众所周知,Mybatis本身没有提供基于数据库方言的分页功能,而是基于JDBC的游标分页,很容易出现性能问题。网上有很多分页的解决方案,不外乎是基于Mybatis本机的插件机制,通过拦截Sql做分页。但是在像Oracle这样的数据库上,拦截器生成的Sql语句没有变量绑定,而且每次语句的都要去拦截,感觉有点浪费性能。
Mybatis Generator是Mybatis的代码生成工具,可以生成大部分的查询语句。
本文提供的分页解决方案是新增Mybatis Generator插件,在用Mybatis
Generator生成Mybatis代码时,直接生成基于数据库方言的Sql语句,解决Oralce等数据库的变量绑定,且无需使用Mybatis拦截器去拦截语句判断分页。
一、编写Mybatis Generator Dialect插件
/**
- * Copyright (C) 2011 Tgwoo Inc.
- * http:
- */
- package com.tgwoo.core.dao.plugin;
-
- import java.util.List;
-
- import org.mybatis.generator.api.CommentGenerator;
- import org.mybatis.generator.api.IntrospectedTable;
- import org.mybatis.generator.api.PluginAdapter;
- import org.mybatis.generator.api.dom.java.Field;
- import org.mybatis.generator.api.dom.java.FullyQualifiedJavaType;
- import org.mybatis.generator.api.dom.java.JavaVisibility;
- import org.mybatis.generator.api.dom.java.Method;
- import org.mybatis.generator.api.dom.java.Parameter;
- import org.mybatis.generator.api.dom.java.TopLevelClass;
- import org.mybatis.generator.api.dom.xml.Attribute;
- import org.mybatis.generator.api.dom.xml.Document;
- import org.mybatis.generator.api.dom.xml.TextElement;
- import org.mybatis.generator.api.dom.xml.XmlElement;
-
-
-
-
-
- public class OraclePaginationPlugin extends PluginAdapter {
-
- @Override
- public boolean modelExampleClassGenerated(TopLevelClass topLevelClass,
- IntrospectedTable introspectedTable) {
-
- addPage(topLevelClass, introspectedTable, "page");
- return super.modelExampleClassGenerated(topLevelClass,
- introspectedTable);
- }
-
- @Override
- public boolean sqlMapDocumentGenerated(Document document,
- IntrospectedTable introspectedTable) {
- XmlElement parentElement = document.getRootElement();
-
-
- XmlElement paginationPrefixElement = new XmlElement("sql");
- paginationPrefixElement.addAttribute(new Attribute("id",
- "OracleDialectPrefix"));
- XmlElement pageStart = new XmlElement("if");
- pageStart.addAttribute(new Attribute("test", "page != null"));
- pageStart.addElement(new TextElement(
- "select * from ( select row_.*, rownum rownum_ from ( "));
- paginationPrefixElement.addElement(pageStart);
- parentElement.addElement(paginationPrefixElement);
-
-
- XmlElement paginationSuffixElement = new XmlElement("sql");
- paginationSuffixElement.addAttribute(new Attribute("id",
- "OracleDialectSuffix"));
- XmlElement pageEnd = new XmlElement("if");
- pageEnd.addAttribute(new Attribute("test", "page != null"));
- pageEnd.addElement(new TextElement(
- "<![CDATA[ ) row_ ) where rownum_ > #{page.begin} and rownum_ <= #{page.end} ]]>"));
- paginationSuffixElement.addElement(pageEnd);
- parentElement.addElement(paginationSuffixElement);
-
- return super.sqlMapDocumentGenerated(document, introspectedTable);
- }
-
- @Override
- public boolean sqlMapSelectByExampleWithoutBLOBsElementGenerated(
- XmlElement element, IntrospectedTable introspectedTable) {
-
- XmlElement pageStart = new XmlElement("include");
- pageStart.addAttribute(new Attribute("refid", "OracleDialectPrefix"));
- element.getElements().add(0, pageStart);
-
- XmlElement isNotNullElement = new XmlElement("include");
- isNotNullElement.addAttribute(new Attribute("refid",
- "OracleDialectSuffix"));
- element.getElements().add(isNotNullElement);
-
- return super.sqlMapUpdateByExampleWithoutBLOBsElementGenerated(element,
- introspectedTable);
- }
-
-
-
-
-
-
- private void addPage(TopLevelClass topLevelClass,
- IntrospectedTable introspectedTable, String name) {
- topLevelClass.addImportedType(new FullyQualifiedJavaType(
- "com.tgwoo.core.dao.pojo.Page"));
- CommentGenerator commentGenerator = context.getCommentGenerator();
- Field field = new Field();
- field.setVisibility(JavaVisibility.PROTECTED);
- field.setType(new FullyQualifiedJavaType("com.tgwoo.core.dao.pojo.Page"));
- field.setName(name);
- commentGenerator.addFieldComment(field, introspectedTable);
- topLevelClass.addField(field);
- char c = name.charAt(0);
- String camel = Character.toUpperCase(c) + name.substring(1);
- Method method = new Method();
- method.setVisibility(JavaVisibility.PUBLIC);
- method.setName("set" + camel);
- method.addParameter(new Parameter(new FullyQualifiedJavaType(
- "com.tgwoo.core.dao.pojo.Page"), name));
- method.addBodyLine("this." + name + "=" + name + ";");
- commentGenerator.addGeneralMethodComment(method, introspectedTable);
- topLevelClass.addMethod(method);
- method = new Method();
- method.setVisibility(JavaVisibility.PUBLIC);
- method.setReturnType(new FullyQualifiedJavaType(
- "com.tgwoo.core.dao.pojo.Page"));
- method.setName("get" + camel);
- method.addBodyLine("return " + name + ";");
- commentGenerator.addGeneralMethodComment(method, introspectedTable);
- topLevelClass.addMethod(method);
- }
-
-
-
-
- public boolean validate(List<String> warnings) {
- return true;
- }
- }
二、增加插件到Mybatis Generator配置文件中
<?xml version="1.0" encoding="UTF-8" ?>
- <!DOCTYPE generatorConfiguration PUBLIC "-//mybatis.org//DTD MyBatis Generator Configuration 1.0//EN" "http://mybatis.org/dtd/mybatis-generator-config_1_0.dtd" >
- <generatorConfiguration >
- <classPathEntry location="E:\work\eclipseWorkspace\myEclipse\CTSPMTS\WebRoot\WEB-INF\lib\ojdbc14.jar" />
-
- <context id="oracle" >
- <plugin type="org.mybatis.generator.plugins.CaseInsensitiveLikePlugin"></plugin>
- <plugin type="org.mybatis.generator.plugins.SerializablePlugin"></plugin>
-
- <plugin type="com.tgwoo.core.dao.plugin.OraclePaginationPlugin"></plugin>
-
- <commentGenerator>
- <property name="suppressDate" value="true" />
- <property name="suppressAllComments" value="true" />
- </commentGenerator>
-
- <jdbcConnection driverClass="oracle.jdbc.driver.OracleDriver" connectionURL="jdbc:oracle:thin:@192.168.0.2:1521:ctspmt" userId="ctspmt" password="ctspmt123" />
- <javaModelGenerator targetPackage="com.tgwoo.ctspmt.model" targetProject="CTSPMTS/src" />
- <sqlMapGenerator targetPackage="com.tgwoo.ctspmt.data" targetProject="CTSPMTS/src" />
- <javaClientGenerator targetPackage="com.tgwoo.ctspmt.data" targetProject="CTSPMTS/src" type="XMLMAPPER" />
-
-
- <!--
- <table schema="ctspmt" tableName="mt_e_msg" />
- <table schema="ctspmt" tableName="mt_e_msg_log" />
- <table schema="ctspmt" tableName="mt_e_msg_receiver" />
- <table schema="ctspmt" tableName="st_e_org" />
- <table schema="ctspmt" tableName="st_e_role" />
- <table schema="ctspmt" tableName="st_e_user" />
- <table schema="ctspmt" tableName="mt_e_user_msg_conf" />
- <table schema="ctspmt" tableName="mt_j_user_device" />
- <table schema="ctspmt" tableName="st_j_user_role" />
- <table schema="ctspmt" tableName="ST_E_UNIQUE_KEY" />
- --><table schema="ctspmt" tableName="mt_v_msg_item" />
- </context>
-
- </generatorConfiguration>
三、示例
/**
- * Copyright (C) 2011 Tgwoo Inc.
- * http:
- */
- package com.tgwoo.ctspmt.test;
-
- import com.tgwoo.core.config.SpringBeanProxy;
- import com.tgwoo.core.dao.pojo.Page;
- import com.tgwoo.ctspmt.data.MtVMsgItemMapper;
- import com.tgwoo.ctspmt.model.MtVMsgItemExample;
-
-
-
-
-
- public class Test {
-
-
-
- public static void main(String[] args) {
-
- MtVMsgItemMapper mapper = SpringBeanProxy.getCtx().getBean(
- MtVMsgItemMapper.class);
- MtVMsgItemExample ex = new MtVMsgItemExample();
- Page page = new Page(0, 10);
- ex.setPage(page);
- ex.createCriteria().andMsgCodeEqualTo("222");
-
- page.setCount(mapper.countByExample(ex));
- int row = mapper.selectByExample(ex).size();
- System.out.println("============row:" + row + "================");
- }
-
- }
四、分页类
五、生成后的代码
1、Example代码
- package com.tgwoo.ctspmt.model;
-
- import com.tgwoo.core.dao.pojo.Page;
- import java.math.BigDecimal;
- import java.util.ArrayList;
- import java.util.Date;
- import java.util.Iterator;
- import java.util.List;
-
- public class MtVMsgItemExample {
- protected String orderByClause;
-
- protected boolean distinct;
-
- protected List<Criteria> oredCriteria;
-
- protected Page page;
-
- ...
2、mapper.xml
- ...
- <select id="selectByExample" resultMap="BaseResultMap" parameterType="com.tgwoo.ctspmt.model.MtVMsgItemExample" >
- <include refid="OracleDialectPrefix" />
- select
- <if test="distinct" >
- distinct
- </if>
- <include refid="Base_Column_List" />
- from CTSPMT.MT_V_MSG_ITEM
- <if test="_parameter != null" >
- <include refid="Example_Where_Clause" />
- </if>
- <if test="orderByClause != null" >
- order by ${orderByClause}
- </if>
- <include refid="OracleDialectSuffix" />
- </select>
- ...
- <sql id="OracleDialectPrefix" >
- <if test="page != null" >
- select * from ( select row_.*, rownum rownum_ from (
- </if>
- </sql>
- <sql id="OracleDialectSuffix" >
- <if test="page != null" >
- <![CDATA[ ) row_ ) where rownum_ > #{page.begin} and rownum_ <= #{page.end} ]]>
- </if>
- </sql>
- ...
附件是Mybatis Generatorjar包。
其他数据库的方言可以按照Oracle的去改写,有写好的希望能共享下。
-------------------------------------------------------------------------------------------------------
maven管理:
1、pom.xml
- <build>
- <plugins>
- <plugin>
- <groupId>org.mybatis.generator</groupId>
- <artifactId>mybatis-generator-maven-plugin</artifactId>
- <version>1.3.1</version>
- <executions>
- <execution>
- <id>Generate MyBatis Artifacts</id>
- <goals>
- <goal>generate</goal>
- </goals>
- </execution>
- </executions>
- <dependencies>
- <dependency>
- <groupId>com.oracle</groupId>
- <artifactId>ojdbc14</artifactId>
- <version>10.2.0.4.0</version>
- </dependency>
- </dependencies>
- </plugin>
- </plugins>
- </build>
2、generatorConfig.xml
- <?xml version="1.0" encoding="UTF-8"?>
- <!DOCTYPE generatorConfiguration
- PUBLIC "-//mybatis.org//DTD MyBatis Generator Configuration 1.0//EN"
- "http://mybatis.org/dtd/mybatis-generator-config_1_0.dtd">
- <generatorConfiguration>
- <context id="oracleGenerator" targetRuntime="MyBatis3">
- <plugin type="org.mybatis.generator.plugins.CaseInsensitiveLikePlugin"></plugin>
- <plugin type="org.mybatis.generator.plugins.SerializablePlugin"></plugin>
-
- <plugin
- type="com.tgwoo.test.core.dao.mybatis.generator.plugin.pagination.OraclePaginationPlugin"></plugin>
-
-
- <commentGenerator>
- <property name="suppressDate" value="true" />
- <property name="suppressAllComments" value="true" />
- </commentGenerator>
-
- <jdbcConnection driverClass="oracle.jdbc.driver.OracleDriver"
- connectionURL="jdbc:oracle:thin:@192.168.0.2:1521:test" userId="test"
- password="test123" />
- <javaTypeResolver>
- <property name="forceBigDecimals" value="false" />
- </javaTypeResolver>
-
-
- <javaModelGenerator targetPackage="com.tgwoo.test.dao.model"
- targetProject=".\src\main\java">
- <property name="enableSubPackages" value="false" />
- <property name="trimStrings" value="true" />
- </javaModelGenerator>
-
-
- <sqlMapGenerator targetPackage="com.tgwoo.test.dao"
- targetProject=".\src\main\resources">
- <property name="enableSubPackages" value="false" />
- </sqlMapGenerator>
-
-
- <javaClientGenerator type="XMLMAPPER"
- targetPackage="com.tgwoo.test.dao" targetProject=".\src\main\java">
- <property name="enableSubPackages" value="false" />
- </javaClientGenerator>
-
-
- <table schema="test" tableName="testTable">
- <columnOverride column="id" javaType="Long" />
- </table>
- </context>
- </generatorConfiguration>
3、run
Goals:mybatis-generator:generate
/////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
- package org.leef.db.mybatis.plugin;
-
- import java.util.List;
-
- import org.mybatis.generator.api.CommentGenerator;
- import org.mybatis.generator.api.IntrospectedTable;
- import org.mybatis.generator.api.PluginAdapter;
- import org.mybatis.generator.api.ShellRunner;
- import org.mybatis.generator.api.dom.java.Field;
- import org.mybatis.generator.api.dom.java.FullyQualifiedJavaType;
- import org.mybatis.generator.api.dom.java.JavaVisibility;
- import org.mybatis.generator.api.dom.java.Method;
- import org.mybatis.generator.api.dom.java.Parameter;
- import org.mybatis.generator.api.dom.java.TopLevelClass;
- import org.mybatis.generator.api.dom.xml.Attribute;
- import org.mybatis.generator.api.dom.xml.Document;
- import org.mybatis.generator.api.dom.xml.TextElement;
- import org.mybatis.generator.api.dom.xml.XmlElement;
-
-
-
-
-
- public class OraclePaginationPlugin extends PluginAdapter {
-
- @Override
- public boolean modelExampleClassGenerated(TopLevelClass topLevelClass,
- IntrospectedTable introspectedTable) {
-
- addPage(topLevelClass, introspectedTable, "page");
- addDialect(topLevelClass, introspectedTable, "dialect");
- return super.modelExampleClassGenerated(topLevelClass,
- introspectedTable);
- }
-
- @Override
- public boolean sqlMapDocumentGenerated(Document document,
- IntrospectedTable introspectedTable) {
- XmlElement parentElement = document.getRootElement();
-
-
- XmlElement paginationPrefixElement = new XmlElement("sql");
- paginationPrefixElement.addAttribute(new Attribute("id",
- "OracleDialectPrefix"));
- XmlElement pageStart = new XmlElement("if");
- pageStart.addAttribute(new Attribute("test", "page != null"));
- XmlElement pageDialect1 = new XmlElement("if");
- pageDialect1.addAttribute(new Attribute("test", "dialect == ‘oralce‘"));
- pageStart.addElement(pageDialect1);
- pageDialect1.addElement(new TextElement(
- "select * from ( select row_.*, rownum rownum_ from ( "));
- paginationPrefixElement.addElement(pageStart);
- parentElement.addElement(paginationPrefixElement);
-
-
- XmlElement paginationSuffixElement = new XmlElement("sql");
- paginationSuffixElement.addAttribute(new Attribute("id",
- "OracleDialectSuffix"));
- XmlElement pageEnd = new XmlElement("if");
- pageEnd.addAttribute(new Attribute("test", "page != null"));
- XmlElement pageDialect2 = new XmlElement("if");
- pageDialect2.addAttribute(new Attribute("test", "dialect == ‘oralce‘"));
- pageEnd.addElement(pageDialect2);
- pageDialect2.addElement(new TextElement(
- "<![CDATA[ ) row_ ) where rownum_ > #{page.begin} and rownum_ <= #{page.end} ]]>"));
-
-
- XmlElement mysqlDialect = new XmlElement("if");
- mysqlDialect.addAttribute(new Attribute("test", "dialect == ‘mysql‘"));
- pageEnd.addElement(mysqlDialect);
- mysqlDialect.addElement(new TextElement(
- "limit #{page.start} , #{page.limit}"));
- paginationSuffixElement.addElement(pageEnd);
-
- parentElement.addElement(paginationSuffixElement);
-
- return super.sqlMapDocumentGenerated(document, introspectedTable);
- }
-
- @Override
- public boolean sqlMapSelectByExampleWithoutBLOBsElementGenerated(
- XmlElement element, IntrospectedTable introspectedTable) {
-
- XmlElement pageStart = new XmlElement("include");
- pageStart.addAttribute(new Attribute("refid", "OracleDialectPrefix"));
- element.getElements().add(0, pageStart);
-
- XmlElement isNotNullElement = new XmlElement("include");
- isNotNullElement.addAttribute(new Attribute("refid",
- "OracleDialectSuffix"));
- element.getElements().add(isNotNullElement);
-
- return super.sqlMapUpdateByExampleWithoutBLOBsElementGenerated(element,
- introspectedTable);
- }
-
-
-
-
-
-
- private void addDialect(TopLevelClass topLevelClass,
- IntrospectedTable introspectedTable, String name) {
- CommentGenerator commentGenerator = context.getCommentGenerator();
- Field field = new Field();
- field.setVisibility(JavaVisibility.PRIVATE);
- field.setType(new FullyQualifiedJavaType("String"));
- field.setName(name + " = \"mysql\"");
- commentGenerator.addFieldComment(field, introspectedTable);
- topLevelClass.addField(field);
- char c = name.charAt(0);
- String camel = Character.toUpperCase(c) + name.substring(1);
- Method method = new Method();
- method.setVisibility(JavaVisibility.PUBLIC);
- method.setName("set" + camel);
- method.addParameter(new Parameter(new FullyQualifiedJavaType(
- "String"), name));
- method.addBodyLine("this." + name + "=" + name + ";");
- commentGenerator.addGeneralMethodComment(method, introspectedTable);
- topLevelClass.addMethod(method);
- method = new Method();
- method.setVisibility(JavaVisibility.PUBLIC);
- method.setReturnType(new FullyQualifiedJavaType(
- "String"));
- method.setName("get" + camel);
- method.addBodyLine("return " + name + ";");
- commentGenerator.addGeneralMethodComment(method, introspectedTable);
- topLevelClass.addMethod(method);
- }
-
-
-
-
-
-
- private void addPage(TopLevelClass topLevelClass,
- IntrospectedTable introspectedTable, String name) {
- topLevelClass.addImportedType(new FullyQualifiedJavaType(
- "com.hnisi.e3itm.base.util.Page"));
- CommentGenerator commentGenerator = context.getCommentGenerator();
- Field field = new Field();
- field.setVisibility(JavaVisibility.PROTECTED);
- field.setType(new FullyQualifiedJavaType("com.hnisi.e3itm.base.util.Page"));
- field.setName(name);
- commentGenerator.addFieldComment(field, introspectedTable);
- topLevelClass.addField(field);
- char c = name.charAt(0);
- String camel = Character.toUpperCase(c) + name.substring(1);
- Method method = new Method();
- method.setVisibility(JavaVisibility.PUBLIC);
- method.setName("set" + camel);
- method.addParameter(new Parameter(new FullyQualifiedJavaType(
- "com.hnisi.e3itm.base.util.Page"), name));
- method.addBodyLine("this." + name + "=" + name + ";");
- commentGenerator.addGeneralMethodComment(method, introspectedTable);
- topLevelClass.addMethod(method);
- method = new Method();
- method.setVisibility(JavaVisibility.PUBLIC);
- method.setReturnType(new FullyQualifiedJavaType(
- "com.hnisi.e3itm.base.util.Page"));
- method.setName("get" + camel);
- method.addBodyLine("return " + name + ";");
- commentGenerator.addGeneralMethodComment(method, introspectedTable);
- topLevelClass.addMethod(method);
- }
-
-
-
-
- public boolean validate(List<String> warnings) {
- return true;
- }
-
- public static void generate() {
- String config = PaginationPlugin.class.getClassLoader().getResource(
- "generatorConfig.xml").getFile();
- String[] arg = { "-configfile", config, "-overwrite" };
- ShellRunner.main(arg);
- }
- public static void main(String[] args) {
- generate();
- }
- }
///////////////////////////////////////////////////////////////////////////////////////////////////////
////////////////////////////////////////////////////////////////////////////////////////////////////////
mysql
- package org.leef.db.mybatis.plugin;
- import java.util.List;
- import org.mybatis.generator.api.CommentGenerator;
- import org.mybatis.generator.api.IntrospectedTable;
- import org.mybatis.generator.api.PluginAdapter;
- import org.mybatis.generator.api.ShellRunner;
- import org.mybatis.generator.api.dom.java.Field;
- import org.mybatis.generator.api.dom.java.FullyQualifiedJavaType;
- import org.mybatis.generator.api.dom.java.JavaVisibility;
- import org.mybatis.generator.api.dom.java.Method;
- import org.mybatis.generator.api.dom.java.Parameter;
- import org.mybatis.generator.api.dom.java.TopLevelClass;
- import org.mybatis.generator.api.dom.xml.Attribute;
- import org.mybatis.generator.api.dom.xml.TextElement;
- import org.mybatis.generator.api.dom.xml.XmlElement;
-
-
-
-
-
-
- public class PaginationPlugin extends PluginAdapter {
- @Override
- public boolean modelExampleClassGenerated(TopLevelClass topLevelClass,
- IntrospectedTable introspectedTable) {
-
- addLimit(topLevelClass, introspectedTable, "limitStart");
- addLimit(topLevelClass, introspectedTable, "limitEnd");
- return super.modelExampleClassGenerated(topLevelClass,
- introspectedTable);
- }
- @Override
- public boolean sqlMapSelectByExampleWithoutBLOBsElementGenerated(
- XmlElement element, IntrospectedTable introspectedTable) {
- XmlElement isParameterPresenteElemen = (XmlElement) element
- .getElements().get(element.getElements().size() - 1);
- XmlElement isNotNullElement = new XmlElement("isGreaterEqual");
- isNotNullElement.addAttribute(new Attribute("property", "limitStart"));
- isNotNullElement.addAttribute(new Attribute("compareValue", "0"));
- isNotNullElement.addElement(new TextElement(
- "limit $limitStart$ , $limitEnd$"));
- isParameterPresenteElemen.addElement(isNotNullElement);
- return super.sqlMapUpdateByExampleWithoutBLOBsElementGenerated(element,
- introspectedTable);
- }
- private void addLimit(TopLevelClass topLevelClass,
- IntrospectedTable introspectedTable, String name) {
- CommentGenerator commentGenerator = context.getCommentGenerator();
- Field field = new Field();
- field.setVisibility(JavaVisibility.PROTECTED);
- field.setType(FullyQualifiedJavaType.getIntInstance());
- field.setName(name);
- field.setInitializationString("-1");
- commentGenerator.addFieldComment(field, introspectedTable);
- topLevelClass.addField(field);
- char c = name.charAt(0);
- String camel = Character.toUpperCase(c) + name.substring(1);
- Method method = new Method();
- method.setVisibility(JavaVisibility.PUBLIC);
- method.setName("set" + camel);
- method.addParameter(new Parameter(FullyQualifiedJavaType
- .getIntInstance(), name));
- method.addBodyLine("this." + name + "=" + name + ";");
- commentGenerator.addGeneralMethodComment(method, introspectedTable);
- topLevelClass.addMethod(method);
- method = new Method();
- method.setVisibility(JavaVisibility.PUBLIC);
- method.setReturnType(FullyQualifiedJavaType.getIntInstance());
- method.setName("get" + camel);
- method.addBodyLine("return " + name + ";");
- commentGenerator.addGeneralMethodComment(method, introspectedTable);
- topLevelClass.addMethod(method);
- }
-
-
-
- public boolean validate(List<String> warnings) {
- return true;
- }
- public static void generate() {
- String config = PaginationPlugin.class.getClassLoader().getResource(
- "generatorConfig.xml").getFile();
- String[] arg = { "-configfile", config, "-overwrite" };
- ShellRunner.main(arg);
- }
- public static void main(String[] args) {
- generate();
- }
- }