String sqlStr, Object... params) {
        return formatSqlIfNeed(true, sqlStr, params);
    }

    /**
     * <p>
     * 根据需要格式化SQL<BR>
     * <BR>
     * Format SQL for methods: EntityWrapper.where/and/or...("name={0}", value);
     * ALL the {<b>i</b>} will be replaced with #{MPGENVAL<b>i</b>}<BR>
     * <BR>
     * ew.where("sample_name=<b>{0}</b>", "haha").and("sample_age &gt;<b>{0}</b>
     * and sample_age&lt;<b>{1}</b>", 18, 30) <b>TO</b>
     * sample_name=<b>#{MPGENVAL1}</b> and sample_age&gt;#<b>{MPGENVAL2}</b> and
     * sample_age&lt;<b>#{MPGENVAL3}</b><BR>
     * </p>
     *
     * @param need   是否需要格式化
     * @param sqlStr SQL语句部分
     * @param params 参数集
     * @return this
     */
    protected String formatSqlIfNeed(boolean need, String sqlStr, Object... params) {
        if (!need || StringUtils.isEmpty(sqlStr)) {
            return null;
        }
        // #200
        if (ArrayUtils.isNotEmpty(params)) {
            for (int i = 0; i < params.length; ++i) {
                String genParamName = MP_GENERAL_PARAMNAME + paramNameSeq.incrementAndGet();
                sqlStr = sqlStr.replace(String.format(PLACE_HOLDER, i),
                        String.format(MYBATIS_PLUS_TOKEN, getParamAlias(), genParamName));
                paramNameValuePairs.put(genParamName, params[i]);
            }
        }
        return sqlStr;
    }

    /**
     * <p>
     * 自定义是否输出sql开头为 `WHERE` OR `AND` OR `OR`
     * </p>
     *
     * @param bool
     * @return this
     */
    public Wrapper<T> isWhere(Boolean bool) {
        this.isWhere = bool;
        return this;
    }

    /**
     * <p>
     * SQL LIMIT
     * </p>
     *
     * @param begin 起始
     * @param end   结束
     * @return this
     */
    public Wrapper<T> limit(int begin, int end) {
        sql.LIMIT(begin, end);
        return this;
    }

    /**
     * Fix issue 200.
     *
     * @return
     * @since 2.0.3
     */
    public Map<String, Object> getParamNameValuePairs() {
        return paramNameValuePairs;
    }

    public String getParamAlias() {
        return StringUtils.isEmpty(paramAlias) ? DEFAULT_PARAM_ALIAS : paramAlias;
    }

    /**
     * <p>
     * 调用该方法时 应当在吃初始化时优先设置该值 不要重复设置该值 要不然我就给你抛异常了
     * </p>
     *
     * @param paramAlias
     * @return
     */
    public Wrapper<T> setParamAlias(String paramAlias) {
        if (StringUtils.isNotEmpty(getSqlSegment())) {
            throw new MybatisPlusException("Error: Please call this method when initializing!");
        }
        if (StringUtils.isNotEmpty(this.paramAlias)) {
            throw new MybatisPlusException("Error: Please do not call the method repeatedly!");
        }
        this.paramAlias = paramAlias;
        return this;
    }
}

最后说一句,阅读源码,你会收获很多,看到别人的处理方式,你会有很大进步的。哈哈,今天你学到了吗

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