springboot整合mongodb问题1-Decimal128和BigDecimal的转换之mongodb转换器使用（转）

中国化学 發表於 2019-10-19 11:30:00

springboot整合mongodb问题1-Decimal128和BigDecimal的转换之mongodb转换器使用（转）

转自：https://blog.csdn.net/weixin_41792559/article/details/79575524
1.Decimal128的了解 由于mongodb4.3以上新加了Decimal128类型。Decimal128类型对小数给了最好的支持，而double类型对小数存在精度的问题。个人觉得Decimal128还是不错的。但是我测试发现spring-data-mongodb 1.*和现在的spring-data-mongodb2.0.5目前不支持Decimal128自动转换为java的BigDecimal类型。 异常： No converter found capable of converting from type to type 大概就是描述：没有Decimal128转换成BigDecimal的转换器。
<img src="https://img2018.cnblogs.com/blog/1088776/201910/1088776-20191019112407987-1886580310.png">
 
 
<img src="https://img2018.cnblogs.com/blog/1088776/201910/1088776-20191019112420529-1983540814.png">
 
 
2.访问mongodb方式：spring-data-mongodb的MongoTemplate。 目前先以spring-data-mongodb的MongoTemplate方式为案例。之后我会增加mongodb原始的dom处理方式，以及spring-boot-starter-data-mongodb下开启了对Repository的支持方式进行测试一下。（进行了测试） 代码：https://github.com/topsnowwolf/mongodbit
3.如何解决Decimal128，BigDecimal的类型转换问题呢？ 思路：没有转换器我们新加一个转换。如何新加呢？增加之后如何配置呢？这就是重点了。 首先spring增加类型转换器有三种方式。
1.实现GenericConverter接口
2.实现ConverterFactory接口
3.实现Converter接口
这三种方式分别如何实现类型转换器，我就不多说了。网上很多例子。
下面我就以实现Converter接口方式的来实现。
自定义类型转换器：
<div class="cnblogs_code">
<pre>package com.wolf.mongodbit.converter;

import org.bson.types.Decimal128;
import org.springframework.core.convert.converter.Converter;
import org.springframework.data.convert.ReadingConverter;
import org.springframework.data.convert.WritingConverter;

import java.math.BigDecimal;

@ReadingConverter
@WritingConverter
public class BigDecimalToDecimal128Converter implements Converter<BigDecimal, Decimal128> {

public Decimal128 convert(BigDecimal bigDecimal) {
 return new Decimal128(bigDecimal);
}

}</pre>
</div>
<div class="cnblogs_code">
<pre>package com.wolf.mongodbit.converter;

import org.bson.types.Decimal128;
import org.springframework.core.convert.converter.Converter;
import org.springframework.data.convert.ReadingConverter;
import org.springframework.data.convert.WritingConverter;

import java.math.BigDecimal;

@ReadingConverter
@WritingConverter
public class Decimal128ToBigDecimalConverter implements Converter<Decimal128, BigDecimal> {

public BigDecimal convert(Decimal128 decimal128) {
 return decimal128.bigDecimalValue();
}

}</pre>
</div>
下面我就分析一下MongoTemplate的源码。
我们先带着问题去看。我们增加了转换器，这个转换器是给访问mongodb用的，那肯定是给MongoTemplate设置新的转换器了。
打开MongoTemplate这个类，果然如此。MongoTemplate的构造方法中就有一个参数是设置类型转换器的。看到希望了。哈哈！
<div class="cnblogs_code">
<pre> public MongoTemplate(MongoDbFactory mongoDbFactory, MongoConverter mongoConverter) {
 this.writeConcernResolver = DefaultWriteConcernResolver.INSTANCE;
 this.writeResultChecking = WriteResultChecking.NONE;
 Assert.notNull(mongoDbFactory, "MongoDbFactory must not be null!");
 this.mongoDbFactory = mongoDbFactory;
 this.exceptionTranslator = mongoDbFactory.getExceptionTranslator();
 this.mongoConverter = mongoConverter == null ? getDefaultMongoConverter(mongoDbFactory) : mongoConverter;
 this.queryMapper = new QueryMapper(this.mongoConverter);
 this.updateMapper = new UpdateMapper(this.mongoConverter);
 this.mappingContext = this.mongoConverter.getMappingContext();
 if (null != this.mappingContext && this.mappingContext instanceof MongoMappingContext) {
 this.indexCreator = new MongoPersistentEntityIndexCreator((MongoMappingContext)this.mappingContext, mongoDbFactory);
 this.eventPublisher = new MongoMappingEventPublisher(this.indexCreator);
 if (this.mappingContext instanceof ApplicationEventPublisherAware) {
 ((ApplicationEventPublisherAware)this.mappingContext).setApplicationEventPublisher(this.eventPublisher);
 }
 }

}</pre>
</div>
最终发现MongoConverter是一个接口。那一定有实现它的类。查一下api发现，抽象的类AbstractMongoConverter，最后是MappingMongoConverter类。此时就会发现AbstractMongoConverter类中有setCustomConversions设置自定义类型转换器的set方法。现在兴奋了吧！！！
现在大概的思路就是通过创建一个MappingMongoConverter对象，将定义的类型转换器调用setCustomConversions方法进行注册。最后调用MongoTemplate的构造方法得到MongoTemplate对象。
废话不多说上代码：
自定义一个配置类：
<div class="cnblogs_code">
<pre>package com.wolf.mongodbit.config;

import com.mongodb.MongoClient;
import com.mongodb.MongoClientURI;
import com.wolf.mongodbit.converter.BigDecimalToDecimal128Converter;
import com.wolf.mongodbit.converter.Decimal128ToBigDecimalConverter;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.data.mongodb.MongoDbFactory;
import org.springframework.data.mongodb.config.AbstractMongoConfiguration;
import org.springframework.data.mongodb.core.MongoTemplate;
import org.springframework.data.mongodb.core.SimpleMongoDbFactory;
import org.springframework.data.mongodb.core.convert.DefaultDbRefResolver;
import org.springframework.data.mongodb.core.convert.MappingMongoConverter;
import org.springframework.data.mongodb.core.convert.MongoCustomConversions;
import org.springframework.data.mongodb.core.mapping.MongoMappingContext;

import java.util.ArrayList;
import java.util.List;
@Configuration
public class MongodbConfig extends AbstractMongoConfiguration{
private String dbName = "wolf";
@Override
public MongoClient mongoClient() {
 MongoClient mongoClient = new MongoClient();
 return mongoClient;
}

@Override
protected String getDatabaseName() {
 return dbName;
}
@Bean
public MappingMongoConverter mappingMongoConverter() throws Exception {
 DefaultDbRefResolver dbRefResolver = new DefaultDbRefResolver(this.dbFactory());
 MappingMongoConverter converter = new MappingMongoConverter(dbRefResolver, this.mongoMappingContext());
 List<Object> list = new ArrayList<>();
 list.add(new BigDecimalToDecimal128Converter());//自定义的类型转换器
 list.add(new Decimal128ToBigDecimalConverter());//自定义的类型转换器
 converter.setCustomConversions(new MongoCustomConversions(list));
 return converter;
}
@Bean
public MongoDbFactory dbFactory() throws Exception {
 return new SimpleMongoDbFactory(new MongoClientURI("mongodb://localhost:27017/wolf"));
}
@Bean
public MongoMappingContext mongoMappingContext() {
 MongoMappingContext mappingContext = new MongoMappingContext();
 return mappingContext;
}
@Bean
public MongoTemplate mongoTemplate() throws Exception {
 return new MongoTemplate(this.dbFactory(), this.mappingMongoConverter());
}
}</pre>
</div>
实体类：
<div class="cnblogs_code">
<pre>package com.wolf.mongodbit.entity.mongodb;

import lombok.Data;

@Data
public class Address {
private String aCode;
private String add;
}</pre>
</div>
<div class="cnblogs_code">
<pre>package com.wolf.mongodbit.entity.mongodb;

import lombok.Data;
import org.bson.types.ObjectId;
import org.springframework.data.mongodb.core.mapping.Document;

import java.util.Date;

@Document(collection="blacklist")
@Data
public class Blacklist {
private ObjectId objectId;
private String username;
private String userid;
private String blacktype;
private String status;
private Date update;
private Date indate;
private Address address;
private Comments comments;
}</pre>
</div>
<div class="cnblogs_code">
<pre>package com.wolf.mongodbit.entity.mongodb;

import lombok.Data;

import java.math.BigDecimal;
@Data
public class Comments {
private String cause;
private String desc;
private BigDecimal money;
}</pre>
</div>
测试的controller：
<div class="cnblogs_code">
<pre>package com.wolf.mongodbit.controller;

import com.wolf.mongodbit.entity.mongodb.Blacklist;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.mongodb.core.MongoTemplate;
import org.springframework.data.mongodb.core.query.Query;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import java.util.List;

import static org.springframework.data.mongodb.core.query.Criteria.where;
import static org.springframework.data.mongodb.core.query.Query.query;

@RestController
@RequestMapping("/mongodb")
public class BlackListController {
private final static Logger logger = LoggerFactory.getLogger(BlackListController.class);
@Autowired
private MongoTemplate mongoTemplate;
@PostMapping("/check")
private Blacklist checkBlack(Blacklist blackList){
 List<Blacklist> list = mongoTemplate.find(query(where("userid").is(blackList.getUserid())), Blacklist.class);
 logger.info("springboot+mongodb:size={}",list.size());
 if(list.size()>0)
 return list.get(0);
 return null;
}
}</pre>
</div>
pom配置文件：
<div class="cnblogs_code">
<pre><?xml version="1.0" encoding="UTF-8"?>
<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/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>

<groupId>com.wolf</groupId>
<artifactId>mongodbit</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>jar</packaging>

<name>mongodbit</name>
<description>Demo project for Spring Boot</description>

<parent>
 <groupId>org.springframework.boot</groupId>
 <artifactId>spring-boot-starter-parent</artifactId>
 <version>2.0.0.RELEASE</version>
 <relativePath/> 
</parent>

<properties>
 <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
 <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
 <java.version>1.8</java.version>
</properties>

<dependencies>
 <dependency>
 <groupId>org.springframework.boot</groupId>
 <artifactId>spring-boot-starter-web</artifactId>
 </dependency>

 <dependency>
 <groupId>org.springframework.boot</groupId>
 <artifactId>spring-boot-starter-test</artifactId>
 <scope>test</scope>
 </dependency>

 
 <dependency>
 <groupId>org.projectlombok</groupId>
 <artifactId>lombok</artifactId>
 </dependency>
 

 
 <dependency>
 <groupId>org.springframework.data</groupId>
 <artifactId>spring-data-mongodb</artifactId>
 </dependency>
 
 
</dependencies>

<build>
 <plugins>
 <plugin>
 <groupId>org.springframework.boot</groupId>
 <artifactId>spring-boot-maven-plugin</artifactId>
 </plugin>
 </plugins>
</build>

</project></pre>
</div>
yml配置文件：
<div class="cnblogs_code">
<pre>#访问项目的url前缀
server:
servlet:
context-path: /mongodb</pre>
</div>
mongodb的测试数据：
<div class="cnblogs_code">
<pre>var blacklist1 = {
 "username" : "snowwolf",
 "userid" : "2018001014344",
 "address" : {
 "aCode" : "0020",
 "add" : "广州"
 },
 "certificate":{
 "certificateid":"20018554111134",
 "certificatetype":"01",
 "desc":"学生证"
 },
 "blacktype" : "01",
 "comments":{
 "cause":"01",
 "desc":"逾期欠费",
 "money":NumberDecimal("18889.09")
 },
 "status":"01",
 "update" : ISODate("2017-12-06T04:26:18.354Z"),
 "indate" : ISODate("2017-12-06T04:26:18.354Z")

};
var blacklist2 = {
 "username" : "lison",
 "userid" : "2018001014345",
 "address" : {
 "aCode" : "0075",
 "add" : "深圳"
 },
 "certificate":{
 "certificateid":"20018554111134",
 "certificatetype":"02",
 "desc":"护照"
 },
 "blacktype" : "01",
 "comments":{
 "cause":"02",
 "desc":"恶意欠费",
 "money":NumberDecimal("188890.00")
 },
 "status":"01",
 "update" : ISODate("2016-01-06T04:26:18.354Z"),
 "indate" : ISODate("2015-12-06T04:26:18.354Z")

};
var blacklist3 = {
 "username":"tom",
 "userid":"2018001014346",
 "address":{
 "aCode" : "0020",
 "add" : "广州"
 },
 "certificate":{
 "certificateid":"20018554111136",
 "certificatetype":"01",
 "desc":"学生证"
 },
 "blacktype":"01",
 "comments":{
 "cause":"03",
 "desc":"公安机关确定的涉嫌短信欺诈、诈骗等犯罪行为的用户"
 },
 "status":"01",
 "update":ISODate("2017-12-06T04:26:18.354Z"),
 "indate":ISODate("2017-12-06T04:26:18.354Z")

};

db.blacklist.insert(blacklist1);
db.blacklist.insert(blacklist2);
db.blacklist.insert(blacklist3);
</pre>
</div>
在postman中测试：
<img src="https://img2018.cnblogs.com/blog/1088776/201910/1088776-20191019112849330-1275450623.png">
 
 
结果完美！
 
时间有限，有些地方可能不是很完美！不足之处请大牛指出，谢谢！
有需要代码的我之后将会发布到git上！
https://github.com/topsnowwolf/mongodbit
  
来源：https://www.cnblogs.com/muxi0407/p/11703316.html

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springboot整合mongodb问题1-Decimal128和BigDecimal的转换之mongodb转换器使用（转）