Java 如何正确扩展Mongo';什么是文档类?
我创建了一个类Java 如何正确扩展Mongo';什么是文档类?,java,mongodb,Java,Mongodb,我创建了一个类User,它扩展了文档User只是在一些字符串和int周围有一些简单的构造函数和getter/setter。但是,当我尝试将用户类插入Mongo时,会出现以下错误: Exception in thread "main" org.bson.codecs.configuration.CodecConfigurationException: Can't find a codec for class com.foo.User. at org.bson.codecs.configur
User
,它扩展了文档
User
只是在一些字符串和int周围有一些简单的构造函数和getter/setter。但是,当我尝试将用户类插入Mongo时,会出现以下错误:
Exception in thread "main" org.bson.codecs.configuration.CodecConfigurationException: Can't find a codec for class com.foo.User.
at org.bson.codecs.configuration.CodecCache.getOrThrow(CodecCache.java:46)
at org.bson.codecs.configuration.ProvidersCodecRegistry.get(ProvidersCodecRegistry.java:63)
at org.bson.codecs.configuration.ProvidersCodecRegistry.get(ProvidersCodecRegistry.java:37)
at org.bson.BsonDocumentWrapper.asBsonDocument(BsonDocumentWrapper.java:62)
at com.mongodb.MongoCollectionImpl.documentToBsonDocument(MongoCollectionImpl.java:507)
at com.mongodb.MongoCollectionImpl.insertMany(MongoCollectionImpl.java:292)
at com.mongodb.MongoCollectionImpl.insertMany(MongoCollectionImpl.java:282)
at com.foo.bar.main(bar.java:27)
听起来我需要使用一些Mongo编解码器的东西,但我对它不熟悉,一些快速的谷歌搜索会返回一些看起来相当先进的结果
如何正确编写User
类以在Mongo中使用?以下是我的课堂参考:
public class User extends Document {
User(String user, List<Document > history, boolean isActive, String location){
this.append("_id", user)
.append("history", history)
.append("isActive", isActive)
.append("location", location);
}
public List<Document > getHistory(){
return this.get("history", ArrayList.class);
}
public void addToHistory(Document event){
List<Document> history = this.getHistory();
history.add(event);
this.append("history", history);
}
public boolean hasMet(User otherUser){
List<String> usersIveMet = this.getUsersMet(),
usersTheyMet = otherUser.getUsersMet();
return !Collections.disjoint(usersIveMet, usersTheyMet);
}
public List<String> getUsersMet() {
List<Document> usersHistory = this.getHistory();
List<String> usersMet = usersHistory.stream()
.map(doc -> Arrays.asList(doc.getString("user1"), doc.getString("user1")))
.filter(u -> !u.equals(this.getUser()))
.flatMap(u -> u.stream())
.collect(Collectors.toList());
return usersMet;
}
public String getUser(){
return this.getString("_id");
}
}
公共类用户扩展文档{
用户(字符串用户、列表历史记录、布尔值isActive、字符串位置){
此。追加(“\u id”,用户)
.append(“历史”,历史)
.append(“isActive”,isActive)
.附加(“位置”,位置);
}
公共列表getHistory(){
返回这个.get(“history”,ArrayList.class);
}
公共作废addToHistory(文档事件){
List history=this.getHistory();
添加(事件);
本附录(“历史”,历史);
}
公共布尔值hasMet(用户otherUser){
List usersIveMet=this.getUsersMet(),
usersThemet=otherUser.getUsersMet();
return!Collections.disjoint(usersIveMet,userthemet);
}
公共列表getUsersMet(){
List usersHistory=this.getHistory();
List usersMet=usersHistory.stream()
.map(doc->Arrays.asList(doc.getString(“user1”)、doc.getString(“user1”))
.filter(u->!u.equals(this.getUser()))
.flatMap(u->u.stream())
.collect(Collectors.toList());
返回usersMet;
}
公共字符串getUser(){
返回这个.getString(“_id”);
}
}
由于您试图创建新对象(即使您从文档扩展),Mongo无法识别它,因此您需要提供编码/解码,以便让Mongo了解您的对象(至少我看不到除此之外的其他方式)
我和你的用户类玩了一会儿,然后让它工作起来。
下面是我如何定义用户类的:
public class User {
private List<Document> history;
private String id;
private Boolean isActive;
private String location;
// Getters and setters. Omitted for brevity..
}
public class UserCodec implements Codec<User> {
private CodecRegistry codecRegistry;
public UserCodec(CodecRegistry codecRegistry) {
this.codecRegistry = codecRegistry;
}
@Override
public User decode(BsonReader reader, DecoderContext decoderContext) {
reader.readStartDocument();
String id = reader.readString("id");
Boolean isActive = reader.readBoolean("isActive");
String location = reader.readString("location");
Codec<Document> historyCodec = codecRegistry.get(Document.class);
List<Document> history = new ArrayList<>();
reader.readStartArray();
while (reader.readBsonType() != BsonType.END_OF_DOCUMENT) {
history.add(historyCodec.decode(reader, decoderContext));
}
reader.readEndArray();
reader.readEndDocument();
User user = new User();
user.setId(id);
user.setIsActive(isActive);
user.setLocation(location);
user.setHistory(history);
return user;
}
@Override
public void encode(BsonWriter writer, User user, EncoderContext encoderContext) {
writer.writeStartDocument();
writer.writeName("id");
writer.writeString(user.getId());
writer.writeName("isActive");
writer.writeBoolean(user.getIsActive());
writer.writeName("location");
writer.writeString(user.getLocation());
writer.writeStartArray("history");
for (Document document : user.getHistory()) {
Codec<Document> documentCodec = codecRegistry.get(Document.class);
encoderContext.encodeWithChildContext(documentCodec, writer, document);
}
writer.writeEndArray();
writer.writeEndDocument();
}
@Override
public Class<User> getEncoderClass() {
return User.class;
}
}
公共类用户{
私人名单历史;
私有字符串id;
私有布尔非活动;
私有字符串位置;
//getter和setter。为简洁起见省略。。
}
然后,您需要为您的用户类提供编码/解码逻辑:
public class User {
private List<Document> history;
private String id;
private Boolean isActive;
private String location;
// Getters and setters. Omitted for brevity..
}
public class UserCodec implements Codec<User> {
private CodecRegistry codecRegistry;
public UserCodec(CodecRegistry codecRegistry) {
this.codecRegistry = codecRegistry;
}
@Override
public User decode(BsonReader reader, DecoderContext decoderContext) {
reader.readStartDocument();
String id = reader.readString("id");
Boolean isActive = reader.readBoolean("isActive");
String location = reader.readString("location");
Codec<Document> historyCodec = codecRegistry.get(Document.class);
List<Document> history = new ArrayList<>();
reader.readStartArray();
while (reader.readBsonType() != BsonType.END_OF_DOCUMENT) {
history.add(historyCodec.decode(reader, decoderContext));
}
reader.readEndArray();
reader.readEndDocument();
User user = new User();
user.setId(id);
user.setIsActive(isActive);
user.setLocation(location);
user.setHistory(history);
return user;
}
@Override
public void encode(BsonWriter writer, User user, EncoderContext encoderContext) {
writer.writeStartDocument();
writer.writeName("id");
writer.writeString(user.getId());
writer.writeName("isActive");
writer.writeBoolean(user.getIsActive());
writer.writeName("location");
writer.writeString(user.getLocation());
writer.writeStartArray("history");
for (Document document : user.getHistory()) {
Codec<Document> documentCodec = codecRegistry.get(Document.class);
encoderContext.encodeWithChildContext(documentCodec, writer, document);
}
writer.writeEndArray();
writer.writeEndDocument();
}
@Override
public Class<User> getEncoderClass() {
return User.class;
}
}
public类UserCodec实现编解码器{
私人编码中心注册中心;
公共用户编解码器(编解码器注册表编解码器注册表){
this.codecRegistry=codecRegistry;
}
@凌驾
公共用户解码(BsonReader阅读器,DecoderContext DecoderContext){
reader.readStartDocument();
String id=reader.readString(“id”);
Boolean isActive=reader.readBoolean(“isActive”);
字符串位置=reader.readString(“位置”);
Codec historyCodec=codecRegistry.get(Document.class);
列表历史记录=新建ArrayList();
reader.readStartArray();
while(reader.readBsonType()!=BsonType.END\u文档){
添加(historyCodec.decode(reader,decoderContext));
}
reader.readEndArray();
reader.readEndDocument();
用户=新用户();
user.setId(id);
user.setIsActive(isActive);
user.setLocation(位置);
user.setHistory(历史记录);
返回用户;
}
@凌驾
公共无效编码(BsonWriter编写器、用户用户、EncoderContext EncoderContext){
writer.writeStartDocument();
writer.writeName(“id”);
writer.writeString(user.getId());
writer.writeName(“isActive”);
writebolean(user.getIsActive());
writer.writeName(“位置”);
writer.writeString(user.getLocation());
作者:WriteStartaray(“历史”);
对于(文档:user.getHistory()){
Codec documentCodec=codecRegistry.get(Document.class);
encoderContext.encodeWithChildContext(documentCodec、writer、document);
}
writer.writeEndArray();
writer.writeEndDocument();
}
@凌驾
公共类getEncoderClass(){
返回User.class;
}
}
然后,在开始序列化/反序列化之前,需要提供用于类型检查的编解码器
public class UserCodecProvider implements CodecProvider {
@Override
@SuppressWarnings("unchecked")
public <T> Codec<T> get(Class<T> clazz, CodecRegistry registry) {
if (clazz == User.class) {
return (Codec<T>) new UserCodec(registry);
}
return null;
}
}
public类UserCodecProvider实现CodecProvider{
@凌驾
@抑制警告(“未选中”)
公共编解码器获取(类clazz,编解码器注册表){
if(clazz==User.class){
返回(编解码器)新用户编解码器(注册表);
}
返回null;
}
}
最后,您需要将提供商注册到您的MongoClient,仅此而已
public class MongoDb {
private MongoDatabase db;
public MongoDb() {
CodecRegistry codecRegistry = CodecRegistries.fromRegistries(
CodecRegistries.fromProviders(new UserCodecProvider()),
MongoClient.getDefaultCodecRegistry());
MongoClientOptions options = MongoClientOptions.builder()
.codecRegistry(codecRegistry).build();
MongoClient mongoClient = new MongoClient(new ServerAddress(), options);
db = mongoClient.getDatabase("test");
}
public void addUser(User user) {
MongoCollection<User> collection = db.getCollection("user").withDocumentClass(User.class);
collection.insertOne(user);
}
public static void main(String[] args) {
MongoDb mongoDb = new MongoDb();
Document history1 = new Document();
history1.append("field1", "value1");
history1.append("field2", "value2");
history1.append("field3", "value3");
List<Document> history = new ArrayList<>();
history.add(history1);
User user = new User();
user.setId("someId1");
user.setIsActive(true);
user.setLocation("someLocation");
user.setHistory(history);
mongoDb.addUser(user);
}
}
公共类MongoDb{
私有MongoDatabase数据库;
公共MongoDb(){
CodecRegistry CodecRegistry=CodecRegistries.fromRegistries(
CodeRegistries.fromProviders(新的UserCodecProvider()),
MongoClient.getDefaultCodecRegistry());
MongoClientOptions=MongoClientOptions.builder()
.codecRegistry(codecRegistry).build();
MongoClient MongoClient=新的MongoClient(新服务器地址(),选项);
db=mongoClient.getDatabase(“测试”);
}
public void addUser(用户){
MongoCollection collection=db.getCollection(“用户”).withDocumentClass(user.class);
collection.insertOne(用户);
}
公共静态void main(字符串[]args){
MongoDb MongoDb=新的MongoDb();
文档历史1=新文档();
历史1.附加(“字段1”、“值1”);
历史1.附加(“字段2”、“值2”);
历史1.附加(“字段3”、“值3”);
列表历史记录=新建ArrayList();
历史。添加(历史1);
用户=新用户();
user.setId(“someId1”);
user.setIsActive(true);
user.setLocation(“someLocation”);
user.setHistory(历史记录