背景：

我发现我要用到一个批量添加的方法，但是generator并没有提供，要是每次都自己去写一遍又很麻烦，然后就各种尝试，最后决定改generator的源码（第一次修改别人的源码，尝试了10次才成功，历时4个小时）

此篇以mybatis-generator-core-1.3.2这个版本作为工具，如果你的版本不一样请自己注意别直接拷贝拷错了

准备工作：

随便创建个maven项目，然后在pom.xml里面将相关的依赖加入

<dependency>
			<groupId>org.apache.ant</groupId>
			<artifactId>ant</artifactId>
			<version>1.8.2</version>
		</dependency>

		<dependency>
			<groupId>log4j</groupId>
			<artifactId>log4j</artifactId>
			<version>1.2.17</version>
		</dependency>

有上面两个依赖，（其实那个log4j的依赖到底要不要我也不知道，只是之前忘记为什么加上去的了）

然后使用maven 的Download Sources 将generator 的源码包下载下来，

然后在你的maven的jar包仓库就可以看到源码包了：如图

绿线是我的maven仓库的jar包位置，至于你的位子你自己自己知道

源码包是我画红箭头的那个包，然后使用解压工具将这个解压就可以了

解压出来有两个包，一个是org包，一个是META-INF包

将整个org文件夹拖进工程里

导入后如下图：

导入org包完成后要把pom.xml里的generaotr依赖删除（重要）

准备工作结束；

开始改源码：

第一步：需要改动的地方，

先看图

第一个红箭头对应的那个类 XMLMapperGenerator 这个类是管你的SQL.xml文件内到底要加载多少个sql元素的，直白点说，就是你的sql文件要放几个insert 几个select 几个update

第二个红箭头指向的是那个包：这个包里面放的全部都是生成sql的java文件

第三个红箭头是我加进去的java文件

接下来看下XMLMapperGenerator 这个类改动的具体位置

还是看图吧

先在这个类里面添加个方法

自己改下方法名，以及该方法调用哪个类

然后看下图中 要记得调用该方法，这样你的新sql才会进去

第二步：写自己需要的类

下面是我添加的那个生产sql的类

package org.mybatis.generator.codegen.mybatis3.xmlmapper.elements;

import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;

import org.mybatis.generator.api.IntrospectedColumn;
import org.mybatis.generator.api.dom.OutputUtilities;
import org.mybatis.generator.api.dom.xml.Attribute;
import org.mybatis.generator.api.dom.xml.TextElement;
import org.mybatis.generator.api.dom.xml.XmlElement;
import static org.mybatis.generator.internal.util.StringUtility.escapeStringForJava;
import static org.mybatis.generator.internal.util.StringUtility.stringHasValue;

public class InsertBatchGenerator extends AbstractXmlElementGenerator {

	@Override
	public void addElements(XmlElement parentElement) {
		XmlElement answer = new XmlElement("insert");
		answer.addAttribute(new Attribute("id","insertBatch"));
		answer.addAttribute(new Attribute("parameterType","java.lang.List"));
		XmlElement foreach = new XmlElement("foreach");
		foreach.addAttribute(new Attribute("collection","list"));
		foreach.addAttribute(new Attribute("index","i"));
		foreach.addAttribute(new Attribute("item","o"));
		foreach.addAttribute(new Attribute("separator",","));
		context.getCommentGenerator().addComment(answer);
		StringBuilder insertClause = new StringBuilder();
		StringBuilder valuesClause = new StringBuilder();
		insertClause.append("insert into ");
		insertClause.append(introspectedTable.getFullyQualifiedTableNameAtRuntime());
		insertClause.append(" (");
		valuesClause.append(" (");
		List<String> valuesClauses = new ArrayList<String>();
		Iterator<IntrospectedColumn> iter = introspectedTable.getAllColumns().iterator();
		while (iter.hasNext()) {
			IntrospectedColumn introspectedColumn = iter.next();
			if (introspectedColumn.isIdentity()) {
				// cannot set values on identity fields
				continue;
			}

			insertClause.append(getEscapedColumnName(introspectedColumn));
			valuesClause.append(getParameterClause(introspectedColumn));
			if (iter.hasNext()) {
				insertClause.append(","); //$NON-NLS-1$
				valuesClause.append(","); //$NON-NLS-1$
			}

			if (valuesClause.length() > 80) {
				answer.addElement(new TextElement(insertClause.toString()));
				insertClause.setLength(0);
				OutputUtilities.xmlIndent(insertClause,1);

				valuesClauses.add(valuesClause.toString());
				valuesClause.setLength(0);
				OutputUtilities.xmlIndent(valuesClause,1);
			}
		}

		insertClause.append(") values ");
		answer.addElement(new TextElement(insertClause.toString()));

		valuesClause.append(')');

		for (String clause : valuesClauses) {
			foreach.addElement(new TextElement(clause));
		}
		foreach.addElement(new TextElement(valuesClause.toString()));
		answer.addElement(foreach);
		 if (context.getPlugins().sqlMapInsertElementGenerated(answer,introspectedTable)) {
	            parentElement.addElement(answer);
	        }

	}
	/*
	 * Copyright 2009 The Apache Software Foundation
	 *
	 * 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
	 *
	 * http://www.apache.org/licenses/LICENSE-2.0
	 *
	 * 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.
	 */

	public static String getParameterClause(IntrospectedColumn introspectedColumn) {
		return getParameterClause(introspectedColumn,null);
	}

	public static String getParameterClause(IntrospectedColumn introspectedColumn,String prefix) {
		StringBuilder sb = new StringBuilder();

		sb.append("#{"); //$NON-NLS-1$
		sb.append("o.");
		sb.append(introspectedColumn.getJavaProperty(prefix));
		sb.append(",jdbcType="); //$NON-NLS-1$
		sb.append(introspectedColumn.getJdbcTypeName());

		if (stringHasValue(introspectedColumn.getTypeHandler())) {
			sb.append(",typeHandler="); //$NON-NLS-1$
			sb.append(introspectedColumn.getTypeHandler());
		}

		sb.append('}');

		return sb.toString();
	}

	/**
	 * The phrase to use in a select list. If there is a table alias,the value
	 * will be "alias.columnName as alias_columnName"
	 * 
	 * @return the proper phrase
	 */
	public static String getSelectListPhrase(IntrospectedColumn introspectedColumn) {
		if (stringHasValue(introspectedColumn.getTableAlias())) {
			StringBuilder sb = new StringBuilder();

			sb.append(getAliasedEscapedColumnName(introspectedColumn));
			sb.append(" as "); //$NON-NLS-1$
			if (introspectedColumn.isColumnNameDelimited()) {
				sb.append(introspectedColumn.getContext().getBeginningDelimiter());
			}
			sb.append(introspectedColumn.getTableAlias());
			sb.append('_');
			sb.append(escapeStringForMyBatis3(introspectedColumn.getActualColumnName()));
			if (introspectedColumn.isColumnNameDelimited()) {
				sb.append(introspectedColumn.getContext().getEndingDelimiter());
			}
			return sb.toString();
		} else {
			return getEscapedColumnName(introspectedColumn);
		}
	}

	public static String getEscapedColumnName(IntrospectedColumn introspectedColumn) {
		StringBuilder sb = new StringBuilder();
		sb.append(escapeStringForMyBatis3(introspectedColumn.getActualColumnName()));

		if (introspectedColumn.isColumnNameDelimited()) {
			sb.insert(0,introspectedColumn.getContext().getBeginningDelimiter());
			sb.append(introspectedColumn.getContext().getEndingDelimiter());
		}

		return sb.toString();
	}

	/**
	 * Calculates the string to use in select phrases in SqlMaps.
	 * 
	 * @return the aliased escaped column name
	 */
	public static String getAliasedEscapedColumnName(IntrospectedColumn introspectedColumn) {
		if (stringHasValue(introspectedColumn.getTableAlias())) {
			StringBuilder sb = new StringBuilder();

			sb.append(introspectedColumn.getTableAlias());
			sb.append('.');
			sb.append(getEscapedColumnName(introspectedColumn));
			return sb.toString();
		} else {
			return getEscapedColumnName(introspectedColumn);
		}
	}

	/**
	 * The aliased column name for a select statement generated by the example
	 * clauses. This is not appropriate for selects in SqlMaps because the
	 * column is not escaped for MyBatis. If there is a table alias,the value
	 * will be alias.columnName.
	 * 
	 * This method is used in the Example classes and the returned value will be
	 * in a Java string. So we need to escape double quotes if they are the
	 * delimiters.
	 * 
	 * @return the aliased column name
	 */
	public static String getAliasedActualColumnName(IntrospectedColumn introspectedColumn) {
		StringBuilder sb = new StringBuilder();
		if (stringHasValue(introspectedColumn.getTableAlias())) {
			sb.append(introspectedColumn.getTableAlias());
			sb.append('.');
		}

		if (introspectedColumn.isColumnNameDelimited()) {
			sb.append(escapeStringForJava(introspectedColumn.getContext().getBeginningDelimiter()));
		}

		sb.append(introspectedColumn.getActualColumnName());

		if (introspectedColumn.isColumnNameDelimited()) {
			sb.append(escapeStringForJava(introspectedColumn.getContext().getEndingDelimiter()));
		}

		return sb.toString();
	}

	/**
	 * The renamed column name for a select statement. If there is a table
	 * alias,the value will be alias_columnName. This is appropriate for use in
	 * a result map.
	 * 
	 * @return the renamed column name
	 */
	public static String getRenamedColumnNameForResultMap(IntrospectedColumn introspectedColumn) {
		if (stringHasValue(introspectedColumn.getTableAlias())) {
			StringBuilder sb = new StringBuilder();

			sb.append(introspectedColumn.getTableAlias());
			sb.append('_');
			sb.append(introspectedColumn.getActualColumnName());
			return sb.toString();
		} else {
			return introspectedColumn.getActualColumnName();
		}
	}

	public static String escapeStringForMyBatis3(String s) {
		// nothing to do for MyBatis3 so far
		return s;
	}
}

修改源码的时候尽量不要去动原来的代码，不然可能会影响到一些你不知道的功能的使用

我是将需要用的源码拷贝到我的类里面直接写成方法来调用的，这样就能即添加了自己的所需，又不用担心影响到久的方法或者功能的使用，

至于我的InsertBatchGenerator这个类是怎么写出来的就不详细打注释了，你可以去参考一下里面那些类就知道了记得自己写的生产sql的类要继承AbstractXmlElementGenerator这个类哦

最后：

直接将整个项目导出，记得导成jar包哦，然后丢回自己的maven仓库，把名字久的mybatis-generator-core-1.3.2.jar删除

然后吧自己的jar改成这个名字就可以用了

（编辑：李大同）

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