MyBatis学习一

MyBatis是弱项，所以需要补一下，那么就做个测试

先准备下jar包，如图：

只是为了学MyBatis就没必要弄其他那么多了，Junit启动就可以了。先配置一个log4j，找之前的文件复制了一个，如下：

log4j.rootLogger =DEBUG,stdoutlog4j.appender.stdout = org.apache.log4j.ConsoleAppenderlog4j.appender.stdout.Target = System.outlog4j.appender.stdout.layout = org.apache.log4j.PatternLayoutlog4j.appender.stdout.layout.ConversionPattern = %-d{yyyy-MM-dd HH:mm:ss}  [ %t:%r ] - [ %p ]  %m%n

然后就是mybaits-conf.xml

<?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>     <environments default="development">        <environment id="development">            <transactionManager type="JDBC" />            <!-- 配置数据库连接信息 -->            <dataSource type="POOLED">                <property name="driver" value="oracle.jdbc.driver.OracleDriver" />                <property name="url" value="jdbc:oracle:thin:@localhost:1521:testdev" />                <property name="username" value="oa01" />                <property name="password" value="oa01" />            </dataSource>        </environment>    </environments>    <mappers>       <!-- 批量导入 -->        <package name="cn.hd.dao" />    </mappers></configuration>

建表，随便弄一个测试一下，sql如下：

create table T_USER(  USERID    NUMBER not null,  USERNAME  VARCHAR2(20),  PASSWORD  VARCHAR2(20),  REALNAME  VARCHAR2(20),  DID       NUMBER,  JID       NUMBER)

po

package cn.hd.po;public class User {private int userid;private String username;private String password;private String realname;private int jid;private int did;   /** * @return the jid */public int getJid() {return jid;}/** * @param jid the jid to set */public void setJid(int jid) {this.jid = jid;}/** * @return the did */public int getDid() {return did;}/** * @param did the did to set */public void setDid(int did) {this.did = did;}/** * @return the userid */public int getUserid() {return userid;}/** * @param userid *            the userid to set */public void setUserid(int userid) {this.userid = userid;}/** * @return the username */public String getUsername() {return username;}/** * @param username *            the username to set */public void setUsername(String username) {this.username = username;}/** * @return the password */public String getPassword() {return password;}/** * @param password *            the password to set */public void setPassword(String password) {this.password = password;}/** * @return the realname */public String getRealname() {return realname;}/** * @param realname *            the realname to set */public void setRealname(String realname) {this.realname = realname;}}

Mapping

package cn.hd.dao;import java.util.List;import cn.hd.po.User;public interface UserMapper {   List<User> queryAll();   User findById(int userid);}

Junit测试类

package cn.hd.test;import java.io.Reader;import java.util.List;import org.apache.ibatis.io.Resources;import org.apache.ibatis.session.SqlSession;import org.apache.ibatis.session.SqlSessionFactory;import org.apache.ibatis.session.SqlSessionFactoryBuilder;import org.apache.log4j.Logger;import org.junit.After;import org.junit.Before;import org.junit.Test;import cn.hd.po.User;public class TestMyBatis {Logger logger=Logger.getLogger(TestMyBatis.class);SqlSession session ;@Beforepublic void setUp() throws Exception {logger.info("单元测试开始");// 1、加载配置文件Reader reader = Resources.getResourceAsReader("mybaits-conf.xml");SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(reader);// 2) session = factory.openSession();}@Afterpublic void tearDown() throws Exception {session.close();logger.info("单元测试结束");}@Testpublic void testFindById() {        User user=session.selectOne("cn.hd.dao.UserMapper.findById", 2);        System.out.println(user.getRealname());}@Testpublic void testFindAll() {        List<User> user=session.selectList("cn.hd.dao.UserMapper.queryAll");        for(User u :user)        {        System.out.println(u.getRealname());        }}}

最后贴出项目结构

ok，最后来一个错误总结。

org.apache.ibatis.exceptions.TooManyResultsException: Expected one result (or null) to be returned by selectOne(), but found: 2at org.apache.ibatis.session.defaults.DefaultSqlSession.selectOne(DefaultSqlSession.java:81)at org.apache.ibatis.session.defaults.DefaultSqlSession.selectOne(DefaultSqlSession.java:71)at cn.hd.test.TestMyBatis.testFindAll(TestMyBatis.java:42

以上错误是因为使用的session.selectOne查询的多条数据。这里改成session.selectList既可。

org.apache.ibatis.exceptions.PersistenceException: ### Error querying database.  Cause: org.apache.ibatis.type.TypeException: Could not set parameters for mapping: ParameterMapping{property='vlues', mode=IN, javaType=class java.lang.Integer, jdbcType=null, numericScale=null, resultMapId='null', jdbcTypeName='null', expression='null'}. Cause: org.apache.ibatis.type.TypeException: Error setting null for parameter #1 with JdbcType OTHER . Try setting a different JdbcType for this parameter or a different jdbcTypeForNull configuration property. Cause: java.sql.SQLException: 无效的列类型### The error may exist in cn/hd/dao/UserMapper.xml### The error may involve cn.hd.dao.UserMapper.findById-Inline### The error occurred while setting parameters### SQL: select  *  from t_user where userid=?### Cause: org.apache.ibatis.type.TypeException: Could not set parameters for mapping: ParameterMapping{property='vlues', mode=IN, javaType=class java.lang.Integer, jdbcType=null, numericScale=null, resultMapId='null', jdbcTypeName='null', expression='null'}. Cause: org.apache.ibatis.type.TypeException: Error setting null for parameter #1 with JdbcType OTHER . Try setting a different JdbcType for this parameter or a different jdbcTypeForNull configuration property. Cause: java.sql.SQLException: 无效的列类型at org.apache.ibatis.exceptions.ExceptionFactory.wrapException(ExceptionFactory.java:30)at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:150)Caused by: org.apache.ibatis.type.TypeException: Could not set parameters for mapping: ParameterMapping{property='vlues', mode=IN, javaType=class java.lang.Integer, jdbcType=null, numericScale=null, resultMapId='null', jdbcTypeName='null', expression='null'}. Cause: org.apache.ibatis.type.TypeException: Error setting null for parameter #1 with JdbcType OTHER . Try setting a different JdbcType for this parameter or a different jdbcTypeForNull configuration property. Cause: java.sql.SQLException: 无效的列类型at org.apache.ibatis.scripting.defaults.DefaultParameterHandler.setParameters(DefaultParameterHandler.java:89)... 29 moreCaused by: org.apache.ibatis.type.TypeException: Error setting null for parameter #1 with JdbcType OTHER . Try setting a different JdbcType for this parameter or a different jdbcTypeForNull configuration property. Cause: java.sql.SQLException: 无效的列类型at org.apache.ibatis.type.BaseTypeHandler.setParameter(BaseTypeHandler.java:47)at org.apache.ibatis.scripting.defaults.DefaultParameterHandler.setParameters(DefaultParameterHandler.java:87)... 38 moreCaused by: java.sql.SQLException: 无效的列类型at oracle.jdbc.driver.DatabaseError.throwSqlException(DatabaseError.java:112)... 39 more

这个错误是应该传入参数的时候没有传入参数，加上既可。