Mybatis查询语句sql拼装与Ognl源码解析

@[toc]

## Mybatis查询语句sql拼装源码解析

### 带着问题学习源码（从加载mapper到sql拼装）

#### 问题现象

**后端用Integer接收0传入param.pushStatus,为什么param.pushStatus !=''判断为false**

后端使用Integer接收

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#### 原因

mapper接口传入的参数类型为Integer值为0时，mybaits 在进行 **param.pushStatus !=''**的时候会默认<font color='red'>""和0 都转换成double进行比较都是0.0 </font> ，结果不是重点，重点在于下面过程。

#### 源码解析（Mybatis-plus)

Mybatis-plus很多类重写了Mybatis，此处以Mybatis-plus源码出发

##### 1、加载SqlSessionFactory

项目启动会通过springboot的自动装配原理加载MybatisPlusAutoConfiguration从而加载SqlSessionFactory（加载mapper到MybatisSqlSessionFactoryBean）

```java

public SqlSessionFactory sqlSessionFactory(DataSource dataSource) throws Exception {

MybatisSqlSessionFactoryBean factory = new MybatisSqlSessionFactoryBean();

factory.setDataSource(dataSource);

...

if (StringUtils.hasText(this.properties.getConfigLocation())) {

//下面的ConfigLocation为：classpath:mybatis/mybatis-config.xml

factory.setConfigLocation(this.resourceLoader.getResource(this.properties.getConfigLocation()));

}

...

//这里是装载插件（之后会加入责任链中）适用于慢sql查询拦截器等

if (!ObjectUtils.isEmpty(this.interceptors)) {

factory.setPlugins(this.interceptors);

}

...

//...注入很多属性比如：自定义枚举包、注入主键生成器、注入sql注入器、注入ID生成器等

factory.getObject();

}

//factory.getObject()--会进行后置属性设置（MybatisSqlSessionFactoryBean）

```

```java

//MybatisSqlSessionFactoryBean

//这里关注mapper的设置

protected SqlSessionFactory buildSqlSessionFactory() throws Exception {

MybatisXMLConfigBuilder xmlConfigBuilder = null;

if (this.configuration != null) {

...

} else if (this.configLocation != null) {

// this.configLocation 里面包括mybatis/mybatis-config.xml

//如果在配置文件有<mapper>标签解析

xmlConfigBuilder = new MybatisXMLConfigBuilder(this.configLocation.getInputStream(), null, this.configurationProperties);

targetConfiguration = xmlConfigBuilder.getConfiguration();

} else {

...

}

......

if (xmlConfigBuilder != null) {

try {

//第一种--解析配置文件mybatis-config.xml信息

xmlConfigBuilder.parse();

}

......

//mapperLocations是提前扫描自定义的classpath:mapper/*.xml文件

//例如：file [E:\code\trade\trade\target\classes\mapper\SellReconciliationMapper.xml]

if (this.mapperLocations != null) {

if (this.mapperLocations.length == 0) {

...

} else {

//循环遍历所有的xxxx.xml

for (Resource mapperLocation : this.mapperLocations) {

if (mapperLocation == null) {

continue;

}

try {

XMLMapperBuilder xmlMapperBuilder = new XMLMapperBuilder(mapperLocation.getInputStream(),

targetConfiguration, mapperLocation.toString(), targetConfiguration.getSqlFragments());

//这里解析mapper

xmlMapperBuilder.parse();

}

```

###### xmlConfigBuilder.parse();

```java

public Configuration parse() {

if (parsed) {

throw new BuilderException("Each XMLConfigBuilder can only be used once.");

}

parsed = true;

parseConfiguration(parser.evalNode("/configuration"));

return configuration;

}

private void parseConfiguration(XNode root) {

try {

//将mybatis-config.xml通过XPath解析成XNode再进行解析

propertiesElement(root.evalNode("properties"));

Properties settings = settingsAsProperties(root.evalNode("settings"));

loadCustomVfs(settings);

loadCustomLogImpl(settings);

typeAliasesElement(root.evalNode("typeAliases"));

pluginElement(root.evalNode("plugins"));

objectFactoryElement(root.evalNode("objectFactory"));

objectWrapperFactoryElement(root.evalNode("objectWrapperFactory"));

reflectorFactoryElement(root.evalNode("reflectorFactory"));

settingsElement(settings);

environmentsElement(root.evalNode("environments"));

databaseIdProviderElement(root.evalNode("databaseIdProvider"));

typeHandlerElement(root.evalNode("typeHandlers"));

//这里可以配置mapper

mapperElement(root.evalNode("mappers"));

} catch (Exception e) {

throw new BuilderException("Error parsing SQL Mapper Configuration. Cause: " + e, e);

}

```

###### xmlMapperBuilder.parse();

```java

public void parse() {

if (!configuration.isResourceLoaded(resource)) {

//前面已经获取了SellReconciliationMapper.xml，通过命名空间解析mapper

configurationElement(parser.evalNode("/mapper"));

configuration.addLoadedResource(resource);

//再通过命名空间绑定mapper

bindMapperForNamespace();

}

//解析ResultMap等属性

parsePendingResultMaps();

parsePendingCacheRefs();

parsePendingStatements();

}

private void bindMapperForNamespace() {

//com.jdh.trade.mapper.SellReconciliationMapper

String namespace = builderAssistant.getCurrentNamespace();

if (namespace != null) {

Class<?> boundType = null;

try {

//获取命名空间获取mapper接口

boundType = Resources.classForName(namespace);

}

if (boundType != null && !configuration.hasMapper(boundType)) {

//Spring可能不知道真正的资源名，所以我们设置了一个标志

//防止从映射器接口再次加载这个资源

configuration.addLoadedResource("namespace:" + namespace);

//关键这里将mapper增加到map中

configuration.addMapper(boundType);

}

//key mapper接口 value mapper代理工厂

//private final Map<Class<?>, MybatisMapperProxyFactory<?>> knownMappers = new HashMap<>();

@Override

public <T> void addMapper(Class<T> type) {

if (type.isInterface()) {

...

boolean loadCompleted = false;

try {

//!!!!保存到map!!!!

knownMappers.put(type, new MybatisMapperProxyFactory<>(type));

//在运行解析器之前添加类型是很重要的否则，将自动尝试绑定映射器解析器。如果类型已经知道，则不会尝试.

MybatisMapperAnnotationBuilder parser = new MybatisMapperAnnotationBuilder(config, type);

parser.parse();

loadCompleted = true;

}...

}

```

##### 2、mapper接口生成代理对象

@service 加载bean之后会通过

doGetObjectFromFactoryBean方法中执行factory.getObject()获取到bean实例MybatisMapperProxy。

```java

//MapperFactoryBean

//对于mybatis相关的mapper

@Override

public T getObject() throws Exception {

//this.mapperInterface 相当于接口com.jdh.trade.mapper.xxxMapper

return getSqlSession().getMapper(this.mapperInterface);

}

//SqlSessionTemplate

@Override

public <T> T getMapper(Class<T> type) {

return getConfiguration().getMapper(type, this);

}

//MybatisMapperRegistry

@Override

public <T> T getMapper(Class<T> type, SqlSession sqlSession) {

//knownMappers 这个map是上面保存的

final MybatisMapperProxyFactory<T> mapperProxyFactory = (MybatisMapperProxyFactory<T>) knownMappers.get(type);

...

try {

//生成代理对象

return mapperProxyFactory.newInstance(sqlSession);

} catch (Exception e) {

throw new BindingException("Error getting mapper instance. Cause: " + e, e);

}

//MybatisMapperProxyFactory

//mapperProxyFactory.newInstance(sqlSession);

protected T newInstance(MybatisMapperProxy<T> mapperProxy) {

//Proxy 生成动态代理实例

return (T) Proxy.newProxyInstance(mapperInterface.getClassLoader(), new Class[]{mapperInterface}, mapperProxy);

}

public T newInstance(SqlSession sqlSession) {

final MybatisMapperProxy<T> mapperProxy = new MybatisMapperProxy<>(sqlSession, mapperInterface, methodCache);

return newInstance(mapperProxy);

}

```

##### 3、调用查询方法

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执行mapper的查询等语句就会进入代理对象的invoke方法

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InvocationHandler接口是proxy代理实例的调用处理程序实现的一个接口，每一个proxy代理实例都有一个关联的调用处理程序；在代理实例调用方法时，方法调用被编码分派到调用处理程序的invoke方法。

MybatisMapperProxy

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从缓存获取MybatisMapperMethod-属性如下

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最终执行sql走的是MybatisMapperMethod.execute(sqlSession, args)

```java

public Object execute(SqlSession sqlSession, Object[] args) {

Object result;

//根据是查询还是更新进入不同分支

switch (command.getType()) {

case INSERT: {

Object param = method.convertArgsToSqlCommandParam(args);

result = rowCountResult(sqlSession.insert(command.getName(), param));

break;

}

case UPDATE: {

Object param = method.convertArgsToSqlCommandParam(args);

result = rowCountResult(sqlSession.update(command.getName(), param));

break;

}

case DELETE: {

Object param = method.convertArgsToSqlCommandParam(args);

result = rowCountResult(sqlSession.delete(command.getName(), param));

break;

}

case SELECT:

if (method.returnsVoid() && method.hasResultHandler()) {

executeWithResultHandler(sqlSession, args);

result = null;

} else if (method.returnsMany()) {

//比如 selectList 就会走这里

result = executeForMany(sqlSession, args);

} else if (method.returnsMap()) {

result = executeForMap(sqlSession, args);

} else if (method.returnsCursor()) {

result = executeForCursor(sqlSession, args);

} else {

Object param = method.convertArgsToSqlCommandParam(args);

// 分页查询

if (IPage.class.isAssignableFrom(method.getReturnType())) {

...

//关注这里执行分页默认也是执行selectList

result = executeForIPage(sqlSession, args);

...

}

/**

* TODO IPage 专用

private <E> List<E> executeForIPage(SqlSession sqlSession, Object[] args) {

Object param = method.convertArgsToSqlCommandParam(args);

//执行SqlSessionTemplate的selectList

return sqlSession.selectList(command.getName(), param);

}

@Override

public <E> List<E> selectList(String statement, Object parameter) {

//DefaultSqlSession

return this.sqlSessionProxy.selectList(statement, parameter);

}

```

###### DefaultSqlSession代理对象获取sqlSession

```java

private class SqlSessionInterceptor implements InvocationHandler {

@Override

public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {

//加载sqlSession-getSqlSession-通过sessionFactory.openSession(executorType);

//从中会获取执行器和加载插件

SqlSession sqlSession = getSqlSession(SqlSessionTemplate.this.sqlSessionFactory,

SqlSessionTemplate.this.executorType, SqlSessionTemplate.this.exceptionTranslator);

try {

//拿到sqlSession才能去执行查询

Object result = method.invoke(sqlSession, args);

....

}

```

```java

public static SqlSession getSqlSession(SqlSessionFactory sessionFactory, ExecutorType executorType,

PersistenceExceptionTranslator exceptionTranslator) {

...

//DefaultSqlSessionFactory.openSession

session = sessionFactory.openSession(executorType);

...

return session;

}

@Override

public SqlSession openSession(ExecutorType execType) {

return openSessionFromDataSource(execType, null, false);

}

private SqlSession openSessionFromDataSource(ExecutorType execType, TransactionIsolationLevel level, boolean autoCommit) {

Transaction tx = null;

try {

final Environment environment = configuration.getEnvironment();

final TransactionFactory transactionFactory = getTransactionFactoryFromEnvironment(environment);

//新建事务

tx = transactionFactory.newTransaction(environment.getDataSource(), level, autoCommit);

//创建执行器 MybatisConfiguration.newExecutor

//(默认是simple执行器)

final Executor executor = configuration.newExecutor(tx, execType);

//最后返回默认DefaultSqlSession

return new DefaultSqlSession(configuration, executor, autoCommit);

} catch (Exception e) {

closeTransaction(tx); // may have fetched a connection so lets call close()

throw ExceptionFactory.wrapException("Error opening session. Cause: " + e, e);

} finally {

ErrorContext.instance().reset();

}

```

###### 装饰者模式创建executor和责任链模式interceptorChain加载插件

```java

@Override

public Executor newExecutor(Transaction transaction, ExecutorType executorType) {

executorType = executorType == null ? defaultExecutorType : executorType;

executorType = executorType == null ? ExecutorType.SIMPLE : executorType;

Executor executor;

if (ExecutorType.BATCH == executorType) {

executor = new MybatisBatchExecutor(this, transaction);

} else if (ExecutorType.REUSE == executorType) {

executor = new MybatisReuseExecutor(this, transaction);

} else {

executor = new MybatisSimpleExecutor(this, transaction);

}

if (cacheEnabled) {

//装饰者模式装饰了简单执行器

executor = new MybatisCachingExecutor(executor);

}

//责任链进行增加所有执行器并执行plugin

//通过判断插件，new Plugin(target, interceptor, signatureMap))生成MybatisCachingExecutor代理对象!!!

executor = (Executor) interceptorChain.pluginAll(executor);

return executor;

}

```

##### 继续执行查询

DefaultSqlSession.selectList

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```java

//DefaultSqlSession

@Override

public <E> List<E> selectList(String statement, Object parameter) {

return this.selectList(statement, parameter, RowBounds.DEFAULT);

}

@Override

//rowBounds 是用来逻辑分页（按照条件将数据从数据库查询到内存中，在内存中进行分页）

//wrapCollection(parameter)是用来装饰集合或者数组参数里面有查询条件

public <E> List<E> selectList(String statement, Object parameter, RowBounds rowBounds) {

try {

//statement:

//名字com.jdh.trade.mapper.SellReconciliationMapper.selectSellReconciliationByPage

//获取MappedStatement对象，通过配置信息从StrictMap缓存中获取

MappedStatement ms = configuration.getMappedStatement(statement);

//执行executor对象里面的query方法

//这里的executor是在DefaultSqlSessionFactory中，

//mybatis 通过Configuration对象创建的对应CachingExecutor

//mybatis-plus 通过MybatisConfiguration 创建MybatisCachingExecutor

//根据不同的配置，会有不同的Executor 无论那个执行器查询最终都会到下面的查询

return executor.query(ms, wrapCollection(parameter), rowBounds, Executor.NO_RESULT_HANDLER);

}

```

这一次获得MappedStatement ms 如下

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###### 关键查询

```java

MybatisCachingExecutor

@Override

public <E> List<E> query(MappedStatement ms, Object parameterObject, RowBounds rowBounds, ResultHandler resultHandler) throws SQLException {

//组装sql--我们主要研究这里的组装

BoundSql boundSql = ms.getBoundSql(parameterObject);

//获取一级缓存key

CacheKey key = createCacheKey(ms, parameterObject, rowBounds, boundSql);

//从缓存查询还是直接查询数据库等

return query(ms, parameterObject, rowBounds, resultHandler, key, boundSql);

}

```

```java

MappedStatement

public BoundSql getBoundSql(Object parameterObject) {

//sqlSource 为 DynamicSqlSource(动态sql拼接)见上图

//SqlSouce里面已经解析mapper对应的sql

//已经被解析为MixedSqlNode

BoundSql boundSql = sqlSource.getBoundSql(parameterObject);

....

return boundSql;

}

```

```xml

<select id="selectSellReconciliationByPage"

resultType="com.jdh.trade.model.bankcontribution.resp.QuerySellReconciliationResp">

SELECT

...

WHERE sr.root_code = po.root_code

...

and sr.push_status = #{param.pushStatus}

</select>

```

###### 解析sql过程

```java

@Override

public BoundSql getBoundSql(Object parameterObject) {

//下面有实体属性

DynamicContext context = new DynamicContext(configuration, parameterObject);

//处理一个个的sqlNode 编译出一个完整的xml的sql

//rootSqlNode是 MixedSqlNode 合并sql节点

//${} 已经在静态节点赋值了因为是直接静态判断${ 然后替换会有sql注入风险

rootSqlNode.apply(context);

//创建sql信息解析器

SqlSourceBuilder sqlSourceParser = new SqlSourceBuilder(configuration);

//获取入参类型

Class<?> parameterType = parameterObject == null ? Object.class : parameterObject.getClass();

//执行解析:将带有#{}和${}的sql语句进行解析，然后封装到StaticSqlSource中

//比如and sr.push_status = #{param.pushStatus} 解析成 and sr.push_status = ?

SqlSource sqlSource = sqlSourceParser.parse(context.getSql(), parameterType, context.getBindings());

//将解析后的sql语句还有入参绑定到一起（封装到一个对象中，此时还没有将参数替换到SQL占位符？）

//此时变为静态绑定 StaticSqlSource

BoundSql boundSql = sqlSource.getBoundSql(parameterObject);

context.getBindings().forEach(boundSql::setAdditionalParameter);

return boundSql;

}

```

###### sql解析为MixedSqlNode节点

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**将每一个节点进行各自的解析然后拼装xml的sql 到 sqlBuilder （其实是装入string属性)**

我们来看一下 rootSqlNode.apply(context);

###### rootSqlNode.apply(context)

每个节点根据自己的规则判断是否组装到sqlBuilder

MixedSqlNode.apply

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这里我们注意一下为什么IfSqlNode节点会失效呢

<font color='red'>注意:为什么param.pushStatus != '' 进入这个方法会返回false</font>

```java

@Override

public boolean apply(DynamicContext context) {

//test = param.pushStatus != null and param.pushStatus != ''

//context.getBindings() 有前端传的参数条件

//判断符合条件就加入

if (evaluator.evaluateBoolean(test, context.getBindings())) {

contents.apply(context);

return true;

}

return false;

}

```

调用ExpressionEvaluator.evaluateBoolean 进行判断

```java

public boolean evaluateBoolean(String expression, Object parameterObject) {

//问题出现在这里 value 返回了false

Object value = OgnlCache.getValue(expression, parameterObject);

if (value instanceof Boolean) {

//从这里返回boolean值 false

return (Boolean) value;

}

if (value instanceof Number) {

return new BigDecimal(String.valueOf(value)).compareTo(BigDecimal.ZERO) != 0;

}

return value != null;

}

```

再调用OgnlCache.getValue方法获取校验结果

```java

//表达式expression = param.pushStatus != null and param.pushStatus != ''

//root 入参

public static Object getValue(String expression, Object root) {

try {

//Mybatis底层校验使用Ognl语法

Map context = Ognl.createDefaultContext(root, MEMBER_ACCESS, CLASS_RESOLVER, null);

//这里调用Ognl.getValue进行比较

return Ognl.getValue(parseExpression(expression), context, root);

} catch (OgnlException e) {

throw new BuilderException("Error evaluating expression '" + expression + "'. Cause: " + e, e);

}

```

parseExpression(expression) 会从缓存中读取Node 如果没有去解析成特定类型的Node对象

![\[外链图片转存失败,源站可能有防盗链机制,建议将图片保存下来直接上传(img-jtSyNZzf-1650516052834)(http://10.0.17.20/server/index.php?s=/api/attachment/visitFile/sign/7f5a45ede1b4c446ca6c010177e944aa)\]](https://img-blog.csdnimg.cn/bd19badffcab45b2922ab70e97345819.png)

```java

//OgnlCache

private static Object parseExpression(String expression) throws OgnlException {

Object node = expressionCache.get(expression);

if (node == null) {

node = Ognl.parseExpression(expression);

expressionCache.put(expression, node);

}

return node;

}

```

比如这里转化成 ASTAND

以下节点都是继承SimpleNode

![\[外链图片转存失败,源站可能有防盗链机制,建议将图片保存下来直接上传(img-0pTTkrP2-1650516052835)(http://10.0.17.20/server/index.php?s=/api/attachment/visitFile/sign/79511546ca850b7612af95c39ef14591)\]](https://img-blog.csdnimg.cn/94023c27a12d4fb4a47f8a5bd263ca8a.png?x-oss-process=image/watermark,type_d3F5LXplbmhlaQ,shadow_50,text_Q1NETiBATWlNaW5n5LuU,size_20,color_FFFFFF,t_70,g_se,x_16)

Ognl.getValue(parseExpression(expression), context, root)获取最终结果

```java

public static Object getValue(Object tree, Map context, Object root)

throws OgnlException

{

return getValue(tree, context, root, null);

}

/**

* 计算给定的OGNL表达式树，从给定的根对象中提取值。通过addDefaultContext()为给定的上下文和根设置默认上下文。

* @param tree

* 要计算的OGNL表达式树，由parseExpression()返回

如：(param.pushStatus != null) && (param.pushStatus != "")

* @param context

* 求值的命名上下文

* @param root

* OGNL表达式的根对象

* @return 返回计算表达式的结果

public static Object getValue(Object tree, Map context, Object root, Class resultType) throws OgnlException {

OgnlContext ognlContext = (OgnlContext)addDefaultContext(root, context);

//根据解析表达式获取的节点该例子为 ASTAND

Node node = (Node)tree;

Object result;

if (node.getAccessor() != null) {

result = node.getAccessor().get(ognlContext, root);

} else {

//调用父类SimpleNode的getValue方法

//该节点为 ASTAND

result = node.getValue(ognlContext, root);

}

...

return result;

}

```

###### ASTAND节点树进行解析

![\[外链图片转存失败,源站可能有防盗链机制,建议将图片保存下来直接上传(img-Uv5gijjR-1650516052836)(http://10.0.17.20/server/index.php?s=/api/attachment/visitFile/sign/4553a1d57700a78d5d412db1f5a5a389)\]](https://img-blog.csdnimg.cn/162fa2950cd84f239eb568b39cc4e968.png?x-oss-process=image/watermark,type_d3F5LXplbmhlaQ,shadow_50,text_Q1NETiBATWlNaW5n5LuU,size_20,color_FFFFFF,t_70,g_se,x_16)

调用父类 SimpleNode. getValue

以下两个方法方法为父类方法

```java

public final Object getValue(OgnlContext context, Object source) throws OgnlException {

Object result = null;

if (context.getTraceEvaluations()) {

...

} else {

//获取常量值

result = this.evaluateGetValueBody(context, source);

}

return result;

}

```

![\[外链图片转存失败,源站可能有防盗链机制,建议将图片保存下来直接上传(img-gCaqx2zA-1650516052836)(http://10.0.17.20/server/index.php?s=/api/attachment/visitFile/sign/b89e9fd510e869daf43bccaf08a6ac61)\]](https://img-blog.csdnimg.cn/9b1c7262557a4211a5774818005bc628.png?x-oss-process=image/watermark,type_d3F5LXplbmhlaQ,shadow_50,text_Q1NETiBATWlNaW5n5LuU,size_20,color_FFFFFF,t_70,g_se,x_16)

调用子类自己的判断实现getValueBody 从节点树叶子节点ASTConst一层一层根据规则返回结果给上一层

###### ASTAnd

```java

protected Object getValueBody(OgnlContext context, Object source) throws OgnlException {

Object result = null;

int last = this._children.length - 1;

for(int i = 0; i <= last; ++i) {

result = this._children[i].getValue(context, source);

if (i != last && !OgnlOps.booleanValue(result)) {

break;

}

return result;

}

```

![\[外链图片转存失败,源站可能有防盗链机制,建议将图片保存下来直接上传(img-s4tnU2yD-1650516052837)(http://10.0.17.20/server/index.php?s=/api/attachment/visitFile/sign/eb2e2e018bc33c8ee5b76a11252e2fb1)\]](https://img-blog.csdnimg.cn/38a998291734448e90c9cbcd2ee4c9aa.png?x-oss-process=image/watermark,type_d3F5LXplbmhlaQ,shadow_50,text_Q1NETiBATWlNaW5n5LuU,size_20,color_FFFFFF,t_70,g_se,x_16)

###### ASTNotEq

```java

protected Object getValueBody(OgnlContext context, Object source) throws OgnlException {

Object v1 = this._children[0].getValue(context, source);

Object v2 = this._children[1].getValue(context, source);

return OgnlOps.equal(v1, v2) ? Boolean.FALSE : Boolean.TRUE;

}

```

![\[外链图片转存失败,源站可能有防盗链机制,建议将图片保存下来直接上传(img-HyFxeqay-1650516052837)(http://10.0.17.20/server/index.php?s=/api/attachment/visitFile/sign/6ada714321b6458785e31fabe2887a86)\]](https://img-blog.csdnimg.cn/49b92c25ffa1462f8ce2b5ab4a353aef.png?x-oss-process=image/watermark,type_d3F5LXplbmhlaQ,shadow_50,text_Q1NETiBATWlNaW5n5LuU,size_20,color_FFFFFF,t_70,g_se,x_16)

<font color='red'>这里出现了问题为什么 0 和 '' equal会相等</font>

```java

public static boolean equal(Object v1, Object v2) {

if (v1 == null) {

return v2 == null;

//!isEqual 判断出问题

} else if (v1 != v2 && !isEqual(v1, v2)) {

if (v1 instanceof Number && v2 instanceof Number) {

return ((Number)v1).doubleValue() == ((Number)v2).doubleValue();

} else {

return false;

}

} else {

return true;

}

```

<font color='red'>!isEqual(v1, v2) 判断成了相等返回true</font>

```java

public static boolean isEqual(Object object1, Object object2) {

...

{

//前面根据Ognl的算法

result = compareWithConversion(object1, object2) == 0;

}

return result;

}

public static int compareWithConversion(Object v1, Object v2) {

...

double dv1 = doubleValue(v1);

double dv2 = doubleValue(v2);

return dv1 == dv2 ? 0 : (dv1 < dv2 ? -1 : 1);

}

```

![\[外链图片转存失败,源站可能有防盗链机制,建议将图片保存下来直接上传(img-tP6PMJ3z-1650516052838)(http://10.0.17.20/server/index.php?s=/api/attachment/visitFile/sign/d51079b0f256d5537fae3039142a2542)\]](https://img-blog.csdnimg.cn/0ccec46131624ee39dd901e7a849baa1.png)

###### 4、问题根源

```java

public static double doubleValue(Object value) throws NumberFormatException {

if (value == null) {

return 0.0D;

} else {

Class c = value.getClass();

if (c.getSuperclass() == Number.class) {

return ((Number)value).doubleValue();

} else if (c == Boolean.class) {

return (Boolean)value ? 1.0D : 0.0D;

} else if (c == Character.class) {

return (double)(Character)value;

} else {

//这里将''改成了0.0D

String s = stringValue(value, true);

return s.length() == 0 ? 0.0D : Double.parseDouble(s);

}

```

最后是 "" 转换成了0.0 去比较了

###### ASTChain

```java

protected Object getValueBody(OgnlContext context, Object source) throws OgnlException {

Object result = source;

int i = 0;

for(int ilast = this._children.length - 1; i <= ilast; ++i) {

boolean handled = false;

if (i < ilast && this._children[i] instanceof ASTProperty) {

ASTProperty propertyNode = (ASTProperty)this._children[i];

int indexType = propertyNode.getIndexedPropertyType(context, result);

...

}

if (!handled) {

//将最后的链值返回

result = this._children[i].getValue(context, result);

}

return result;

}

```

###### ASTProperty

```java

protected Object getValueBody(OgnlContext context, Object source) throws OgnlException {

//通过ASTConst 直接获取返回值如 param 或 pushStatus 再读取入参对应的值

Object property = this.getProperty(context, source);

//根据 param 或 pushStatus 返回对应的值

Object result = OgnlRuntime.getProperty(context, source, property);

if (result == null) {

result = OgnlRuntime.getNullHandler(OgnlRuntime.getTargetClass(source)).nullPropertyValue(context, source, property);

}

return result;

}

```

###### ASTConst

```java

protected Object getValueBody(OgnlContext context, Object source) throws OgnlException {

return this.value;

}

```

#### 解决

（1）不用Integer接收，使用String类型接收

（2）去掉【参数！=’‘】的非空判断

![\[外链图片转存失败,源站可能有防盗链机制,建议将图片保存下来直接上传(img-Sex5LBqb-1650516052838)(http://10.0.17.20/server/index.php?s=/api/attachment/visitFile/sign/e872d96804f4039fa5878d896d0f970f)\]](https://img-blog.csdnimg.cn/cf172267c941471a8ea0bf6402ca0f08.png)

> 番外：如果String类型需要判断！=0，则需要写成 xxx != '0'.toString()

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