原因：java.net.ConnectException:连接被拒绝：连接

我无法用我的数据库解决此连接问题。我试着从 localhost到127.0.0.1也没有成功。 我已经解决了以前的错误，即使在那时，我也没有成功地连接它

import java.sql.Connection;
import java.sql.DriverManager;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class DemoApplication{
    public static void main(String[] args) {

        SpringApplication.run(DemoApplication.class, args);

        try
        {
          String url = "jdbc:mysql://localhost:3306/Doctor"; 
          Connection conn = DriverManager.getConnection(url,"adminManu","adminManu");  
        }
        catch (Exception e)
        {
          System.err.println("D'oh! Got an exception!"); 
          System.err.println(e.getMessage()); 
        } 

    }

Minhasências： 我在pom.xml中的依赖项如下：

<dependencies>
        <dependency>
            <groupId>org.hibernate</groupId>
            <artifactId>hibernate-core</artifactId>
            <version>5.4.22.Final</version>
        </dependency>
        <dependency>
            <groupId>org.hibernate</groupId>
            <artifactId>hibernate-entitymanager</artifactId>
            <version>5.2.3.Final</version>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-actuator</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jpa</artifactId>
            <version>2.0.9.RELEASE</version>
        </dependency>

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

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.49</version>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
            <exclusions>
                <exclusion>
                    <groupId>org.junit.vintage</groupId>
                    <artifactId>junit-vintage-engine</artifactId>
                </exclusion>
            </exclusions>
        </dependency>

    </dependencies>

org.hibernate
冬眠核心
5.4.22.最终版本
org.hibernate
休眠实体管理器
5.2.3.最终版本
org.springframework.boot
弹簧靴起动器执行器
org.springframework.boot
spring引导启动器数据jpa
2.0.9.1发布
org.springframework.boot
SpringBootStarterWeb
org.springframework.boot
弹簧靴开发工具
运行时
mysql
mysql连接器java
5.1.49
运行时
org.projectlombok
龙目
真的
org.springframework.boot
弹簧起动试验
测试
org.junit.vintage
朱尼特老式发动机

一份备忘录： 我收到的信息是：

The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.        
        at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) ~[na:na]
        at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62) ~[na:na]     
        at java.base/jdk.internal.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45) ~[na:na]
        at java.base/java.lang.reflect.Constructor.newInstance(Constructor.java:490) ~[na:na]
        at com.mysql.jdbc.Util.handleNewInstance(Util.java:403) ~[mysql-connector-java-5.1.49.jar:5.1.49]
        at com.mysql.jdbc.SQLError.createCommunicationsException(SQLError.java:990) ~[mysql-connector-java-5.1.49.jar:5.1.49]
        at com.mysql.jdbc.MysqlIO.<init>(MysqlIO.java:335) ~[mysql-connector-java-5.1.49.jar:5.1.49]
        at com.mysql.jdbc.ConnectionImpl.coreConnect(ConnectionImpl.java:2187) ~[mysql-connector-java-5.1.49.jar:5.1.49]
        at com.mysql.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:2220) ~[mysql-connector-java-5.1.49.jar:5.1.49]
        at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2015) ~[mysql-connector-java-5.1.49.jar:5.1.49]
        at com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:768) ~[mysql-connector-java-5.1.49.jar:5.1.49]
        at com.mysql.jdbc.JDBC4Connection.<init>(JDBC4Connection.java:47) ~[mysql-connector-java-5.1.49.jar:5.1.49]
        at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) ~[na:na]
        at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62) ~[na:na]     
        at java.base/jdk.internal.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45) ~[na:na]
        at java.base/java.lang.reflect.Constructor.newInstance(Constructor.java:490) ~[na:na]
        at com.mysql.jdbc.Util.handleNewInstance(Util.java:403) ~[mysql-connector-java-5.1.49.jar:5.1.49]
        at com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:385) ~[mysql-connector-java-5.1.49.jar:5.1.49]
        at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:323) ~[mysql-connector-java-5.1.49.jar:5.1.49]
        at com.zaxxer.hikari.util.DriverDataSource.getConnection(DriverDataSource.java:117) ~[HikariCP-2.7.9.jar:na]
        at com.zaxxer.hikari.util.DriverDataSource.getConnection(DriverDataSource.java:123) ~[HikariCP-2.7.9.jar:na]
        at com.zaxxer.hikari.pool.PoolBase.newConnection(PoolBase.java:365) ~[HikariCP-2.7.9.jar:na]
        at com.zaxxer.hikari.pool.PoolBase.newPoolEntry(PoolBase.java:194) ~[HikariCP-2.7.9.jar:na]
        at com.zaxxer.hikari.pool.HikariPool.createPoolEntry(HikariPool.java:460) ~[HikariCP-2.7.9.jar:na]
        at com.zaxxer.hikari.pool.HikariPool.checkFailFast(HikariPool.java:534) ~[HikariCP-2.7.9.jar:na]
        at com.zaxxer.hikari.pool.HikariPool.<init>(HikariPool.java:115) ~[HikariCP-2.7.9.jar:na]
        at com.zaxxer.hikari.HikariDataSource.getConnection(HikariDataSource.java:112) ~[HikariCP-2.7.9.jar:na]
        at org.hibernate.engine.jdbc.connections.internal.DatasourceConnectionProviderImpl.getConnection(DatasourceConnectionProviderImpl.java:122) ~[hibernate-core-5.4.22.Final.jar:5.4.22.Final]
        at org.hibernate.engine.jdbc.env.internal.JdbcEnvironmentInitiator$ConnectionProviderJdbcConnectionAccess.obtainConnection(JdbcEnvironmentInitiator.java:180) ~[hibernate-core-5.4.22.Final.jar:5.4.22.Final]
        at org.hibernate.resource.transaction.backend.jdbc.internal.DdlTransactionIsolatorNonJtaImpl.getIsolatedConnection(DdlTransactionIsolatorNonJtaImpl.java:43) ~[hibernate-core-5.4.22.Final.jar:5.4.22.Final]
        ... 40 common frames omitted
Caused by: java.net.ConnectException: Connection refused: connect
        at java.base/java.net.PlainSocketImpl.waitForConnect(Native Method) ~[na:na]
        at java.base/java.net.PlainSocketImpl.socketConnect(PlainSocketImpl.java:107) ~[na:na]
        at java.base/java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:399) ~[na:na]
        at java.base/java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:242) ~[na:na]
        at java.base/java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:224) ~[na:na]
        at java.base/java.net.SocksSocketImpl.connect(SocksSocketImpl.java:403) ~[na:na]
        at java.base/java.net.Socket.connect(Socket.java:608) ~[na:na]
        at com.mysql.jdbc.StandardSocketFactory.connect(StandardSocketFactory.java:211) ~[mysql-connector-java-5.1.49.jar:5.1.49]       
        at com.mysql.jdbc.MysqlIO.<init>(MysqlIO.java:299) ~[mysql-connector-java-5.1.49.jar:5.1.49]
        ... 63 common frames omitted

成功发送到服务器的最后一个数据包是0毫秒前的。驱动程序尚未从服务器收到任何数据包。
在java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance0（本机方法）~[na:na]
在java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance（NativeConstructorAccessorImpl.java:62）~[na:na]
在java.base/jdk.internal.reflect.DelegatingConstructorAccessorImpl.newInstance（DelegatingConstructorAccessorImpl.java:45）~[na:na]
在java.base/java.lang.reflect.Constructor.newInstance（Constructor.java:490）~[na:na]
在com.mysql.jdbc.Util.handleNewInstance（Util.java:403）~[mysql-connector-java-5.1.49.jar:5.1.49]
在com.mysql.jdbc.SQLError.createCommunicationsException（SQLError.java:990）~[mysql-connector-java-5.1.49.jar:5.1.49]
在com.mysql.jdbc.MysqlIO.（MysqlIO.java:335）~[mysql-connector-java-5.1.49.jar:5.1.49]
在com.mysql.jdbc.ConnectionImpl.coreConnect（ConnectionImpl.java:2187）~[mysql-connector-java-5.1.49.jar:5.1.49]
在com.mysql.jdbc.ConnectionImpl.connectoneryOnly（ConnectionImpl.java:2220）~[mysql-connector-java-5.1.49.jar:5.1.49]
在com.mysql.jdbc.ConnectionImpl.createNewIO（ConnectionImpl.java:2015）~[mysql-connector-java-5.1.49.jar:5.1.49]
在com.mysql.jdbc.ConnectionImpl.（ConnectionImpl.java:768）~[mysql-connector-java-5.1.49.jar:5.1.49]
在com.mysql.jdbc.JDBC4Connection.（JDBC4Connection.java:47）~[mysql-connector-java-5.1.49.jar:5.1.49]
在java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance0（本机方法）~[na:na]
在java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance（NativeConstructorAccessorImpl.java:62）~[na:na]
在java.base/jdk.internal.reflect.DelegatingConstructorAccessorImpl.newInstance（DelegatingConstructorAccessorImpl.java:45）~[na:na]
在java.base/java.lang.reflect.Constructor.newInstance（Constructor.java:490）~[na:na]
在com.mysql.jdbc.Util.handleNewInstance（Util.java:403）~[mysql-connector-java-5.1.49.jar:5.1.49]
在com.mysql.jdbc.ConnectionImpl.getInstance（ConnectionImpl.java:385）~[mysql-connector-java-5.1.49.jar:5.1.49]
在com.mysql.jdbc.NonRegisteringDriver.connect（NonRegisteringDriver.java:323）~[mysql-connector-java-5.1.49.jar:5.1.49]
在com.zaxxer.hikari.util.DriverDataSource.getConnection（DriverDataSource.java:117）~[HikariCP-2.7.9.jar:na]
在com.zaxxer.hikari.util.DriverDataSource.getConnection（DriverDataSource.java:123）~[HikariCP-2.7.9.jar:na]
在com.zaxxer.hikari.pool.PoolBase.newConnection（PoolBase.java:365）~[HikariCP-2.7.9.jar:na]
在com.zaxxer.hikari.pool.PoolBase.newPoolEntry（PoolBase.java:194）~[HikariCP-2.7.9.jar:na]
在com.zaxxer.hikari.pool.HikariPool.createPoolEntry（HikariPool.java:460）~[HikariCP-2.7.9.jar:na]
在com.zaxxer.hikari.pool.HikariPool.checkFailFast（HikariPool.java:534）~[HikariCP-2.7.9.jar:na]
在com.zaxxer.hikari.pool.HikariPool.（HikariPool.java:115）~[HikariCP-2.7.9.jar:na]
在com.zaxxer.hikari.HikariDataSource.getConnection（HikariDataSource.java:112）~[HikariCP-2.7.9.jar:na]
在org.hibernate.engine.jdbc.connections.internal.DatasourceConnectionProviderImpl.getConnection（DatasourceConnectionProviderImpl.java:122）~[hibernate-core-5.4.22.Final.jar:5.4.22.Final]
在org.hibernate.engine.jdbc.env.internal.jdbconvironmentinitiator$connectionProviderjdbconnectionAccess.获得连接（jdbconvironmentinitiator.java:180）~[hibernate-core-5.4.22.Final.jar:5.4.22.Final]
在org.hibernate.resource.transaction.backend.jdbc.internal.DdlTransactionIsolatorNonJtaImpl.getIsolatedConnection（DdlTransactionIsolatorNonJtaImpl.java:43）~[hibernate-core-5.4.22.Final.jar:5.4.22.Final]
... 省略40个公共帧
原因：java.net.ConnectException:连接被拒绝：连接
在java.base/java.net.PlainSocketImpl.waitForConnect（本机方法）~[na:na]
在java.base/java.net.PlainSocketImpl.socketConnect（PlainSocketImpl.java:107）~[na:na]
在java.base/java.net.AbstractPlainSocketImpl.doConnect（AbstractPlainSocketImpl.java:399）~[na:na]
在java.base/java.net.AbstractPlainSocketImpl.connectToAddress（AbstractPlainSocketImpl.java:242）~[na:na]
在java.base/java.net.AbstractPlainSocketImpl.connect（AbstractPlainSocketImpl.java:224）~[na:na]
位于java.base/java.net.socksocketimpl.connect（Sock