前几天写了个mongodb原生的工具类,参考“http://ylcodes01.blog.51cto.com/5607366/1933342”,
项目里需要做分布式,所以现在集成到spring中,今天结合spring-mongodb写了一些常用的工具。
package com.stbr.common.mongodb.base;
import com.mongodb.WriteResult;
import com.stbr.common.mongodb.util.MongoFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.domain.Sort;
import org.springframework.data.mongodb.core.MongoTemplate;
import org.springframework.data.mongodb.core.query.Criteria;
import org.springframework.data.mongodb.core.query.Query;
import org.springframework.data.mongodb.core.query.Update;
import java.lang.reflect.ParameterizedType;
import java.util.List;
import java.util.Map;
public class BaseMongoDao<T> implements IBaseMongoDao<T>{
private Class<T> clazz;
@Autowired
private MongoTemplate mongoTemplate;
@Autowired
private MongoFactory mongoFactory;
public BaseMongoDao() {
ParameterizedType parameterizedType = (ParameterizedType) getClass().getGenericSuperclass();
clazz = (Class<T>) parameterizedType.getActualTypeArguments()[0];
}
@Override
public void insert(T entity) {
mongoTemplate.insert(entity);
}
@Override
public T findOne(String id) {
Query query = new Query();
query.addCriteria(new Criteria("_id").is(id));
return getMongoTemplate().findOne(query,clazz);
}
@Override
public List<T> find(Query query) {
return getMongoTemplate().find(query,clazz);
}
@Override
public Long findCount(Query query) {
return getMongoTemplate().count(query,clazz);
}
@Override
public List<T> findList(Integer skip, Integer limit,Query query) {
query.with(new Sort(new Sort.Order(Sort.Direction.ASC,"createTime")));
query.skip(skip).limit(limit);
return find(query);
}
@Override
public Integer update(Query query, Update update) throws Exception {
WriteResult writeResult = getMongoTemplate().updateFirst(query,update,clazz);
return (null == writeResult ? 0 : writeResult.getN());
}
@Override
public Integer update(T entity) throws Exception {
Map<String,Object> map = mongoFactory.converObjectToParams(entity);
Query query = new Query();
query.addCriteria(new Criteria("_id").is(map.get("id")));
Update update = (Update) map.get("update");
return this.update(query,update);
}
@Override
public Integer remove(T entity) {
WriteResult writeResult = getMongoTemplate().remove(entity);
return (null == writeResult ? 0 : writeResult.getN());
}
@Override
public Integer remove(Query query, T entity) {
WriteResult writeResult = getMongoTemplate().remove(query,entity.getClass());
return (null == writeResult ? 0 : writeResult.getN());
}
public MongoTemplate getMongoTemplate(){
return mongoTemplate;
}
}
package com.stbr.common.mongodb.base;
import org.springframework.data.mongodb.core.query.Query;
import org.springframework.data.mongodb.core.query.Update;
import java.util.List;
public interface IBaseMongoDao<T> {
public T findOne(String id);
public List<T> find(Query query);
public Long findCount(Query query);
public List<T> findList(Integer skip,Integer limit,Query query);
public void insert(T entity);
public Integer update(Query query, Update update) throws Exception;
public Integer update(T entity) throws Exception;
public Integer remove(T entity);
public Integer remove(Query query,T entity);
}
package com.stbr.common.mongodb.dao;
import com.stbr.common.mongodb.base.IBaseMongoDao;
import com.stbr.common.mongodb.model.MongoEntity;
public interface IMongoEntityDao extends IBaseMongoDao<MongoEntity>{
public MongoEntity getMongoEntityById(String id);
}
package com.stbr.common.mongodb.dao;
import com.stbr.common.mongodb.base.BaseMongoDao;
import com.stbr.common.mongodb.model.MongoEntity;
import org.springframework.stereotype.Repository;
@Repository
public class MongoEntityDao extends BaseMongoDao<MongoEntity> implements IMongoEntityDao{
@Override
public MongoEntity getMongoEntityById(String id) {
MongoEntity mongoEntity = findOne(id);
return mongoEntity;
}
}
package com.stbr.common.mongodb.model;
import org.springframework.data.annotation.Id;
import org.springframework.data.mongodb.core.mapping.Document;
@Document(collection = "mongoLogInfo")
public class MongoEntity {
@Id
private String id;//主键
private String interfaceMethod;//接口方法名称
private String businessName;//业务名称
private String clientReqParams;//客户端请求参数
private String serviceRepParams;//服务端响应参数
private String logInfo;//日志内容:包括异常等
private Long clientReqTime;//客户端调用时间
private Long serviceRepTime;//服务端响应时间
private Long duration;//持续时间
private String clientReqIpPort;//客户端请求IP和PORT
private String serviceRepIpPort;//服务端响应IP和PORT
private String ifSuccess;//服务调用是否成功标识,1成功2失败
private Long createTime;//插入时间
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
public String getInterfaceMethod() {
return interfaceMethod;
}
public void setInterfaceMethod(String interfaceMethod) {
this.interfaceMethod = interfaceMethod;
}
public String getBusinessName() {
return businessName;
}
public void setBusinessName(String businessName) {
this.businessName = businessName;
}
public String getClientReqParams() {
return clientReqParams;
}
public void setClientReqParams(String clientReqParams) {
this.clientReqParams = clientReqParams;
}
public String getServiceRepParams() {
return serviceRepParams;
}
public void setServiceRepParams(String serviceRepParams) {
this.serviceRepParams = serviceRepParams;
}
public String getLogInfo() {
return logInfo;
}
public void setLogInfo(String logInfo) {
this.logInfo = logInfo;
}
public Long getClientReqTime() {
return clientReqTime;
}
public void setClientReqTime(Long clientReqTime) {
this.clientReqTime = clientReqTime;
}
public Long getServiceRepTime() {
return serviceRepTime;
}
public void setServiceRepTime(Long serviceRepTime) {
this.serviceRepTime = serviceRepTime;
}
public Long getDuration() {
return duration;
}
public void setDuration(Long duration) {
this.duration = duration;
}
public String getClientReqIpPort() {
return clientReqIpPort;
}
public void setClientReqIpPort(String clientReqIpPort) {
this.clientReqIpPort = clientReqIpPort;
}
public String getServiceRepIpPort() {
return serviceRepIpPort;
}
public void setServiceRepIpPort(String serviceRepIpPort) {
this.serviceRepIpPort = serviceRepIpPort;
}
public String getIfSuccess() {
return ifSuccess;
}
public void setIfSuccess(String ifSuccess) {
this.ifSuccess = ifSuccess;
}
public Long getCreateTime() {
return createTime;
}
public void setCreateTime(Long createTime) {
this.createTime = createTime;
}
}
package com.stbr.common.mongodb.util;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.mongodb.core.query.Update;
import org.springframework.stereotype.Component;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;
@Component
public class MongoFactory {
@Autowired
private MongoObjectParams objectParams;
public Map<String,Object> converObjectToParams(Object object) throws Exception {
Map<String,Object> map = new HashMap<String,Object>();
Update update = new Update();
Map<String,String> params = objectParams.createParams(object);
String id = params.get("id");
Set<Map.Entry<String,String>> sets = params.entrySet();
Iterator<Map.Entry<String,String>> iteratos = sets.iterator();
while(iteratos.hasNext()){
Map.Entry<String,String> entry = iteratos.next();
String key = entry.getKey();
String value = entry.getValue();
if(!key.equals("id")){
update.set(key,value);
}
}
map.put("id",id);
map.put("update",update);
return map;
}
}
package com.stbr.common.mongodb.util;
import org.springframework.stereotype.Component;
import java.lang.reflect.Field;
import java.util.HashMap;
import java.util.Map;
@Component
public class MongoObjectParams {
private String javaType = "java";
/**
* 获取查询的参数
*
* @param object
* @return
* @throws Exception
*/
public Map<String, String> createParams(Object object) throws Exception {
Map<String, String> params = new HashMap<String, String>();
setIntoParams(params,object, null);
return params;
}
private void setIntoParams(Map<String, String> params,Object object, String fatherName) throws IllegalAccessException,
Exception {
Field[] fields = object.getClass().getDeclaredFields();
for (Field file : fields) {
boolean accessFlag = file.isAccessible();
file.setAccessible(true);
String name = file.getName();
Object value = file.get(object);
if(file.getType().getName().equals("java.lang.Class")){
break;
}else if(file.getType().getName().contains(javaType)){
if(fatherName != null && !fatherName.equals(" ")){
name = fatherName+"."+name;
}
if(value != null){
params.put(name, value+"");
}
}else{
if(value != null){
setIntoParams(params,file.get(object), name);
}
}
file.setAccessible(accessFlag);
}
}
}
package com.stbr.common.mongodb.util;
import org.springframework.core.convert.converter.Converter;
import java.sql.Timestamp;
import java.util.Date;
public class MongoTimestampConverter implements Converter<Date,Timestamp> {
@Override
public Timestamp convert(Date date) {
if(null != date){
return new Timestamp(date.getTime());
}
return null;
}
}
mongo.properties
mongo.host=192.168.200.234
mongo.port=10143
spring-mongodb.xml
<?xml version="1.0" encoding="UTF-8" ?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:context="http://www.springframework.org/schema/context"
xmlns:mongo="http://www.springframework.org/schema/data/mongo"
xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans-4.2.xsd
http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context-4.2.xsd
http://www.springframework.org/schema/data/mongo
http://www.springframework.org/schema/data/mongo/spring-mongo-1.10.xsd">
<!-- 不引入这个导致test中的注入不成功 -->
<context:component-scan base-package="com.stbr.common" />
<context:property-placeholder location="classpath:mongo.properties"/>
<mongo:mongo-client host="${mongo.host}" port="${mongo.port}" id="mongo">
<mongo:client-options write-concern="SAFE" />
</mongo:mongo-client>
<!-- mongo的工厂,通过它来取得mongo实例,dbname为mongodb的数据库名,没有的话会自动创建 -->
<mongo:db-factory dbname="runoob" mongo-ref="mongo" id="mongoDbFactory"/>
<bean id="mappingContext"
class="org.springframework.data.mongodb.core.mapping.MongoMappingContext" />
<!-- 默认Mongodb类型映射 -->
<bean id="defaultMongoTypeMapper"
class="org.springframework.data.mongodb.core.convert.DefaultMongoTypeMapper">
<constructor-arg name="typeKey">
<null /><!-- 这里设置为空,可以把 spring data mongodb 多余保存的_class字段去掉 -->
</constructor-arg>
</bean>
<!-- 转换器:1、去掉write的_class字段 2、TimestampConverter -->
<mongo:mapping-converter id="mongoConverter" base-package="com.stbr.common.mongodb.util" type-mapper-ref="defaultMongoTypeMapper">
<mongo:custom-converters>
<mongo:converter>
<bean class="com.stbr.common.mongodb.util.MongoTimestampConverter" />
</mongo:converter>
</mongo:custom-converters>
</mongo:mapping-converter>
<!-- mongodb的主要操作对象,所有对mongodb的增删改查的操作都是通过它完成 -->
<bean id="mongoTemplate" class="org.springframework.data.mongodb.core.MongoTemplate">
<constructor-arg name="mongoDbFactory" ref="mongoDbFactory" />
<constructor-arg name="mongoConverter" ref="mongoConverter" />
</bean>
<context:annotation-config />
</beans>
上述spring-mongodb.xml要注意的地方:由于现在用的是mongodb3.X版本,所以
就不要使用mongo:mongo标签了,要改成mongo:mongo-client,一些参数要改变了,
具体看下源码和文档即可。
可能报错如下:
mongo-options' is no longer supported for MongoDB
package com.stbr.common.mongodb.test;
import com.stbr.common.mongodb.dao.IMongoEntityDao;
import com.stbr.common.mongodb.model.MongoEntity;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.mongodb.core.query.Criteria;
import org.springframework.data.mongodb.core.query.Query;
import org.springframework.test.context.ContextConfiguration;
import org.springframework.test.context.junit4.SpringJUnit4Cla***unner;
import java.util.Date;
import java.util.List;
@RunWith(SpringJUnit4Cla***unner.class)
@ContextConfiguration(locations = "classpath:spring-mongodb.xml")
public class MongdbTest {
@Autowired
private IMongoEntityDao mongoEntityDao;
/**
* 根据主键获取实体
*/
@Test
public void testFindOne(){
MongoEntity mongoEntity = mongoEntityDao.getMongoEntityById("593e3f8ba4977227581b398c");
System.out.println(mongoEntity);
}
/**
* 根据过滤条件获取集合列表
*/
@Test
public void testFind(){
Query query = new Query();
List<MongoEntity> list1 = mongoEntityDao.find(query);
System.out.println(list1.size());
query = new Query();
query.addCriteria(new Criteria("InterfaceMethod").nin("InterfaceMethod5"));
List<MongoEntity> list2 = mongoEntityDao.find(query);
for(MongoEntity mongoEntity : list2){
System.out.println(mongoEntity);
}
}
/**
* 根据过滤条件获取查询个数
*/
@Test
public void testFindCount(){
Query query = new Query();
query.addCriteria(new Criteria("InterfaceMethod").nin("InterfaceMethod5"));
System.out.println(mongoEntityDao.findCount(query));
}
/**
* 根据过滤条件获取分页集合
* skip:从第几条开始,但不包括这条数据
* limit:每页几条数据
*/
@Test
public void testFindList(){
Query query = new Query();
query.addCriteria(new Criteria("InterfaceMethod").nin("InterfaceMethod11"));
List<MongoEntity> list = mongoEntityDao.findList(10,5,query);
for(MongoEntity mongoEntity : list){
System.out.println(mongoEntity.getBusinessName());
}
}
/**
* 实体新增
*/
@Test
public void testInsert(){
for(int i = 7; i < 30 ; i++){
MongoEntity mongoEntity = new MongoEntity();
mongoEntity.setInterfaceMethod("InterfaceMethod" + i);
mongoEntity.setBusinessName("BusinessName" + i);
mongoEntity.setClientReqIpPort("ClientReqIpPort" + i);
mongoEntity.setServiceRepIpPort("ServiceRepIpPort" + i);
mongoEntity.setLogInfo("LogInfo" + i);
Long time1 = new Date().getTime();
mongoEntity.setClientReqTime(time1);
Long time2 = new Date().getTime();
mongoEntity.setServiceRepTime(time2);
mongoEntity.setDuration(time2 - time1);
mongoEntity.setClientReqIpPort("ClientReqIpPort" + i);
mongoEntity.setServiceRepIpPort("ServiceRepIpPort" + i);
mongoEntity.setIfSuccess("1");
mongoEntity.setCreateTime(new Date().getTime());
mongoEntityDao.insert(mongoEntity);
}
}
/**
* 通过传入的实体ID更新实体中的其他内容
* @throws Exception
*/
@Test
public void testUpdateEntity() throws Exception{
MongoEntity mongoEntity = mongoEntityDao.findOne("593e3f8ba4977227581b398c");
System.out.println("1------------->" + mongoEntity.getBusinessName());
mongoEntity.setBusinessName("setBusinessNametest");
mongoEntityDao.update(mongoEntity);
mongoEntity = mongoEntityDao.findOne("593e3f8ba4977227581b398c");
System.out.println("2------------->" + mongoEntity.getBusinessName());
}
/**
* 删除实体对象
*/
@Test
public void testRemove(){
MongoEntity mongoEntity = mongoEntityDao.findOne("593e4f1ca4977223d8f705aa");
System.out.println(mongoEntity);
mongoEntityDao.remove(mongoEntity);
mongoEntity = mongoEntityDao.findOne("593e4f1ca4977223d8f705aa");
System.out.println(mongoEntity);
}
/**
* 通过过滤条件和实体对象删除对应数据
*/
@Test
public void testRemoveByQuery(){
Query query = new Query();
query.addCriteria(new Criteria("_id").is("593e4f1ca4977223d8f705a3"));
MongoEntity entity = new MongoEntity();
System.out.println(mongoEntityDao.remove(query,entity));
}
}
pom.xml
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>TestSpringMongo3</groupId>
<artifactId>TestSpringMongo3</artifactId>
<packaging>war</packaging>
<version>1.0-SNAPSHOT</version>
<name>TestSpringMongo3 Maven Webapp</name>
<!-- 设定主仓库 -->
<repositories>
<!-- nexus私服 -->
<repository>
<id>nexus-repos</id>
<name>Team Nexus Repository</name>
<url>http://192.168.200.205:8081/nexus/content/groups/public/</url>
<releases>
<enabled>true</enabled>
</releases>
<snapshots>
<enabled>true</enabled>
</snapshots>
</repository>
</repositories>
<!-- 设定插件仓库 -->
<pluginRepositories>
<pluginRepository>
<id>nexus-repos</id>
<name>Team Nexus Repository</name>
<url>http://192.168.200.205:8081/nexus/content/groups/public/</url>
<releases>
<enabled>true</enabled>
</releases>
<snapshots>
<enabled>true</enabled>
</snapshots>
</pluginRepository>
</pluginRepositories>
<properties>
<endorsed.dir>${project.build.directory}/endorsed</endorsed.dir>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<!-- 设置变量:用于统一管理Library的版本 -->
<javax.version>7.0</javax.version>
<javax.servlet.version>3.1.0</javax.servlet.version>
<javax.servlet.jstl.version>1.2</javax.servlet.jstl.version>
<log4j.version>1.2.16</log4j.version>
<org.slf4j.version>1.7.1</org.slf4j.version>
<junit.version>4.12</junit.version>
<org.htmlparser.version>2.1</org.htmlparser.version>
<org.springframework.version>4.3.7.RELEASE</org.springframework.version>
<spring-data-mongodb.version>1.10.4.RELEASE</spring-data-mongodb.version>
<mongodb-version>3.4.2</mongodb-version>
<javax.validation.version>1.1.0.Final</javax.validation.version>
<org.hibernate.version>5.0.2.Final</org.hibernate.version>
</properties>
<dependencies>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>${junit.version}</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>javax</groupId>
<artifactId>javaee-web-api</artifactId>
<version>${javax.version}</version>
<scope>provided</scope>
</dependency>
<dependency>
<groupId>javax.servlet</groupId>
<artifactId>jstl</artifactId>
<version>${javax.servlet.jstl.version}</version>
<scope>runtime</scope>
</dependency>
<dependency>
<groupId>javax.servlet</groupId>
<artifactId>javax.servlet-api</artifactId>
<version>${javax.servlet.version}</version>
</dependency>
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-jdk14</artifactId>
<version>${org.slf4j.version}</version>
</dependency>
<dependency>
<groupId>log4j</groupId>
<artifactId>log4j</artifactId>
<version>${log4j.version}</version>
</dependency>
<dependency>
<groupId>org.htmlparser</groupId>
<artifactId>htmlparser</artifactId>
<version>${org.htmlparser.version}</version>
</dependency>
<!-- spring framework -->
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-aop</artifactId>
<version>${org.springframework.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-context-support</artifactId>
<version>${org.springframework.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-beans</artifactId>
<version>${org.springframework.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-context</artifactId>
<version>${org.springframework.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-core</artifactId>
<version>${org.springframework.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-expression</artifactId>
<version>${org.springframework.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-web</artifactId>
<version>${org.springframework.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-webmvc</artifactId>
<version>${org.springframework.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-test</artifactId>
<version>${org.springframework.version}</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.springframework.data</groupId>
<artifactId>spring-data-mongodb</artifactId>
<version>${spring-data-mongodb.version}</version>
</dependency>
<!-- javax.validation相关 -->
<dependency>
<groupId>javax.validation</groupId>
<artifactId>validation-api</artifactId>
<version>${javax.validation.version}</version>
</dependency>
<dependency>
<groupId>org.hibernate</groupId>
<artifactId>hibernate-validator</artifactId>
<version>${org.hibernate.version}</version>
</dependency>
</dependencies>
<build>
<finalName>TestSpringMongo3</finalName>
<resources>
<resource>
<directory>src/main/java</directory>
<includes>
<include>**/*.xml</include>
<include>**/*.properties</include>
</includes>
<filtering>false</filtering>
</resource>
<resource>
<directory>src/main/resources</directory>
<includes>
<include>**/*.xml</include>
<include>**/*.properties</include>
</includes>
<filtering>false</filtering>
</resource>
</resources>
<plugins>
<plugin>
<artifactId>maven-compiler-plugin</artifactId>
<version>2.5.1</version>
<configuration>
<source>1.6</source>
<target>1.6</target>
<encoding>UTF-8</encoding>
</configuration>
</plugin>
<plugin>
<artifactId>maven-surefire-plugin</artifactId>
<version>2.12.4</version>
<configuration>
<includes>
<include>**/*Tests.java</include>
</includes>
</configuration>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-resources-plugin</artifactId>
<version>2.6</version>
<configuration>
<encoding>UTF-8</encoding>
</configuration>
</plugin>
</plugins>
</build>
</project>
#上述pom.xml一定要注意一个问题:
当上述org.hibernate.version配置为5.0.2.Final改成5.4.1Final时,那么要多一个配置,如下:
<javax.el-version>2.2.4</javax.el-version>
<dependency>
<groupId>org.glassfish.web</groupId>
<artifactId>javax.el</artifactId>
<version>${javax.el-version}</version>
</dependency>
不然,也许会报错如下:
Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'org.springframework.validation.beanvalidation.LocalValidatorFactoryBean#0': Invocation of init method failed; nested exception is javax.validation.ValidationException: HV000183: Unable to initialize 'javax.el.ExpressionFactory'. Check that you have the EL dependencies on the classpath, or use ParameterMessageInterpolator instead
Caused by: javax.validation.ValidationException: HV000183: Unable to initialize 'javax.el.ExpressionFactory'. Check that you have the EL dependencies on the classpath, or use ParameterMessageInterpolator instead
at org.hibernate.validator.messageinterpolation.ResourceBundleMessageInterpolator.buildExpressionFactory(ResourceBundleMessageInterpolator.java:102)
at org.hibernate.validator.messageinterpolation.ResourceBundleMessageInterpolator.
at org.hibernate.validator.internal.engine.ConfigurationImpl.getDefaultMessageInterpolator(ConfigurationImpl.java:423)
Caused by: javax.el.ELException: Provider com.sun.el.ExpressionFactoryImpl not found
Caused by: java.lang.ClassNotFoundException: com.sun.el.ExpressionFactoryImpl
标题:spring4.3.7整合mongodb3.2.1
作者:yazong
地址:https://blog.llyweb.com/articles/2017/06/12/1578155301294.html