Spring Boot Mongodb

Spring注解学习，有助于更好的理解下面代码：

@ConditionOnClass表明该@Configuration仅仅在一定条件下才会被加载，这里的条件是Mongo.class位于类路径上
@EnableConfigurationProperties将Spring Boot的配置文件（application.properties）中的spring.data.mongodb.*属性映射为MongoProperties并注入到MongoAutoConfiguration中。
@ConditionalOnMissingBean说明Spring Boot仅仅在当前上下文中不存在Mongo对象时，才会实例化一个Bean。这个逻辑也体现了Spring
Boot的另外一个特性——自定义的Bean优先于框架的默认配置，我们如果显式的在业务代码中定义了一个Mongo对象，那么Spring Boot就不再创建。

一、先看看spring boot mongo部分源码片段

/*

 * Copyright 2012-2015 the original author or authors.

 *

 * Licensed under the Apache License, Version 2.0 (the "License");

 * you may not use this file except in compliance with the License.

 * You may obtain a copy of the License at

 *

 *      http://www.apache.org/licenses/LICENSE-2.0

 *

 * Unless required by applicable law or agreed to in writing, software

 * distributed under the License is distributed on an "AS IS" BASIS,

 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 * See the License for the specific language governing permissions and

 * limitations under the License.

 */

package org.springframework.boot.autoconfigure.mongo;

import java.net.UnknownHostException;

import javax.annotation.PreDestroy;

import org.springframework.beans.factory.annotation.Autowired;

import org.springframework.boot.autoconfigure.EnableAutoConfiguration;

import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;

import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;

import org.springframework.boot.context.properties.EnableConfigurationProperties;

import org.springframework.context.annotation.Bean;

import org.springframework.context.annotation.Configuration;

import org.springframework.core.env.Environment;

import com.mongodb.MongoClient;

import com.mongodb.MongoClientOptions;

/**

 * {@link EnableAutoConfiguration Auto-configuration} for Mongo.

 *

 * @author Dave Syer

 * @author Oliver Gierke

 * @author Phillip Webb

 */

@Configuration

@ConditionalOnClass(MongoClient.class)

@EnableConfigurationProperties(MongoProperties.class)

@ConditionalOnMissingBean(type = "org.springframework.data.mongodb.MongoDbFactory")

public class MongoAutoConfiguration {

	@Autowired

	private MongoProperties properties;

	@Autowired(required = false)

	private MongoClientOptions options;

	@Autowired

	private Environment environment;

	private MongoClient mongo;

	@PreDestroy

	public void close() {

		if (this.mongo != null) {

			this.mongo.close();

		}

	}

	@Bean

	@ConditionalOnMissingBean

	public MongoClient mongo() throws UnknownHostException {

		this.mongo = this.properties.createMongoClient(this.options, this.environment);

		return this.mongo;

	}

}

/*

 * Copyright 2012-2015 the original author or authors.

 *

 * Licensed under the Apache License, Version 2.0 (the "License");

 * you may not use this file except in compliance with the License.

 * You may obtain a copy of the License at

 *

 *      http://www.apache.org/licenses/LICENSE-2.0

 *

 * Unless required by applicable law or agreed to in writing, software

 * distributed under the License is distributed on an "AS IS" BASIS,

 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 * See the License for the specific language governing permissions and

 * limitations under the License.

 */

package org.springframework.boot.autoconfigure.mongo;

import java.net.UnknownHostException;

import java.util.Collection;

import java.util.Collections;

import java.util.HashSet;

import java.util.Set;

import org.springframework.beans.BeanUtils;

import org.springframework.beans.factory.BeanClassLoaderAware;

import org.springframework.beans.factory.BeanFactory;

import org.springframework.beans.factory.NoSuchBeanDefinitionException;

import org.springframework.beans.factory.annotation.Autowired;

import org.springframework.beans.factory.config.BeanDefinition;

import org.springframework.boot.autoconfigure.AutoConfigurationPackages;

import org.springframework.boot.autoconfigure.AutoConfigureAfter;

import org.springframework.boot.autoconfigure.EnableAutoConfiguration;

import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;

import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;

import org.springframework.boot.context.properties.EnableConfigurationProperties;

import org.springframework.context.annotation.Bean;

import org.springframework.context.annotation.ClassPathScanningCandidateComponentProvider;

import org.springframework.context.annotation.Configuration;

import org.springframework.core.env.Environment;

import org.springframework.core.io.ResourceLoader;

import org.springframework.core.type.filter.AnnotationTypeFilter;

import org.springframework.dao.DataAccessException;

import org.springframework.dao.support.PersistenceExceptionTranslator;

import org.springframework.data.annotation.Persistent;

import org.springframework.data.mapping.model.FieldNamingStrategy;

import org.springframework.data.mongodb.MongoDbFactory;

import org.springframework.data.mongodb.core.MongoTemplate;

import org.springframework.data.mongodb.core.SimpleMongoDbFactory;

import org.springframework.data.mongodb.core.convert.CustomConversions;

import org.springframework.data.mongodb.core.convert.DbRefResolver;

import org.springframework.data.mongodb.core.convert.DefaultDbRefResolver;

import org.springframework.data.mongodb.core.convert.MappingMongoConverter;

import org.springframework.data.mongodb.core.convert.MongoConverter;

import org.springframework.data.mongodb.core.mapping.Document;

import org.springframework.data.mongodb.core.mapping.MongoMappingContext;

import org.springframework.data.mongodb.gridfs.GridFsTemplate;

import org.springframework.util.Assert;

import org.springframework.util.ClassUtils;

import org.springframework.util.StringUtils;

import com.mongodb.DB;

import com.mongodb.Mongo;

import com.mongodb.MongoClient;

/**

 * {@link EnableAutoConfiguration Auto-configuration} for Spring Data's mongo support.

 * <p>

 * Registers a {@link MongoTemplate} and {@link GridFsTemplate} beans if no other beans of

 * the same type are configured.

 * <P>

 * Honors the {@literal spring.data.mongodb.database} property if set, otherwise connects

 * to the {@literal test} database.

 *

 * @author Dave Syer

 * @author Oliver Gierke

 * @author Josh Long

 * @author Phillip Webb

 * @author Eddú Meléndez

 * @since 1.1.0

 */

@Configuration

@ConditionalOnClass({ Mongo.class, MongoTemplate.class })

@EnableConfigurationProperties(MongoProperties.class)

@AutoConfigureAfter(MongoAutoConfiguration.class)

public class MongoDataAutoConfiguration implements BeanClassLoaderAware {

	@Autowired

	private MongoProperties properties;

	@Autowired

	private Environment environment;

	@Autowired

	private ResourceLoader resourceLoader;

	private ClassLoader classLoader;

	@Override

	public void setBeanClassLoader(ClassLoader classLoader) {

		this.classLoader = classLoader;

	}

	@Bean

	@ConditionalOnMissingBean(MongoDbFactory.class)

	public SimpleMongoDbFactory mongoDbFactory(MongoClient mongo) throws Exception {

		String database = this.properties.getMongoClientDatabase();

		return new SimpleMongoDbFactory(mongo, database);

	}

	@Bean

	@ConditionalOnMissingBean

	public MongoTemplate mongoTemplate(MongoDbFactory mongoDbFactory,

			MongoConverter converter) throws UnknownHostException {

		return new MongoTemplate(mongoDbFactory, converter);

	}

	@Bean

	@ConditionalOnMissingBean(MongoConverter.class)

	public MappingMongoConverter mappingMongoConverter(MongoDbFactory factory,

			MongoMappingContext context, BeanFactory beanFactory) {

		DbRefResolver dbRefResolver = new DefaultDbRefResolver(factory);

		MappingMongoConverter mappingConverter = new MappingMongoConverter(dbRefResolver,

				context);

		try {

			mappingConverter.setCustomConversions(beanFactory

					.getBean(CustomConversions.class));

		}

		catch (NoSuchBeanDefinitionException ex) {

			// Ignore

		}

		return mappingConverter;

	}

	@Bean

	@ConditionalOnMissingBean

	public MongoMappingContext mongoMappingContext(BeanFactory beanFactory)

			throws ClassNotFoundException {

		MongoMappingContext context = new MongoMappingContext();

		context.setInitialEntitySet(getInitialEntitySet(beanFactory));

		Class<? extends FieldNamingStrategy> strategyClass = this.properties

				.getFieldNamingStrategy();

		if (strategyClass != null) {

			context.setFieldNamingStrategy(BeanUtils.instantiate(strategyClass));

		}

		return context;

	}

	private Set<Class<?>> getInitialEntitySet(BeanFactory beanFactory)

			throws ClassNotFoundException {

		Set<Class<?>> entitySet = new HashSet<Class<?>>();

		ClassPathScanningCandidateComponentProvider scanner = new ClassPathScanningCandidateComponentProvider(

				false);

		scanner.setEnvironment(this.environment);

		scanner.setResourceLoader(this.resourceLoader);

		scanner.addIncludeFilter(new AnnotationTypeFilter(Document.class));

		scanner.addIncludeFilter(new AnnotationTypeFilter(Persistent.class));

		for (String basePackage : getMappingBasePackages(beanFactory)) {

			if (StringUtils.hasText(basePackage)) {

				for (BeanDefinition candidate : scanner

						.findCandidateComponents(basePackage)) {

					entitySet.add(ClassUtils.forName(candidate.getBeanClassName(),

							this.classLoader));

				}

			}

		}

		return entitySet;

	}

	private static Collection<String> getMappingBasePackages(BeanFactory beanFactory) {

		try {

			return AutoConfigurationPackages.get(beanFactory);

		}

		catch (IllegalStateException ex) {

			// no auto-configuration package registered yet

			return Collections.emptyList();

		}

	}

	@Bean

	@ConditionalOnMissingBean

	public GridFsTemplate gridFsTemplate(MongoDbFactory mongoDbFactory,

			MongoTemplate mongoTemplate) {

		return new GridFsTemplate(new GridFsMongoDbFactory(mongoDbFactory,

				this.properties), mongoTemplate.getConverter());

	}

	/**

	 * {@link MongoDbFactory} decorator to respect

	 * {@link MongoProperties#getGridFsDatabase()} if set.

	 */

	private static class GridFsMongoDbFactory implements MongoDbFactory {

		private final MongoDbFactory mongoDbFactory;

		private final MongoProperties properties;

		public GridFsMongoDbFactory(MongoDbFactory mongoDbFactory,

				MongoProperties properties) {

			Assert.notNull(mongoDbFactory, "MongoDbFactory must not be null");

			Assert.notNull(properties, "Properties must not be null");

			this.mongoDbFactory = mongoDbFactory;

			this.properties = properties;

		}

		@Override

		public DB getDb() throws DataAccessException {

			String gridFsDatabase = this.properties.getGridFsDatabase();

			if (StringUtils.hasText(gridFsDatabase)) {

				return this.mongoDbFactory.getDb(gridFsDatabase);

			}

			return this.mongoDbFactory.getDb();

		}

		@Override

		public DB getDb(String dbName) throws DataAccessException {

			return this.mongoDbFactory.getDb(dbName);

		}

		@Override

		public PersistenceExceptionTranslator getExceptionTranslator() {

			return this.mongoDbFactory.getExceptionTranslator();

		}

	}

}

/*

 * Copyright 2012-2015 the original author or authors.

 *

 * Licensed under the Apache License, Version 2.0 (the "License");

 * you may not use this file except in compliance with the License.

 * You may obtain a copy of the License at

 *

 *      http://www.apache.org/licenses/LICENSE-2.0

 *

 * Unless required by applicable law or agreed to in writing, software

 * distributed under the License is distributed on an "AS IS" BASIS,

 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 * See the License for the specific language governing permissions and

 * limitations under the License.

 */

package org.springframework.boot.autoconfigure.mongo;

import java.net.UnknownHostException;

import java.util.Arrays;

import java.util.List;

import org.springframework.boot.context.properties.ConfigurationProperties;

import org.springframework.core.env.Environment;

import org.springframework.data.mapping.model.FieldNamingStrategy;

import com.mongodb.MongoClient;

import com.mongodb.MongoClientOptions;

import com.mongodb.MongoClientOptions.Builder;

import com.mongodb.MongoClientURI;

import com.mongodb.MongoCredential;

import com.mongodb.ServerAddress;

/**

 * Configuration properties for Mongo.

 *

 * @author Dave Syer

 * @author Phillip Webb

 * @author Josh Long

 * @author Andy Wilkinson

 * @author Eddú Meléndez

 */

@ConfigurationProperties(prefix = "spring.data.mongodb")

public class MongoProperties {

	/**

	 * Default port used when the configured port is {@code null}.

	 */

	public static final int DEFAULT_PORT = 27017;

	/**

	 * Mongo server host.

	 */

	private String host;

	/**

	 * Mongo server port.

	 */

	private Integer port = null;

	/**

	 * Mongo database URI. When set, host and port are ignored.

	 */

	private String uri = "mongodb://localhost/test";

	/**

	 * Database name.

	 */

	private String database;

	/**

	 * Authentication database name.

	 */

	private String authenticationDatabase;

	/**

	 * GridFS database name.

	 */

	private String gridFsDatabase;

	/**

	 * Login user of the mongo server.

	 */

	private String username;

	/**

	 * Login password of the mongo server.

	 */

	private char[] password;

	/**

	 * Fully qualified name of the FieldNamingStrategy to use.

	 */

	private Class<? extends FieldNamingStrategy> fieldNamingStrategy;

	public String getHost() {

		return this.host;

	}

	public void setHost(String host) {

		this.host = host;

	}

	public String getDatabase() {

		return this.database;

	}

	public void setDatabase(String database) {

		this.database = database;

	}

	public String getAuthenticationDatabase() {

		return this.authenticationDatabase;

	}

	public void setAuthenticationDatabase(String authenticationDatabase) {

		this.authenticationDatabase = authenticationDatabase;

	}

	public String getUsername() {

		return this.username;

	}

	public void setUsername(String username) {

		this.username = username;

	}

	public char[] getPassword() {

		return this.password;

	}

	public void setPassword(char[] password) {

		this.password = password;

	}

	public Class<? extends FieldNamingStrategy> getFieldNamingStrategy() {

		return this.fieldNamingStrategy;

	}

	public void setFieldNamingStrategy(

			Class<? extends FieldNamingStrategy> fieldNamingStrategy) {

		this.fieldNamingStrategy = fieldNamingStrategy;

	}

	public void clearPassword() {

		if (this.password == null) {

			return;

		}

		for (int i = 0; i < this.password.length; i++) {

			this.password[i] = 0;

		}

	}

	public String getUri() {

		return this.uri;

	}

	public void setUri(String uri) {

		this.uri = uri;

	}

	public Integer getPort() {

		return this.port;

	}

	public void setPort(Integer port) {

		this.port = port;

	}

	public String getGridFsDatabase() {

		return this.gridFsDatabase;

	}

	public void setGridFsDatabase(String gridFsDatabase) {

		this.gridFsDatabase = gridFsDatabase;

	}

	public String getMongoClientDatabase() {

		if (this.database != null) {

			return this.database;

		}

		return new MongoClientURI(this.uri).getDatabase();

	}

	/**

	 * Creates a {@link MongoClient} using the given {@code options}

	 *

	 * @param options the options

	 * @return the Mongo client

	 * @throws UnknownHostException if the configured host is unknown

	 * @deprecated Since 1.3.0 in favour of

	 * {@link #createMongoClient(MongoClientOptions, Environment)}

	 */

	@Deprecated

	public MongoClient createMongoClient(MongoClientOptions options)

			throws UnknownHostException {

		return this.createMongoClient(options, null);

	}

	/**

	 * Creates a {@link MongoClient} using the given {@code options} and

	 * {@code environment}. If the configured port is zero, the value of the

	 * {@code local.mongo.port} property retrieved from the {@code environment} is used

	 * to configure the client.

	 *

	 * @param options the options

	 * @param environment the environment

	 * @return the Mongo client

	 * @throws UnknownHostException if the configured host is unknown

	 */

	public MongoClient createMongoClient(MongoClientOptions options,

			Environment environment) throws UnknownHostException {

		try {

			if (hasCustomAddress() || hasCustomCredentials()) {

				if (options == null) {

					options = MongoClientOptions.builder().build();

				}

				List<MongoCredential> credentials = null;

				if (hasCustomCredentials()) {

					String database = this.authenticationDatabase == null ? getMongoClientDatabase()

							: this.authenticationDatabase;

					credentials = Arrays.asList(MongoCredential.createMongoCRCredential(

							this.username, database, this.password));

				}

				String host = this.host == null ? "localhost" : this.host;

				int port = determinePort(environment);

				return new MongoClient(Arrays.asList(new ServerAddress(host, port)),

						credentials, options);

			}

			// The options and credentials are in the URI

			return new MongoClient(new MongoClientURI(this.uri, builder(options)));

		}

		finally {

			clearPassword();

		}

	}

	private boolean hasCustomAddress() {

		return this.host != null || this.port != null;

	}

	private boolean hasCustomCredentials() {

		return this.username != null && this.password != null;

	}

	private int determinePort(Environment environment) {

		if (this.port == null) {

			return DEFAULT_PORT;

		}

		if (this.port == 0) {

			if (environment != null) {

				String localPort = environment.getProperty("local.mongo.port");

				if (localPort != null) {

					return Integer.valueOf(localPort);

				}

			}

			throw new IllegalStateException(

					"spring.data.mongodb.port=0 and no local mongo port configuration "

							+ "is available");

		}

		return this.port;

	}

	private Builder builder(MongoClientOptions options) {

		Builder builder = MongoClientOptions.builder();

		if (options != null) {

			builder.alwaysUseMBeans(options.isAlwaysUseMBeans());

			builder.connectionsPerHost(options.getConnectionsPerHost());

			builder.connectTimeout(options.getConnectTimeout());

			builder.cursorFinalizerEnabled(options.isCursorFinalizerEnabled());

			builder.dbDecoderFactory(options.getDbDecoderFactory());

			builder.dbEncoderFactory(options.getDbEncoderFactory());

			builder.description(options.getDescription());

			builder.maxWaitTime(options.getMaxWaitTime());

			builder.readPreference(options.getReadPreference());

			builder.socketFactory(options.getSocketFactory());

			builder.socketKeepAlive(options.isSocketKeepAlive());

			builder.socketTimeout(options.getSocketTimeout());

			builder.threadsAllowedToBlockForConnectionMultiplier(options

					.getThreadsAllowedToBlockForConnectionMultiplier());

			builder.writeConcern(options.getWriteConcern());

		}

		return builder;

	}

}

------------------------------------------------------------------------------------------------------------------------------------------------------

以上为spring boot mongo的片段，可以看出spring boot已经配置好了，也就是说springboot启动后@Bean创建的对象可以直接使用@Autowrite直接使用

关注点（spring boot启动会直接读取application.yml或者是application.properties，这里我用的是yml）

@ConfigurationProperties(prefix = "spring.data.mongodb")

public class MongoProperties

启动入口

Applicaiton.java

package com.modou.weixin;

import org.springframework.beans.factory.annotation.Autowired;

import org.springframework.boot.CommandLineRunner;

import org.springframework.boot.SpringApplication;

import org.springframework.boot.autoconfigure.EnableAutoConfiguration;

import org.springframework.context.annotation.ComponentScan;

import org.springframework.context.annotation.Configuration;

import org.springframework.data.mongodb.core.MongoTemplate;

/**

 * Created by chababa on 15/8/22.

 */

@Configuration

@ComponentScan(basePackages={"com.modou.conf","com.modou.weixin"})

@EnableAutoConfiguration

public class Application implements CommandLineRunner{

	@Autowired

	MongoTemplate template;

	public static void main(String[] args) {

		SpringApplication.run(Application.class, args);

	}

	@Override

	public void run(String... args) throws Exception {

		System.err.println(template != null);

	}

}

注入MongoTemplate结果

# SPRING PROFILES

spring:

    # HTTP ENCODING

    http:

        encoding.charset: UTF-8

        encoding.enable: true

        encoding.force: true

    data:

        mongodb:

               host: 127.0.0.1

               port: 27017

               username:

               password:

               database: xx

               authenticationDatabase:

巴特西

Spring Boot Mongodb

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