1.mybatis使用pageHelper分页功能受影响
PageHelper的实现也是通过interceptor拦截实现的，所以二者如果在没有配置好拦截顺序的情况下，就会出现相互干扰的情况。这个需要在配置文件或者配置类中解决，拦截器是个集合，支持添加多个拦截器，其中拦截顺序也是需要注意的。
拦截器配置类如下：
import com.github.pagehelper.PageInterceptor;
import com.pingan.haofang.standard.common.interceptor.QueryByAppInterceptor;
import org.apache.ibatis.session.SqlSessionFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import javax.annotation.PostConstruct;
import java.util.List;
import java.util.Properties;
@Configuration
public class MybatisPageHelp {
@Autowired
private List<SqlSessionFactory> sqlSessionFactoryList;
/**
* 接受分页插件额外的属性
* @return
*/
@Bean
@ConfigurationProperties(prefix = "pagehelper")
public Properties pageHelperProperties() {
return new Properties();
}
@PostConstruct
public void addPageInterceptor() {
QueryByAppInterceptor queryByAppInterceptor = new QueryByAppInterceptor();
PageInterceptor pageInterceptor = new PageInterceptor();
Properties properties = new Properties();
//先把一般方式配置的属性放进去
properties.putAll(pageHelperProperties());
//在把特殊配置放进去，close-conn 利用上面方式时，就是 close-conn 而不是 closeConn，所以需要额外的一步
pageInterceptor.setProperties(properties);
for (SqlSessionFactory sqlSessionFactory : sqlSessionFactoryList) {
sqlSessionFactory.getConfiguration().addInterceptor(pageInterceptor);
sqlSessionFactory.getConfiguration().addInterceptor(queryByAppInterceptor);
}
}
}
2.拦截器优化后代码：相比上一篇博客拦截器的实现这里不再利用反射改变sql语句，而是直接更换了查询语句对象。
package com.pingan.haofang.standard.common.interceptor;
import com.pingan.haofang.standard.common.annotation.interceptor.QueryConfigInterceptor;
import com.pingan.haofang.standard.common.context.ManageThreadContext;
import com.pingan.haofang.standard.common.context.ManageUser;
import com.pingan.haofang.standard.common.context.SpringContextHelper;
import com.pingan.haofang.standard.common.exception.PolicyException;
import com.pingan.haofang.standard.common.util.StringUtil;
import com.pingan.haofang.standard.configmapping.dao.ConfigMapDao;
import com.pingan.haofang.standard.configmapping.domain.ConfigMapping;
import org.apache.ibatis.cache.CacheKey;
import org.apache.ibatis.executor.Executor;
import org.apache.ibatis.mapping.BoundSql;
import org.apache.ibatis.mapping.MappedStatement;
import org.apache.ibatis.mapping.ParameterMapping;
import org.apache.ibatis.mapping.SqlSource;
import org.apache.ibatis.plugin.*;
import org.apache.ibatis.session.ResultHandler;
import org.apache.ibatis.session.RowBounds;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.lang.reflect.Method;
import java.util.List;
import java.util.Properties;
@Intercepts(
{
@Signature(type = Executor.class, method = "query", args = {MappedStatement.class, Object.class, RowBounds.class, ResultHandler.class}),
@Signature(type = Executor.class, method = "query", args = {MappedStatement.class, Object.class, RowBounds.class, ResultHandler.class, CacheKey.class, BoundSql.class}),
}
)
public class QueryByAppInterceptor implements Interceptor {
private static final Logger log = LoggerFactory.getLogger(QueryByAppInterceptor.class);
static int MAPPED_STATEMENT_INDEX = 0;// 这是对应上面的args的序号
private ConfigMapDao configMapDao;
@Override
public Object intercept(Invocation invocation) throws Throwable {
Object result = null;
ManageUser currentUser = ManageThreadContext.getManageVisitor();
//当前用户为空不拦截
if(currentUser == null){
return invocation.proceed();
}
String appCode = currentUser.getCurrentApp();
String version = currentUser.getCurrentAppVersion();
//如果是管理员则不拦截
if (currentUser.isAdmin()) {
return invocation.proceed();
}
// 应用不存在不拦截
if(StringUtil.isBlank(appCode) || StringUtil.isBlank(version)){
return invocation.proceed();
}
configMapDao = SpringContextHelper.getBean(ConfigMapDao.class);
Object[] args = invocation.getArgs();
MappedStatement ms = (MappedStatement) args[0];
//id为执行的mapper方法的全路径名，如com.uv.dao.UserMapper.insertUser
String mId = ms.getId();
//sql语句类型 select、delete、insert、update
String sqlCommandType = ms.getSqlCommandType().toString();
Object parameter = args[1];
BoundSql boundSql = ms.getBoundSql(parameter);;
//获取到原始sql语句
String sql = boundSql.getSql();
//注解逻辑判断 添加注解了才拦截
Class<?> classType = Class.forName(mId.substring(0, mId.lastIndexOf(".")));
String mName = mId.substring(mId.lastIndexOf(".") + 1, mId.length());
Method method1 = null;
for (Method method : classType.getDeclaredMethods()) {
if( !mName.equals(method.getName()) ){
continue;
}else{
if(method.isAnnotationPresent(QueryConfigInterceptor.class)){
QueryConfigInterceptor interceptorAnnotation = method.getAnnotation(QueryConfigInterceptor.class);
if (interceptorAnnotation.flag()){
method1 = method;
}
}
break;
}
}
if(method1 != null){
//组装新的sql
String mSql = this.process(sql, appCode, version);
// 重新new一个查询语句对像
BoundSql newBoundSql = new BoundSql(ms.getConfiguration(), mSql, boundSql.getParameterMappings(), boundSql.getParameterObject());
// 把新的查询放到statement里
MappedStatement newMs = copyFromMappedStatement(ms, new BoundSqlSqlSource(newBoundSql));
for (ParameterMapping mapping : boundSql.getParameterMappings()) {
String prop = mapping.getProperty();
if (boundSql.hasAdditionalParameter(prop)) {
newBoundSql.setAdditionalParameter(prop, boundSql.getAdditionalParameter(prop));
}
}
final Object[] queryArgs = invocation.getArgs();
queryArgs[MAPPED_STATEMENT_INDEX] = newMs;
// //通过反射修改sql语句
// Field field = boundSql.getClass().getDeclaredField("sql");
// field.setAccessible(true);
// field.set(boundSql, mSql);
}
return invocation.proceed();
}
private String process(String sql, String appCode, String version ){
String msql="";
//此处隐去与拦截器不相关的sql处理相关逻辑
return mSql;
}
public static class BoundSqlSqlSource implements SqlSource {
private BoundSql boundSql;
public BoundSqlSqlSource(BoundSql boundSql) {
this.boundSql = boundSql;
}
public BoundSql getBoundSql(Object parameterObject) {
return boundSql;
}
}
private MappedStatement copyFromMappedStatement(MappedStatement ms, SqlSource newSqlSource) {
MappedStatement.Builder builder = new MappedStatement.Builder(ms.getConfiguration(), ms.getId(), newSqlSource, ms.getSqlCommandType());
builder.resource(ms.getResource());
builder.fetchSize(ms.getFetchSize());
builder.statementType(ms.getStatementType());
builder.keyGenerator(ms.getKeyGenerator());
if (ms.getKeyProperties() != null && ms.getKeyProperties().length > 0) {
builder.keyProperty(ms.getKeyProperties()[0]);
}
builder.timeout(ms.getTimeout());
builder.parameterMap(ms.getParameterMap());
builder.resultMaps(ms.getResultMaps());
builder.resultSetType(ms.getResultSetType());
builder.cache(ms.getCache());
builder.flushCacheRequired(ms.isFlushCacheRequired());
builder.useCache(ms.isUseCache());
return builder.build();
}
@Override
public Object plugin(Object target) {
return Plugin.wrap(target, this);
}
@Override
public void setProperties(Properties properties) {
}
}
3.多个拦截器执行有顺序之分，具体可以从官网介绍中寻找答案
https://pagehelper.github.io/docs/interceptor/
4.许多小伙伴反应按照第一篇博客操作，拦截器没生效，最大的可能就是：拦截器没有注入。第一个版本是在拦截器类上添加@Component注解,但是这个会导致pageHelper分页发生冲突，所以我们需要在配置类中将拦截器注入，并且由添加顺序来控制拦截顺序，具体代码看第2点。
