java - 没有可用的 'javax.sql.DataSource' 类型的合格 bean

Question

我正在使用 spring mvc 版本 5。

我在 Autowiring 问题中苦苦挣扎。我正在关注 Spring Security JDBC 教程。这是AppConfiguration.class:

package com.blog.configuration;

import javax.sql.DataSource;

import org.apache.commons.dbcp2.BasicDataSource;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Bean;

import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.PropertySource;
import org.springframework.core.Ordered;
import org.springframework.core.env.Environment;
import org.springframework.web.servlet.config.annotation.EnableWebMvc;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;
import org.springframework.web.servlet.config.annotation.ResourceHandlerRegistry;
import org.springframework.web.servlet.config.annotation.ViewControllerRegistry;
import org.springframework.web.servlet.view.InternalResourceViewResolver;
import org.springframework.web.servlet.view.JstlView;

@Configuration
@EnableWebMvc
@ComponentScan({ "com.blog" })
@PropertySource("classpath:db.properties")
public class AppConfiguration implements WebMvcConfigurer {

    @Autowired
    private Environment env;

    @Bean
    public InternalResourceViewResolver viewResolver() {
        InternalResourceViewResolver viewResolver = new InternalResourceViewResolver();
        viewResolver.setViewClass(JstlView.class);
        viewResolver.setPrefix("/WEB-INF/views/");
        viewResolver.setSuffix(".jsp");
        return viewResolver;
    }

    /**
     * Configure ResourceHandlers to serve static resources like CSS/ Javascript
     * etc...
     */
    public void addResourceHandlers(ResourceHandlerRegistry registry) {
        registry.addResourceHandler("/resources/**").addResourceLocations("/resources/");
    }

    /**
     * configure spring security custom login page
     */
    @Override
    public void addViewControllers(ViewControllerRegistry registry) {
        registry.addViewController("/login").setViewName("login-page");
        registry.setOrder(Ordered.HIGHEST_PRECEDENCE);
    }

    @Bean
    public DataSource dataSource() {
        BasicDataSource dataSource = new BasicDataSource();
        dataSource.setDriverClassName(env.getProperty("mysql.driver"));
        dataSource.setUrl(env.getProperty("mysql.jdbcUrl"));
        dataSource.setUsername(env.getProperty("mysql.username"));
        dataSource.setPassword(env.getProperty("mysql.password"));
        return dataSource;
    }

}

这是SecurityConfig.class:

package com.blog.configuration;

import javax.sql.DataSource;

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

import org.springframework.context.annotation.Bean;
import org.springframework.security.config.annotation.authentication.builders.AuthenticationManagerBuilder;
import org.springframework.security.config.annotation.web.builders.HttpSecurity;
import org.springframework.security.config.annotation.web.configuration.EnableWebSecurity;
import org.springframework.security.config.annotation.web.configuration.WebSecurityConfigurerAdapter;
import org.springframework.security.crypto.bcrypt.BCryptPasswordEncoder;
import org.springframework.security.crypto.password.PasswordEncoder;

@EnableWebSecurity
public class SecurityConfig extends WebSecurityConfigurerAdapter {

    @Autowired
    private DataSource dataSource;

    @Autowired
    PasswordEncoder passwordEncoder;

    @Override
    protected void configure(AuthenticationManagerBuilder auth) throws Exception {

        auth.jdbcAuthentication().dataSource(dataSource)
                .usersByUsernameQuery("select username, password, enabled" + " from users where username=?")
                .authoritiesByUsernameQuery("select username, authority " + "from authorities where username=?")
                .passwordEncoder(new BCryptPasswordEncoder());

    }

    @Bean
    public PasswordEncoder passwordEncoder() {
        return new BCryptPasswordEncoder();
    }

    @Override
    protected void configure(HttpSecurity http) throws Exception {
        http.authorizeRequests().antMatchers("/").permitAll().antMatchers("/resources/**").permitAll()
                .antMatchers("/admin/**").hasRole("ADMIN").and().formLogin().loginPage("/login").permitAll();
    }

}

和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/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <groupId>com.demo</groupId>
    <artifactId>blog</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>blog Maven Webapp</name>
    <packaging>war</packaging>
    <properties>
        <maven.compiler.source>1.8</maven.compiler.source>
        <maven.compiler.target>1.8</maven.compiler.target>
        <failOnMissingWebXml>false</failOnMissingWebXml>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.security</groupId>
            <artifactId>spring-security-web</artifactId>
            <version>5.0.0.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>org.springframework.security</groupId>
            <artifactId>spring-security-config</artifactId>
            <version>5.0.0.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-webmvc</artifactId>
            <version>5.0.2.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-jdbc</artifactId>
            <version>5.0.2.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>javax.servlet-api</artifactId>
            <version>3.1.0</version>
            <scope>provided</scope>
        </dependency>
        <dependency>
            <groupId>javax.servlet.jsp</groupId>
            <artifactId>javax.servlet.jsp-api</artifactId>
            <version>2.3.1</version>
            <scope>provided</scope>
        </dependency>
        <dependency>
            <groupId>javax.servlet.jsp.jstl</groupId>
            <artifactId>javax.servlet.jsp.jstl-api</artifactId>
            <version>1.2.1</version>
    </dependency>
    <dependency>
        <groupId>taglibs</groupId>
        <artifactId>standard</artifactId>
        <version>1.1.2</version>
    </dependency>
    <dependency>
        <groupId>org.apache.commons</groupId>
        <artifactId>commons-dbcp2</artifactId>
        <version>2.1.1</version>
    </dependency>
    <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
        <version>6.0.6</version>
    </dependency>
</dependencies>
<build>
    <plugins>
        <!-- Maven jetty plugin for testing war -->
        <plugin>
            <groupId>org.eclipse.jetty</groupId>
            <artifactId>jetty-maven-plugin</artifactId>
            <version>9.4.8.v20171121</version>
        </plugin>
    </plugins>
</build>

数据源 Autowiring 不起作用，我不知道为什么。它给我错误:没有可用的“javax.sql.DataSource”类型的合格 bean。有什么问题吗？

Answer 1

将您的 bean 创建代码移至根配置类(在您的情况下为SecurityConfiguration。)

@Bean
public DataSource dataSource() {
    BasicDataSource dataSource = new BasicDataSource();
    dataSource.setDriverClassName(env.getProperty("mysql.driver"));
    dataSource.setUrl(env.getProperty("mysql.jdbcUrl"));
    dataSource.setUsername(env.getProperty("mysql.username"));
    dataSource.setPassword(env.getProperty("mysql.password"));
    return dataSource;
}

将以上代码移至根配置。
因为 servlet 上下文中定义的 bean 在根/应用程序上下文中不可见，因为根上下文首先初始化，然后是 servlet 上下文。

如果您在根上下文中定义 bean，则可以在 servlet 上下文中使用( Autowiring )它。

_{root-context 和 servlet-context 的含义}

根上下文 ------ 上下文由 ContextLoaderListener 加载
Servlet 上下文 --- 由 DispatcherServlet 加载的上下文

_{如果你想知道什么是rootContext，什么是servletContext，并且还想清楚如何在上下文之间访问bean Refer my answer from this link}