13.6 SpringBoot集成Mongodb開發問題@EnableMongoRepositories路徑配置

APPLICATION FAILED TO START

Description:

Parameter 0 of constructor in com.restfeel.controller.BlogController required a bean of type 'com.restfeel.biz.BlogService' that could not be found.

Action:

Consider defining a bean of type 'com.restfeel.biz.BlogService' in your configuration.

:bootRun FAILED

FAILURE: Build failed with an exception.

• What went wrong:
  Execution failed for task ':bootRun'.

代碼

package com.restfeel.service

import com.restfeel.entity.Blog
import org.springframework.data.mongodb.repository.MongoRepository
import org.springframework.data.mongodb.repository.Query
import org.springframework.data.repository.query.Param

interface BlogService : MongoRepository<Blog, String> {

    @Query("{ 'title' : ?0 }")
    fun findByTitle(@Param("title") title: String): Iterable<Blog>

}




package com.restfeel.controller

import com.restfeel.service.BlogService
import com.restfeel.entity.Blog
import org.springframework.boot.autoconfigure.EnableAutoConfiguration
import org.springframework.context.annotation.ComponentScan
import org.springframework.stereotype.Controller
import org.springframework.transaction.annotation.Propagation
import org.springframework.transaction.annotation.Transactional
import org.springframework.ui.Model
import org.springframework.web.bind.annotation.GetMapping
import org.springframework.web.bind.annotation.RequestParam
import org.springframework.web.bind.annotation.ResponseBody
import java.util.*

/**
 * * 注意:
 *      這里要使用@Controller注解
 *      而不要使用@RestController
 *      否則return "index";只是返回字符串"index"， 不能跳轉到index.html
 *
 *      @RestController is a stereotype annotation that combines @ResponseBody and @Controller.
 *      @RestController注解相當于@ResponseBody ＋ @Controller合在一起的作用。
 */

@Controller
@EnableAutoConfiguration
@ComponentScan
@Transactional(propagation = Propagation.REQUIRES_NEW)
class BlogController(val blogService: BlogService) {
    @GetMapping("/blogs.do")
    fun listAll(model: Model): String {
        val now = Date();
        blogService.save(Blog("SpringBoot極簡教程", "XXX", "JasonChen", now, now, 0, now, "", 0))
        blogService.save(Blog("SpringBoot極簡教程", "XXX", "BluceLi", now, now, 0, now, "", 0))
        blogService.save(Blog("SpringBoot極簡教程", "XXX", "MichelleChen", now, now, 0, now, "", 0))

        val allblogs = blogService.findAll()
        model.addAttribute("blogs", allblogs)
        return "jsp/blog/list"
    }

    @GetMapping("/listblogs")
    @ResponseBody
    fun listblogs(model: Model) = blogService.findAll()

    @GetMapping("/findBlog")
    @ResponseBody
    fun findBlog(@RequestParam(value = "title") title: String) = blogService.findByTitle(title)

}

原因

@EnableMongoRepositories路徑配置問題，AbstractMongoConfiguration掃描dao層包路徑的配置要細心。

package com.restfeel.config

import com.mongodb.Mongo
import com.mongodb.MongoClient
import com.mongodb.MongoCredential
import com.mongodb.ServerAddress
import org.springframework.beans.factory.annotation.Autowired
import org.springframework.context.annotation.Bean
import org.springframework.context.annotation.Configuration
import org.springframework.core.env.Environment
import org.springframework.data.mongodb.config.AbstractMongoConfiguration
import org.springframework.data.mongodb.repository.config.EnableMongoRepositories

/**
 * Created by jack on 2017/3/29.
 */


@Configuration
@EnableMongoRepositories(*arrayOf("com.restfeel.dao", "com.???.???"))
class PersistenceConfig : AbstractMongoConfiguration() {

    @Autowired
    private val env: Environment? = null

    override fun getDatabaseName(): String {
        return env!!.getProperty("mongodb.name")
    }


    @Bean
    @Throws(Exception::class)
    override fun mongo(): Mongo {
        return MongoClient(listOf(ServerAddress(env!!.getProperty("mongodb.host"), env!!.getProperty("mongodb.port", Int::class.java))),
                listOf(MongoCredential
                        .createCredential(env!!.getProperty("mongodb.username"), env!!.getProperty("mongodb.name"),
                                env!!.getProperty("mongodb.password").toCharArray())))
    }

//    override fun getMappingBasePackage(): String {
//        return "com.restfiddle.dao"
//    }

    /**
     * 這地方是配置掃描繼承Repository類的所有接口類的路徑的，路徑配置錯誤，bean就不會創建了。
     * 東海陳光劍 Jason Chen @蔣村花園如意苑 2017.3.30 01:41:35
     */
    override fun getMappingBasePackages(): Collection<String> {
        return setOf("com.restfeel.dao", "com.restfeel.service")
    }
}

原理

比如說，有代碼

@Autowired
private UserDao userDao;

其中UserDao來自

public interface UserDao extends CrudRepository<User, Long>

無論在哪兒也找不到這個Bean是在哪兒定義的，但是代碼還能正常工作。@Autowired 默認找不到會報錯，再不然就是null，不會創建bean。

我們正常會推測：這是 CrudRepository導致的， CrudRepository會自動創建一個Bean。事實如此，這個是spring data jpa的功能，它會掃描Repository的子類并實現它們。