读写分离样例

dxfl/pom.xml

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+<?xml version="1.0" encoding="UTF-8"?>
+<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.example</groupId>
+    <artifactId>dxfl</artifactId>
+    <version>0.0.1-SNAPSHOT</version>
+    <packaging>jar</packaging>
+
+    <name>dxfl</name>
+    <description>Demo project for Spring Boot</description>
+
+    <parent>
+        <groupId>org.springframework.boot</groupId>
+        <artifactId>spring-boot-starter-parent</artifactId>
+        <version>2.0.4.RELEASE</version>
+        <relativePath/> <!-- lookup parent from repository -->
+    </parent>
+
+    <properties>
+        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
+        <java.version>1.8</java.version>
+    </properties>
+
+    <dependencies>
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-aop</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-jdbc</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-web</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>org.mybatis.spring.boot</groupId>
+            <artifactId>mybatis-spring-boot-starter</artifactId>
+            <version>1.3.2</version>
+        </dependency>
+        <dependency>
+            <groupId>com.alibaba</groupId>
+            <artifactId>druid</artifactId>
+            <version>1.0.9</version>
+        </dependency>
+
+        <dependency>
+            <groupId>mysql</groupId>
+            <artifactId>mysql-connector-java</artifactId>
+            <scope>runtime</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-test</artifactId>
+            <scope>test</scope>
+        </dependency>
+    </dependencies>
+
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.springframework.boot</groupId>
+                <artifactId>spring-boot-maven-plugin</artifactId>
+            </plugin>
+        </plugins>
+    </build>
+
+
+</project>

dxfl/src/main/java/com/example/dxfl/DxflApplication.java

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+package com.example.dxfl;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+import org.springframework.transaction.annotation.EnableTransactionManagement;
+
+@SpringBootApplication
+@EnableTransactionManagement(order = 10)
+public class DxflApplication {
+
+    public static void main(String[] args) {
+        SpringApplication.run(DxflApplication.class, args);
+    }
+}

dxfl/src/main/java/com/example/dxfl/config/DbContextHolder.java

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+package com.example.dxfl.config;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * Description 这里切换读/写模式
+ * 原理是利用ThreadLocal保存当前线程是否处于读模式（通过开始READ_ONLY注解在开始操作前设置模式为读模式，
+ * 操作结束后清除该数据，避免内存泄漏，同时也为了后续在该线程进行写操作时任然为读模式
+ * @author fxb
+ * @date 2018-08-31
+ */
+public class DbContextHolder {
+
+    private static Logger log = LoggerFactory.getLogger(DbContextHolder.class);
+    public static final String WRITE = "write";
+    public static final String READ = "read";
+
+    private static ThreadLocal<String> contextHolder= new ThreadLocal<>();
+
+    public static void setDbType(String dbType) {
+        if (dbType == null) {
+            log.error("dbType为空");
+            throw new NullPointerException();
+        }
+        log.info("设置dbType为：{}",dbType);
+        contextHolder.set(dbType);
+    }
+
+    public static String getDbType() {
+        return contextHolder.get() == null ? WRITE : contextHolder.get();
+    }
+
+    public static void clearDbType() {
+        contextHolder.remove();
+    }
+}

dxfl/src/main/java/com/example/dxfl/config/MyAbstractRoutingDataSource.java

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+package com.example.dxfl.config;
+
+import com.example.dxfl.util.NumberUtil;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.springframework.beans.factory.annotation.Value;
+import org.springframework.jdbc.datasource.lookup.AbstractRoutingDataSource;
+
+/**
+ * Description
+ *
+ * @author fxb
+ * @date 2018-09-03
+ */
+public class MyAbstractRoutingDataSource extends AbstractRoutingDataSource {
+
+    @Value("${mysql.datasource.num}")
+    private int num;
+
+    private final Logger log = LoggerFactory.getLogger(this.getClass());
+
+    @Override
+    protected Object determineCurrentLookupKey() {
+        String typeKey = DbContextHolder.getDbType();
+        if (typeKey == DbContextHolder.WRITE) {
+            log.info("使用了写库");
+            return typeKey;
+        }
+        //使用随机数决定使用哪个读库
+        int sum = NumberUtil.getRandom(1, num);
+        log.info("使用了读库{}", sum);
+        return DbContextHolder.READ + sum;
+    }
+}

dxfl/src/main/java/com/example/dxfl/config/ReadOnly.java

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+package com.example.dxfl.config;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+/**
+ * Description 通过该接口注释的service使用读模式，其他使用写模式
+ *
+ * 接口注释只是一种办法，如果项目已经有代码了，通过注释可以不修改任何业务代码加持读写分离
+ * 也可以通过切面根据方法开头来设置读写模式，例如getXXX()使用读模式，其他使用写模式
+ *
+ * @author fxb
+ * @date 2018-08-31
+ */
+@Target({ElementType.METHOD,ElementType.TYPE})
+@Retention(RetentionPolicy.RUNTIME)
+public @interface ReadOnly {
+}

dxfl/src/main/java/com/example/dxfl/config/ReadOnlyInterceptor.java

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+package com.example.dxfl.config;
+
+import org.aspectj.lang.ProceedingJoinPoint;
+import org.aspectj.lang.annotation.Around;
+import org.aspectj.lang.annotation.Aspect;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.springframework.core.Ordered;
+import org.springframework.stereotype.Component;
+
+/**
+ * Description
+ *
+ * @author fxb
+ * @date 2018-08-31
+ */
+@Aspect
+@Component
+public class ReadOnlyInterceptor implements Ordered {
+    private static final Logger log= LoggerFactory.getLogger(ReadOnlyInterceptor.class);
+
+    @Around("@annotation(readOnly)")
+    public Object setRead(ProceedingJoinPoint joinPoint,ReadOnly readOnly) throws Throwable{
+        try{
+            DbContextHolder.setDbType(DbContextHolder.READ);
+            return joinPoint.proceed();
+        }finally {
+            DbContextHolder.clearDbType();
+            log.info("清除threadLocal");
+        }
+    }
+
+    @Override
+    public int getOrder() {
+        return 0;
+    }
+}

dxfl/src/main/java/com/example/dxfl/config/WriteOrReadDatabaseConfig.java

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+package com.example.dxfl.config;
+
+import com.alibaba.druid.pool.DruidDataSource;
+import org.apache.ibatis.session.SqlSessionFactory;
+import org.mybatis.spring.SqlSessionFactoryBean;
+import org.mybatis.spring.annotation.MapperScan;
+import org.springframework.beans.factory.annotation.Value;
+import org.springframework.boot.context.properties.ConfigurationProperties;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.context.annotation.Primary;
+import org.springframework.core.io.support.PathMatchingResourcePatternResolver;
+import org.springframework.core.io.support.ResourcePatternResolver;
+import org.springframework.jdbc.datasource.DataSourceTransactionManager;
+import org.springframework.jdbc.datasource.lookup.AbstractRoutingDataSource;
+
+import javax.sql.DataSource;
+import java.util.HashMap;
+import java.util.Map;
+
+/**
+ * Description
+ *
+ * @author fxb
+ * @date 2018-09-03
+ */
+@Configuration
+@MapperScan(basePackages = "com.example.dxfl.mapper", sqlSessionFactoryRef = "sqlSessionFactory")
+public class WriteOrReadDatabaseConfig {
+
+    @Value("${mysql.datasource.type-aliases-package}")
+    private String typeAliasesPackage;
+
+    @Value("${mysql.datasource.mapper-locations}")
+    private String mapperLocation;
+
+    @Value("${mysql.datasource.config-location}")
+    private String configLocation;
+
+
+    /**
+     * 写数据源
+     *
+     * @Primary 标志这个 Bean 如果在多个同类 Bean 候选时，该 Bean 优先被考虑。
+     * 多数据源配置的时候注意，必须要有一个主数据源，用 @Primary 标志该 Bean
+     */
+    @Primary
+    @Bean
+    @ConfigurationProperties(prefix = "mysql.datasource.write")
+    public DataSource writeDataSource() {
+        return new DruidDataSource();
+    }
+
+    /**
+     * 读数据源
+     */
+    @Bean
+    @ConfigurationProperties(prefix = "mysql.datasource.read")
+    public DataSource read1() {
+        return new DruidDataSource();
+    }
+
+
+    /**
+     * 多数据源需要自己设置sqlSessionFactory
+     */
+    @Bean
+    public SqlSessionFactory sqlSessionFactory() throws Exception {
+        SqlSessionFactoryBean bean = new SqlSessionFactoryBean();
+        bean.setDataSource(routingDataSource());
+        ResourcePatternResolver resolver = new PathMatchingResourcePatternResolver();
+        // 实体类对应的位置
+        bean.setTypeAliasesPackage(typeAliasesPackage);
+        // mybatis的XML的配置
+        bean.setMapperLocations(resolver.getResources(mapperLocation));
+        bean.setConfigLocation(resolver.getResource(configLocation));
+        return bean.getObject();
+    }
+
+    /**
+     * 设置事务，事务需要知道当前使用的是哪个数据源才能进行事务处理
+     */
+    @Bean
+    public DataSourceTransactionManager dataSourceTransactionManager() {
+        return new DataSourceTransactionManager(routingDataSource());
+    }
+
+    /**
+     * 设置数据源路由，通过该类中的determineCurrentLookupKey决定使用哪个数据源
+     */
+    @Bean
+    public AbstractRoutingDataSource routingDataSource() {
+        MyAbstractRoutingDataSource proxy = new MyAbstractRoutingDataSource();
+        Map<Object, Object> targetDataSources = new HashMap<>(2);
+        targetDataSources.put(DbContextHolder.WRITE, writeDataSource());
+        targetDataSources.put(DbContextHolder.READ+"1", read1());
+        proxy.setDefaultTargetDataSource(writeDataSource());
+        proxy.setTargetDataSources(targetDataSources);
+        return proxy;
+    }
+
+
+}

dxfl/src/main/java/com/example/dxfl/controller/TestController.java

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+package com.example.dxfl.controller;
+
+import com.example.dxfl.service.TestService;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.RestController;
+
+/**
+ * Description
+ *
+ * @author fxb
+ * @date 2018-09-04
+ */
+@RestController
+public class TestController {
+
+    private final TestService testService;
+
+    @Autowired
+    public TestController(TestService testService) {
+        this.testService = testService;
+    }
+
+    @GetMapping("/getAll")
+    public Object getAll(){
+        return testService.getAll();
+    }
+
+    @GetMapping("insertOne")
+    public void insertOne(){
+        testService.insertOne();
+    }
+
+    @GetMapping("readAndWrite")
+    public void readAndWrite(){
+        testService.testReadAndWrite();
+    }
+
+    @GetMapping("transInsert")
+    public void transInsert(){
+        testService.transInsert();
+    }
+
+}

dxfl/src/main/java/com/example/dxfl/entity/Test.java

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+package com.example.dxfl.entity;
+
+/**
+ * Description
+ *
+ * @author fxb
+ * @date 2018-09-04
+ */
+public class Test {
+    private Integer id;
+    private String name;
+
+    public Integer getId() {
+        return id;
+    }
+
+    public void setId(Integer id) {
+        this.id = id;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+}

dxfl/src/main/java/com/example/dxfl/mapper/TestMapper.java

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+package com.example.dxfl.mapper;
+
+import com.example.dxfl.entity.Test;
+import org.apache.ibatis.annotations.Param;
+
+import java.util.List;
+
+/**
+ * Description
+ *
+ * @author fxb
+ * @date 2018-09-04
+ */
+public interface TestMapper {
+    /**
+     * 获取全部数据
+     * @return List<Test>
+     */
+    List<Test> getAll();
+
+    /**
+     * 插入一条数据
+     * @param test 数据
+     */
+    void insertOne(@Param("test") Test test);
+}

dxfl/src/main/java/com/example/dxfl/service/TestService.java

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+package com.example.dxfl.service;
+
+import com.example.dxfl.config.ReadOnly;
+import com.example.dxfl.entity.Test;
+import com.example.dxfl.mapper.TestMapper;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.stereotype.Service;
+import org.springframework.transaction.annotation.Transactional;
+
+import java.util.List;
+
+/**
+ * Description
+ *
+ * @author fxb
+ * @date 2018-09-04
+ */
+@Service
+public class TestService {
+
+    private final TestMapper testMapper;
+
+    @Autowired
+    public TestService(TestMapper testMapper) {
+        this.testMapper = testMapper;
+    }
+
+    /**
+     * 测试读取，应该使用读库
+     */
+    @ReadOnly
+    public List<Test> getAll() {
+        return testMapper.getAll();
+    }
+
+    /**
+     * 测试读取和插入,应该使用写库
+     */
+    public void testReadAndWrite() {
+        this.getAll();
+        this.insertOne();
+    }
+
+    /**
+     * 测试插入数据,应该使用写库
+     */
+    public void insertOne() {
+        Test test = new Test();
+        test.setName("fxb");
+        testMapper.insertOne(test);
+    }
+
+    /**
+     * 测试事务能否正常工作
+     */
+    @Transactional(rollbackFor = RuntimeException.class)
+    public void transInsert(){
+        Test test = new Test();
+        test.setName("heiheihei");
+        testMapper.insertOne(test);
+        throw new RuntimeException("测试事务");
+    }
+}

dxfl/src/main/java/com/example/dxfl/util/NumberUtil.java

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+package com.example.dxfl.util;
+
+/**
+ * Description
+ *
+ * @author fxb
+ * @date 2018-09-07
+ */
+public class NumberUtil {
+
+    public static int getRandom(int min, int max) {
+        return (int) Math.floor(Math.random() * (max - min + 1)) + min;
+    }
+}

dxfl/src/main/resources/application.yml

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+mysql:
+  datasource:
+    #读库数目
+    num: 1
+    type-aliases-package: com.example.dxfl.dao
+    mapper-locations: classpath:/mapper/*.xml
+    config-location: classpath:/mybatis-config.xml
+    write:
+      url: jdbc:mysql://192.168.226.5:3306/test?useUnicode=true&characterEncoding=utf-8&useSSL=true
+      username: root
+      password: 123456
+      driver-class-name: com.mysql.jdbc.Driver
+    read:
+      url: jdbc:mysql://192.168.226.6:3306/test?useUnicode=true&characterEncoding=utf-8&useSSL=true
+      username: root
+      password: 123456
+      driver-class-name: com.mysql.jdbc.Driver

dxfl/src/main/resources/mapper/test.xml

@@ -0,0 +1,14 @@
+<?xml version="1.0" encoding="UTF-8" ?>
+<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd" >
+<mapper namespace="com.example.dxfl.mapper.TestMapper">
+
+    <select id="getAll" resultType="com.example.dxfl.entity.Test">
+        select * from test
+    </select>
+
+    <insert id="insertOne" parameterType="com.example.dxfl.entity.Test">
+        insert into test value (#{test.id},#{test.name})
+    </insert>
+
+
+</mapper>

dxfl/src/main/resources/mybatis-config.xml

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+<?xml version="1.0" encoding="UTF-8" ?>
+<!DOCTYPE configuration PUBLIC "-//mybatis.org//DTD Config 3.0//EN" "http://mybatis.org/dtd/mybatis-3-config.dtd">
+<configuration>
+    <settings>
+        <!-- 使全局的映射器启用或禁用缓存。 -->
+        <setting name="cacheEnabled" value="true" />
+        <!-- 全局启用或禁用延迟加载。当禁用时，所有关联对象都会即时加载。 -->
+        <setting name="lazyLoadingEnabled" value="true" />
+        <!-- 当启用时，有延迟加载属性的对象在被调用时将会完全加载任意属性。否则，每种属性将会按需要加载。 -->
+        <setting name="aggressiveLazyLoading" value="true"/>
+        <!-- 是否允许单条sql 返回多个数据集  (取决于驱动的兼容性) default:true -->
+        <setting name="multipleResultSetsEnabled" value="true" />
+        <!-- 是否可以使用列的别名 (取决于驱动的兼容性) default:true -->
+        <setting name="useColumnLabel" value="true" />
+        <!-- 允许JDBC 生成主键。需要驱动器支持。如果设为了true，这个设置将强制使用被生成的主键，有一些驱动器不兼容不过仍然可以执行。  default:false  -->
+        <setting name="useGeneratedKeys" value="false" />
+        <!-- 指定 MyBatis 如何自动映射 数据基表的列 NONE：不隐射　PARTIAL:部分  FULL:全部  -->
+        <setting name="autoMappingBehavior" value="PARTIAL" />
+        <!-- 这是默认的执行类型  （SIMPLE: 简单； REUSE: 执行器可能重复使用prepared statements语句；BATCH: 执行器可以重复执行语句和批量更新）  -->
+        <setting name="defaultExecutorType" value="SIMPLE" />
+
+        <setting name="defaultStatementTimeout" value="25" />
+
+        <setting name="defaultFetchSize" value="100" />
+
+        <setting name="safeRowBoundsEnabled" value="false" />
+        <!-- 使用驼峰命名法转换字段。 -->
+        <setting name="mapUnderscoreToCamelCase" value="true" />
+        <!-- 设置本地缓存范围 session:就会有数据的共享  statement:语句范围 (这样就不会有数据的共享 ) default:session -->
+        <setting name="localCacheScope" value="SESSION" />
+        <!-- 默认为OTHER,为了解决oracle插入null报错的问题要设置为NULL -->
+        <setting name="jdbcTypeForNull" value="NULL" />
+        <setting name="lazyLoadTriggerMethods" value="equals,clone,hashCode,toString" />
+    </settings>
+
+</configuration>

dxfl/src/test/java/com/example/dxfl/DxflApplicationTests.java

@@ -0,0 +1,16 @@
+package com.example.dxfl;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.test.context.junit4.SpringRunner;
+
+@RunWith(SpringRunner.class)
+@SpringBootTest
+public class DxflApplicationTests {
+
+    @Test
+    public void contextLoads() {
+    }
+
+}

dxfl/src/test/java/com/example/dxfl/TestServiceTest.java

@@ -0,0 +1,32 @@
+package com.example.dxfl;
+
+import com.example.dxfl.service.TestService;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.test.context.junit4.SpringRunner;
+
+/**
+ * Description
+ *
+ * @author fxb
+ * @date 2018-09-05
+ */
+@RunWith(SpringRunner.class)
+@SpringBootTest
+public class TestServiceTest {
+
+    @Autowired
+    private TestService testService;
+
+    @Test
+    public void insertOne(){
+        testService.insertOne();
+    }
+
+    @Test
+    public void getAll(){
+        testService.getAll();
+    }
+}