概述

我们前面几篇文章，所列举的接口方法中只有一个参数，参数的类型可以分为两种

1. 基本类型

2. JavaBean

当参数是一个基本类型的时候，它在XML文件中对应的SQL语句只会使用一个参数，比如delete方法

当参数类型是一个JavaBean类型的时候，它在XML文件中对应的SQL语句中会有多个参数，比如 insert 、 update

在实际应用中使用多个参数的情况再常见不过来。 前面的博文，我们有个方法是将多个参数合并到一个JavaBean中，并使用这个Bean作为接口方法的参数。 这种方法虽然方便，单并不适合全部的情况，因为不可能只为了两三个参数去创建新的JavaBean。

因此对于参数比较少的情况，有两种方式可以采用

• 使用Map类型作为参数
• 使用@Param注解

使用Map类型作为参数需要手工创建MAP并且对参数进行赋值，并不简洁。这里推荐使用@Param注解的方式

模拟场景:根据用户ID和角色的enable状态来查询用户的所有角色

工程结构

多个基本类型参数的场景

我们先来看下如果在接口中使用多个参数但不是用Param注解的情况

1.UserRoleMapper接口增加接口方法

package com.artisan.mybatis.xml.mapper;

import java.util.List;

import com.artisan.mybatis.xml.domain.SysRole;

public interface UserRoleMapper {

    /**
     * 
     * 
     * @Title: selectSysRolesByUserIdAndRoleEnable
     * 
     * @Description: 根据用户ID和角色的Enable属性查询角色
     * 
     * @param userId
     * @param enable
     * @return
     * 
     * @return: List<SysRole>
     */
    List<SysRole> selectSysRolesByUserIdAndRoleEnable(Long userId, Integer enable);


}

2.UserRoleMapper.xml配置查询语句

<?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" >

<!-- 当Mapper接口和XML文件关联的时候， namespace的值就需要配置成接口的全限定名称 -->                    
<mapper namespace="com.artisan.mybatis.xml.mapper.UserRoleMapper">

    <select 
        id="selectSysRolesByUserIdAndRoleEnable" 
        resultType="com.artisan.mybatis.xml.domain.SysRole">
        SELECT
            c.id,
            c.role_name roleName,
            c.enabled,
            c.create_by createBy,
            c.create_time createTime
        FROM
            sys_user a
        INNER JOIN sys_user_role b ON a.id = b.user_id
        INNER JOIN sys_role c ON b.role_id = c.id
        WHERE
            a.id = #{userId}
        AND c.enabled = #{enabled}
    </select>

</mapper>                   

3.单元测试

package com.artisan.mybatis.xml.mapper;

import java.util.List;

import org.apache.ibatis.session.SqlSession;
import org.apache.log4j.Logger;
import org.junit.Assert;
import org.junit.Test;

import com.artisan.mybatis.xml.domain.SysRole;

/**
 * 
 * 
 * @ClassName: UserRoleMapperTest
 * 
 * @Description: UserRoleMapperTest测试类
 * 
 * @author: Mr.Yang
 * 
 * @date: 2018年4月16日 下午3:34:45
 */
public class UserRoleMapperTest extends BaseMapperTest {

    private static final Logger logger = Logger.getLogger(UserRoleMapperTest.class);
    private SqlSession sqlSession;
    @Test
    public void selectSysRolesByUserIdAndRoleEnableTest(){

        logger.info("selectSysRolesByUserIdAndRoleEnableTest");

        try {
            // 获取SqlSession
            sqlSession = getSqlSession();
            // 获取UserRoleMapper
            UserRoleMapper userRoleMapper = sqlSession.getMapper(UserRoleMapper.class);

            // 通过接口调用方法
            List<SysRole> roleList = userRoleMapper.selectSysRolesByUserIdAndRoleEnable((long) 1, 1);

            // 期望roleList不为空
            Assert.assertNotNull(roleList);
            // 期望roleList> 0
            Assert.assertTrue(roleList.size() > 0);

            for (SysRole sysRole : roleList) {
                logger.info(sysRole);
            }
        } catch (Exception e) {
            e.printStackTrace();
        }finally{
            sqlSession.close();
            logger.info("sqlSession close successfully ");
        }
    }

}

选中方法，执行单元测试

会得到如下异常

org.apache.ibatis.exceptions.PersistenceException: 
### Error querying database.  Cause: org.apache.ibatis.binding.BindingException: Parameter 'userId' not found. Available parameters are [1, 0, param1, param2]
### Cause: org.apache.ibatis.binding.BindingException: Parameter 'userId' not found. Available parameters are [1, 0, param1, param2]
    at org.apache.ibatis.exceptions.ExceptionFactory.wrapException(ExceptionFactory.java:30)
    at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:122)
    at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:113)
    at org.apache.ibatis.binding.MapperMethod.executeForMany(MapperMethod.java:122)
    at org.apache.ibatis.binding.MapperMethod.execute(MapperMethod.java:64)
    at org.apache.ibatis.binding.MapperProxy.invoke(MapperProxy.java:53)
    at com.sun.proxy.$Proxy6.selectSysRolesByUserIdAndRoleEnable(Unknown Source)
    at com.artisan.mybatis.xml.mapper.UserRoleMapperTest.selectSysRolesByUserIdAndRoleEnableTest(UserRoleMapperTest.java:40)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:606)
    at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)
    at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
    at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)
    at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
    at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:78)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:57)
    at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
    at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
    at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
    at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
    at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
    at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:26)
    at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
    at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:50)
    at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:459)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:675)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:382)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:192)
Caused by: org.apache.ibatis.binding.BindingException: Parameter 'userId' not found. Available parameters are [1, 0, param1, param2]
    at org.apache.ibatis.binding.MapperMethod$ParamMap.get(MapperMethod.java:168)
    at org.apache.ibatis.reflection.wrapper.MapWrapper.get(MapWrapper.java:45)
    at org.apache.ibatis.reflection.MetaObject.getValue(MetaObject.java:122)
    at org.apache.ibatis.executor.BaseExecutor.createCacheKey(BaseExecutor.java:212)
    at org.apache.ibatis.executor.CachingExecutor.createCacheKey(CachingExecutor.java:139)
    at org.apache.ibatis.executor.CachingExecutor.query(CachingExecutor.java:81)
    at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:120)

重点信息

### Cause: org.apache.ibatis.binding.BindingException: Parameter 'userId' not found. Available parameters are [1, 0, param1, param2]

这个错误标识，xml可用的参数只有 0、1、param1、param2 , 没有userId.

1, 0, param1, param2 都是Mybatis根据参数位置自定义的名字，如果将xml中的#{userId} 改为#{0}或者#{param1} ，将#{enbale}改为#{1}或者#{param2} ，这个方法是可以被正常调用的 。 这里只是为了演示，实际上并不建议这么做。

修复

现在在接口方法的参数前添加@Param注解

package com.artisan.mybatis.xml.mapper;

import java.util.List;

import org.apache.ibatis.annotations.Param;

import com.artisan.mybatis.xml.domain.SysRole;

public interface UserRoleMapper {

    /**
     * 
     * 
     * @Title: selectSysRolesByUserIdAndRoleEnable
     * 
     * @Description: 根据用户ID和角色的Enable属性查询角色
     * 
     * @param userId
     * @param enable
     * @return
     * 
     * @return: List<SysRole>
     */
    List<SysRole> selectSysRolesByUserIdAndRoleEnable(@Param("userId") Long userId, @Param("enable") Integer enable);


}

重新运行单元测试

2018-04-16 19:43:22,404  INFO [main] (BaseMapperTest.java:26) - sessionFactory bulit successfully
2018-04-16 19:43:22,408  INFO [main] (BaseMapperTest.java:29) - reader close successfully
2018-04-16 19:43:22,412  INFO [main] (UserRoleMapperTest.java:31) - selectSysRolesByUserIdAndRoleEnableTest
2018-04-16 19:43:22,910 DEBUG [main] (BaseJdbcLogger.java:142) - ==>  Preparing: SELECT c.id, c.role_name roleName, c.enabled, c.create_by createBy, c.create_time createTime FROM sys_user a INNER JOIN sys_user_role b ON a.id = b.user_id INNER JOIN sys_role c ON b.role_id = c.id WHERE a.id = ? AND c.enabled = ? 
2018-04-16 19:43:22,988 DEBUG [main] (BaseJdbcLogger.java:142) - ==> Parameters: 1(Long), 1(Integer)
2018-04-16 19:43:23,025 TRACE [main] (BaseJdbcLogger.java:148) - <==    Columns: id, roleName, enabled, createBy, createTime
2018-04-16 19:43:23,026 TRACE [main] (BaseJdbcLogger.java:148) - <==        Row: 1, 管理员, 1, 1, 2018-04-13 21:12:46.0
2018-04-16 19:43:23,031 TRACE [main] (BaseJdbcLogger.java:148) - <==        Row: 2, 普通用户, 1, 1, 2018-04-13 21:12:46.0
2018-04-16 19:43:23,032 DEBUG [main] (BaseJdbcLogger.java:142) - <==      Total: 2
2018-04-16 19:43:23,033  INFO [main] (UserRoleMapperTest.java:48) - SysRole [id=1, roleName=管理员, enabled=1, createBy=1, createTime=Fri Apr 13 21:12:46 BOT 2018, user=null, privilegeList=null]
2018-04-16 19:43:23,037  INFO [main] (UserRoleMapperTest.java:48) - SysRole [id=2, roleName=普通用户, enabled=1, createBy=1, createTime=Fri Apr 13 21:12:46 BOT 2018, user=null, privilegeList=null]
2018-04-16 19:43:23,039  INFO [main] (UserRoleMapperTest.java:54) - sqlSession close successfully 

测试通过了，这时的XML文件中对应的SQL的可用参数变成了【userId，enable，param1,param2】 ,如果#{userId} 改为#{param1} ，将#{enbale}改为#{param2}也是可以通过的。

给参数配置@Param注解后，mybatis就会自动将参数封装成Map类型，@Param注解值会作为Map的key 因此在SQL部分就会通过配置的注解值来使用参数。

多个参数为JavaBean类型场景

1. UserRoleMapper接口增加接口方法

// 传递多个JavaBean的场景
    List<SysRole> selectSysRolesByUserIdAndRoleEnable2(@Param("sysUser") SysUser sysUser, @Param("sysRole") SysRole sysRole);

这个时候，在XML中就不能直接使用#{userId}和#{enabled}了，而是要通过点取值方式使用 #{sysUser.id} 和 #{sysRole.enabled} 从两个JavaBean中取出指定属性的值。

2.UserRoleMapper.xml配置SQL

<!-- 传递多个Bean的场景 -->    
    <select 
        id="selectSysRolesByUserIdAndRoleEnable2" 
        resultType="com.artisan.mybatis.xml.domain.SysRole">
        SELECT
            c.id,
            c.role_name roleName,
            c.enabled,
            c.create_by createBy,
            c.create_time createTime
        FROM
            sys_user a
        INNER JOIN sys_user_role b ON a.id = b.user_id
        INNER JOIN sys_role c ON b.role_id = c.id
        WHERE
            a.id = #{sysUser.id}
        AND c.enabled = #{sysRole.enabled}
    </select>

3.单元测试

@Test
    public void selectSysRolesByUserIdAndRoleEnable2Test() {

        logger.info("selectSysRolesByUserIdAndRoleEnable2Test");

        try {
            // 获取SqlSession
            sqlSession = getSqlSession();
            // 获取UserRoleMapper
            UserRoleMapper userRoleMapper = sqlSession.getMapper(UserRoleMapper.class);

            // 构造SysUser
            SysUser sysUser = new SysUser();
            sysUser.setId((long) 1);
            // 构造SysRole
            SysRole sysRole = new SysRole();
            sysRole.setEnabled(1);

            // 通过接口调用方法
            List<SysRole> roleList = userRoleMapper.selectSysRolesByUserIdAndRoleEnable2(sysUser, sysRole);

            // 期望roleList不为空
            Assert.assertNotNull(roleList);
            // 期望roleList> 0
            Assert.assertTrue(roleList.size() > 0);

            for (SysRole sysRole2 : roleList) {
                logger.info(sysRole2);
            }
        } catch (Exception e) {
            e.printStackTrace();
        }finally{
            sqlSession.close();
            logger.info("sqlSession close successfully ");
        }
    }

日志

2018-04-16 20:13:06,731  INFO [main] (BaseMapperTest.java:26) - sessionFactory bulit successfully
2018-04-16 20:13:06,734  INFO [main] (BaseMapperTest.java:29) - reader close successfully
2018-04-16 20:13:06,738  INFO [main] (UserRoleMapperTest.java:62) - selectSysRolesByUserIdAndRoleEnable2Test
2018-04-16 20:13:07,361 DEBUG [main] (BaseJdbcLogger.java:142) - ==>  Preparing: SELECT c.id, c.role_name roleName, c.enabled, c.create_by createBy, c.create_time createTime FROM sys_user a INNER JOIN sys_user_role b ON a.id = b.user_id INNER JOIN sys_role c ON b.role_id = c.id WHERE a.id = ? AND c.enabled = ? 
2018-04-16 20:13:07,449 DEBUG [main] (BaseJdbcLogger.java:142) - ==> Parameters: 1(Long), 1(Integer)
2018-04-16 20:13:07,483 TRACE [main] (BaseJdbcLogger.java:148) - <==    Columns: id, roleName, enabled, createBy, createTime
2018-04-16 20:13:07,484 TRACE [main] (BaseJdbcLogger.java:148) - <==        Row: 1, 管理员, 1, 1, 2018-04-13 21:12:46.0
2018-04-16 20:13:07,487 TRACE [main] (BaseJdbcLogger.java:148) - <==        Row: 2, 普通用户, 1, 1, 2018-04-13 21:12:46.0
2018-04-16 20:13:07,488 DEBUG [main] (BaseJdbcLogger.java:142) - <==      Total: 2
2018-04-16 20:13:07,489  INFO [main] (UserRoleMapperTest.java:86) - SysRole [id=1, roleName=管理员, enabled=1, createBy=1, createTime=Fri Apr 13 21:12:46 BOT 2018, user=null, privilegeList=null]
2018-04-16 20:13:07,494  INFO [main] (UserRoleMapperTest.java:86) - SysRole [id=2, roleName=普通用户, enabled=1, createBy=1, createTime=Fri Apr 13 21:12:46 BOT 2018, user=null, privilegeList=null]
2018-04-16 20:13:07,495  INFO [main] (UserRoleMapperTest.java:92) - sqlSession close successfully 

小结

除了上述常用的类型，接口的参数还可以是集合或者数组，后续介绍。