自己现实mybatis分页插件整合springboot 运行

悠悠 2022-06-02 03:29 164阅读 0赞

参考文章

http://blog.csdn.net/u012506661/article/details/53235725

分页插件  代码   主要是实现了interceptor  mybatis的拦截器

/** *自定义分页插件 * 有2中方法可以实现 * 1.通过拦截Executor.class这个类 这种方法其实比较耗 * 2.通过拦截StatementHandler.class来实现拦截 */ @Intercepts(@Signature(type = StatementHandler.class, method = "prepare", args = {Connection.class, Integer.class}))
    public class PageHelpInterceptor implements org.apache.ibatis.plugin.Interceptor {
    
    
        //默认使用MySQL   也可以通过springboot配置的时候注入
        public String dialect = "mysql";
    
        //主要是进行拦截
        public Object intercept(Invocation invocation) throws Throwable {
            //通过反射获取RoutingStatementHandler这个类
            RoutingStatementHandler routingStatementHandler = (RoutingStatementHandler) invocation.getTarget();
            //通过反射获取StatementHandler
            StatementHandler delegate = (StatementHandler) ReflectUtil.getFieldValue(routingStatementHandler, "delegate");
            //获取BoundSql对象里面有参数，sql等东西
            BoundSql boundSql = delegate.getBoundSql();
            Object object = boundSql.getParameterObject();
            if (object instanceof Page) {
                //分页设置
                Page<?> page = (Page<?>) object;
                String sql = boundSql.getSql();
                //处理sql语句
                String pageSql = getPageSql(sql, page);
                //这里处理获取总的记录数  需要的参数  这里相当于在执行sql语句之前  先进行统计总的记录数保存在page对象中
                MappedStatement mappedStatement = (MappedStatement) ReflectUtil.getFieldValue(delegate, "mappedStatement");
                Connection connection = (Connection) invocation.getArgs()[0];
    
                //获取总的记录数
                setTotal(page, mappedStatement, connection);
                ReflectUtil.setFieldValue(boundSql, "sql", pageSql);
            }
            return invocation.proceed();
        }
    
        private void setTotal(Page<?> page, MappedStatement mappedStatement, Connection connection) {
            BoundSql boundSql = mappedStatement.getBoundSql(page);
            String countSql = getCountSql(boundSql.getSql());
            List<ParameterMapping> parameterMappings = boundSql.getParameterMappings();
            BoundSql bs = new BoundSql(mappedStatement.getConfiguration(), countSql, parameterMappings, page);
            ParameterHandler parameterHandler = new DefaultParameterHandler(mappedStatement, page, bs);
            PreparedStatement ps = null;
            ResultSet resultSet = null;
            try {
                ps = connection.prepareStatement(countSql);
                parameterHandler.setParameters(ps);
                resultSet = ps.executeQuery();
                while (resultSet.next()) {
                    page.setTotal(resultSet.getInt(1));
                }
            } catch (SQLException e) {
                e.printStackTrace();
            } finally {
                try {
                    if (resultSet != null) {
                        resultSet.close();
    
                    }
                    if (ps != null) {
                        ps.close();
    
                    }
                } catch (SQLException e) {
                    e.printStackTrace();
                }
            }
        }
    
    
        public String getCountSql(String sql) {
    
            String countSql = "select count(*) from (" + sql+" ) temp";
            return countSql;
        }
    
        //对sql语句进行重新编写
        private String getPageSql(String sql, Page<?> page) {
            StringBuilder sb = new StringBuilder(200);
            if (dialect.equalsIgnoreCase("mysql")) {
                sb.append(sql);
                sb.append(" limit " + (page.getPageNum() - 1) * page.getPageSize() + " , " + page.getPageSize());
            } else if (dialect.equalsIgnoreCase("oracle")) {
                sb.append("select * from ( select temp.*,rownum row_id from (");
                sb.append(sql);
                sb.append(" ) temp where rownum<=" + page.getPageSize() * page.getPageNum() + " )");
                sb.append(" where row_id>" + (page.getPageNum() - 1) * page.getPageSize());
            }
            return sb.toString();
    
        }
    
        //查询总的记录数
    
        //只对executor进行拦截,当目标类为executor是，才进行对对象进行分装
        public Object plugin(Object o) {
            if (o instanceof StatementHandler) {
                return Plugin.wrap(o, this);
            } else {
                return o;
            }
    
        }
    
        public void setProperties(Properties properties) {
                String d = properties.getProperty("dialect");
                if(d!=null){
                    this.dialect = d;
                }
        }
    }

反射器代码   主要通过反射器可以拿到私有的对象   这个主要参考了 网上其他博主的代码

public class ReflectUtil {
        /** * 利用反射获取指定对象的指定属性 * @param obj 目标对象 * @param fieldName 目标属性 * @return 目标属性的值 */ public static Object getFieldValue(Object obj, String fieldName) {
            Object result = null;
            Field field = ReflectUtil.getField(obj, fieldName);
            if (field != null) {
                field.setAccessible(true);
                try {
                    result = field.get(obj);
                } catch (IllegalArgumentException e) {
                    // TODO Auto-generated catch block e.printStackTrace();
                } catch (IllegalAccessException e) {
                    // TODO Auto-generated catch block e.printStackTrace();
                }
            }
            return result;
        }
    
        /** * 利用反射获取指定对象里面的指定属性 * @param obj 目标对象 * @param fieldName 目标属性 * @return 目标字段 */ private static Field getField(Object obj, String fieldName) {
            Field field = null;
            for (Class<?> clazz=obj.getClass(); clazz != Object.class; clazz=clazz.getSuperclass()) {
                try {
                    field = clazz.getDeclaredField(fieldName);
                    break;
                } catch (NoSuchFieldException e) {
                    //这里不用做处理，子类没有该字段可能对应的父类有，都没有就返回null。
                }
            }
            return field;
        }
    
        /** * 利用反射设置指定对象的指定属性为指定的值 * @param obj 目标对象 * @param fieldName 目标属性 * @param fieldValue 目标值 */ public static void setFieldValue(Object obj, String fieldName,
                                         String fieldValue) {
            Field field = ReflectUtil.getField(obj, fieldName);
            if (field != null) {
                try {
                    field.setAccessible(true);
                    field.set(obj, fieldValue);
                } catch (IllegalArgumentException e) {
                    // TODO Auto-generated catch block e.printStackTrace();
                } catch (IllegalAccessException e) {
                    // TODO Auto-generated catch block e.printStackTrace();
                }
            }
        }
    
    }

springboot里面的配置文件   这个配置文件是 主数据源的配置文件

@Configuration
    @MapperScan(basePackages = "com.quipoo.mybatis.primaryMapper",sqlSessionTemplateRef = "primarySqlSessionTemplate")
    public class PrimaryDataSourceConfig {
    
        @Bean(name = "primaryDataSource")
        @ConfigurationProperties(prefix = "spring.datasource.primary")
        @Primary
        public DataSource dataSource() {
            return DataSourceBuilder.create().build();
        }
    
        @Bean(name = "primarySqlSessionFactory")
        @Primary
        public SqlSessionFactory sqlSessionFactory(@Qualifier("primaryDataSource") DataSource dataSource) throws Exception {
            SqlSessionFactoryBean bean = new SqlSessionFactoryBean();
            bean.setDataSource(dataSource);
            bean.setMapperLocations(new PathMatchingResourcePatternResolver().getResources("classpath:/mybatis1/*.xml"));
            Properties properties = new Properties();
            properties.setProperty("dialect","mysql");
            PageHelpInterceptor pageHelpInterceptor = new PageHelpInterceptor();
            pageHelpInterceptor.setProperties(properties);
            bean.setPlugins(new Interceptor[]{pageHelpInterceptor});
            return bean.getObject();
        }
    
        @Bean(name = "primaryTransactionManager")
        @Primary
        public DataSourceTransactionManager transactionManager(@Qualifier("primaryDataSource") DataSource dataSource) {
            return new DataSourceTransactionManager(dataSource);
        }
    
        @Bean(name = "primarySqlSessionTemplate")
        @Primary
        public SqlSessionTemplate sqlSessionTemplate(@Qualifier("primarySqlSessionFactory") SqlSessionFactory sqlSessionFactory) throws Exception {
            return new SqlSessionTemplate(sqlSessionFactory);
        }
    }